KaLia Burnette | University of Alabama at Birmingham (original) (raw)

Papers by KaLia Burnette

Hybrid insulin peptides (HIPs) form in pancreatic beta-cells through the formation of peptide bon... more Hybrid insulin peptides (HIPs) form in pancreatic beta-cells through the formation of peptide bonds between proinsulin fragments and other peptides. HIPs have been identified in pancreatic islets by mass spectrometry and are targeted by CD4 T cells in patients with Type 1 Diabetes (T1D), as well as by pathogenic CD4 T cell clones in non-obese diabetic (NOD) mice. The mechanism of HIP formation is currently poorly understood; however, it is well established that proteases can drive the formation of new peptide bonds in a side reaction during peptide bond hydrolysis. Here, we used a proteomic strategy on enriched insulin granules and identified cathepsin D (CatD) as the primary protease driving the specific formation of HIPs targeted by disease-relevant CD4 T cells in T1D. We also established that NOD islets deficient in cathepsin L (CatL), another protease implicated in the formation of disease-relevant HIPs, contain elevated levels of HIPs, indicating a role for CatL in the proteoly...

International Journal of Surgery

Background: There are many causes of systemic complement activation, which may have detrimental e... more Background: There are many causes of systemic complement activation, which may have detrimental effects on a pig xenograft. Transgenic expression of one or more human complement-regulatory proteins (hCRPs), e.g., hCD46, provides some protection to the xenograft, but it is not known whether it protects the xenograft from the effects of systemic complement activation. We used wild-type (WT) pig aortic endothelial cells (pAECs) to activate complement, and determined whether the expression of hCD46 on a1,3galactosyltransferase geneknockout (GTKO) pAECs protected them from injury. Methods: CFSE-labeled and non-labeled pAECs from a WT, a GTKO, or a GTKO/hCD46 pig were separately incubated with heat-inactivated pooled human serum in vitro. Antibody pre-bonded CFSE-labeled and nonlabeled pAECs were mixed, and then incubated with rabbit complement. The complement-dependent cytotoxicity was measured by flow cytometry. Results: There was significantly less lysis of GTKO/CD46 pAECs (6%) by 50% human serum compared to that of WT (91%, p<0.001) or GTKO (32%, p<0.01) pAECs. The lysis of GTKO pAECs was significantly increased when mixed with WT pAECs (p<0.05). In contrast, there was no significant change in cytotoxicity of GTKO/CD46 pAECs when mixed with WT pAECs. Conclusions: The expression of hCD46 protected pAECs from systemic complement activation

Xenotransplantation, 2020

Xenotransplantation using genetically-engineered pig organs offers an unlimited supply of organs ... more Xenotransplantation using genetically-engineered pig organs offers an unlimited supply of organs for patients with end-stage organ failure. There are three known pig xenoantigens against which most humans have natural anti-pig antibodies. Knockout of all three of the genes (GGTA1/CMAH/β4GalNT2) responsible for producing these antigens in pigs, i.e., triple-knockout [TKO] pigs, markedly reduces binding of human natural antibodies to cells from these pigs (1, 2

Journal of biomedical materials research. Part B, Applied biomaterials, Jan 2, 2018

Esophageal diseases may require resectioning of the damaged portion. The current standard of care... more Esophageal diseases may require resectioning of the damaged portion. The current standard of care requires the replacement of the esophagus with the stomach or the intestine. Such procedures have high rates of mortality and morbidity; therefore, the use of alternative conduits is needed. A tissue engineering approach that allows for the regeneration of esophageal tissues would have significant clinical application. A cell-seeded synthetic scaffold could replace the resected part of the esophagus and elicit tissue regrowth. In order to ideally recreate a functioning esophagus, its two crucial tissue layers should be induced: an epithelium on the luminal surface and a muscle layer on the exterior surface. To create a bioengineered esophagus with both tissue layers, a multilayer (ML) tubular scaffold design was considered. Luminal and exterior layers were electrospun with broad pore size to promote penetration and proliferation of mesenchymal stem cells on the lumen and smooth muscle c...

Diabetes

Type 1 diabetes is characterized by beta-cell-specific autoimmune destruction, leading to life-lo... more Type 1 diabetes is characterized by beta-cell-specific autoimmune destruction, leading to life-long exogenous insulin-dependence. Islet transplantation can restore proper glycemic control, but graft longevity remains low due to immune-mediated rejection. The use of nanothin encapsulation materials consisting of poly (N-vinylpyrrolidone) (PVPON) and tannic acid (TA) , an antioxidant, can delay islet allograft rejection and decrease inflammatory immune responses. However, when (PVPON/TA) -encapsulated C57BL/6 islets were transplanted into streptozocin-treated diabetic NOD mice in the absence of systemic immunosuppression, only 50% of recipients maintained long-term allograft function. Therefore, modification of (PVPON/TA) coatings to include immune inhibitors are needed to prolong islet allograft survival. The adaptability of our (PVPON/TA) layers allow for its conjugation to CTLA-4-Ig, a fusion protein that can block CD28-mediated co-stimulation of T cells. We hypothesize that the ad...

