IL-17A and IL-17F repair HIV-1 gp140 damaged Caco-2 cell barriers by upregulating tight junction genes

Molecular characteristics of rhesus macaque interferon-lambda receptor 1 (mmuIFNLR1): Sequence identity, distribution and alteration after simian-human immunodeficiency virus infection in the skin and buccal mucosa

Interferon-lambda receptor 1 (IFNLR1) is the key to interferon-lambda's biological activities. Rhesus macaques (Macaca mulatta) are supposedly more suitable for translational studies on interferon lambda-associated human diseases, yet little is known about their IFNLR1 (mmuIFNLR1). In this study, we cloned the coding sequence of mmuIFNLR1, examined its variants, and determined the distribution of mmuIFNLR1 mRNA and immunoreactivity in the buccal mucosa and arm skin of normal and immunodeficiency virus (SHIV/SIV) infected rhesus macaques. It was found that mmuIFNLR1 has 93.1% amino acid sequence identity to that of humans; all the amino acid residues of mmuIFNLR1 signal peptide, transmembrane region, PxxLxF motif and those essential for ligand binding are identical to that of humans; 6 variants of mmuIFNLR1, including the ones corresponding to that of humans were detected; IFNLR1 immunoreactivity was localized in primarily the epithelia of buccal mucosa and arm skin; SHIV/SIV infection could affect the levels of mmuIFNLR1 mRNA and immunoreactivity. These data expanded our knowledge on mmuIFNLR1 and provided a scientific basis for rational use of rhesus macaques in studies of IFN-λ associated human diseases like AIDS. Future studies testing IFNLR1-targeting therapeutics in rhesus macaques were warranted.

Mechanisms of mucosal immunity at the female reproductive tract involved in defense against HIV infection

Human immunodeficiency virus-1 remains a major global health threat. Since the virus is often transmitted through sexual intercourse and women account for the majority of new infections within the most endemic regions, research on mucosal immunity at the female reproductive tract (FRT) is of paramount importance. At the FRT, there are intrinsic barriers to HIV-1 infection, such as epithelial cells and the microbiome, and immune cells of both the innate and adaptive arms are prepared to respond in case the virus overcomes the first line of defense. In this review, we discuss recent findings on FRT mucosal mechanisms of HIV-1 defense and highlight research gaps. While defense from HIV-1 infection at the FRT has been understudied, current and future research is essential to develop new therapeutics and vaccines that can protect this unique mucosal site from HIV-1.

Human TFF2-Fc fusion protein alleviates DSS-induced ulcerative colitis in C57BL/6 mice by promoting intestinal epithelial cells repair and inhibiting macrophage inflammation

The clinical drugs for ulcerative colitis mainly affect the inflammatory symposiums with limited outcomes and various side effects. Repairing the damaged intestinal mucosa is a promising and alternative strategy to treat ulcerative colitis. Trefoil factor family 2 (TFF2) could repair the intestinal mucosa, however, it has a short half-life in vivo. To improve the stability of TFF2, we have prepared a new fusion protein TFF2-Fc with much stability, investigated the therapeutic effect of TFF2-Fc on ulcerative colitis, and further illustrated the related mechanisms. We found that intrarectally administered TFF2-Fc alleviated the weight loss, the colon shortening, the disease activity index, the intestinal tissue injury, and the lymphocyte infiltration in dextran sulfate sodium (DSS)-induced colitis mice. In vitro, TFF2-Fc inhibited Caco2 cells injury and apoptosis, promoted cellular migration, and increased the expression of Occludin and ZO-1 by activating P-ERK in the presence of H₂O₂ or inflammatory conditioned medium (LPS-RAW264.7/CM). Moreover, TFF2-Fc could reduce lipopolysaccharide (LPS)-induced production of inflammation cytokines and reactive oxygen species in RAW264.7 cells, and also inhibits the polarization of RAW264.7 cells to M1 phenotype by reducing glucose consumption and lactate production. Taken together, in this work, we have prepared a novel fusion protein TFF2-Fc, which could alleviate ulcerative colitis in vivo via promoting intestinal epithelial cells repair and inhibiting macrophage inflammation, and TFF2-Fc might serve as a promising ulcerative colitis therapeutic agent.

Cytokines and intestinal epithelial permeability: A systematic review

BACKGROUND

The intestinal mucosa is composed of a well-organized epithelium, acting as a physical barrier to harmful luminal contents, while simultaneously ensuring absorption of physiological nutrients and solutes. Increased intestinal permeability has been described in various chronic diseases, leading to abnormal activation of subepithelial immune cells and overproduction of inflammatory mediators. This review aimed to summarize and evaluate the effects of cytokines on intestinal permeability.

METHODS

A systematic review of the literature was performed in the Medline, Cochrane and Embase databases, up to 01/04/2022, to identify published studies assessing the direct effect of cytokines on intestinal permeability. We collected data on the study design, the method of assessment of intestinal permeability, the type of intervention and the subsequent effect on gut permeability.

RESULTS

A total of 120 publications were included, describing a total of 89 in vitro and 44 in vivo studies. TNFα, IFNγ or IL-1β were the most frequently studied cytokines, inducing an increase in intestinal permeability through a myosin light-chain-mediated mechanism. In situations associated with intestinal barrier disruption, such as inflammatory bowel diseases, in vivo studies showed that anti-TNFα treatment decreased intestinal permeability while achieving clinical recovery. In contrast to TNFα, IL-10 decreased permeability in conditions associated with intestinal hyperpermeability. For some cytokines (e.g. IL-17, IL-23), results are conflicting, with both an increase and a decrease in gut permeability reported, depending on the study model, methodology, or the studied conditions (e.g. burn injury, colitis, ischemia, sepsis).

