Nutrition & Food Science
Permanent URI for this communityhttp://hdl.handle.net/1903/2267
null
Browse
4 results
Search Results
Item ROLE OF TRPV4 MECHANOSENSING REGULATING MACROPHAGE FUNCTIONS IN INFLAMMATORY DISEASES(2024) Dutta, Bidisha; Rahaman, Shaik O; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Macrophages are the most versatile cells of the hematopoietic system with roles in homeostasis, host-tissue development, innate immune response and tissue repair. Although the inflammatory activation and maintenance signals are tightly regulated, an imbalance in them results in unchecked inflammation resulting in cellular and tissue damage. Macrophages can affect most if not all phases of inflammation owing to their ability to adopt distinct functional states, secrete cytokines and phagocytose pathogens and debris. Recent evidence suggests that beyond biochemical cues, mechanical forces, like changing matrix stiffness in the tissue microenvironment, can shape immune cell functions involved in inflammation. These cells convert mechanical stimuli to biochemical signals in a process called mechanotransduction, regulating a multitude of cellular functions. However, knowledge about the molecular mediators of mechanotransduction and their functions in macrophage phenotypic and functional change is largely missing, highlighting the need for studying mechanosensory molecules such as ion channels. The present study focuses on the role of a specific mechanosensitive ion channel, Transient Receptor Potential Vanilloid 4 (TRPV4), in the regulation of macrophage mediated inflammatory responses. Given its emerging role in inflammatory diseases like fibrosis, arthritis, foreign body response (FBR), TRPV4’s contribution to macrophage behavior in inflammation is of growing interest. Employing cellular imaging and molecular biology techniques such as Ca2+ influx assays, immunohistochemistry, immunoblotting, and single nuclei RNA sequencing we delineate mechanisms by which biomechanical stimuli-mediated activation of TRPV4 affects macrophage function. We elucidate TRPV4’s role in macrophage mechanotransduction, providing a mechanistic understanding of inflammatory disease pathophysiology which could lead to the development of potential therapeutics for disease intervention.Item Three Clostridium species with Health Imparting Properties: In vitro Screening for Probiotic Potential(2024) Mochama, Victor Moronge; Obanda, Diana; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This research aimed to unlock the probiotic potential of the genus Clostridium, which is often overshadowed by the predominant focus on pathogenic species. The study specifically targeted three promising Clostridium species: C. disporicum, C. celatum, and C. vincentii, which have shown potential in mitigating diet-induced obesity. Despite the challenges presented by the anaerobic growth requirements of Clostridium bacteria, the study capitalized on their capacity to sporulate. This characteristic provides an avenue to use them as probiotics, with resilient and dormant spores capable of surviving food processing and harsh stomach conditions. The resilience of these spores was examined by exposing them to oxygen, heat, gastrointestinal juices, and bile salts. The spores survived oxygen exposure, exhibited resilience to both bile salts and gastric acids, and demonstrated a survival temperature of 70°C. When exposed to suitable germination conditions in vitro, the spores successfully germinated. The study assessed the colonization potential of the bacteria by evaluating their adhesion ability, and all bacteria were found to have the adhesion ability. Furthermore, a safety assessment was conducted by examining hemolytic activity and antibiotic susceptibility to selected antibiotics. The bacteria were found to be susceptible to the antibiotics and did not exhibit hemolytic activity. Bile salt hydrolase (BSH) activity and antibacterial activities were also assessed, and none of the bacteria exhibited BSH activity or antibacterial activity. Antioxidant tests revealed that C. vincentii had the highest antioxidant properties. Assessment of anti-inflammatory properties showed that C. celatum downregulated the gene expression of cytokine inflammation markers IL-6, IL-1, and iNOS while upregulating TGF-β expression. In summary all 3 bacterial species showed good probiotic potential from the in vitro tests. Particularly the formation of resistant spores that later germinated to vegetative cells that produced molecular patterns with antioxidant and anti-inflammatory properties. This necessitates further studies on their probiotic properties.Item EVALUATION OF THE COPPER HOMEOSTASIS AND SILVER RESISTANCE ISLAND AND ITS ROLE IN PERSISTENCE OF SALMONELLA ENTERICA(2023) Haendiges, Julie; Tikekar, Rohan; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Salmonella enterica is one of the leading bacterial cause of foodborne illness in the UnitedStates. Although there are many serovars, only a small subset causes human illness. Since Salmonella is ubiquitous in the environment, the Food and Drug Administration has established regulations for food processors to ensure that the products are free of contamination. Low-moisture foods are commonly ready-to-eat, and due to the low water activity do not promote growth of bacteria. However, Salmonella has been shown to persist in these foods. There havebeen two outbreaks and multiple recalls in the United States due to contaminated pistachios. Based on a retrospective study, results show that there is evidence of a contamination in the growing orchard and a significant number of Salmonella isolates from the environments contain the Copper Homeostasis and Silver Resistance Island (CHASRI) cassette. This raises several questions: what is the prevalence of CHASRI among different Salmonella isolates from food and environmental