Type 1 diabetes (T1D) is an autoimmune disease characterized by autoreactive T cell-mediated dest... more Type 1 diabetes (T1D) is an autoimmune disease characterized by autoreactive T cell-mediated destruction of insulin-producing pancreatic beta-cells. Loss of beta-cells leads to insulin insufficiency and hyperglycemia, with patients eventually requiring lifelong insulin therapy to maintain normal glycemic control. Since T1D has been historically defined as a disease of immune system dysregulation, there has been little focus on the state and response of beta-cells and how they may also contribute to their own demise. Major hurdles to identifying a cure for T1D include a limited understanding of disease etiology and how functional and transcriptional beta-cell heterogeneity may be involved in disease progression. Recent studies indicate that the beta-cell response is not simply a passive aspect of T1D pathogenesis, but rather an interplay between the beta-cell and the immune system actively contributing to disease. Here, we comprehensively review the current literature describing beta...

Scientific reports, Jan 7, 2018

Treatment of esophageal disease can necessitate resection and reconstruction of the esophagus. Cu... more Treatment of esophageal disease can necessitate resection and reconstruction of the esophagus. Current reconstruction approaches are limited to utilization of an autologous conduit such as stomach, small bowel, or colon. A tissue engineered construct providing an alternative for esophageal replacement in circumferential, full thickness resection would have significant clinical applications. In the current study, we demonstrate that regeneration of esophageal tissue is feasible and reproducible in a large animal model using synthetic polyurethane electro-spun grafts seeded with autologous adipose-derived mesenchymal stem cells (aMSCs) and a disposable bioreactor. The scaffolds were not incorporated into the regrown esophageal tissue and were retrieved endoscopically. Animals underwent adipose tissue biopsy to harvest and expand autologous aMSCs for seeding on electro-spun polyurethane conduits in a bioreactor. Anesthetized pigs underwent full thickness circumferential resection of th...

Hybrid insulin peptides (HIPs) form in pancreatic beta-cells through the formation of peptide bon... more Hybrid insulin peptides (HIPs) form in pancreatic beta-cells through the formation of peptide bonds between proinsulin fragments and other peptides. HIPs have been identified in pancreatic islets by mass spectrometry and are targeted by CD4 T cells in patients with Type 1 Diabetes (T1D), as well as by pathogenic CD4 T cell clones in non-obese diabetic (NOD) mice. The mechanism of HIP formation is currently poorly understood; however, it is well established that proteases can drive the formation of new peptide bonds in a side reaction during peptide bond hydrolysis. Here, we used a proteomic strategy on enriched insulin granules and identified cathepsin D (CatD) as the primary protease driving the specific formation of HIPs targeted by disease-relevant CD4 T cells in T1D. We also established that NOD islets deficient in cathepsin L (CatL), another protease implicated in the formation of disease-relevant HIPs, contain elevated levels of HIPs, indicating a role for CatL in the proteoly...

International Journal of Surgery

Background: There are many causes of systemic complement activation, which may have detrimental e... more Background: There are many causes of systemic complement activation, which may have detrimental effects on a pig xenograft. Transgenic expression of one or more human complement-regulatory proteins (hCRPs), e.g., hCD46, provides some protection to the xenograft, but it is not known whether it protects the xenograft from the effects of systemic complement activation. We used wild-type (WT) pig aortic endothelial cells (pAECs) to activate complement, and determined whether the expression of hCD46 on a1,3galactosyltransferase geneknockout (GTKO) pAECs protected them from injury. Methods: CFSE-labeled and non-labeled pAECs from a WT, a GTKO, or a GTKO/hCD46 pig were separately incubated with heat-inactivated pooled human serum in vitro. Antibody pre-bonded CFSE-labeled and nonlabeled pAECs were mixed, and then incubated with rabbit complement. The complement-dependent cytotoxicity was measured by flow cytometry. Results: There was significantly less lysis of GTKO/CD46 pAECs (6%) by 50% human serum compared to that of WT (91%, p<0.001) or GTKO (32%, p<0.01) pAECs. The lysis of GTKO pAECs was significantly increased when mixed with WT pAECs (p<0.05). In contrast, there was no significant change in cytotoxicity of GTKO/CD46 pAECs when mixed with WT pAECs. Conclusions: The expression of hCD46 protected pAECs from systemic complement activation

