Upregulation of retinal dehydrogenase 2 in alternatively activated macrophages during retinoid-dependent type-2 immunity to helminth infection in mice.

Although the vitamin A metabolite retinoic acid (RA) plays a critical role in immune function, RA synthesis during infection is poorly understood. Here, we show that retinal dehydrogenases (Raldh), required for the synthesis of RA, are induced during a retinoid-dependent type-2 immune response elicited by Schistosoma mansoni infection, but not during a retinoid-independent anti-viral immune response. Vitamin A deficient mice have a selective defect in T(H)2 responses to S. mansoni, but retained normal LCMV specific T(H)1 responses. A combination of in situ imaging, intra-vital imaging, and sort purification revealed that alternatively activated macrophages (AAMφ) express high levels of Raldh2 during S. mansoni infection. IL-4 induces Raldh2 expression in bone marrow-derived macrophages in vitro and peritoneal macrophages in vivo. Finally, in vivo derived AAMφ have an enhanced capacity to induce Foxp3 expression in CD4+ cells through an RA dependent mechanism, especially in combination with TGF-ß. The regulation of Raldh enzymes during infection is pathogen specific and reflects differential requirements for RA during effector responses. Specifically, AAMφ are an inducible source of RA synthesis during helminth infections and T(H)2 responses that may be important in regulating immune responses.

CyDisCo production of functional recombinant SARS-CoV-2 spike receptor binding domain.

The COVID-19 pandemic caused by SARS-CoV-2 has applied significant pressure on overtaxed healthcare around the world, underscoring the urgent need for rapid diagnosis and treatment. We have developed a bacterial strategy for the expression and purification of a SARS-CoV-2 spike protein receptor binding domain (RBD) that includes the SD1 domain. Bacterial cytoplasm is a reductive environment, which is problematic when the recombinant protein of interest requires complicated folding and/or processing. The use of the CyDisCo system (cytoplasmic disulfide bond formation in E. coli) bypasses this issue by pre-expressing a sulfhydryl oxidase and a disulfide isomerase, allowing the recombinant protein to be correctly folded with disulfide bonds for protein integrity and functionality. We show that it is possible to quickly and inexpensively produce an active RBD in bacteria that is capable of recognizing and binding to the ACE2 (angiotensin-converting enzyme) receptor as well as antibodies in COVID-19 patient sera.

Bromelain Inhibits SARS-CoV-2 Infection in VeroE6 Cells.

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). The initial interaction between Transmembrane Serine Protease 2 (TMPRSS2) primed SARS-CoV-2 spike (S) protein and host cell receptor angiotensin-converting enzyme 2 (ACE-2) is a pre-requisite step for this novel coronavirus pathogenesis. Here, we expressed a GFP-tagged SARS-CoV-2 S-Ectodomain in Tni insect cells. That contained sialic acid-enriched N- and O-glycans. Surface resonance plasmon (SPR) and Luminex assay showed that the purified S-Ectodomain binding to human ACE-2 and immunoreactivity with COVID-19 positive samples. We demonstrate that bromelain (isolated from pineapple stem and used as a dietary supplement) treatment diminishes the expression of ACE-2 and TMPRSS2 in VeroE6 cells and dramatically lowers the expression of S-Ectodomain. Importantly, bromelain treatment reduced the interaction between S-Ectodomain and VeroE6 cells. Most importantly, bromelain treatment significantly diminished the SARS-CoV-2 infection in VeroE6 cells. Altogether, our results suggest that bromelain or bromelain rich pineapple stem may be used as an antiviral against COVID-19. HIGHLIGHTS: Bromelain inhibits / cleaves the expression of ACE-2 and TMPRSS2Bromelain cleaves / degrades SARS-CoV-2 spike proteinBromelain inhibits S-Ectodomain binding and SARS-CoV-2 infection.

Discordance between peripheral and colonic markers of inflammation during suppressive ART.

