SummaryFibrosis in response to tissue damage or persistent inflammation is a pathological hallmark of many chronic degenerative diseases. By using a model of acute peritoneal inflammation, we have examined how repeated inflammatory activation promotes fibrotic tissue injury. In this context, fibrosis was strictly dependent on interleukin-6 (IL-6). Repeat inflammation induced IL-6-mediated T helper 1 (Th1) cell effector commitment and the emergence of STAT1 (signal transducer and activator of transcription-1) activity within the peritoneal membrane. Fibrosis was not observed in mice lacking interferon-γ (IFN-γ), STAT1, or RAG-1. Here, IFN-γ and STAT1 signaling disrupted the turnover of extracellular matrix by metalloproteases. Whereas IL-6-deficient mice resisted fibrosis, transfer of polarized Th1 cells or inhibition of MMP activity reversed this outcome. Thus, IL-6 causes compromised tissue repair by shifting acute inflammation into a more chronic profibrotic state through induction of Th1 cell responses as a consequence of recurrent inflammation.

Deep learning for protein interactions The use of deep learning has revolutionized the field of protein modeling. Humphreys et al . combined this approach with proteome-wide, coevolution-guided protein interaction identification to conduct a large-scale screen of protein-protein interactions in yeast (see the Perspective by Pereira and Schwede). The authors generated predicted interactions and accurate structures for complexes spanning key biological processes in Saccharomyces cerevisiae . The complexes include larger protein assemblies such as trimers, tetramers, and pentamers and provide insights into biological function. —VV

cytokines ͉ immune evasion ͉ T lymphocytes ͉ costimulation E fficient activation and differentiation of T cells depends on recognition of antigen and cooperating signals (cosignaling) that provoke either positive or inhibitory effects. Inhibitory pathways help maintain immune tolerance to self tissues. In the absence of inhibitory signals or with sustained positive cosignaling, tolerance can be overridden, leading to autoimmune responses. Two major groups of cosignaling receptors are recognized, those with an Ig-like fold, such as CTLA-4 (1), CD28 (2), PD1 (3), and B and T lymphocyte attenuator (BTLA) (4, 5), and those belonging to the TNF receptor (TNFR) superfamily, including OX40, 41BB, CD27, CD30, and herpesvirus entry mediator (HVEM; TNFR superfamily 14) among others (6-9). Generally, positive cosignaling receptors in the Ig family act by sustaining antigen receptor-associated kinase activity, whereas their inhibitory counterparts contain an immunoreceptor tyrosine-based inhibitory motif that recruits phosphatases [e.g., Src homology 2 (SH2) domain phosphatase-1; SH2 domaincontaining inositol polyphosphate 5-phosphatase] attenuating antigen receptor signaling (1, 2, 10). By contrast, the cosignaling TNFRs activate serine kinases promoting expression of survival and proinflammatory genes through the transcription factors NF-B and activator protein 1, whereas some other TNFRs induce apoptosis, negatively regulating T cells by cellular elimination (6).A unique inhibitory cosignaling pathway for T cells was recently defined (11,12), which involves the engagement of BTLA by HVEM, connecting the Ig and TNFR cosignaling families. HVEM binding activates tyrosine phosphorylation of the immunoreceptor tyrosine-based inhibitory motif in BTLA and induces the association with the protein tyrosine phosphatases Src homology domain 1 and 2 required for inhibitory signaling (13). However, HVEM can also act as a positive cosignaling receptor (reviewed in ref. 8) by binding TNF-related ligands LIGHT (TNF superfamily 14) and lymphotoxin ␣ (LT␣, TNF superfamily 2) (14). A fourth ligand of HVEM is envelope glycoprotein D (gD) of herpes simplex virus (HSV; ␣-herpesvirus) from which its name was derived (15, 16).Thus, HVEM has the potential to serve as a molecular switch mediating either positive or inhibitory signaling, depending on which of its four ligands are bound. Moreover, the directionality of signaling is not clear, as the hierarchy of ligand occupancy and relative affinities of the interactors are not well defined. The N-terminal extracellular region of HVEM is composed of four pseudorepeats of a cysteine-rich domain (CRD), characteristic of the TNFR superfamily; each repeat contains three disulfide bonds that fold into complex loops depending in part on the spacing of the cysteines (17). Mutagenesis studies (18) . Domain-swapping experiments revealed the CRD1 of HVEM was sufficient to mediate BTLA binding (11). These observations raised the issue of the location of the BTLA binding site relative to gD and LIGHT.Here, w...

