Amruta Manke - Academia.edu (original) (raw)

Papers by Amruta Manke

Research paper thumbnail of www.mdpi.com/journal/ijms Article Effect of Fiber Length on Carbon Nanotube-Induced Fibrogenesis

Abstract: Given their extremely small size and light weight, carbon nanotubes (CNTs) can be readi... more Abstract: Given their extremely small size and light weight, carbon nanotubes (CNTs) can be readily inhaled by human lungs resulting in increased rates of pulmonary disorders, particularly fibrosis. Although the fibrogenic potential of CNTs is well established, there is a lack of consensus regarding the contribution of physicochemical attributes of CNTs on the underlying fibrotic outcome. We designed an experimentally validated in vitro fibroblast culture model aimed at investigating the effect of fiber length on single-walled CNT (SWCNT)-induced pulmonary fibrosis. The fibrogenic response to short and long

Research paper thumbnail of Review Article Mechanisms of Nanoparticle-Induced Oxidative

Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduct... more Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The rapidly emerging field of nanotechnology has offered innovative discoveries in the medical, industrial, and consumer sectors. The unique physicochemical and electrical properties of engineered nanoparticles (NP) make them highly desirable in a variety of applications. However, these novel properties of NP are fraught with concerns for environmental and occupational exposure. Changes in structural and physicochemical properties of NP can lead to changes in biological activities including ROS generation, one of the most frequently reported NP-associated toxicities. Oxidative stress induced by engineered NP is due to acellular factors such as particle surface, size, composition, and presence of metals, while cellular responses such as mitochondrial respiration, NP-cell interaction, and immune cell activation are responsibl...

Research paper thumbnail of Mechanisms Underlying the Fibrogenic Responses of Carbon Nanotubes

Advances in Molecular Toxicology, 2018

Abstract Carbon nanotubes (CNTs) are newly developed engineered nanomaterials with remarkable pro... more Abstract Carbon nanotubes (CNTs) are newly developed engineered nanomaterials with remarkable properties employed for a wide range of numerous commercial and industrial applications. However, CNT exposure in various settings is a significant concern as CNTs are readily inhaled into human lungs resulting in debilitating pulmonary responses, most notably fibrosis. Several rodent studies have demonstrated consistent adverse pulmonary effects including inflammation and granulomatous lesions leading to interstitial and subpleural fibrosis. Some of the crucial mechanistic steps involved during CNT-induced fibrosis range from generation of reactive oxygen species, inflammation, release of proinflammatory cytokines that initiate several intracellular cell signaling cascades, and expansion of the pool of myofibroblast via epithelial–mesenchymal transition. Furthermore, physicochemical properties of CNT including length and surface functionalization can influence their fibrogenic activity. The objective of this chapter is to review, summarize, and discuss major cellular and molecular mechanisms driving CNT-induced fibrogenesis.

Research paper thumbnail of Role of Nitric Oxide in Cancer Stem Cell Regulation and Metastasis

There is increasing evidence to support the role of cancer stem cells (CSCs) in cancer developmen... more There is increasing evidence to support the role of cancer stem cells (CSCs) in cancer development, chemoresistance, and relapse; resulting in poor prognosis and high mortality rate of cancer. The tumor microenvironment has been implicated to have an influence on cancer cells in many ways, where cell signaling molecules and mediators including proinflammatory cytokines and reactive species are frequently upregulated. Among them, the concentrations of nitric oxide (NO), a reactive nitrogen species synthesized by many cell types, are found to be upregulated in many cancer microenvironments, and elevated NO levels have been linked to advanced stage and poor survival of cancer patients. A plethora of studies demonstrate the oncogenic activity of NO in tumor progression; however, the underlying mechanisms remain poorly understood. This chapter summarizes and discusses the effects of NO on tumorigenesis and metastasis with a focus on CSC regulation and its effect on tumor progression. NO ...

Research paper thumbnail of Development of a peripherally restricted aryl urea based cb1 receptor antagonist for alcoholic steatosis

Research paper thumbnail of Induction of lung cancer stem-like cells by chronic exposure to carbon nanotubes

Research paper thumbnail of Effect of Fiber Length on Carbon Nanotube-Induced Fibrogenesis

