sunil tomar - Academia.edu (original) (raw)

Papers by sunil tomar

Clinical & Experimental Allergy

IntroductionFood allergic reactions can be severe and potentially life‐threatening and the underl... more IntroductionFood allergic reactions can be severe and potentially life‐threatening and the underlying immunological processes that contribute to the severity of reactions are poorly understood. The aim of this study is to integrate bulk RNA‐sequencing of human and mouse peripheral blood mononuclear cells during food allergic reactions and in vivo mouse models of food allergy to identify dysregulated immunological processes associated with severe food allergic reactions.MethodsBulk transcriptomics of whole blood from human and mouse following food allergic reactions combined with integrative differential expressed gene bivariate and module eigengene network analyses to identify the whole blood transcriptome associated with food allergy severity. In vivo validation immune cell and gene expression in mice following IgE‐mediated reaction.ResultsBulk transcriptomics of whole blood from mice with different severity of food allergy identified gene ontology (GO) biological processes associa...

The Journal of Immunology

The prevalence of food allergy is increasing significantly in developed nations. Accumulating evi... more The prevalence of food allergy is increasing significantly in developed nations. Accumulating evidences suggest a pivotal role of intestinal mast cells (MCs), TH2 cytokines, and IgE in the pathophysiology of food allergy. We have recently identified the novel IL-9 producing mucosal mast cells (MMC9s), which can produce high levels of IL-9, IL-13, and mast cells mediators. Mice deficient of IL-4 signals fail to develop MMC9s and become resistant to IgE-mediated food allergy. However, it remains unclear whether IL-4 can directly regulate the development and function of MMC9s. In a skin sensitization induced food allergy model, Il4RaF709 mice which have gain-of-function mutations in IL-4Ra were found to produce much higher levels of ovalbumin (OVA) specific IgE and mast cell protease-1 in blood and became more susceptible to experimental food allergy. While the occurrence of MMC9s and type-2 innate lymphoid cells (ILC2s) were comparable between wild type (WT) and Il4RaF709 mice, repeat...

Journal of Immunology, May 1, 2018

We have recently described an IL-9 producing mucosal mast cell population (MMC9s) that drives int... more We have recently described an IL-9 producing mucosal mast cell population (MMC9s) that drives intestinal mastocytosis and food-induced anaphylaxis. The cytokine signaling pathways involved in the regulation of MMC9 function in food allergic reactions are currently not well understood. Employing a murine model of food-induced anaphylaxis and WT, gain-of-function Il4Ra F709 mice, and Il4Rα −/− mice we revealed an important role for IL-4 signaling in the enhancement of MMC9 frequency and this positively correlated with elevated serum levels of MCPT-1, CD4 + TH2 cells, intestinal mastocytosis and increased susceptibility to food-induced anaphylaxis. Employing an adoptive transfer model of food allergy, we show direct IL-4 signaling is required for increased levels of MMC9 and development of food-induced anaphylaxis. RNA-seq analysis of purified WT, Il4Ra F709 and Il4Rα −/− MMC9s identified that IL-4-signaling pathway differentially regulates 238 genes that were identified to be associated with inflammatory responses and cytokine signaling processes by GO network analyses. Functional analysis revealed that IL-4 upregulates IL-9 and not IL-13 production in MMC9s. These results suggest that IL-4 signaling directly regulates MMC9 gene expression and function and onset of food-induced anaphylaxis. These studies suggest that targeting MMC9s through IL-4 signaling blockade maybe therapeutically beneficial for prevention and treatment of food allergy.

Journal of Allergy and Clinical Immunology, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Frontiers in Immunology, 2021

Food allergy is an emerging epidemic, and the underlying mechanisms are not well defined partly d... more Food allergy is an emerging epidemic, and the underlying mechanisms are not well defined partly due to the lack of robust adjuvant free experimental models of dietary antigen sensitization. As housing mice at thermoneutrality (Tn) - the temperature of metabolic homeostasis (26–30°C) – has been shown to improve modeling various human diseases involved in inflammation, we tested the impact of Tn housing on an experimental model of food sensitization. Here we demonstrate that WT BALB/c mice housed under standard temperature (18–20°C, Ts) conditions translocated the luminal antigens in the small intestine (SI) across the epithelium via goblet cell antigen passages (GAPs). In contrast, food allergy sensitive Il4raF709 mice housed under standard temperature conditions translocated the luminal antigens in the SI across the epithelium via secretory antigen passages (SAPs). Activation of SI antigen passages and oral challenge of Il4raF709 mice with egg allergens at standard temperature predi...

