Chronic HCV infection promotes cytotoxicity in antigen-specific CD8+ T cells regardless of virus specificity

IntroductionDespite advancements in hepatitis C virus (HCV) infection treatment, HCV still represents a significant public health burden. Besides progressive hepatic damage, viral persistence has lasting effects on innate and adaptive immune responses. Lack of a complete understanding of the factors driving an effective HCV response contributes to the failure to develop a vaccine for prevention. This study advances the existing knowledge on HCV-specific CD8+ T cells and describes the impact of current or past HCV infection on CD8+ T cells specific for other viruses.MethodsWe used barcoded-dextramers to identify and sort CD8+ T cells specific for HCV, cytomegalovirus, and influenza, and characterized them using single-cell RNA sequencing technology. Our cohort included chronic (cHCV), spontaneously resolved (rHCV), and subjects undergoing direct-acting antiviral (DAA) therapy.ResultsWe show that HCV-specific CD8+ T cells have cytotoxic features in patients with cHCV, which is progressively reduced with DAA therapy and persists 12 weeks after treatment completion. We also observe a shift in the CD8+ T cell phenotype on DAA treatment, with decreased effector memory and exhausted cell signatures. In rHCV, we also detected a smaller proportion of effector memory cells compared to cHCV. The proportion of CD8+ exhausted T cells in cHCV and rHCV subjects was comparable. Moreover, we also observed that non-HCV virus-specific CD8+ T cells exhibit robust cytotoxic traits during cHCV infection.DiscussionAltogether, our findings suggest that cHCV infection promotes cytotoxicity in CD8+ T cells regardless of virus specificity. The immunological changes caused by cHCV infection in CD8+ T cells may contribute to worsening the ongoing hepatic damage caused by HCV infection or exacerbate the immune response to possible co-infections. Our data provide a resource to groups exploring the underlying mechanisms of HCV-specific T cell spontaneous and treatment-induced resolution to inform the development of effective vaccines against HCV infection

Etiology of end-stage liver cirrhosis impacts hepatic natural killer cell heterogenicity

The natural killer (NK) cell population is a critical component of the innate immune compartment of the liver, and its functions are deeply affected by the surrounding environment. In the late stage of fibrosis, NK cells become dysfunctional, but the influence of disease etiology on NK cell behavior during cirrhosis remains unclear. Using single-cell RNA sequencing (scRNA-seq), we characterized the hepatic NK cells from end-stage cirrhotic livers from subjects with non-alcoholic steatohepatitis (NASH), chronic hepatitis C infection (HCV) and primary sclerosing cholangitis (PSC). Here, we show that although NK cells shared similar dysfunctions, the disease etiology impacts hepatic NK cell heterogeneity. Therapeutical strategies targeting NK cells for the prevention or treatment of fibrosis should consider liver disease etiology in their design

LXR Deficiency Confers Increased Protection against Visceral Leishmania Infection in Mice

Leishmania spp. are protozoan single-cell parasites that are transmitted to humans by the bite of an infected sand fly, and can cause a wide spectrum of disease, ranging from self-healing skin lesions to potentially fatal systemic infections. Certain species of Leishmania that cause visceral (systemic) disease are a source of significant mortality worldwide. Here, we use a mouse model of visceral Leishmania infection to investigate the effect of a host gene called LXR. The LXRs have demonstrated important functions in both cholesterol regulation and inflammation. These processes, in turn, are closely related to lipid metabolism and the development of atherosclerosis. LXRs have also previously been shown to be involved in protection against other intracellular pathogens that infect macrophages, including certain bacteria. We demonstrate here that LXR is involved in susceptibility to Leishmania, as animals deficient in the LXR gene are much more resistant to infection with the parasite. We also demonstrate that macrophages lacking LXR kill parasites more readily, and make higher levels of nitric oxide (an antimicrobial mediator) and IL-1β (an inflammatory cytokine) in response to Leishmania infection. These results could have important implications in designing therapeutics against this deadly pathogen, as well as other intracellular microbial pathogens

Simultaneous transcriptional profiling of Leishmania major and its murine macrophage host cell reveals insights into host-pathogen interactions

