Faculty Bibliography

BACKGROUND & AIMS/OBJECTIVE:Lipoprotein assembly in the small intestine and liver is critical for the transport of dietary and endogenous lipids. Pla2g12b has recently been shown to play a role in lipoprotein assembly in mice livers and zebrafish larvae. Pla2g12b knockout and mutant (MUT) mice with the C129Y missense mutation have low plasma cholesterol levels. However, the role of Pla2g12b in the intestine and the reason why C129Y mutation decreases plasma lipids are unknown. METHODS:) and WT control mice were used in parallel to study plasma lipids and lipoproteins, lipid absorption and hepatic lipoprotein production studies. Transmission electron microscopy was used to visualize lipid transit through enterocytes. RESULTS:We observed that Pla2g12b expression was the highest in the duodenum. Furthermore, male and female chow fed 3-month-old MUT mice and wildtype (WT) mice expressed similar amounts of Pla2g12b protein and several genes in lipid metabolism. Nonetheless, the MUT mice had significantly lower plasma triglyceride (TG), cholesterol, HDL-C, LDL-C, apoB48, and apoB100 levels than WT mice. Several mechanisms for lower plasma lipids and lipoproteins in MUT mice were investigated. C129Y mutation had no effect on the expression of Pla2g12b and several other proteins necessary for lipid transport. Therefore, the low plasma lipid levels in MUT mice were neither due to the absence of Pla2g12b protein nor due to reductions in critical proteins in lipid transport. Next, we addressed the role of Pla2g12b in hepatic lipid mobilization and intestinal lipid absorption. MUT livers exhibited normal TG synthesis, defective TG secretion, and enhanced fat accumulation. MUT mice also showed defective intestinal TG absorption, intracellular lipid accumulation, and elevated TG excretion in the feces. CONCLUSIONS:We propose that C129 in Pla2g12b is critical for the assembly and secretion of lipoproteins by the liver and intestine.

BACKGROUND & AIM/UNASSIGNED:Metabolic dysfunction-associated steatotic liver disease (MASLD) is a growing health issue. Identifying factors that prevent hepatic lipid accumulation could inform new MASLD prevention or treatment strategies. We previously demonstrated that adipocyte microsomal triglyceride transfer protein (MTP) regulates intracellular lipolysis by inhibiting adipose triglyceride lipase activity. The aim of this study was to investigate the impact of adipose MTP deficiency on MASLD. METHODS/UNASSIGNED: RESULTS/UNASSIGNED: CONCLUSION/UNASSIGNED:These findings highlight the importance of regulated FA flux from adipose tissue to the liver and the liver's adaptive capacity to utilize adipose-derived FAs in maintaining hepatic health. Modulation of adipocyte FA release may represent a therapeutic strategy to reduce hepatic steatosis. IMPACT AND IMPLICATIONS/UNASSIGNED:This study provides significant insights into the role of adipose-specific microsomal triglyceride transfer protein in regulating hepatic lipid metabolism and its potential implications for treating metabolic dysfunction-associated steatotic liver disease. By demonstrating that microsomal triglyceride transfer protein deficiency in adipose tissue leads to increased fatty acid oxidation and reduced hepatic steatosis through enhanced PPARα activation, the research underscores the importance of adipose-liver crosstalk in maintaining liver health. These findings suggest that targeting adipocyte fatty acid release could be a promising therapeutic strategy to mitigate hepatic lipid accumulation and combat metabolic dysfunction-associated steatotic liver disease, offering a novel approach to addressing this growing health issue.

