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Cytolytic T-cell cytotoxicity is mediated through perforin and Fas lytic pathways.

The recent generation of perforin knock-out mice has demonstrated a crucial role for the pore-forming perforin in cytolytic T-lymphocyte (CTL)-mediated cytolysis. Perforin-deficient mice failed to clear lymphocytic choriomeningitis virus in vivo, yet substantial killing activity still remained in perforin-free CTLs in vitro, indicating the presence of (a) further lytic pathway(s). Fas is an apoptosis-signalling receptor molecule on the surface of a number of different cells. Here we report that both perforin-deficient and Fas-ligand-deficient CTLs show impaired lytic activity on all target cel…

Atypical Phenotype of Predominant Autoimmune Cytopenia and Impaired Perforin Expression in XMEN Syndrome.

X-linked immunodeficiency with magnesium defect, Epstein-Barr virus (EBV) infection, and neoplasia (XMEN) is caused by a pathogenic variant … t that some patients may exhibit only partial symptoms. Furthermore, our study confirmed defects in perforin expression in XMEN syndrome. We observed a significant reduction in perforin expression within CD8+ T-cells and NK cells which may lead to increased susceptibility to recurrent infections and autoimmune complications frequently observed in XMEN pati …

Spectrum of perforin gene mutations in familial hemophagocytic lymphohistiocytosis (FHL) patients in India.

BACKGROUND: Inherited perforin deficiency is a rare autosomal recessive disorder that causes severe form of hemophagocytic lymphohistiocytosis (FHL2). The main aim of this study was to analyze the nature of gene mutations in a cohort of Indian patients with FHL2 and to utilize this knowledge for genetic counseling and prenatal diagnosis. METHODS: 13 HLH patients with abnormal perforin expression on NK cells by flow cytometry were included in the study. The entire coding region and intronic splice sites of the PRF1 gene were sequenced from the genomic DNA of these patients. RESULTS: 10 patien…

Perforin is recaptured by natural killer cells following target cells stimulation for cytotoxicity.

When encountering target cells, NK (natural killer) cells exocytose Pfn (perforin) and granzyme B to kill challengers. We previously reported that granzyme B is recycled and reused by NK cells via clathrin-dependent endocytosis. However, whether Pfn, a main secretory vesicle content, indispensible to granzyme B killing, undergoes endocytosis remains unknown. We demonstrate that Pfn is recaptured by early endosomes of NK cells via a clathrin-dependent endocytosis after target cell stimulation. Inhibition of clathrin-dependent endocytosis significantly attenuated the cytotoxicity of NK cells. Th…

Hepadnaviral infection augments hepatocyte cytotoxicity mediated by both CD95 ligand and perforin pathways.

BACKGROUND/AIM: Recently, we documented that hepatocytes can eliminate contacted cells via the CD95 ligand (CD95L)-CD95 pathway and that they are also equipped in perforin and granzyme B and can eradicate other cells via the granule exocytosis mechanism. The aim of this study was to assess whether hepadnaviral infection modifies hepatocyte-mediated cell killing. METHODS: Primary hepatocytes from woodchucks with progressing or resolved hepadnaviral hepatitis and hepatocyte lines transfected with woodchuck hepatitis virus (WHV) genes were examined for cytotoxic effector activity against cell ta…

Increased airway granzyme b and perforin in current and ex-smoking COPD subjects.

Increased bronchial epithelial cell apoptosis and CD8+ T-cell numbers in the blood and airways have been reported in COPD. These cells can induce apoptosis via the granzyme-b/perforin-mediated pathway. We hypothesized that increased levels of granzyme-b/perforin would be detected in COPD, contributing to apoptosis and tissue damage. Intracellular granzyme-b/perforin were measured in blood-derived T-cells and natural killer (NK) cells from COPD subjects (30 current and 30 ex-smokers), 20 asymptomatic current-smokers and 30 never-smokers, and bronchoalveolar lavage (BAL)-derived T-cells from a c…

Perforin-deficient CD8+ T cells mediate fatal lymphocytic choriomeningitis despite impaired cytokine production.

Intracerebral (i.c.) infection with lymphocytic choriomeningitis virus (LCMV) is one of the most studied models for virus-induced immunopathology, and based on results from perforin-deficient mice, it is currently assumed that fatal disease directly reflects perforin-mediated cell lysis. However, recent studies have revealed additional functional defects within the effector T cells of LCMV-infected perforin-deficient mice, raising the possibility that perforin may not be directly involved in mediating lethal disease. For this reason, we decided to reevaluate the role of perforin in determining…

Клетки CD8+T требуют перфорина для удаления вируса Западного Нила от инфицированных нейронов.