Xenotransplantation, 2020

Xenotransplantation using genetically-engineered pig organs offers an unlimited supply of organs ... more Xenotransplantation using genetically-engineered pig organs offers an unlimited supply of organs for patients with end-stage organ failure. There are three known pig xenoantigens against which most humans have natural anti-pig antibodies. Knockout of all three of the genes (GGTA1/CMAH/β4GalNT2) responsible for producing these antigens in pigs, i.e., triple-knockout [TKO] pigs, markedly reduces binding of human natural antibodies to cells from these pigs (1, 2

Journal of biomedical materials research. Part B, Applied biomaterials, Jan 2, 2018

Esophageal diseases may require resectioning of the damaged portion. The current standard of care... more Esophageal diseases may require resectioning of the damaged portion. The current standard of care requires the replacement of the esophagus with the stomach or the intestine. Such procedures have high rates of mortality and morbidity; therefore, the use of alternative conduits is needed. A tissue engineering approach that allows for the regeneration of esophageal tissues would have significant clinical application. A cell-seeded synthetic scaffold could replace the resected part of the esophagus and elicit tissue regrowth. In order to ideally recreate a functioning esophagus, its two crucial tissue layers should be induced: an epithelium on the luminal surface and a muscle layer on the exterior surface. To create a bioengineered esophagus with both tissue layers, a multilayer (ML) tubular scaffold design was considered. Luminal and exterior layers were electrospun with broad pore size to promote penetration and proliferation of mesenchymal stem cells on the lumen and smooth muscle c...

Diabetes

Type 1 diabetes is characterized by beta-cell-specific autoimmune destruction, leading to life-lo... more Type 1 diabetes is characterized by beta-cell-specific autoimmune destruction, leading to life-long exogenous insulin-dependence. Islet transplantation can restore proper glycemic control, but graft longevity remains low due to immune-mediated rejection. The use of nanothin encapsulation materials consisting of poly (N-vinylpyrrolidone) (PVPON) and tannic acid (TA) , an antioxidant, can delay islet allograft rejection and decrease inflammatory immune responses. However, when (PVPON/TA) -encapsulated C57BL/6 islets were transplanted into streptozocin-treated diabetic NOD mice in the absence of systemic immunosuppression, only 50% of recipients maintained long-term allograft function. Therefore, modification of (PVPON/TA) coatings to include immune inhibitors are needed to prolong islet allograft survival. The adaptability of our (PVPON/TA) layers allow for its conjugation to CTLA-4-Ig, a fusion protein that can block CD28-mediated co-stimulation of T cells. We hypothesize that the ad...

Type 1 diabetes (T1D) is an autoimmune disease characterized by autoreactive T cell-mediated dest... more Type 1 diabetes (T1D) is an autoimmune disease characterized by autoreactive T cell-mediated destruction of insulin-producing pancreatic beta-cells. Loss of beta-cells leads to insulin insufficiency and hyperglycemia, with patients eventually requiring lifelong insulin therapy to maintain normal glycemic control. Since T1D has been historically defined as a disease of immune system dysregulation, there has been little focus on the state and response of beta-cells and how they may also contribute to their own demise. Major hurdles to identifying a cure for T1D include a limited understanding of disease etiology and how functional and transcriptional beta-cell heterogeneity may be involved in disease progression. Recent studies indicate that the beta-cell response is not simply a passive aspect of T1D pathogenesis, but rather an interplay between the beta-cell and the immune system actively contributing to disease. Here, we comprehensively review the current literature describing beta...

Scientific reports, Jan 7, 2018

Treatment of esophageal disease can necessitate resection and reconstruction of the esophagus. Cu... more Treatment of esophageal disease can necessitate resection and reconstruction of the esophagus. Current reconstruction approaches are limited to utilization of an autologous conduit such as stomach, small bowel, or colon. A tissue engineered construct providing an alternative for esophageal replacement in circumferential, full thickness resection would have significant clinical applications. In the current study, we demonstrate that regeneration of esophageal tissue is feasible and reproducible in a large animal model using synthetic polyurethane electro-spun grafts seeded with autologous adipose-derived mesenchymal stem cells (aMSCs) and a disposable bioreactor. The scaffolds were not incorporated into the regrown esophageal tissue and were retrieved endoscopically. Animals underwent adipose tissue biopsy to harvest and expand autologous aMSCs for seeding on electro-spun polyurethane conduits in a bioreactor. Anesthetized pigs underwent full thickness circumferential resection of th...