Bromelain inhibits SARS-CoV-2 infection via targeting ACE-2, TMPRSS2, and spike protein

The new coronavirus, SARS-CoV-2, transmits rapidly from human-to-human resulting in the ongoing pandemic. SARS-CoV-2 infects angiotensin-converting enzyme 2 (ACE-2) expressing lung, heart, kidney, intestine, gall bladder, and testicular tissues of patients, leading to organ failure and sometimes death.1, 2 Currently, COVID-19 patients are treated with different agents, including favilavir, remdesivir, chloroquine, hydroxychloroquine, lopinavir, darunavir, and tocilizumab.3, 4 However, the safety and efficacy of those drugs against COVID-19 still need further confirmation by randomized clinical trials. Hence, there is an emergent need to repurpose the existing drugs or develop new virus-based and host-based antivirals against SARS-CoV-2. Bromelain is a cysteine protease isolated from pineapple stem and is used as a dietary supplement for treating patients with pain, inflammation,5 thrombosis,6 and cancerPeer Reviewe

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-β. 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

Discordance Between Peripheral and Colonic Markers of Inflammation During Suppressive ART

ObjectivePersistent 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.DesignImmunologic 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).MethodsPeripheral blood and rectosigmoid colon biopsies were analyzed by flow cytometry, enzyme-linked immunosorbent assay, and quantitative polymerase chain reaction.ResultsNonresponders 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.ConclusionsThese 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

Bromelain inhibits SARS‐CoV‐2 infection via targeting ACE‐2, TMPRSS2, and spike protein

The new coronavirus, SARS-CoV-2, transmits rapidly from human-to-human resulting in the ongoing pandemic. SARS-CoV-2 infects angiotensin-converting enzyme 2 (ACE-2) expressing lung, heart, kidney, intestine, gall bladder, and testicular tissues of patients, leading to organ failure and sometimes death.1, 2 Currently, COVID-19 patients are treated with different agents, including favilavir, remdesivir, chloroquine, hydroxychloroquine, lopinavir, darunavir, and tocilizumab.3, 4 However, the safety and efficacy of those drugs against COVID-19 still need further confirmation by randomized clinical trials. Hence, there is an emergent need to repurpose the existing drugs or develop new virus-based and host-based antivirals against SARS-CoV-2. Bromelain is a cysteine protease isolated from pineapple stem and is used as a dietary supplement for treating patients with pain, inflammation,5 thrombosis,6 and cancerPeer Reviewe

IL-4 induces Stat6-dependent Raldh2 expression in macrophages <i>in vitro</i> and <i>in vivo</i>.

<p>(<b>A</b>) qRT-PCR analysis of cytokine-treated bone marrow-derived macrophages from WT and Stat6^−/− mice. Expression is normalized to HPRT and presented as a fold-change above untreated cells. (<b>B, C</b>) qRT-PCR analysis of peritoneal macrophages elicited by i.p. administration of thioglycollate (TG) and/or IL-4 complexes (IL-4c) from WT and Stat6^−/− mice. Expression is normalized to GAPDH. n = 2–4 mice per group. Error bars illustrate SEM; #p<0.001. <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1002883#s2" target="_blank">Results</a> are representative of two (B) or three (A) independent experiments.</p

Vitamin A deficiency impairs <i>S. mansoni</i>-elicited Th2 responses.

<p>(<b>A</b>) Quantification of <i>S. mansoni</i> eggs deposited per gram of liver. (<b>B–D</b>) Histopathology of liver tissue sections stained with hemotoxylin and eosin and evaluated for granuloma volume (B), eosinophil infiltration (C), and microvesicular liver damage (D). (<b>E</b>) Flow cytometric analysis of intracellular cytokines expressed by cells harvested from the liver and colon following a 5-hour stimulation with PMA and ionomycin in the presence of brefeldin A. Representative contour plots are gated on live CD4⁺ T cells. n = 3–5 mice per group. (<b>F</b>) Cytometric bead array analysis of cytokine concentrations in culture supernatants. 3×10⁵ hepatic leukocytes harvested from <i>S. mansoni</i>-infected (Inf) and control (Cont) mice were cultured for 72 hours in the presence of egg homogenate (50 µg/mL), adult worm homogenate (50 µg/mL), or media alone. n = 3–4 mice per group. (<b>G</b>) qRT-PCR analysis of cytokine expression in hepatic leukocytes. Expression is normalized to HPRT. n = 3–5 mice per group. Error bars illustrate SEM; *p<0.05, **p<0.01, #p<0.001. <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1002883#s2" target="_blank">Results</a> are representative of two (A–D) or three (E, G) independent experiments.</p

Type-2 inflammatory cells express Raldh2 and Raldh3, with Raldh2 most highly expressed in macrophages.

<p>(<b>A</b>) qRT-PCR analysis of retinal dehydrogenase (Raldh) expression (isoforms 1–3) in hepatic inflammatory infiltrates. Expression is normalized to HPRT and presented as fold-change above the average expression in LCMV samples. n = 3–5 mice per group. (<b>B</b>) Fluorescence microscopy of a hepatic granuloma co-stained with antibodies recognizing CD11b (green) and Raldh (red). Arrows point to cells within granulomas that co-stain for CD11b and Raldh. Scale bar = 50 µm. (<b>C</b>) qRT-PCR analysis of Raldh isoform expression in sorted macrophages (Mac), eosinophils (Eos), and T cells. Expression levels were normalized and presented relative to HPRT expression. Expression levels of Raldh isoforms are presented here on the same scale (different from panel A) in order to illustrate that Raldh2 is the most highly expressed isoform. Hepatic leukocytes from <i>S. mansoni</i>-infected mice were pre-sorted by microbead selection of Siglec-F⁺ cells. Cell fractions were then sorted to >90% purity by FACS, according to the gating strategy shown. A modified Giemsa stain demonstrated the expected morphology of sorted cells. n = 3 mice per group. Error bars illustrate SEM; #p<0.001. <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1002883#s2" target="_blank">Results</a> are representative of two (C) or three (A, B) independent experiments.</p

Retinoid-dependent CCR9 expression is variably induced during infection.

<p>Flow cytometric analysis of cells harvested at 7 weeks (<i>S. mansoni</i>) or 7 days (LCMV) post-infection (p.i.) from A+ or A− mice. Representative contour plots are gated on live CD4⁺ T cells. n = 3–5 mice per group. Error bars illustrate SEM; *p<0.05, **p<0.01, #p<0.001. <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1002883#s2" target="_blank">Results</a> are representative of three independent experiments. MLN = mesenteric lymph node.</p