COVID-19, which is caused by infection with SARS-CoV-2, is characterized by lung pathology and extrapulmonary complications
. Type I interferons (IFNs) have an essential role in the pathogenesis of ...COVID-19 (refs
). Although rapid induction of type I IFNs limits virus propagation, a sustained increase in the levels of type I IFNs in the late phase of the infection is associated with aberrant inflammation and poor clinical outcome
. Here we show that the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, which controls immunity to cytosolic DNA, is a critical driver of aberrant type I IFN responses in COVID-19 (ref.
). Profiling COVID-19 skin manifestations, we uncover a STING-dependent type I IFN signature that is primarily mediated by macrophages adjacent to areas of endothelial cell damage. Moreover, cGAS-STING activity was detected in lung samples from patients with COVID-19 with prominent tissue destruction, and was associated with type I IFN responses. A lung-on-chip model revealed that, in addition to macrophages, infection with SARS-CoV-2 activates cGAS-STING signalling in endothelial cells through mitochondrial DNA release, which leads to cell death and type I IFN production. In mice, pharmacological inhibition of STING reduces severe lung inflammation induced by SARS-CoV-2 and improves disease outcome. Collectively, our study establishes a mechanistic basis of pathological type I IFN responses in COVID-19 and reveals a principle for the development of host-directed therapeutics.
Talimogene laherparepvec (T-VEC) is a genetically modified herpes simplex 1 virus (HSV-1) approved for cancer therapy. We investigate its effect on the clinical, histological, single-cell ...transcriptomic, and immune repertoire level using repeated fine-needle aspirates (FNAs) of injected and noninjected lesions in primary cutaneous B cell lymphoma (pCBCL). Thirteen patients received intralesional T-VEC, 11 of which demonstrate tumor response in the injected lesions. Using single-cell sequencing of the FNAs, we identify the malignant population and separate three pCBCL subtypes. Twenty-four hours after the injection, we detect HSV-1T-VEC transcripts in malignant and nonmalignant cells of the injected lesion but not of the noninjected lesion. Oncolytic virotherapy results in a rapid eradication of malignant cells. It also leads to interferon pathway activation and early influx of natural killer cells, monocytes, and dendritic cells. These events are followed by enrichment in cytotoxic T cells and a decrease of regulatory T cells in injected and noninjected lesions.
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•34 longitudinal samples from oncolytic virotherapy-treated patients analyzed•Malignant population and subtypes of primary cutaneous B cell lymphoma identified•Cell-type-unselective replication and cytopathic effect of oncolytic virotherapy•Rapid reduction of malignant population and tumor microenvironment remodeling
Using single-cell sequencing of longitudinally collected samples from primary cutaneous B cell lymphoma patients treated with oncolytic virotherapy, Ramelyte et al. show that malignant cells can be rapidly eliminated but viral replication is not restricted in malignant cells. In addition, remodeling of tumor microenvironment can happen in both injected and noninjected lesions.
Background Atopic dermatitis (AD) is a T cell–mediated inflammatory skin disease, with TH 2 cells initiating acute flares. This inflamed skin is immediately colonized with Staphylococcus aureus , ...which provides potent Toll-like receptor (TLR) 2 ligands. However, the effect of TLR2 ligands on the development of TH 2-mediated AD inflammation remains unclear. Objective We investigated the progression of TH 2 cell–mediated dermatitis after TLR2 activation. Methods Using models for acute AD with TH 2 cells initiating cutaneous inflammation, we investigated the consequences of TLR2 activation. Dermatitis, as assessed by changes in ear skin thickness and histology, was analyzed in different BALB/c and C57BL/6 wild-type and knockout mouse strains, and immune profiling was carried out by using in vitro and ex vivo cytokine analyses. Results We show that TH 2 cell–mediated dermatitis is self–limiting and depends on IL-4. Activation of TLR2 converted the limited TH 2 dermatitis to chronic cutaneous inflammation. We demonstrate that the concerted activation of TLR2 and IL-4 receptor on dendritic cells is sufficient for this conversion. As an underlying mechanism, we found that the combinatorial sensing of the innate TLR2 ligands and the adaptive TH 2 cytokine IL-4 suppressed anti-inflammatory IL-10 and consequently led to the exacerbation and persistence of dermatitis. Conclusion Our data demonstrate that innate TLR2 signals convert transient TH 2 cell–mediated dermatitis into persistent inflammation, as seen in chronic human AD, through IL-4–mediated suppression of IL-10. For the first time, these data show how initial AD lesions convert to chronic inflammation and provide another rationale for targeting IL-4 in patients with AD, a therapeutic approach that is currently under development.