OBJECTIVE: Persistent systemic inflammation is associated with the inability of some HIV-infected patients to normalize circulating CD4 T-cell levels after years of suppressive antiretroviral therapy. In this study, we sought to understand whether such systemic inflammation is also associated with detectable signs of inflammation in biopsies from the rectosigmoid colon. DESIGN: Immunologic and virological parameters were studied in the peripheral blood and in rectosigmoid colon biopsies from individuals with viral suppression for at least 2 years and with peripheral CD4 T-cell levels of <350 cells per cubic millimeter (immunologic nonresponders, n = 18) or >500 cells per cubic millimeter (immunologic responders, n = 16). METHODS: Peripheral blood and rectosigmoid colon biopsies were analyzed by flow cytometry, enzyme-linked immunosorbent assay, and quantitative polymerase chain reaction. RESULTS: Nonresponders had elevated T-cell activation and inflammatory cytokines in the circulation, but inflammatory gene expression in colon biopsies was not different as compared with responders, and there was little relationship between blood and colon markers of inflammation. Blood inflammatory markers were positively associated with soluble CD14 levels indicative of monocyte activation. CONCLUSIONS: These findings demonstrate that, in the context of treated HIV disease, it is easier to detect parameters of inflammation (including blood monocyte activation) in the peripheral blood than in isolated rectosigmoid colon biopsies. Accordingly, interventions to block such inflammation in this population might be most conveniently and accurately assessed in blood.

Dysbiosis of the gut microbiota is associated with HIV disease progression and tryptophan catabolism.

Progressive HIV infection is characterized by dysregulation of the intestinal immune barrier, translocation of immunostimulatory microbial products, and chronic systemic inflammation that is thought to drive progression of disease to AIDS. Elements of this pathologic process persist despite viral suppression during highly active antiretroviral therapy (HAART), and drivers of these phenomena remain poorly understood. Disrupted intestinal immunity can precipitate dysbiosis that induces chronic inflammation in the mucosa and periphery of mice. However, putative microbial drivers of HIV-associated immunopathology versus recovery have not been identified in humans. Using high-resolution bacterial community profiling, we identified a dysbiotic mucosal-adherent community enriched in Proteobacteria and depleted of Bacteroidia members that was associated with markers of mucosal immune disruption, T cell activation, and chronic inflammation in HIV-infected subjects. Furthermore, this dysbiosis was evident among HIV-infected subjects undergoing HAART, and the extent of dysbiosis correlated with activity of the kynurenine pathway of tryptophan catabolism and plasma concentrations of the inflammatory cytokine interleukin-6 (IL-6), two established markers of disease progression. Gut-resident bacteria with capacity to catabolize tryptophan through the kynurenine pathway were found to be enriched in HIV-infected subjects, strongly correlated with kynurenine levels in HIV-infected subjects, and capable of kynurenine production in vitro. These observations demonstrate a link between mucosal-adherent colonic bacteria and immunopathogenesis during progressive HIV infection that is apparent even in the setting of viral suppression during HAART. This link suggests that gut-resident microbial populations may influence intestinal homeostasis during HIV disease.

Helminthic therapy: improving mucosal barrier function.

The epidemiology of autoimmune diseases and helminth infections led to suggestions that helminths could improve inflammatory conditions, which was then tested using animal models. This has translated to clinical investigations aimed at the safe and controlled reintroduction of helminthic exposure to patients suffering from autoimmune diseases (so-called 'helminthic therapy') in an effort to mitigate the inflammatory response. In this review, we summarize the results of recent clinical trials of helminthic therapy, with particular attention to mechanisms of action. Whereas previous reviews have emphasized immune regulatory mechanisms activated by helminths, we propose that enhancement of mucosal barrier function may have an equally important role in improving conditions of inflammatory bowel diseases.

IL-22+ CD4+ T cells are associated with therapeutic trichuris trichiura infection in an ulcerative colitis patient.

Ulcerative colitis, a type of inflammatory bowel disease, is less common in countries endemic for helminth infections, suggesting that helminth colonization may have the potential to regulate intestinal inflammation in inflammatory bowel diseases. Indeed, therapeutic effects of experimental helminth infection have been reported in both animal models and clinical trials. Here, we provide a comprehensive cellular and molecular portrait of dynamic changes in the intestinal mucosa of an individual who infected himself with Trichuris trichiura to treat his symptoms of ulcerative colitis. Tissue with active colitis had a prominent population of mucosal T helper (T(H)) cells that produced the inflammatory cytokine interleukin-17 (IL-17) but not IL-22, a cytokine involved in mucosal healing. After helminth exposure, the disease went into remission, and IL-22-producing T(H) cells accumulated in the mucosa. Genes involved in carbohydrate and lipid metabolism were up-regulated in helminth-colonized tissue, whereas tissues with active colitis showed up-regulation of proinflammatory genes such as IL-17, IL-13RA2, and CHI3L1. Therefore, T. trichiura colonization of the intestine may reduce symptomatic colitis by promoting goblet cell hyperplasia and mucus production through T(H)2 cytokines and IL-22. Improved understanding of the physiological effects of helminth infection may lead to new therapies for inflammatory bowel diseases.