: Food allergy is a harmful immune reaction driven by uncontrolled type-2 immune responses. Curre... more : Food allergy is a harmful immune reaction driven by uncontrolled type-2 immune responses. Current knowledge provide limited insights into why only some, rather than all food allergic individuals are prone to develop life-threatening anaphylaxis. We have identified a novel multi-functional IL-9-producing mucosal mast cells (MMC9s) that produce large amounts of IL-9, IL-13, and mast cell mediators. The objective of this proposal is to identify the factors that regulate MMC9 induction, which represents the key cellular checkpoint to develop food-induced anaphylaxis. The central hypothesis is that signals induced by IL-4 and antigen/IgE/FcR complex crosslinking act together to induce mast cell (MC) progenitors to develop into the pathogenic MMC9s, which amplify anaphylactic response to dietary allergens. We have established genetically modified murine strains, a new reconstitution model of experimental food allergy, and the system to acquire duodenal biopsy samples from food allergic ...

Cellular and Molecular Gastroenterology and Hepatology, 2021

Background & Aims CD4+ T cells are regulated by activating and inhibitory cues, and dysregula... more Background & Aims CD4+ T cells are regulated by activating and inhibitory cues, and dysregulation of these proper regulatory inputs predisposes these cells to aberrant inflammation and exacerbation of disease. We investigated the role of the inhibitory receptor paired immunoglobulin-like receptor B (PIR-B) in the regulation of the CD4+ T-cell inflammatory response and exacerbation of the colitic phenotype. Methods We used Il10-/- spontaneous and CD4+CD45RBhi T-cell transfer models of colitis with PIR-B-deficient (Pirb-/-) mice. Flow cytometry, Western blot, and RNA sequencing analysis was performed on wild-type and Pirb-/- CD4+ T cells. In silico analyses were performed on RNA sequencing data set of ileal biopsy samples from pediatric CD and non–inflammatory bowel disease patients and sorted human memory CD4+ T cells. Results We identified PIR-B expression on memory CD4+ interleukin (IL)17a+ cells. We show that PIR-B regulates CD4+ T-helper 17 cell (Th17)-dependent chronic intestinal inflammatory responses and the development of colitis. Mechanistically, we show that the PIR-B– Src-homology region 2 domain-containing phosphatase-1/2 axis tempers mammalian target of rapamycin complex 1 signaling and mammalian target of rapamycin complex 1–dependent caspase-3/7 apoptosis, resulting in CD4+ IL17a+ cell survival. In silico analyses showed enrichment of transcriptional signatures for Th17 cells (RORC, RORA, and IL17A) and tissue resident memory (HOBIT, IL7R, and BLIMP1) networks in PIR-B+ murine CD4+ T cells and human CD4+ T cells that express the human homologue leukocyte immunoglobulin-like receptor subfamily B member 3 (LILRB3). High levels of LILRB3 expression were associated strongly with mucosal injury and a proinflammatory Th17 signature, and this signature was restricted to a treatment-naïve, severe pediatric CD population. Conclusions Our findings show an intrinsic role for PIR-B/LILRB3 in the regulation of CD4+ IL17a+ T-cell pathogenic memory responses.

F1000Research, 2020

Food allergens are innocuous proteins that promote tolerogenic adaptive immune responses in healt... more Food allergens are innocuous proteins that promote tolerogenic adaptive immune responses in healthy individuals yet in other individuals induce an allergic adaptive immune response characterized by the presence of antigen-specific immunoglobulin E and type-2 immune cells. The cellular and molecular processes that determine a tolerogenic versus non-tolerogenic immune response to dietary antigens are not fully elucidated. Recently, there have been advances in the identification of roles for microbial communities and anatomical sites of dietary antigen exposure and presentation that have provided new insights into the key regulatory steps in the tolerogenic versus non-tolerogenic decision-making processes. Herein, we will review and discuss recent findings in cellular and molecular processes underlying food sensitization and tolerance, immunological processes underlying severity of food-induced anaphylaxis, and insights obtained from immunotherapy trials.