IJMS, 2014

Given their extremely small size and light weight, carbon nanotubes (CNTs) can be readily inhaled... more Given their extremely small size and light weight, carbon nanotubes (CNTs) can be readily inhaled by human lungs resulting in increased rates of pulmonary disorders, particularly fibrosis. Although the fibrogenic potential of CNTs is well established, there is a lack of consensus regarding the contribution of physicochemical attributes of CNTs on the underlying fibrotic outcome. We designed an experimentally validated in vitro fibroblast culture model aimed at investigating the effect of fiber length on single-walled CNT (SWCNT)-induced pulmonary fibrosis. The fibrogenic response to short and long SWCNTs was assessed via oxidative stress generation, collagen expression and transforming growth factor-beta (TGF-β) production as potential fibrosis biomarkers. OPEN ACCESS Long SWCNTs were significantly more potent than short SWCNTs in terms of reactive oxygen species (ROS) response, collagen production and TGF-β release. Furthermore, our finding on the length-dependent in vitro fibrogenic response was validated by the in vivo lung fibrosis outcome, thus supporting the predictive value of the in vitro model. Our results also demonstrated the key role of ROS in SWCNT-induced collagen expression and TGF-β activation, indicating the potential mechanisms of length-dependent SWCNT-induced fibrosis. Together, our study provides new evidence for the role of fiber length in SWCNT-induced lung fibrosis and offers a rapid cell-based assay for fibrogenicity testing of nanomaterials with the ability to predict pulmonary fibrogenic response in vivo.

Research paper thumbnail of OR4-5DEVELOPMENT OF a peripherally restricted CB1 receptor antagonist FOR ALCOHOLIC STEATOSIS

Alcohol and Alcoholism, 2017

Research paper thumbnail of SLUG is required for SOX 9 stabilization and functions to promote cancer stem cells and metastasis in human lung carcinoma

Siriraj Center of Excellence for Stem Cell Research, Faculty of Medicine Siriraj Hospital, Mahido... more Siriraj Center of Excellence for Stem Cell Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand; Pharmaceutical and Pharmacological Sciences Program, Mary Babb Randolph Cancer Center, Stem Cell and Tissue Engineering Laboratory, Flow Cytometry Core Facility, Animal Models and Imaging Facility, West Virginia University, Morgantown, WV 26506, USA; Natural Science Division, Alderson Broaddus University, Philippi, WV 26416, USA, Allergy and Clinical Immunology Branch, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA; CellBased Drug and Health Product Development Research Unit, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand.

Research paper thumbnail of Functionalized 6-(Piperidin-1-yl)-8,9-Diphenyl Purines as Inverse Agonists of the CB1 Receptor – SAR Efforts Towards Selectivity and Peripheralization

Bioorganic & Medicinal Chemistry

Research paper thumbnail of Functionalized 6-(Piperidin-1-yl)-8,9-Diphenyl Purines as Peripherally Restricted Inverse Agonists of the CB1 Receptor

Journal of Medicinal Chemistry

Research paper thumbnail of Synthesis and pharmacological characterization of functionalized 6-piperazin-1-yl-purines as cannabinoid receptor 1 (CB1) inverse agonists

Bioorganic & Medicinal Chemistry

Research paper thumbnail of A peripherally restricted purine antagonist of type 1 cannabinoid (CB1) receptor blocks alcoholic steatosis in mice

Journal of medicinal chemistry, Jan 24, 2018

Type 1 cannabinoid receptor (CB1) antagonists have demonstrated promise for the treatment of obes... more Type 1 cannabinoid receptor (CB1) antagonists have demonstrated promise for the treatment of obesity, liver disease, metabolic syndrome and dyslipidemias. However, inhibition of CB1 receptors in the central nervous system can produce adverse effects including depression, anxiety and suicidal ideation. Efforts are now underway to produce peripherally restricted CB1 antagonists to circumvent CNS-associated undesirable effects. In this study, a series of analogs were explored in which the 4-aminopiperidine group of 2 was replaced with aryl and heteroaryl substituted piperazine groups both with and without a spacer. This resulted in mildly basic, potent antagonists of human CB1 (hCB1). The 2-chlorobenzyl piperazine 25 was found to be potent (Ki = 8 nM), >1000-fold selective for hCB1 over hCB2, possess favorable ADME properties including no hERG liability, high oral absorption, and negligible CNS penetration. Compound 25 was tested in a mouse model of alcohol induced liver steatosis a...

Research paper thumbnail of Abstract 3752: Induction of lung cancer stem-like cells by chronic exposure to carbon nanotubes

Research paper thumbnail of Role of Stem-like Cells in Carbon Nanotube-Induced Pulmonary Fibrosis

