University of Texas Medical Branch

About: University of Texas Medical Branch is a education organization based out in Galveston, Texas, United States. It is known for research contribution in the topics: Population & Virus. The organization has 22033 authors who have published 38268 publications receiving 1517502 citations. The organization is also known as: The University of Texas Medical Branch at Galveston & UTMB.

Complement Activation Contributes to Severe Acute Respiratory Syndrome Coronavirus Pathogenesis

Abstract: Acute respiratory distress syndrome (ARDS) is immune-driven pathologies that are observed in severe cases of severe acute respiratory syndrome coronavirus (SARS-CoV) infection. SARS-CoV emerged in 2002 to 2003 and led to a global outbreak of SARS. As with the outcome of human infection, intranasal infection of C57BL/6J mice with mouse-adapted SARS-CoV results in high-titer virus replication within the lung, induction of inflammatory cytokines and chemokines, and immune cell infiltration within the lung. Using this model, we investigated the role of the complement system during SARS-CoV infection. We observed activation of the complement cascade in the lung as early as day 1 following SARS-CoV infection. To test whether this activation contributed to protective or pathologic outcomes, we utilized mice deficient in C3 (C3–/–), the central component of the complement system. Relative to C57BL/6J control mice, SARS-CoV-infected C3–/– mice exhibited significantly less weight loss and less respiratory dysfunction despite equivalent viral loads in the lung. Significantly fewer neutrophils and inflammatory monocytes were present in the lungs of C3–/– mice than in C56BL/6J controls, and subsequent studies revealed reduced lung pathology and lower cytokine and chemokine levels in both the lungs and the sera of C3–/– mice than in controls. These studies identify the complement system as an important host mediator of SARS-CoV-induced disease and suggest that complement activation regulates a systemic proinflammatory response to SARS-CoV infection. Furthermore, these data suggest that SARS-CoV-mediated disease is largely immune driven and that inhibiting complement signaling after SARS-CoV infection might function as an effective immune therapeutic. IMPORTANCE The complement system is a critical part of host defense to many bacterial, viral, and fungal infections. It works alongside pattern recognition receptors to stimulate host defense systems in advance of activation of the adaptive immune response. In this study, we directly test the role of complement in SARS-CoV pathogenesis using a mouse model and show that respiratory disease is significantly reduced in the absence of complement even though viral load is unchanged. Complement-deficient mice have reduced neutrophilia in their lungs and reduced systemic inflammation, consistent with the observation that SARS-CoV pathogenesis is an immune-driven disease. These data suggest that inhibition of complement signaling might be an effective treatment option following coronavirus infection.

Tumor-derived hydrogen sulfide, produced by cystathionine-β-synthase, stimulates bioenergetics, cell proliferation, and angiogenesis in colon cancer

Abstract: The physiological functions of hydrogen sulfide (H2S) include vasorelaxation, stimulation of cellular bioenergetics, and promotion of angiogenesis. Analysis of human colon cancer biopsies and patient-matched normal margin mucosa revealed the selective up-regulation of the H2S-producing enzyme cystathionine-β-synthase (CBS) in colon cancer, resulting in an increased rate of H2S production. Similarly, colon cancer-derived epithelial cell lines (HCT116, HT-29, LoVo) exhibited selective CBS up-regulation and increased H2S production, compared with the nonmalignant colonic mucosa cells, NCM356. CBS localized to the cytosol, as well as the mitochondrial outer membrane. ShRNA-mediated silencing of CBS or its pharmacological inhibition with aminooxyacetic acid reduced HCT116 cell proliferation, migration, and invasion; reduced endothelial cell migration in tumor/endothelial cell cocultures; and suppressed mitochondrial function (oxygen consumption, ATP turnover, and respiratory reserve capacity), as well as glycolysis. Treatment of nude mice with aminooxyacetic acid attenuated the growth of patient-derived colon cancer xenografts and reduced tumor blood flow. Similarly, CBS silencing of the tumor cells decreased xenograft growth and suppressed neovessel density, suggesting a role for endogenous H2S in tumor angiogenesis. In contrast to CBS, silencing of cystathionine-γ-lyase (the expression of which was unchanged in colon cancer) did not affect tumor growth or bioenergetics. In conclusion, H2S produced from CBS serves to (i) maintain colon cancer cellular bioenergetics, thereby supporting tumor growth and proliferation, and (ii) promote angiogenesis and vasorelaxation, consequently providing the tumor with blood and nutritients. The current findings identify CBS-derived H2S as a tumor growth factor and anticancer drug target.

Depression predicts increased incidence of adverse health outcomes in older Mexican Americans with type 2 diabetes.

Abstract: OBJECTIVE —To examine the separate and combined effects of depression and diabetes on the incidence of adverse health outcomes among older Mexican Americans. RESEARCH DESIGN AND METHODS —Longitudinal data from the Hispanic Established Population for the Epidemiologic Study of the Elderly (EPESE) survey were used to examine the main effects and interaction effects of diabetes and depressive symptoms (measured with the Center for Epidemiologic Study of Depression) or clinical diagnostic criteria (measured with the Composite International Diagnostic Interview Depression Module) on the development of macrovascular complications (including cardiovascular disease, stroke, and kidney disease), microvascular complications (including nephropathy, neuropathy, retinopathy, and amputations), functional disability, and mortality over 7 years in a sample of 2,830 Mexican Americans aged ≥65 years. RESULTS —The interaction of diabetes and depression was found to be synergistic, predicting greater mortality, greater incidence of both macro- and microvascular complications, and greater incidence of disability in activities of daily living, even when controlling for sociodemographic characteristics such as sex, age, education, acculturation, and marital status. Importantly, this interaction was found to predict not only greater incidence but also earlier incidence of adverse events in older adults. CONCLUSIONS —Whether a marker for underlying disease severity, an indicator of diminished self-care motivation, or the result of physiologic changes, the interaction of depression and diabetes has a synergistic effect on the health of older Mexican Americans, increasing the risk for poor outcomes. This is of particular clinical importance because although depression is often underrecognized in older adults, effective treatment is available and can result in improved medical outcomes.