Pancreatic cancer is one of the most common invasive malignancies and the fourth leading cause of cancer related mortality in U.S., thus developing new strategies to control pancreatic cancer is an important mission. We investigated the mechanism of capsaicin, the major pungent ingredient of red-chili pepper, in inducing apoptosis in pancreatic cancer cells. Treatment of AsPC-1 and BxPC-3 cells with capsaicin resulted in a dose-dependent inhibition of cell-viability and induction of apoptosis which was associated with the generation of ROS and persistent disruption of mitochondrial membrane potential. These effects were significantly blocked when the cells were pretreated with a general antioxidant N-acetyl cysteine (NAC). Exposure of AsPC-1 and BxPC-3 cells to capsaicin was also associated with increased expression of Bax, down-regulation of bcl-2, survivin and significant release of cytochrome c and AIF in the cytosol. On the contrary, above-mentioned effects were not observed in the normal acinar cells in response to capsaicin-treatment. Capsaicin-treatment resulted in the activation of JNK and JNK inhibitor SP600125 afforded protection against capsaicin-induced apoptosis. Furthermore, capsaicin when given orally markedly suppressed the growth of AsPC-1 pancreatic tumor xenografts in athymic nude mice, without side effects. Tumors from capsaicin treated mice demonstrated increased apoptosis, which was related to the activation of JNK and increased cytosolic protein expression of Bax, cytochrome c, AIF and cleaved caspase-3, as compared with controls. Taken together, these results show that capsaicin is an effective inhibitor of in vitro and in vivo growth of pancreatic cancer cells. These findings provide the rationale for further clinical investigation of capsaicin against pancreatic cancer.

Emerging studies increasingly demonstrate the importance of the throat and salivary glands as sites of virus replication and transmission in early COVID-19 disease. SARS-CoV-2 is an enveloped virus, characterized by an outer lipid membrane derived from the host cell from which it buds. While it is highly sensitive to agents that disrupt lipid biomembranes, there has been no discussion about the potential role of oral rinsing in preventing transmission. Here, we review known mechanisms of viral lipid membrane disruption by widely available dental mouthwash components that include ethanol, chlorhexidine, cetylpyridinium chloride, hydrogen peroxide, and povidone-iodine. We also assess existing formulations for their potential ability to disrupt the SARS-CoV-2 lipid envelope, based on their concentrations of these agents, and conclude that several deserve clinical evaluation. We highlight that already published research on other enveloped viruses, including coronaviruses, directly supports the idea that oral rinsing should be considered as a potential way to reduce transmission of SARS-CoV-2. Research to test this could include evaluating existing or specifically tailored new formulations in well-designed viral inactivation assays, then in clinical trials. Population-based interventions could be undertaken with available mouthwashes, with active monitoring of outcome to determine efficacy. This is an under-researched area of major clinical need.

The salivary glands represent a major site of cytomegalovirus replication and transmission to other hosts. Despite control of viral infection by strong T cell responses in visceral organs cytomegalovirus replication continues in the salivary glands of mice, suggesting that the virus exploits the mucosal microenvironment. Here, we show that T cell immunity in the salivary glands is limited by the induction of CD4 T cells expressing the regulatory cytokine interleukin (IL)-10. Blockade of IL-10 receptor (IL-10R) with an antagonist antibody dramatically reduced viral load in the salivary glands, but not in the spleen. The mucosa-specific protection afforded by IL-10R blockade was associated with an increased accumulation of CD4 T cells expressing interferon γ, suggesting that IL-10R signaling limits effector T cell differentiation. Consistent with this, an agonist antibody targeting the tumor necrosis factor receptor superfamily member OX40 (TNFRSF4) enhanced effector T cell differentiation and increased the number of interferon γ–producing T cells, thus limiting virus replication in the salivary glands. Collectively, the results indicate that modulating effector T cell differentiation can counteract pathogen exploitation of the mucosa, thus limiting persistent virus replication and transmission.

Respiratory infections are the third leading cause of death worldwide. Illness is caused by pathogen replication and disruption of airway homeostasis by excessive expansion of cell numbers. One strategy to prevent lung immune–mediated damage involves reducing the cellular burden. To date, antiinflammatory strategies have affected both antigen-specific and naive immune repertoires. Here we report a novel form of immune intervention that specifically targets recently activated T cells alone. OX40 (CD134) is absent on naive T cells but up-regulated 1–2 d after antigen activation. OX40–immunoglobulin fusion proteins block the interaction of OX40 with its ligand on antigen-presenting cells and eliminate weight loss and cachexia without preventing virus clearance. Reduced proliferation and enhanced apoptosis of lung cells accompanied the improved clinical phenotype. Manipulation of this late costimulatory pathway has clear therapeutic potential for the treatment of dysregulated lung immune responses.

SummarySince the development of vaccinia virus as a vaccine vector in 1984, the utility of numerous viruses in vaccination strategies has been explored. In recent years, key improvements to existing vectors such as those based on adenovirus have led to significant improvements in immunogenicity and efficacy. Furthermore, exciting new vectors that exploit viruses such as cytomegalovirus (CMV) and vesicular stomatitis virus (VSV) have emerged. Herein, we summarize these recent developments in viral vector technologies, focusing on novel vectors based on CMV, VSV, measles and modified adenovirus. We discuss the potential utility of these exciting approaches in eliciting protection against infectious diseases.