Transforming growth factor-β signaling (TGF-β) maintains a balanced physiological function including cell growth, differentiation, and proliferation and regulation of immune system by modulating either SMAD2/3 and SMAD7 (SMAD-dependent) or SMAD-independent signaling pathways under normal conditions. Increased production of TGF-β promotes immunosuppression in Human Immunodeficiency Virus (HIV)/Simian Immunodeficiency Virus (SIV) infection. However, the cellular source and downstream events of increased TGF-β production that attributes to its pathological manifestations remain unknown. Here, we have shown increased production of TGF-β in a majority of intestinal CD3−CD20−CD68+ cells from acute and chronically SIV infected rhesus macaques, which negatively correlated with the frequency of jejunum CD4+ T cells. No significant changes in intestinal TGF-β receptor II expression were observed but increased production of the pSMAD2/3 protein and SMAD3 gene expression in jejunum tissues that were accompanied by a downregulation of SMAD7 protein and gene expression. Enhanced TGF-β production by intestinal CD3−CD20−CD68+ cells and increased TGF-β/SMAD-dependent signaling might be due to a disruption of a negative feedback loop mediated by SMAD7. This suggests that SIV infection impacts the SMAD-dependent signaling pathway of TGF-β and provides a potential framework for further study to understand the role of viral factor(s) in modulating TGF-β production and downregulating SMAD7 expression in SIV. Regulation of mucosal TGF-β expression by therapeutic TGF-β blockers may help to create effective antiviral mucosal immune responses.

Epithelial cell injury and impaired epithelial regeneration are considered key features in HIV pathogenesis and contribute to HIV-induced generalized immune activation. Understanding the molecular mechanisms underlying the disrupted epithelial regeneration might provide an alternative approach for the treatment of HIV-mediated enteropathy and immune activation. We have observed a significant increased presence of α defensin5+ (HD5) Paneth cells and proliferating Ki67+ epithelial cells as well as decreased expression of E-cadherin expression in epithelial cells during SIV infection. SIV infection did not significantly influence the frequency of LGR5+ stem cells, but the frequency of HD5+ cells was significantly higher compared to uninfected controls in jejunum. Our global transcriptomics analysis of enteroids provided novel information about highly significant changes in several important pathways like metabolic, TCA cycle, and oxidative phosphorylation, where the majority of the differentially expressed genes were downregulated in enteroids grown from chronically SIV-infected macaques compared to the SIV-uninfected controls. Despite the lack of significant reduction in LGR5+ stem cell population, the dysregulation of several intestinal stem cell niche factors including Notch, mTOR, AMPK and Wnt pathways as well as persistence of inflammatory cytokines and chemokines and loss of epithelial barrier function in enteroids further supports that SIV infection impacts on epithelial cell proliferation and intestinal homeostasis.

No abstract

One key advantage of properly performed formalin‐based embalming is that quality and duration of tissue preservation is very good. This advantage is however associated with the need for specialized equipment, effective approved ventilation systems in preparation and dissecting environments, as well as regulated air monitoring and chemical disposal protocols for formaldehyde. As part of a study of methods to reduce levels of formaldehyde in air while preserving tissue quality, formalin‐embalmed gross anatomy specimens were pre‐soaked and dissected under water. This report describes the effect on both the quality of tissue preservation and dissection of upper limb specimens. Sections of upper limbs that had been embalmed in 10% formalin for at least 90 days were immersed in water for 12 or 48 hours (water was changed after 24 hours). Following pre‐soaking in water, specimens were dissected under water using standard dissecting instruments to expose muscles in the forearm and hand. One upper limb specimen did not receive water treatment and was dissected normally in air for comparison. The dissecting experience under water was technically less challenging (easier than normal dissecting in air), less force was required to reflect skin, and tissue quality and appearance of specimens dissected under water were significantly enhanced when compared to untreated specimens dissected in the normal manner. Our findings suggest that over a seven‐month period, water immersion treatment of formalin‐embalmed limbs does not affect quality of tissue preservation, did not result in tissue swelling or development of mold, and facilitated the production of high quality prosected specimens for teaching. This approach is cost effective and environmentally safe.Support or Funding InformationNone