Recent studies have shown that pulmonary exposure to (CNT) results in rapid and progressive inter... more Recent studies have shown that pulmonary exposure to (CNT) results in rapid and progressive interstitial lung fibrosis in animals without causing persistent lung inflammation, which is normally associated with other known fibrogenic agents. This unusual fibrogenic effect of CNT raises important health issues since the exposure could result in deadly and incurable lung fibrosis. Accumulating evidence indicates the fibrogenic potential of carbon nanotubes, however, the underlying mechanism remains poorly addressed. Recent studies have demonstrated the pathogenic role of mesenchymal stem cells in pulmonary fibrosis that differentiate into myofibroblasts and contribute to disease progression. Understanding the molecular/cellular basis of these fibrosis-associated stem cells during lung fibrosis is of critical importance. However, the concept of stemness in the light of nanomaterial-induced fibrosis remains to be explored. Fibroblast cells being the key players in fibrogenesis, we hypothesized that CNT exposure in fibroblasts induce fibroblast stem-like cells (FSCs) which are critical for the CNT-induced fibrogenic response. The long-term broad objective of this project was to develop an in vitro model predictive of in vivo fibrogenic response and to devise preventive strategies for the disease. The specific aims of this study included i) Determining the involvement of stemness phenotype and underlying mechanism in CNT-induced lung fibrosis the and develop in vitro screening assay which may be predictive of the in vivo fibrogenic response; ii) Investigate the redox regulation of stem-like cells involved in CNT-driven fibrosis; iii) Evaluating the impact of nanoparticle length and surface chemical modification influence stemness phenotype and the resulting fibrogenic response. Our findings from Aim 1 indicated that indeed CNTs induced the side population phenotype (indicative of the fibroblast stem-like cell phenotype) of primary lung fibroblasts. The isolated FSCs displayed an elevated expression of fibrogenic and stem cell markers indicating the reliability of the stem cell isolation method as well as supporting their role in CNT-induced fibrogenesis. The study also developed and put forth an in vitro model of CNTinduced fibrotic nodule formation that correlates the development of stemness phenotype and onset of fibrosis. Furthermore, the results from Aim 2 demonstrated that CNT-induced stemness phenotype was under the redox regulation via identifying the key role of peroxides in CNTinduced FSC generation and collagen expression. Moreover, results from our second study revealed that antioxidants abrogated the effect of CNT on stem-like cell generation suggesting crucial role of redox in stemness generation and the fibrogenic effects. Our outcomes from the Aim 3 demonstrated a length-dependent effect on stemness phenotype, with longer CNT inducing higher FSCs compared to short CNTs as evidenced by side population and aldehyde dehydrogenase assays. Pristine CNTs induced higher FSCs compared to modified CNTs; however the effect was not statistically different. Long SWCNTs induced greater fibrogenic response in vivo compared to short SWCNTs, supporting the potential utility of our in vitro FSC [ix]

Research paper thumbnail of Potential in vitro model for testing the effect of exposure to nanoparticles on the lung alveolar epithelial barrier

Sensing and Bio-Sensing Research, 2015

ABSTRACT Pulmonary barrier function plays a pivotal role in protection from inhaled particles. Ho... more ABSTRACT Pulmonary barrier function plays a pivotal role in protection from inhaled particles. However, some nano-scaled particles, such as carbon nanotubes (CNT), have demonstrated the ability to penetrate this barrier in animal models, resulting in an unusual, rapid interstitial fibrosis. To delineate the underlying mechanism and specific bio-effect of inhaled nanoparticles in respiratory toxicity, models of lung epithelial barriers are required that allow accurate representation of in vivo systems; however, there is currently a lack of consistent methods to do so. Thus, this work demonstrates a well-characterized in vitro model of pulmonary barrier function using Calu-3 cells, and provides the experimental conditions required for achieving tight junction complexes in cell culture, with trans-epithelial electrical resistance measurement used as a biosensor for proper barrier formation and integrity. The effects of cell number and serum constituents have been examined and we found that changes in each of these parameters can greatly affect barrier formation. Our data demonstrate that use of 5.0x104 Calu-3 cells/well in the Transwell cell culture system, with 10% serum concentrations in culture media is optimal for assessing epithelial barrier function. In addition, we have utilized CNT exposure to analyze the dose-, time-, and nanoparticle property- dependent alterations of epithelial barrier permeability as a means to validate this model. Such high throughput in vitro cell models of the epithelium could be used to predict the interaction of other nanoparticles with lung epithelial barriers to mimic respiratory behavior in vivo, thus providing essential tools and bio-sensing techniques that can be uniformly employed.

Research paper thumbnail of Induction of Stemlike Cells with Fibrogenic Properties by Carbon Nanotubes and Its Role in Fibrogenesis

Nano Lett., 2014

We developed a three-dimensional fibroblastic nodule model for fibrogenicity testing of nanomater... more We developed a three-dimensional fibroblastic nodule model for fibrogenicity testing of nanomaterials and investigated the role of fibroblast stemlike cells (FSCs) in the fibrogenic process. We showed that carbon nanotubes (CNTs) induced fibroblastic nodule formation in primary human lung fibroblast cultures resembling the fibroblastic foci in clinical fibrosis and promoted FSCs that are highly fibrogenic and a potential driving force of fibrogenesis. This study provides a predictive 3D model and mechanistic insight on CNT fibrogenesis.