Clinical Cancer Research, 2018

Metastatic colonization of ovarian cancer involves productive paracrine/juxtacrine interactions w... more Metastatic colonization of ovarian cancer involves productive paracrine/juxtacrine interactions with the microenvironment. The resulting induction of an adaptive response in the cancer cells enables them to establish themselves in the new microenvironment and take advantage of the new factors available. A key feature of this adaptation is induced changes in gene expression through transcriptional regulation as a result of microenvironmental cues. However, the identities of transcription factors induced by the metastatic microenvironment in ovarian cancer and their mechanism of action are poorly understood. Using an organotypic 3D culture model recapitulating the early events of metastasis, we identified ETS1, a member of the ETS family of TFs, as an essential driver of metastatic colonization. Increased ETS1 expression was induced in metastasizing ovarian cancer cells interacting with the mesothelial cells covering the surface of the omentum. The mechanism of upregulation was throug...

Journal of Allergy and Clinical Immunology, 2020

RATIONALE: MRGPRX2 is a G-protein-coupled receptor that is expressed on human mast cells (hMC). S... more RATIONALE: MRGPRX2 is a G-protein-coupled receptor that is expressed on human mast cells (hMC). Substance P MRGPRX2pathway is a recent described IgE-independent activation route, such as off-target occupation through drugs. Unfortunately, there are no specific MRGPRX2 inhibitors allowing to deepen our insights in the MRGPRX2-activation pathway(s). Therefore, the aim of this study is to explore whether MRGPRX2-expression can be silenced via siRNA technology. METHODS: Human MC were cultured out of CD34 + progenitor cells that were obtained from peripheral blood. MCs were electroporated, with the introduction of a 1000 nM mixture of two MRGPRX2-specific siRNA in a 1:1 ratio or with a negative control, using a Square Wave protocol (500V, 5ms 1 pulse). Five days after electroporation, cells were stimulated with the MRGPRX2 antagonist substance P and anti-FcεRI. For staining of intracellular calcium a Fluo-4 technique was applied. Degranulation were flow cytometric analysed by CD63-upregulation. Results are expressed as median decrease with range (n53). RESULTS: After inserting MRGPRX2-specific siRNA, expression of MRGPRX2 decreases with 83% (76-97). This reduced expression resulted in a significant decrease of 75% (55-77) intracellular calcium staining and CD63 appearance of 95% (89-95) after stimulation with substance P for 20 minutes. In contrast, introduction of MRGPRX2-specific siRNA did not affect intracellular calcium staining (0% (0-11)) nor appearance of CD63 (0% (0-29)) in response to anti-FcεRI. CONCLUSIONS: Our siRNA model is an effective way to silence MRGPRX2-expression and functionality in cultured hMC. Therefore, our technique can be used to explore signaling in the MRGPRX2-pathway and to study pathogenic effects of off-target occupation.

PLOS ONE, 2019

Background Previous studies have revealed an important role for the transcription factor GATA-1 i... more Background Previous studies have revealed an important role for the transcription factor GATA-1 in mast cell maturation and degranulation. However, there have been conflicting reports with respect to the requirement of GATA-1 function in mast cell dependent inflammatory processes. Herein, we examine the requirement of GATA-1 signaling in mast cell effector function and IgE-mast cell-dependent anaphylaxis. Objective To study the requirement of GATA-1 dependent signaling in the development and severity of IgE-mast cell-dependent anaphylaxis in mice. Methods Wild type (Balb/c) and mutant ΔdblGata (Balb/c) mice were employed to study the role of GATA-1 signaling in in vitro IgE-mediated activation of bone marrow derived mast cells (BMMCs). Murine models of passive IgE-mediated and oral antigen-induced IgE-mediated anaphylaxis were employed in mice. Frequency of steady state mast cells in various tissues (duodenum, ear, and tongue), peritoneal cavity, and clinical symptoms (diarrhea, shock, and mast cell activation) and intestinal Type 2 immune cell analysis including CD4 + Th 2 cells, type 2 innate lymphoid cells (ILC2), and IL-9 secreting mucosal mast cells (MMC9) were assessed Results In vitro analysis revealed that ΔdblGata BMMCs exhibit a reduced maturation rate, decreased expression of FcεRIα, and degranulation capacity when compared to their PLOS ONE |