sources? Does presence of CHASRI enable Salmonella to survive better against copper stress? And whether presence of CHASRI provide cross-protection against other stresses such as desiccation and thermal treatment? This dissertation attempts to answer those questions. The prevalence of the CHASRI in Salmonella was determined by the use of publicly availablewhole genome sequencing data. The CHASRI was found in 61 different serovars and types of sources. The presence of the CHASRI in isolates from low-moisture foods that have caused previous outbreaks (peanut butter, nuts, spices) was interesting to note, and leads to future studies on correlations between this island and virulence. Based on results of phylogenetic analysis of CHASRI sequences from closed genomes, we determined there were four types of CHASRI found in Salmonella. Traditionally, the Salmonella Genomic Island-4 (SGI-4) is found but in addition the CHASRI can incorporate by itself, within a variant of SGI-4, or via a rare plasmid. Interestingly, the sequence of the CHASRI from SGI-4 and the variant SGI-4 were highly different. The high SNP differences in sequence along with the difference in the arsenic operon led to the conclusion that these variants arose independently. A Salmonella Senftenberg strain (CFSAN047523), isolated from pistachios, was used to createthree knockouts (∆cus, ∆pco, and ∆CHASRI). Previous studies have looked at the minimum inhibitory concentration (MIC) of strains with and without the CHASRI but have omitted the minimum bactericidal concentration (MBC). In this study, we used the knockouts to test for both MIC and MBC. While the MIC was similar for the strains, the MBC was greater in the wild type and partial CHASRI knockouts. Growth and inactivation kinetics were measured in different concentrations of copper sulfate. At higher levels of copper sulfate, the presence of the CHASRI made cells more resilient to inactivation by copper sulfate. Evidence shows that the stress response in Salmonella has the ability to crosstalk and provideprotection against multiple stresses. To investigate this phenomenon further, our isolates were tested against a multitude of stresses to evaluate for cross-protection that may be due to theCHASRI. Cells undergoing copper stress were better equipped to survive lethal copper concentrations and desiccation if the CHASRI was present. The presence of Salmonella in final pistachio products that have been fully processed identifies that some adaptation and stress response is occurring in the processing facility. Inoculated pistachios with the wild type and ∆CHASRI strain were thermally processed to test for survivors. This study showed that the presence of the CHASRI gave the isolate an advantage to survive thermal processing after desiccation. Overall, this study presents the prevalence of the CHASRI in Salmonella enterica as well as theimportant role it plays in copper tolerance. The evidence of cross-protection and tolerance to copper leads to future research regarding gene expression and virulence assessment.Item Role of Transient Receptor Potential Vanilloid 4 (TRPV4) Calcium-permeable Channels in Fibro-inflammatory Diseases(2021) Goswami, Rishov; Rahaman, Shaik O.; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Tissue fibrosis and foreign body response (FBR) have emerged as two major public health problems globally over the last few decades. While fibrosis is an outcome of a dysregulated wound healing process, FBR, a chronic inflammatory disease, develops when the body responds and reacts to the implantation of biological materials. Interestingly, recent studies have associated these non-specific inflammatory diseases with altering stiffness although the exact underlying mechanisms by which mechanical cues can regulate the diseases remain poorly understood. The objective of this thesis work is to determine how the changing of tissue stiffness and implant rigidity mediates disease progression of fibrosis and FBR respectively. Here we identify a novel role of a polymodal mechanosensitive calcium channel, Transient Receptor Potential Vanilloid 4 (TRPV4), as a potential cell membrane receptor/channel in the pathophysiology of FBR and skin fibrosis associated with Scleroderma, a multisystem idiopathic fibro-inflammatory connective tissue disorder. Our results showed that TRPV4 is over expressed in fibrotic skin tissue and colocalize with alpha-smooth muscle actin (a-SMA), a common myofibroblast marker. Using mouse model, we demonstrated that TRPV4 knockout mice are protected from bleomycin-induced skin fibrosis development. Additionally, in a separate mouse model, we showed that genetic ablation of the TRPV4 channel protects mice from implantation-induced macrophage foreign body giant cell (FBGC) formation, macrophage accumulation, and FBR development to biomaterials. The results of our studies also determined an essential role of TRPV4 for macrophage fusion and the mechanism by which TRPV4 and matrix stiffness leads to cytoskeletal remodeling through a feed-forward functional interaction generating cellular force to modulate FBGC formation. We also identified a mechanosensing domain of TRPV4 which is crucial for FBGC generation. Altogether, the results presented in this thesis suggest TRPV4 as a potential regulator of stiffness-dependent fibrosis and inflammation development, and multinucleated FBGC formation. The results of this thesis work proposes that interaction between TRPV4 and substrate stiffness leads to cytoskeletal remodeling and cellular force generation to modulate FBGC formation under FBR. Overall, the work presented in this thesis provides a better understanding about the role of mechanosensitive calcium channel TRPV4 in the regulation of fibro-inflammatory diseases and highlights the possibilities of therapeutically targeting of this channel for disease management.