Research paper thumbnail of Mechanisms of Nanoparticle-Induced Oxidative Stress and Toxicity

BioMed Research International, 2013

The rapidly emerging field of nanotechnology has offered innovative discoveries in the medical, i... more The rapidly emerging field of nanotechnology has offered innovative discoveries in the medical, industrial, and consumer sectors. The unique physicochemical and electrical properties of engineered nanoparticles (NP) make them highly desirable in a variety of applications. However, these novel properties of NP are fraught with concerns for environmental and occupational exposure. Changes in structural and physicochemical properties of NP can lead to changes in biological activities including ROS generation, one of the most frequently reported NP-associated toxicities. Oxidative stress induced by engineered NP is due to acellular factors such as particle surface, size, composition, and presence of metals, while cellular responses such as mitochondrial respiration, NPcell interaction, and immune cell activation are responsible for ROS-mediated damage. NP-induced oxidative stress responses are torch bearers for further pathophysiological effects including genotoxicity, inflammation, and fibrosis as demonstrated by activation of associated cell signaling pathways. Since oxidative stress is a key determinant of NP-induced injury, it is necessary to characterize the ROS response resulting from NP. Through physicochemical characterization and understanding of the multiple signaling cascades activated by NP-induced ROS, a systemic toxicity screen with oxidative stress as a predictive model for NPinduced injury can be developed.

Research paper thumbnail of Potential Occupational Risks Associated with Pulmonary Toxicity of Carbon Nanotubes

Occupational Medicine & Health Affairs, 2014

Given their remarkable properties, carbon nanotubes (CNTs) have made their way through various in... more Given their remarkable properties, carbon nanotubes (CNTs) have made their way through various industrial and medicinal applications and the overall production of CNTs is expected to grow rapidly in the next few years, thus requiring an additional recruitment of workers. However, their unique applications and desirable properties are fraught with concerns regarding occupational exposure. The concern about worker exposure to CNTs arises from the results of recent animal studies. Short-term and sub-chronic exposure studies in rodents have shown consistent adverse health effects such as pulmonary inflammation, granulomas, fibrosis, genotoxicity and mesothelioma after inhalation or instillation of several types of CNTs. Furthermore, physicochemical properties of CNTs such as dispersion, functionalization and particle size can significantly affect their pulmonary toxicity. Risk estimates from animal studies necessitate implementation of protective measures to limit worker exposure to CNTs. Information on workplace exposure is very limited, however, studies have reported that CNTs can be aerosolized and attain respirable airborne levels during synthesis and processing activities in the workplace. Quantitative risk assessments from sub-chronic animal studies recommend the health-based need to reduce exposures below the recommended exposure limit of 1 μg/m 3 . Practice of prevention measures including the use of engineering controls, personal protective equipment, health surveillance program, safe handling and use, as well as worker training can significantly minimize worker exposure and improve worker health and safety.

Research paper thumbnail of Pulmonary toxicity and fibrogenic response of carbon nanotubes

Toxicology Mechanisms and Methods, 2013

Carbon nanotubes (CNTs) have been a subject of intensive research for a wide range of application... more Carbon nanotubes (CNTs) have been a subject of intensive research for a wide range of applications. However, because of their extremely small size and light weight, CNTs are readily inhaled into human lungs resulting in increased rates of pulmonary disorders, most notably fibrosis. Several studies have demonstrated the fibrogenic effects of CNTs given their ability to translocate into the surrounding areas in the lung causing granulomatous lesions and interstitial and sub-pleural fibrosis. However, the mechanisms underlying the disease process remain obscure due to the lack of understanding of the cellular interactions and molecular targets involved. Interestingly, certain physicochemical properties of CNTs have been shown to affect their respiratory toxicity, thereby becoming significant determinants of fibrogenesis. CNTinduced fibrosis involves a multitude of cell types and is characterized by the early onset of inflammation, oxidative stress and accumulation of extracellular matrix. Increased reactive oxygen species activate various cytokine/growth factor signaling cascades resulting in increased expression of inflammatory and fibrotic genes. Profibrotic growth factors and cytokines contribute directly to fibroblast proliferation and collagen production. Given the role of multiple players during the pathogenesis of CNT-induced fibrosis, the objective of this review is to summarize the key findings and discuss major cellular and molecular events governing pulmonary fibrosis. We also discuss the physicochemical properties of CNTs and their effects on pulmonary toxicities as well as various biological factors contributing to the development of fibrosis.