Cancer letters, Feb 1, 2018

Metastatic colonization involves paracrine/juxtacrine interactions with the microenvironment indu... more Metastatic colonization involves paracrine/juxtacrine interactions with the microenvironment inducing an adaptive response through transcriptional regulation. However, the identities of transcription factors (TFs) induced by the metastatic microenvironment in ovarian cancer (OC) and their mechanism of action is poorly understood. Using an organotypic 3D culture model recapitulating the early events of metastasis, we identified ETS1 as the most upregulated member of the ETS family of TFs in metastasizing OC cells as they interacted with the microenvironment. ETS1 was regulated by p44/42 MAP kinase signaling activated in the OC cells interacting with mesothelial cells at the metastatic site. Human OC tumors had increased expression of ETS1, which predicted poor prognosis. ETS1 regulated OC metastasis both in vitro and in mouse xenografts. A combination of ChIP-seq and RNA-seq analysis and functional rescue experiments revealed FAK as the key transcriptional target and downstream effec...

The Journal of allergy and clinical immunology, Jan 26, 2017

Food allergy (FA) is an increasing problem that has no approved treatment. The pro-TH2 cytokines ... more Food allergy (FA) is an increasing problem that has no approved treatment. The pro-TH2 cytokines IL-25, IL-33, and thymic stromal lymphopoietin (TSLP) are associated with FA, and mAbs to these cytokines are reported to suppress murine FA development. We sought to determine whether anti-pro-TH2 cytokine mAbs can block both FA maintenance and induction. IgE-mediated FA was induced in BALB/c mice by oral gavage with medium-chain triglycerides (MCTs) plus egg white (EW) and was characterized by increased numbers of lamina propria TH2 cells, mast cells, and eosinophils, shock (hypothermia), mast cell degranulation (increased serum mouse mast cell protease 1), increased serum IgG1 anti-EW and IgE levels, and increased IL-4 and IL-13 secretion after MCT/EW challenge. Mice were injected with anti-IL-25, IL-33 receptor, and/or TSLP mAbs before initial oral gavage with MCT/EW to suppress FA development; treatment with the same mAbs was initiated after FA development to suppress established FA...

Seminars in immunopathology, 2016

Food allergy is a harmful immune reaction driven by uncontrolled type 2 immune responses. Conside... more Food allergy is a harmful immune reaction driven by uncontrolled type 2 immune responses. Considerable evidence demonstrates the key roles of mast cells, IgE, and TH2 cytokines in mediating food allergy. However, this evidence provides limited insight into why only some, rather than all, food allergic individuals are prone to develop life-threatening anaphylaxis. Clinical observations suggest that patients sensitized to food through the skin early in life may later develop severe food allergies. Aberrant epidermal thymic stromal lymphopoietin and interleukin (IL) 33 production and genetic predisposition can initiate an allergic immune response mediated by dendritic cells and CD4(+)TH2 cells in inflamed skin. After allergic sensitization, intestinal IL-25 and food ingestion enhance concerted interactions between type 2 innate lymphoid cells (ILC2s) and CD4(+)TH2 cells, which perpetuate allergic reactions from the skin to the gut. IL-4 and cross-linking of antigen/IgE/FcεR complexes i...

Oncotarget, Jan 27, 2016

Genomic analysis of ovarian cancer cell lines has revealed a panel that best represents the most ... more Genomic analysis of ovarian cancer cell lines has revealed a panel that best represents the most common ovarian cancer subtype, high-grade serous ovarian cancer (HGSOC). However, these HGSOC-like cell lines have not been extensively applied by ovarian cancer researchers to date, and the most commonly used cell lines in the ovarian cancer field do not genetically resemble the major clinical type of the disease. For the HGSOC-like lines to serve as suitable models, they need to be characterized for common functional assays. To achieve that objective, we systematically studied a panel of HGSOC cells CAOV3, COV362, Kuramochi, OVCAR4, OVCAR5, OVCAR8, OVSAHO and SNU119 for migration, invasion, proliferation, clonogenicity, EMT phenotype and cisplatin resistance. They exhibited a range of efficacies and OVCAR5, OVCAR8 and Kuramochi were the most aggressive. SNU119 and OVSAHO cells demonstrated the lowest functional activities. Wide differences in expression of EMT markers were observed bet...