Parasites of the genus Leishmania are the causative agents of leishmaniasis, a group of diseases that range in manifestations from skin lesions to fatal visceral disease. The life cycle of Leishmania parasites is split between its insect vector and its mammalian host, where it resides primarily inside of macrophages. Once intracellular, Leishmania parasites must evade or deactivate the host's innate and adaptive immune responses in order to survive and replicate. We performed transcriptome profiling using RNA-seq to simultaneously identify global changes in murine macrophage and L. major gene expression as the parasite entered and persisted within murine macrophages during the first 72 h of an infection. Differential gene expression, pathway, and gene ontology analyses enabled us to identify modulations in host and parasite responses during an infection. The most substantial and dynamic gene expression responses by both macrophage and parasite were observed during early infection. Murine genes related to both pro- and anti-inflammatory immune responses and glycolysis were substantially upregulated and genes related to lipid metabolism, biogenesis, and Fc gamma receptor-mediated phagocytosis were downregulated. Upregulated parasite genes included those aimed at mitigating the effects of an oxidative response by the host immune system while downregulated genes were related to translation, cell signaling, fatty acid biosynthesis, and flagellum structure. The gene expression patterns identified in this work yield signatures that characterize multiple developmental stages of L. major parasites and the coordinated response of Leishmania-infected macrophages in the real-time setting of a dual biological system. This comprehensive dataset offers a clearer and more sensitive picture of the interplay between host and parasite during intracellular infection, providing additional insights into how pathogens are able to evade host defenses and modulate the biological functions of the cell in order to survive in the mammalian environment.https://doi.org/10.1186/s12864-015-2237-

Fatores envolvidos na cronicidade das lesões cutâneas e na progressão da forma cutânea para a forma mucosa tardia da leishmaniose tegumentar americana