Research paper thumbnail of www.mdpi.com/journal/ijms Article Effect of Fiber Length on Carbon Nanotube-Induced Fibrogenesis

Abstract: Given their extremely small size and light weight, carbon nanotubes (CNTs) can be readi... more Abstract: Given their extremely small size and light weight, carbon nanotubes (CNTs) can be readily inhaled by human lungs resulting in increased rates of pulmonary disorders, particularly fibrosis. Although the fibrogenic potential of CNTs is well established, there is a lack of consensus regarding the contribution of physicochemical attributes of CNTs on the underlying fibrotic outcome. We designed an experimentally validated in vitro fibroblast culture model aimed at investigating the effect of fiber length on single-walled CNT (SWCNT)-induced pulmonary fibrosis. The fibrogenic response to short and long

Research paper thumbnail of Review Article Mechanisms of Nanoparticle-Induced Oxidative

Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduct... more Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The rapidly emerging field of nanotechnology has offered innovative discoveries in the medical, industrial, and consumer sectors. The unique physicochemical and electrical properties of engineered nanoparticles (NP) make them highly desirable in a variety of applications. However, these novel properties of NP are fraught with concerns for environmental and occupational exposure. Changes in structural and physicochemical properties of NP can lead to changes in biological activities including ROS generation, one of the most frequently reported NP-associated toxicities. Oxidative stress induced by engineered NP is due to acellular factors such as particle surface, size, composition, and presence of metals, while cellular responses such as mitochondrial respiration, NP-cell interaction, and immune cell activation are responsibl...

Research paper thumbnail of Mechanisms Underlying the Fibrogenic Responses of Carbon Nanotubes

Advances in Molecular Toxicology, 2018

Abstract Carbon nanotubes (CNTs) are newly developed engineered nanomaterials with remarkable pro... more Abstract Carbon nanotubes (CNTs) are newly developed engineered nanomaterials with remarkable properties employed for a wide range of numerous commercial and industrial applications. However, CNT exposure in various settings is a significant concern as CNTs are readily inhaled into human lungs resulting in debilitating pulmonary responses, most notably fibrosis. Several rodent studies have demonstrated consistent adverse pulmonary effects including inflammation and granulomatous lesions leading to interstitial and subpleural fibrosis. Some of the crucial mechanistic steps involved during CNT-induced fibrosis range from generation of reactive oxygen species, inflammation, release of proinflammatory cytokines that initiate several intracellular cell signaling cascades, and expansion of the pool of myofibroblast via epithelial–mesenchymal transition. Furthermore, physicochemical properties of CNT including length and surface functionalization can influence their fibrogenic activity. The objective of this chapter is to review, summarize, and discuss major cellular and molecular mechanisms driving CNT-induced fibrogenesis.

Research paper thumbnail of Role of Nitric Oxide in Cancer Stem Cell Regulation and Metastasis

There is increasing evidence to support the role of cancer stem cells (CSCs) in cancer developmen... more There is increasing evidence to support the role of cancer stem cells (CSCs) in cancer development, chemoresistance, and relapse; resulting in poor prognosis and high mortality rate of cancer. The tumor microenvironment has been implicated to have an influence on cancer cells in many ways, where cell signaling molecules and mediators including proinflammatory cytokines and reactive species are frequently upregulated. Among them, the concentrations of nitric oxide (NO), a reactive nitrogen species synthesized by many cell types, are found to be upregulated in many cancer microenvironments, and elevated NO levels have been linked to advanced stage and poor survival of cancer patients. A plethora of studies demonstrate the oncogenic activity of NO in tumor progression; however, the underlying mechanisms remain poorly understood. This chapter summarizes and discusses the effects of NO on tumorigenesis and metastasis with a focus on CSC regulation and its effect on tumor progression. NO ...

Research paper thumbnail of Development of a peripherally restricted aryl urea based cb1 receptor antagonist for alcoholic steatosis

Research paper thumbnail of Induction of lung cancer stem-like cells by chronic exposure to carbon nanotubes

Research paper thumbnail of Effect of Fiber Length on Carbon Nanotube-Induced Fibrogenesis