Heterogeneity of cancer-associated fibroblasts (CAFs) can result from activation of distinct signaling pathways. We show that in primary human dermal fibroblasts (HDFs), fibroblast growth factor ...(FGF) and transforming growth factor β (TGF-β) signaling oppositely modulate multiple CAF effector genes. Genetic abrogation or pharmacological inhibition of either pathway results in induction of genes responsive to the other, with the ETV1 transcription factor mediating the FGF effects. Duality of FGF/TGF-β signaling and differential ETV1 expression occur in multiple CAF strains and fibroblasts of desmoplastic versus non-desmoplastic skin squamous cell carcinomas (SCCs). Functionally, HDFs with opposite TGF-β versus FGF modulation converge on promoting cancer cell proliferation. However, HDFs with increased TGF-β signaling enhance invasive properties and epithelial-mesenchymal transition (EMT) of SCC cells, whereas HDFs with increased FGF signaling promote macrophage infiltration. The findings point to a duality of FGF versus TGF-β signaling in distinct CAF populations that promote cancer development through modulation of different processes.
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•FGF and TGF-β signaling exert opposite control over multiple CAF effector genes•ETV1 transcription factor mediates FGF effects and suppresses those of TGF-β•Modulation of either pathway leads to different tumor-promoting CAF populations•TGF-β-activated CAFs promote EMT, but FGF-activated CAFs increase inflammation
Bordignon et al. show that activation of FGF and TGF-β control opposite key CAF effectors. Suppression of one pathway leads to activation of the other and results in tumor-promoting CAF populations that elicit EMT versus inflammation. FGF/TGF-β dualism applies to distinct CAF subsets in invading desmoplastic versus non-desmoplastic skin SCCs.
T helper type 9 (TH9) cells can mediate tumor immunity and participate in autoimmune and allergic inflammation in mice, but little is known about the TH9 cells that develop in vivo in humans. We ...isolated T cells from human blood and tissues and found that most memory TH9 cells were skin-tropic or skin-resident. Human TH9 cells coexpressed tumor necrosis factor-α and granzyme B and lacked coproduction of TH1/TH2/TH17 cytokines, and many were specific for Candida albicans. Interleukin-9 (IL-9) production was transient and preceded the up-regulation of other inflammatory cytokines. Blocking studies demonstrated that IL-9 was required for maximal production of interferon-γ, IL-9, IL-13, and IL-17 by skin-tropic T cells. IL-9-producing T cells were increased in the skin lesions of psoriasis, suggesting that these cells may contribute to human inflammatory skin disease. Our results indicate that human TH9 cells are a discrete T cell subset, many are tropic for the skin, and although they may function normally to protect against extracellular pathogens, aberrant activation of these cells may contribute to inflammatory diseases of the skin.
The beneficial effects of nonpathogenic bacteria are increasingly being recognized. We reported in a placebo-controlled study with atopic dermatitis (AD) patients that cutaneous exposure to lysates ...of nonpathogenic bacteria alleviates skin inflammation. To now unravel underlying mechanisms, immune consequences of sensing nonpathogenic bacterium Vitreoscilla filiformis lysate (Vf) were characterized analyzing (1) differentiation of dendritic cells (DCs) and, consecutively, (2) effector functions of DCs and T helper (Th) cells in vitro and in a murine model of AD in NC/Nga mice in vivo. Topical treatment with Vf significantly reduced AD-like inflammation in NC/Nga mice. Importantly, cutaneous exposure to Vf in combination with the allergen FITC significantly also reduced subsequent allergen-induced dermatitis indicating active immune modulation. Indeed, innate sensing of Vf predominantly induced IL-10-producing DCs, which was dependent on Toll-like receptor 2 (TLR2) activation. Vf-induced IL-10+ DCs primed naive CD4+ T helper cells to become regulatory IFN-γlow IL-10high Tr1 (type 1 regulatory T) cells. These IL-10high Tr1 cells were also induced by Vf in vivo and strongly suppressed T effector cells and inflammation. In conclusion, we show that innate sensing of nonpathogenic bacteria by TLR2 induces tolerogenic DCs and regulatory Tr1 cells suppressing T effector cells and cutaneous inflammation. These findings indicate a promising therapeutic strategy for inflammatory skin diseases like AD.
Infective endocarditis is a rare but life-threatening condition, occasionally linked to diverse immunologic manifestations, including mixed cryoglobulinemia. This can lead to cryoglobulinemic ...vasculitis, which has the potential for widespread organ damage. Although some cases have highlighted the relationship between infective endocarditis and cryoglobulinemic vasculitis, no comprehensive epidemiological evaluation or optimal treatment strategies have been advanced for such a combination. We present a case of methicillin-sensitive Staphylococcus aureus infective endocarditis associated with cryoglobulinemic vasculitis and conduct a literature review to compare management and outcomes in similar cases. Our patient presented with classical Meltzer’s triad and mild renal involvement. Cryoimmunofixation confirmed type III cryoglobulinemia, and serum cytokines showed elevated IL-6 levels. The differential diagnosis included infective endocarditis and chronic active hepatitis C virus infection. Rapid symptom resolution after antibiotic treatment identified infective endocarditis as the likely cause of cryoglobulinemic vasculitis. Our case and review of the literature highlight that early identification of the cause of cryoglobulinemic vasculitis is crucial for selecting appropriate treatment and preventing recurrence or morbidity.
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