Submitted by Anderson Silva ([email protected]) on 2012-10-18T17:38:37Z No. of bitstreams: 1 ana_c_m_mira_ioc_bcm_0030_2011.pdf: 1715147 bytes, checksum: 54b54aa7c73f82debfcc2d92f0038a0b (MD5)Made available in DSpace on 2012-10-18T17:38:37Z (GMT). No. of bitstreams: 1 ana_c_m_mira_ioc_bcm_0030_2011.pdf: 1715147 bytes, checksum: 54b54aa7c73f82debfcc2d92f0038a0b (MD5) Previous issue date: 2011Fiocruz LABioMed/UCLALos Angeles Biomedical Research Institute. Molecular Medicine. Torrance, CA, USAA forma de apresentação mais comum da leishmaniose tegumentar americana (LTA) é o aparecimento de uma úlcera auto-limitada no local da picada do inseto vetor. Embora estas lesões requeiram até 6 meses para atingirem a cura completa, o tratamento com antimoniais pentavalentes pode reduzir significativamente este tempo de cicatrização. Entretanto, a quimioterapia nem sempre apresenta resultados satisfatórios, seja por não resolver a injúria tecidual, seja por permitir a persistência parasitária e desenvolvimento de lesões na mucosa oro-nasal. Desta forma, o presente estudo teve como objetivos principais avaliar fatores envolvidos na cronicidade das lesões cutâneas e na progressão da forma cutânea da leishmaniose para a forma mucosa tardia. A cronicidade de lesões cutâneas de diversas etiologias tem sido relacionada ao desequilíbrio da atividade de algumas metaloproteinases de matriz (MMPs), em especial, das gelatinases MMP-2 e MMP-9. Portanto, decidimos avaliar a participação destas enzimas e de seus moduladores nos danos teciduais causados por LTA. Verificamos que a atividade destas gelatinases atinge extensas áreas das lesões de má resposta, a qual estava associada a um elevado número de células produzindo IFN-γ, TGF-β e IL-10, com preponderância da citocina pró-proteolítica IFN-γ. O oposto foi observado nas lesões de boa resposta, onde, paralelamente aos baixos níveis de atividade gelatinolítica e prevalência da citocina anti-inflamatória IL-10, pôde-se observar altos níveis de mRNA para MMP-2 e elevados valores da razão MMP-2:TIMP-2. Sugere-se então que o perfil imunológico in situ controla o balanço entre MMPs e inibidores, determinando assim, o sucesso ou fracasso da cicatrização. Entretanto, mesmo após a cura clínica, alguns indivíduos progridem para a forma mucosa, fato associado com a disseminação parasitária via células fagocíticas. Considerando a importância de MMP-9 na migração de células imunológicas, decidimos estudar a atividade desta gelatinase em cultura de macrófagos humanos infectados por Leishamnia braziliensis. Observamos que a infecção por L. braziliensis induziu ao aumento de atividade de MMP-9 no sobrenadante das culturas e que os níveis de atividade de MMP-9 são maiores nas culturas de macrófagos de indivíduos que, no passado, desenvolveram a forma mucosa. Estes dados sugerem uma diferença fundamental na imunidade inata do hospedeiro, onde o padrão de ativação de MMP-9 pode ser um indicador de predisposição para o desenvolvimento de leishmaniose mucosa. Além da disseminação parasitária, o sistema imunológico também exerce controle sobre a evolução da forma cutânea para a forma mucosa de LTA. Por isso, a análise do transcriptoma do microambiente da lesão cutânea primária de indivíduos com a forma cutânea localizada e daqueles que desenvolveram a forma mucosa tardia pode auxiliar na compreensão deste quadro. Nossos resultados indicaram uma importante diferença da capacidade de resposta imunológica de ambos grupos, onde o grupo cutâneo mostrou maior eficácia no estabelecimento da resposta imune do tipo T helper 1 (Th1), com participação de células Th2 e forte controle imunotolerigênico.The most common clinical presentation of American tegumentary leishmaniasis (ATL) is the development of a self-limited ulcer at the site of the insect vector’s bite. Although these lesions require up to 6 months to completely cure, the treatment with pentavalent antimonials can significantly reduce the healing time. Thus, the present study aimed to evaluate the factors involved in the chronicity of cutaneous lesions and in the progression of cutaneous leishmaniasis to late mucosal form. The chronicity of cutaneous lesions from different etiologies has long been associated to an imbalanced activity of matrix metalloproteinases, especially gelatinases MMP-2 and MMP-9. Therefore, we decided to evaluate the participation of these enzymes and their modulators in the tissue damage caused by ATL. We verified that the gelatinase activity was widespread in the lesions from poor responders, and associated to high rates of cells producing IFN-γ, TGF-β and IL-10, with preponderance of the pro-proteolytic cytokine IFN-γ. The opposite was observed in lesions from good responders, where, in parallel to the low levels of gelatinase activity and the prevalence of the anti-inflammatory cytokine IL-10, we observed high levels of MMP-2 mRNA and high MMP-2:TIMP-2 ratios. This suggests that the in situ immunological profile controls the balance between MMPs and inhibitors, thus determining the healing success or failure. Nevertheless, even after clinical cure, some individuals progress to mucosal forms, a fact associated to parasite dissemination via phagocytic cells. Considering the importance of MMP-9 in the migration of immunological cells, we decided to study this gelatinase activity in human macrophage cultures infected with Leishmania braziliensis. We observed that L. braziliensis infection induced the increase of MMP-9 activity in culture supernatants and that the level of MMP-9 activity was higher in cultures from individuals that, in the past, had developed the mucosal form. These data suggest a fundamental difference in the innate immunity of the host, where the MMP-9 activation pattern may be an indicator for the predisposition of mucosal leishmaniasis development. Besides parasite dissemination, the immunological system also controls the evolution from cutaneous to mucosal form in ATL. Therefore, the transcriptome analysis of the primary cutaneous lesion microenvironment from individuals that had localized cutaneous leishmaniasis and from those who developed the late mucosal form can help to understand this state. Our results indicated an important difference in the immune capacity from both groups, where the cutaneous group showed better efficacy in establishing a type 1 (Th1) immune response, with participation of Th2 cells and a strong immune-tolerigenic control

Circulating Neutrophil Profiles Undergo a Dynamic Shift during Metabolic Dysfunction-Associated Steatohepatitis (MASH) Progression

Neutrophils play a crucial role in host defense against infection. Aberrant neutrophil activation may induce tissue damage via sterile inflammation. Neutrophil accumulation has been identified as a feature of the inflammatory response observed in metabolic dysfunction-associated steatohepatitis (MASH) and has been associated with liver fibrosis and cirrhosis. Here, we performed the transcriptomic analysis of circulating neutrophils from mild and advanced MASH patients to identify the potential mechanism behind neutrophil contribution to MASH progression. Our findings demonstrated that circulating neutrophils from mild and advanced MASH display an increased activated transcriptional program, with the expression of pro-inflammatory factors and an amplified lifespan compared to cells from non-diseased controls. Our results also suggest that MASH progression is associated with a dynamic shift in the profile of circulating neutrophils. In the early stages of MASH, mature neutrophils predominate in the bloodstream. As hepatic inflammation and fibrosis progress, the premature release of immature neutrophils into the circulation occurs. These immature neutrophils exhibit a pro-inflammatory profile that may exacerbate inflammation and promote fibrosis in MASH