IJMS, 2014

Given their extremely small size and light weight, carbon nanotubes (CNTs) can be readily inhaled... more Given their extremely small size and light weight, carbon nanotubes (CNTs) can be readily inhaled by human lungs resulting in increased rates of pulmonary disorders, particularly fibrosis. Although the fibrogenic potential of CNTs is well established, there is a lack of consensus regarding the contribution of physicochemical attributes of CNTs on the underlying fibrotic outcome. We designed an experimentally validated in vitro fibroblast culture model aimed at investigating the effect of fiber length on single-walled CNT (SWCNT)-induced pulmonary fibrosis. The fibrogenic response to short and long SWCNTs was assessed via oxidative stress generation, collagen expression and transforming growth factor-beta (TGF-β) production as potential fibrosis biomarkers. OPEN ACCESS Long SWCNTs were significantly more potent than short SWCNTs in terms of reactive oxygen species (ROS) response, collagen production and TGF-β release. Furthermore, our finding on the length-dependent in vitro fibrogenic response was validated by the in vivo lung fibrosis outcome, thus supporting the predictive value of the in vitro model. Our results also demonstrated the key role of ROS in SWCNT-induced collagen expression and TGF-β activation, indicating the potential mechanisms of length-dependent SWCNT-induced fibrosis. Together, our study provides new evidence for the role of fiber length in SWCNT-induced lung fibrosis and offers a rapid cell-based assay for fibrogenicity testing of nanomaterials with the ability to predict pulmonary fibrogenic response in vivo.

Research paper thumbnail of OR4-5DEVELOPMENT OF a peripherally restricted CB1 receptor antagonist FOR ALCOHOLIC STEATOSIS

Alcohol and Alcoholism, 2017

Research paper thumbnail of SLUG is required for SOX 9 stabilization and functions to promote cancer stem cells and metastasis in human lung carcinoma

Siriraj Center of Excellence for Stem Cell Research, Faculty of Medicine Siriraj Hospital, Mahido... more Siriraj Center of Excellence for Stem Cell Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand; Pharmaceutical and Pharmacological Sciences Program, Mary Babb Randolph Cancer Center, Stem Cell and Tissue Engineering Laboratory, Flow Cytometry Core Facility, Animal Models and Imaging Facility, West Virginia University, Morgantown, WV 26506, USA; Natural Science Division, Alderson Broaddus University, Philippi, WV 26416, USA, Allergy and Clinical Immunology Branch, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA; CellBased Drug and Health Product Development Research Unit, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand.

Research paper thumbnail of Functionalized 6-(Piperidin-1-yl)-8,9-Diphenyl Purines as Inverse Agonists of the CB1 Receptor – SAR Efforts Towards Selectivity and Peripheralization

Bioorganic & Medicinal Chemistry

Research paper thumbnail of Functionalized 6-(Piperidin-1-yl)-8,9-Diphenyl Purines as Peripherally Restricted Inverse Agonists of the CB1 Receptor

Journal of Medicinal Chemistry

Research paper thumbnail of Synthesis and pharmacological characterization of functionalized 6-piperazin-1-yl-purines as cannabinoid receptor 1 (CB1) inverse agonists

Bioorganic & Medicinal Chemistry

Research paper thumbnail of A peripherally restricted purine antagonist of type 1 cannabinoid (CB1) receptor blocks alcoholic steatosis in mice

Journal of medicinal chemistry, Jan 24, 2018

Type 1 cannabinoid receptor (CB1) antagonists have demonstrated promise for the treatment of obes... more Type 1 cannabinoid receptor (CB1) antagonists have demonstrated promise for the treatment of obesity, liver disease, metabolic syndrome and dyslipidemias. However, inhibition of CB1 receptors in the central nervous system can produce adverse effects including depression, anxiety and suicidal ideation. Efforts are now underway to produce peripherally restricted CB1 antagonists to circumvent CNS-associated undesirable effects. In this study, a series of analogs were explored in which the 4-aminopiperidine group of 2 was replaced with aryl and heteroaryl substituted piperazine groups both with and without a spacer. This resulted in mildly basic, potent antagonists of human CB1 (hCB1). The 2-chlorobenzyl piperazine 25 was found to be potent (Ki = 8 nM), >1000-fold selective for hCB1 over hCB2, possess favorable ADME properties including no hERG liability, high oral absorption, and negligible CNS penetration. Compound 25 was tested in a mouse model of alcohol induced liver steatosis a...

Research paper thumbnail of Abstract 3752: Induction of lung cancer stem-like cells by chronic exposure to carbon nanotubes

Research paper thumbnail of Role of Stem-like Cells in Carbon Nanotube-Induced Pulmonary Fibrosis