Gynecologic Oncology, 2015

Objective-Genomic studies of ovarian cancer (OC) cell lines frequently used in research revealed ... more Objective-Genomic studies of ovarian cancer (OC) cell lines frequently used in research revealed that these cells do not fully represent high-grade serous ovarian cancer (HGSOC), the most common OC histologic type. However, OC lines that appear to genomically resemble HGSOC have not been extensively used and their growth characteristics in murine xenografts are essentially unknown.

Oncogene, Jan 23, 2015

The cross-talk between ovarian cancer (OvCa) cells and the metastatic microenvironment is an esse... more The cross-talk between ovarian cancer (OvCa) cells and the metastatic microenvironment is an essential determinant of successful colonization. MicroRNAs (miRNAs) have several critical roles during metastasis; however, the role of microenvironmental cues in the regulation of miRNAs in metastasizing cancer cells has not been studied. Using a three-dimensional culture model that mimics the human omentum, one of the principal sites of OvCa metastasis, we identified and characterized the microenvironment-induced downregulation of a tumor suppressor miRNA, miR-193b, in metastasizing OvCa cells. The direct interaction of the OvCa cells with mesothelial cells, which cover the surface of the omentum, caused a DNA methyltransferase 1-mediated decrease in the expression of miR-193b in the cancer cells. The reduction in miR-193b enabled the metastasizing cancer cells to invade and proliferate into human omental pieces ex vivo and into the omentum of a mouse xenograft model of OvCa metastasis. T...

The Journal of pharmacology and experimental therapeutics, 2015

Acute liver failure (ALF) is a potentially life-threatening disorder without any effective treatm... more Acute liver failure (ALF) is a potentially life-threatening disorder without any effective treatment strategies. d-Galactosamine (GalN)/lipopolysaccharide (LPS)-induced ALF is a widely used animal model to identify novel hepato-protective agents. In the present study, we investigated the potential of a cannabinoid receptor 2 (CB2) agonist, JWH-133 [(6aR,10aR)-3-(1,1-dimethylbutyl)-6a,7,10,10a-tetrahydro-6,6,9-trimethyl-6H-dibenzo[b,d]pyran], in the amelioration of GalN/LPS-induced ALF. JWH-133 treatment protected the mice from ALF-associated mortality, mitigated alanine transaminase and proinflammatory cytokines, suppressed histopathological and apoptotic liver damage, and reduced liver infiltration of mononuclear cells (MNCs). Furthermore, JWH-133 pretreatment of M1/M2-polarized macrophages significantly increased the secretion of anti-inflammatory cytokine interleukin-10 (IL-10) in M1 macrophages and potentiated the expression of M2 markers in M2-polarized macrophages. In vivo, JW...

British journal of pharmacology, 2015

Acute liver failure (ALF) is a severe and potentially lethal clinical syndrome. 3,3'-Diindoly... more Acute liver failure (ALF) is a severe and potentially lethal clinical syndrome. 3,3'-Diindolylmethane (DIM) is a natural plant-derived compound with anti-cancer activities. Recently, DIM has also been shown to have anti-inflammatory properties. Here, we tested the hypothesis that DIM would suppress endotoxin-induced ALF. We investigated the therapeutic potential of DIM in a mouse model of D-galactosamine/Lipopolysaccharide (GalN/LPS)-induced ALF. The efficacy of DIM treatment was assessed by survival, liver histopathology, serum levels of alanine transaminase, pro-inflammatory cytokines and number of activated liver macrophages. Effects of DIM on the expression of two miRNAs, 106a and 20b, and their predicted target gene were measured by qRT-PCR and Western blotting. Effects of DIM on the release of TNF-α from RAW264.7 macrophages transfected with mimics of these miRNAs and activated by LPS was assessed by elisa. DIM treatment protected mice from ALF symptoms and reduced the num...