This work is an in-depth investigation of the in vitro and in vivo biocompatibility of processed and treated residual human hair samples with intact cuticle layers. The specimens included oxidized hair with minimal melanin (BLH) and hair with medium- (M-KAP) and low- (L-KAP) amounts of keratin associated proteins (KAPs), confirmed through gel electrophoresis, electron microscopy, trichrome histological staining, and tensile biomechanics, in comparison to the untreated regular hair (REG) control. All hair groups, high KAPs (H-KAPs: REG and BLH), M-KAP, and L-KAP, are non-cytotoxic in the adipose fibroblast's response to their extracts based on the ISO 10993-5 medical device biomaterial testing standard. In vivo mouse subcutaneous implantation (ISO 10993-6, local effects) at 2 weeks showed a foreign body response (FBR) with thin fibrous encapsulation at 28% relative skin dermis thickness; but the L-KAP implant mitigated a significant decrease in FBR area compared to H-KAPs and a lower number of immune cells of mostly macrophages and mast cells on the biomaterial's surface. In the bulk of the capsules, blood vessels and collagen extracellular matrix densities were similar among groups. These findings suggest that small globular KAPs diffuse out of the cortex to the host-biomaterial interface which induce a slightly-elevated FBR but limited to the implant's surface vicinity. For translatability, we evaluated the effectiveness of the residual hair with the most depleted KAPs (L-KAP) in a 10 mm-diameter, splinted, and full-thickness mouse skin excision wound. Treatment with the L-KAP mesh exhibited an 8% healing improvement per day compared to the untreated control: significantly reducing the projected complete healing time by 30%. On-going research focuses on purer keratin-based and macromolecularly organized residual hair biomaterials for drug-delivery as they are deemed the most biocompatible.

Major depressive disorder is one of the most burdensome mental health disorders. Probiotics have been shown to ameliorate depressive symptoms, though the mechanism remains unclear. This study was conducted to investigate whether extracellular vesicles (EVs) extracted from the probiotic beverage water kefir could influence gene and protein expression in human-derived neuroblastoma cells in vitro. EVs were extracted from lab-cultured water kefir and a control solution without water kefir grains by ultracentrifugation. Water kefir vesicles were imaged via electron microscopy. Neuroblastoma, microglia, and neuroblastoma-microglia co-cultures were exposed to water kefir EVs or negative control medium. Uptake of water kefir EVs was identified by microscopy. All conditions were quantified for brain derived neurotrophic factor, fractalkine, and synaptophysin RNA and protein. Data were analyzed using factorial ANOVAs with significance set at 0.05. Water kefir vesicles were taken up by neuroblastoma cells, and incubation in neuroblastoma-microglia co-culture resulted in significantly higher levels of fractalkine protein compared to media-only control (p = 0.029). To our knowledge, this is the first study to identify potential interactions between EVs derived from the probiotic beverage water kefir and human neuronal cells. Further research is needed to fully elucidate the role played by probiotic-derived EVs in human health.

Nilotinib, a tyrosine kinase inhibitor that targets the Abelson tyrosine kinase (c-Abl) signaling pathway, is FDA-approved to treat chronic myeloid leukemia. Nilotinib has properties indicative of a possible utility in neuroprotection that have prompted exploration of repurposing the drug for the treatment of Alzheimer's disease (AD) and Parkinson's disease (PD). AD is a progressive age-related neurodegenerative disorder characterized by the deposition of extracellular amyloid-β plaques and intracellular neurofibrillary tangles. It is incurable and affects approximately 50 million patients worldwide. Nilotinib reduces c-Abl phosphorylation, amyloid-β levels, and dopaminergic neuron degeneration in preclinical AD models. This study explores the effects of nilotinib on amyloid processing and mitochondrial functioning in the SH-SY5Y human neuroblastoma cell line. SH-SY5Y cells were exposed to nilotinib (1, 5, and 10 µM). Real-time PCR and immunoblot analysis were performed to quantify the expression of genes pertaining to amyloid-β processing and neuronal health. Nilotinib did not significantly change APP, BACE1, or ADAM10 mRNA levels. However, BACE1 protein was significantly increased at 1 µM, and ADAM10 was increased at 10 µM nilotinib without affecting APP protein expression. Further, nilotinib treatment did not affect the expression of genes associated with neuronal health and mitochondrial functioning. Taken together, our findings do not support the efficacy of nilotinib treatment for neuroprotection.