Recent studies have shown that pulmonary exposure to (CNT) results in rapid and progressive inter... more Recent studies have shown that pulmonary exposure to (CNT) results in rapid and progressive interstitial lung fibrosis in animals without causing persistent lung inflammation, which is normally associated with other known fibrogenic agents. This unusual fibrogenic effect of CNT raises important health issues since the exposure could result in deadly and incurable lung fibrosis. Accumulating evidence indicates the fibrogenic potential of carbon nanotubes, however, the underlying mechanism remains poorly addressed. Recent studies have demonstrated the pathogenic role of mesenchymal stem cells in pulmonary fibrosis that differentiate into myofibroblasts and contribute to disease progression. Understanding the molecular/cellular basis of these fibrosis-associated stem cells during lung fibrosis is of critical importance. However, the concept of stemness in the light of nanomaterial-induced fibrosis remains to be explored. Fibroblast cells being the key players in fibrogenesis, we hypothesized that CNT exposure in fibroblasts induce fibroblast stem-like cells (FSCs) which are critical for the CNT-induced fibrogenic response. The long-term broad objective of this project was to develop an in vitro model predictive of in vivo fibrogenic response and to devise preventive strategies for the disease. The specific aims of this study included i) Determining the involvement of stemness phenotype and underlying mechanism in CNT-induced lung fibrosis the and develop in vitro screening assay which may be predictive of the in vivo fibrogenic response; ii) Investigate the redox regulation of stem-like cells involved in CNT-driven fibrosis; iii) Evaluating the impact of nanoparticle length and surface chemical modification influence stemness phenotype and the resulting fibrogenic response. Our findings from Aim 1 indicated that indeed CNTs induced the side population phenotype (indicative of the fibroblast stem-like cell phenotype) of primary lung fibroblasts. The isolated FSCs displayed an elevated expression of fibrogenic and stem cell markers indicating the reliability of the stem cell isolation method as well as supporting their role in CNT-induced fibrogenesis. The study also developed and put forth an in vitro model of CNTinduced fibrotic nodule formation that correlates the development of stemness phenotype and onset of fibrosis. Furthermore, the results from Aim 2 demonstrated that CNT-induced stemness phenotype was under the redox regulation via identifying the key role of peroxides in CNTinduced FSC generation and collagen expression. Moreover, results from our second study revealed that antioxidants abrogated the effect of CNT on stem-like cell generation suggesting crucial role of redox in stemness generation and the fibrogenic effects. Our outcomes from the Aim 3 demonstrated a length-dependent effect on stemness phenotype, with longer CNT inducing higher FSCs compared to short CNTs as evidenced by side population and aldehyde dehydrogenase assays. Pristine CNTs induced higher FSCs compared to modified CNTs; however the effect was not statistically different. Long SWCNTs induced greater fibrogenic response in vivo compared to short SWCNTs, supporting the potential utility of our in vitro FSC [ix]

Research paper thumbnail of Potential in vitro model for testing the effect of exposure to nanoparticles on the lung alveolar epithelial barrier

Sensing and Bio-Sensing Research, 2015

ABSTRACT Pulmonary barrier function plays a pivotal role in protection from inhaled particles. Ho... more ABSTRACT Pulmonary barrier function plays a pivotal role in protection from inhaled particles. However, some nano-scaled particles, such as carbon nanotubes (CNT), have demonstrated the ability to penetrate this barrier in animal models, resulting in an unusual, rapid interstitial fibrosis. To delineate the underlying mechanism and specific bio-effect of inhaled nanoparticles in respiratory toxicity, models of lung epithelial barriers are required that allow accurate representation of in vivo systems; however, there is currently a lack of consistent methods to do so. Thus, this work demonstrates a well-characterized in vitro model of pulmonary barrier function using Calu-3 cells, and provides the experimental conditions required for achieving tight junction complexes in cell culture, with trans-epithelial electrical resistance measurement used as a biosensor for proper barrier formation and integrity. The effects of cell number and serum constituents have been examined and we found that changes in each of these parameters can greatly affect barrier formation. Our data demonstrate that use of 5.0x104 Calu-3 cells/well in the Transwell cell culture system, with 10% serum concentrations in culture media is optimal for assessing epithelial barrier function. In addition, we have utilized CNT exposure to analyze the dose-, time-, and nanoparticle property- dependent alterations of epithelial barrier permeability as a means to validate this model. Such high throughput in vitro cell models of the epithelium could be used to predict the interaction of other nanoparticles with lung epithelial barriers to mimic respiratory behavior in vivo, thus providing essential tools and bio-sensing techniques that can be uniformly employed.

Research paper thumbnail of Induction of Stemlike Cells with Fibrogenic Properties by Carbon Nanotubes and Its Role in Fibrogenesis

Nano Lett., 2014

We developed a three-dimensional fibroblastic nodule model for fibrogenicity testing of nanomater... more We developed a three-dimensional fibroblastic nodule model for fibrogenicity testing of nanomaterials and investigated the role of fibroblast stemlike cells (FSCs) in the fibrogenic process. We showed that carbon nanotubes (CNTs) induced fibroblastic nodule formation in primary human lung fibroblast cultures resembling the fibroblastic foci in clinical fibrosis and promoted FSCs that are highly fibrogenic and a potential driving force of fibrogenesis. This study provides a predictive 3D model and mechanistic insight on CNT fibrogenesis.