CONCLUSION

This systematic review provides evidence that intestinal permeability can be directly influenced by cytokines in numerous conditions. The immune environment probably plays an important role, given the variability of their effect, according to different conditions. A better understanding of these mechanisms could open new therapeutic perspectives for disorders associated with gut barrier dysfunction.

Tight Junctions, the Key Factor in Virus-Related Disease

Tight junctions (TJs) are highly specialized membrane structural domains that hold cells together and form a continuous intercellular barrier in epithelial cells. TJs regulate paracellular permeability and participate in various cellular signaling pathways. As physical barriers, TJs can block viral entry into host cells; however, viruses use a variety of strategies to circumvent this barrier to facilitate their infection. This paper summarizes how viruses evade various barriers during infection by regulating the expression of TJs to facilitate their own entry into the organism causing infection, which will help to develop drugs targeting TJs to contain virus-related disease.

Baicalin Alleviates Short-Term Lincomycin-Induced Intestinal and Liver Injury and Inflammation in Infant Mice

The adverse effects of short-term megadose of antibiotics exposure on the gastrointestinal and liver tissue reactions in young children have been reported. Antibiotic-induced intestinal and liver reactions are usually unpredictable and present a poorly understood pathogenesis. It is, therefore, necessary to develop strategies for reducing the adverse effects of antibiotics. Studies on the harm and rescue measures of antibiotics from the perspective of the gut–liver system are lacking. Here, we demonstrate that lincomycin exposure reduced body weight, disrupted the composition of gut microbiota and intestinal morphology, triggered immune-mediated injury and inflammation, caused liver dysfunction, and affected lipid metabolism. However, baicalin administration attenuated the lincomycin-induced changes. Transcriptome analysis showed that baicalin improved immunity in mice, as evidenced by the decreased levels of intestinal inflammatory cytokines and expression of genes that regulate Th1, Th2, and Th17 cell differentiation, and inhibited mucin type O-glycan biosynthesis pathways. In addition, baicalin improved liver function by upregulating the expression of genes involved in bile acid secretion and lipid degradation, and downregulating genes involved in lipid synthesis in lincomycin-treated mice. Bile acids can regulate intestinal immunity and strengthen hepatoenteric circulation. In addition, baicalin also improved anti-inflammatory bacteria abundance (Blautia and Coprobacillus) and reduced pathogenic bacteria abundance (Proteobacteria, Klebsiella, and Citrobacter) in lincomycin-treated mice. Thus, baicalin can ameliorate antibiotic-induced injury and its associated complications such as liver disease.

Transmission routes of human immunodeficiency virus and affecting factors

Acquired immunodeficiency syndrome (AIDS) was first reported more than 30 years ago among homosexuals in the United States. The epidemiology of this disease indicates that there are three modes of transmission: Blood, mother-to-child, and sexual contact transmission. The pathogen of AIDS is human immunodeficiency virus (HIV), primarily HIV-1. HIV-1 could not break through the structurally and functionally integral skin, and primarily invades the human body through the mucosa irrespective of their integrity. Therefore, the mucosae are the natural transmission routes for HIV-1. The mucosae involved in HIV-1 transmission include the mucosae of the gastrointestinal tract and the urogenital tract. The risks of HIV-1 transmission vary significantly between mucosal sites and individuals, and are associated with mucosal integrity, abundance of target cells, immune status of the host, commensal microbes, and host genetic background. Many factors are closely related to the barrier function of the mucosa, and studies on their roles in HIV-1 invasion could promote the prevention and control of mucosal transmission of HIV-1.

Molecular cloning, expression and biological activity of rhesus macaque interleukin-17A and interleukin-17F

Interleukin-17A (IL-17A) and interleukin-17F (IL-17F) as two potent proinflammatory cytokines and the signature cytokines of Th17 cells play important roles in human autoimmune diseases, inflammation and host defenses. In this study, rhesus macaque IL-17A (rhIL-17A) and IL-17F (rhIL-17F) were cloned and expressed, and their biological activities and in vivo distribution were examined. The resulting data showed that both the rhIL-17A and rhIL-17F genes were consisted of three exons and two introns. RhIL-17A and rhIL-17F shared 96.8% and 93.9% amino acid sequence identity with human IL-17A (huIL-17A) and IL-17F (huIL-17F) respectively and the sequences also shared one N-glycosylation site and six conserved cysteine residues with huIL-17A and huIL-17F. IL-17A and IL-17F transcripts were highly expressed in lymphoid tissues and the intestinal tract of rhesus macaques. Functionally, recombinant rhIL-17A and rhIL-17F showed similar effect on Act1 levels and NF-κB phosphorylation compared with that of commercial human IL-17A and IL-17F. Moreover, the antibacterial proteins (such as β-defensin 2, S100A8, S100A9, RegIIIα and Muc1) and the tight junction associated genes (including CLDN1, CLDN4, OCLN, and ZO1) expressed by Caco-2 cells were largely enhanced after treatment with rhIL-17A and rhIL-17F. Meanwhile, purified rhIL-17A and rhIL-17F could also induce the expression of IL-6 and TNF-α by THP-1 cells. These data indicated that rhesus macaque IL-17A and IL-17F are highly similar to that of humans in both structure and function. Studies on rhIL-17A/rhIL-17F are promising approach to contribute to the understanding of human IL-17A and IL-17F-related intestinal diseases.