PURPOSE/OBJECTIVE:Roux-en-Y gastric bypass (RYGB) leads to the improvement of many obesity-associated conditions. The degree to which post-operative macronutrient composition contributes to metabolic improvement after RYGB is understudied. METHODS:A mouse model of RYGB was used to examine the effects of diet on the post-operative outcomes of RYGB. Obese mice underwent either Sham or RYGB surgery and were administered either chow or HFD and then monitored for an additional 8 weeks. RESULTS:After RYGB, reductions to body weight, fat mass, and lean mass were similar regardless of diet. RYGB and HFD were independently detrimental to bone mineral density and plasma vitamin D levels. Independent of surgery, HFD accelerated hematopoietic stem and progenitor cell proliferation and differentiation and exhibited greater myeloid lineage commitment. Independent of diet, systemic iron deficiency was present after RYGB. In both Sham and RYGB groups, HFD increased energy expenditure. RYGB increased fecal energy loss, and HFD after RYGB increased fecal lipid content. RYGB lowered fasting glucose and liver glycogen levels but HFD had an opposing effect. Indices of insulin sensitivity improved independent of diet. HFD impaired improvements to dyslipidemia, NAFLD, and fibrosis. CONCLUSION/CONCLUSIONS:Post-operative diet plays a significant role in determining the degree to which RYGB reverses obesity-induced metabolic abnormalities such as hyperglycemia, dyslipidemia, and NAFLD. Diet composition may be targeted in order to assist in the treatment of post-RYGB bone mineral density loss and vitamin D deficiency as well as to reverse myeloid lineage commitment. HFD after RYGB continues to pose a significant multidimensional health risk.

Mitochondrial degeneration in various neurodegenerative diseases, specifically in Alzheimer's disease, involves excessive mitochondrial fission and reduced fusion, leading to cell damage. P110 is a seven-amino acid peptide that restores mitochondrial dynamics by acting as an inhibitor of mitochondrial fission. However, the role of P110 as a neuroprotective agent in AD remains unclear. Therefore, we performed cell culture studies to evaluate the neuroprotective effect of P110 on amyloid-β accumulation and mitochondrial functioning. Human SH-SY5Y neuronal cells were incubated with 1 µM and 10 µM of P110, and Real-Time PCR and Western blot analysis were done to quantify the expression of genes pertaining to AD and neuronal health. Exposure of SH-SY5Y cells to P110 significantly increased APP mRNA levels at 1 µM, while BACE1 mRNA levels were increased at both 1 µM and 10 µM. However, protein levels of both APP and BACE1 were significantly reduced at 10 µM of P110. Further, P110 treatment significantly increased ADAM10 and Klotho protein levels at 10 µM. In addition, P110 exposure significantly increased active mitochondria and reduced ROS in live SH-SY5Y cells at both 1 µM and 10 µM concentrations. Taken together, our results indicate that P110 might be useful in attenuating amyloid-β generation and improving neuronal health by maintaining mitochondrial function in neurons.

PURPOSE/OBJECTIVE:Bariatric surgery is emerging as an effective treatment for obesity and the metabolic syndrome. Recently, we demonstrated that Roux-en-Y gastric bypass (RYGB), but not vertical sleeve gastrectomy (VSG), resulted in improvements to white adipose physiology and enhanced brown adipose functioning. Since beneficial alterations to liver health are also expected after bariatric surgery, comparing the post-operative effects of RYGB and VSG on liver physiology is essential to their application in the treatment of non-alcoholic fatty liver disease (NAFLD). MATERIALS AND METHODS/METHODS:The effects of RYGB and VSG on liver physiology were compared using diet induced mouse model of obesity. High-fat diet (HFD) was administered for 12 weeks after surgery and alterations to liver physiology were assessed. RESULTS:Both RYGB and VSG showed decreased liver weight as well as reductions to hepatic cholesterol and triglyceride levels. There were demonstrable improvements to NAFLD activity score (NAS) and fibrosis stage scoring after both surgeries. In RYGB, these beneficial changes to liver function resulted from the downregulation of pro-fibrotic and upregulation anti-fibrotic genes, as well as increased fatty acid oxidation and bile acid flux. For VSG, though similar alterations were observed, they were less potent. However, VSG did significantly downregulate pro-fibrotic genes and showed increased glycogen content paralleled by decreased glycogenolysis which may have contributed to the resolution of NAFLD. CONCLUSION/CONCLUSIONS:RYGB and VSG improve liver physiology and function, but RYGB is more efficacious. Resolutions of NAFLD in RYGB and VSG are achieved through different processes, independent of weight loss.