Research paper thumbnail of Mechanisms of Nanoparticle-Induced Oxidative Stress and Toxicity

BioMed Research International, 2013

The rapidly emerging field of nanotechnology has offered innovative discoveries in the medical, i... more The rapidly emerging field of nanotechnology has offered innovative discoveries in the medical, industrial, and consumer sectors. The unique physicochemical and electrical properties of engineered nanoparticles (NP) make them highly desirable in a variety of applications. However, these novel properties of NP are fraught with concerns for environmental and occupational exposure. Changes in structural and physicochemical properties of NP can lead to changes in biological activities including ROS generation, one of the most frequently reported NP-associated toxicities. Oxidative stress induced by engineered NP is due to acellular factors such as particle surface, size, composition, and presence of metals, while cellular responses such as mitochondrial respiration, NPcell interaction, and immune cell activation are responsible for ROS-mediated damage. NP-induced oxidative stress responses are torch bearers for further pathophysiological effects including genotoxicity, inflammation, and fibrosis as demonstrated by activation of associated cell signaling pathways. Since oxidative stress is a key determinant of NP-induced injury, it is necessary to characterize the ROS response resulting from NP. Through physicochemical characterization and understanding of the multiple signaling cascades activated by NP-induced ROS, a systemic toxicity screen with oxidative stress as a predictive model for NPinduced injury can be developed.

Research paper thumbnail of Potential Occupational Risks Associated with Pulmonary Toxicity of Carbon Nanotubes

Occupational Medicine & Health Affairs, 2014

Given their remarkable properties, carbon nanotubes (CNTs) have made their way through various in... more Given their remarkable properties, carbon nanotubes (CNTs) have made their way through various industrial and medicinal applications and the overall production of CNTs is expected to grow rapidly in the next few years, thus requiring an additional recruitment of workers. However, their unique applications and desirable properties are fraught with concerns regarding occupational exposure. The concern about worker exposure to CNTs arises from the results of recent animal studies. Short-term and sub-chronic exposure studies in rodents have shown consistent adverse health effects such as pulmonary inflammation, granulomas, fibrosis, genotoxicity and mesothelioma after inhalation or instillation of several types of CNTs. Furthermore, physicochemical properties of CNTs such as dispersion, functionalization and particle size can significantly affect their pulmonary toxicity. Risk estimates from animal studies necessitate implementation of protective measures to limit worker exposure to CNTs. Information on workplace exposure is very limited, however, studies have reported that CNTs can be aerosolized and attain respirable airborne levels during synthesis and processing activities in the workplace. Quantitative risk assessments from sub-chronic animal studies recommend the health-based need to reduce exposures below the recommended exposure limit of 1 μg/m 3 . Practice of prevention measures including the use of engineering controls, personal protective equipment, health surveillance program, safe handling and use, as well as worker training can significantly minimize worker exposure and improve worker health and safety.

Research paper thumbnail of Pulmonary toxicity and fibrogenic response of carbon nanotubes

Toxicology Mechanisms and Methods, 2013

Carbon nanotubes (CNTs) have been a subject of intensive research for a wide range of application... more Carbon nanotubes (CNTs) have been a subject of intensive research for a wide range of applications. However, because of their extremely small size and light weight, CNTs are readily inhaled into human lungs resulting in increased rates of pulmonary disorders, most notably fibrosis. Several studies have demonstrated the fibrogenic effects of CNTs given their ability to translocate into the surrounding areas in the lung causing granulomatous lesions and interstitial and sub-pleural fibrosis. However, the mechanisms underlying the disease process remain obscure due to the lack of understanding of the cellular interactions and molecular targets involved. Interestingly, certain physicochemical properties of CNTs have been shown to affect their respiratory toxicity, thereby becoming significant determinants of fibrogenesis. CNTinduced fibrosis involves a multitude of cell types and is characterized by the early onset of inflammation, oxidative stress and accumulation of extracellular matrix. Increased reactive oxygen species activate various cytokine/growth factor signaling cascades resulting in increased expression of inflammatory and fibrotic genes. Profibrotic growth factors and cytokines contribute directly to fibroblast proliferation and collagen production. Given the role of multiple players during the pathogenesis of CNT-induced fibrosis, the objective of this review is to summarize the key findings and discuss major cellular and molecular events governing pulmonary fibrosis. We also discuss the physicochemical properties of CNTs and their effects on pulmonary toxicities as well as various biological factors contributing to the development of fibrosis.