Считается, что повреждение нейронов после заражения вирусом Западного Нила (ВНВ) происходит из-за вирусного и иммунного воздействия. Ранее мы продемонстрировали, что CD8+T клетки необходимы для разрешения инфекции ВНВ в центральной нервной системе (СНС). Клетки CD8+T могут контролировать инфекцию путем производства антивирусных цитокинов (например, гамма-интерферон или альфа-фактор некроза опухоли) или путем инициирования смерти инфицированных клеток через пути, зависящие от перфорина или фаса лиганда. Здесь мы прямо оценили роль перфорина в борьбе с инфекцией линии, которую я изолирую в Нью-Й

Совпадение в аннотации оригинала
Injury to neurons after West Nile virus (WNV) infection is believed to occur because of viral and host immune-mediated effects. Previously, … , gamma interferon or tumor necrosis factor alpha) or by triggering death of infected cells through perforin- or Fas ligand-dependent pathways. Here, we directly evaluated the role of perforin in controlling infection of a lineage I New York isolate of WNV in mice. A genetic deficiency of perforin molecules resulted in higher viral burden in the CNS and in …

A role for perforin in downregulating T-cell responses during chronic viral infection.

Cytotoxic T cells secrete perforin to kill virus-infected cells. In this study we show that perforin also plays a role in immune regulation. Perforin-deficient (perf -/-) mice chronically infected with lymphocytic choriomeningitis virus (LCMV) contained greater numbers of antiviral T cells compared to persistently infected +/+ mice. The enhanced expansion was seen in both CD4 and CD8 T cells, but the most striking difference was in the numbers of LCMV-specific CD8 T cells present in infected perf -/- mice. Persistent LCMV infection of +/+ mice results in both deletion and anergy of antigen-spe…

Perforin and granzyme B lytic protein expression during chronic viral and autoimmune hepatitis.

BACKGROUND: Cytotoxic T lymphocytes and Kupffer cells are essential components of the immune response during liver diseases. Recent studies have highlighted the role of cytotoxic T lymphocytes using Fas and its ligand in induced hepatocyte death during acute and chronic hepatitis. METHODS: In the present work, the main purpose was to investigate perforin and granzyme B expression in liver biopsies of patients with chronic hepatitis (10 HBV, 14 HCV and 10 autoimmune hepatitis) using immunohistochemistry. The liver biopsies of two normal individuals were also studied in the same conditions. RE…

Perforin/Fas-ligand double deficiency is associated with macrophage expansion and severe pancreatitis.

We report that perforin/Fas-ligand double-deficient mice die early of severe pancreatitis. Female mice, in addition, are infertile and suffer from hysterosalpingitis. Tissue destruction is accompanied by infiltration with Mac-1 (CD11b)-positive monocytes/macrophages, Mac-1-positive T cells, and expansion of CD8+ T cells. In vivo inactivation of monocytes/macrophages by carrageenan reverses disease progression and restores fertility of female mice. Perforin/Fas-ligand double-deficient CD4+ or CD8+ CTL are unable to lyse cognate-activated macrophages, and therefore are unable to mediate negative…

Perforin triggers iron-induced mitochondrial damage to drive ferroptosis and anti-tumor immunity.

Cytotoxic CD8+ T cells and natural killer cells are critical effectors of anti-tumor immunity. Cytotoxic lymphocytes eliminate tumor cells by releasing perforin (Prf1), a pore-forming protein that enables granzymes (Gzms) to enter target cells and trigger both caspase-dependent and -independent cell death. Here, we uncover a previously unrecognized, Gzm-independent function of Prf1. We find that Prf1 directly induces tumoral ferroptosis, an iron- and lipid-dependent form of cell death. Mechanistically, Prf1-mediated pore formation drives endocytosis of the transferrin receptor, which increases…

Perforin Expression and Natural Killer-Cell Proportion as Biomarkers in Secondary Hemophagocytic Lymphohistiocytosis.

BACKGROUND Secondary hemophagocytic lymphohistiocytosis (sHLH) is a life-threatening hyperinflammatory syndrome. The immunopathology of cytotoxic lymphocytes in sHLH is complex and differs from primary HLH. This study aimed to characterize the distribution and perforin expression of key cytotoxic lymphocyte subsets in sHLH and assess their clinical and longitudinal significance. MATERIAL AND METHODS In this single-center observational study, peripheral blood from 19 patients with newly diagnosed sHLH and 10 healthy controls was analyzed using multi-color flow cytometry. Proportions of NK cells…

Perforin-2 is dispensable for host defense against Aspergillus fumigatus and Candida albicans.

Myeloid phagocytes are essential for antifungal immunity against pulmonary Aspergillus fumigatus and systemic Candida albicans infections. However, the molecular mechanisms underlying fungal clearance by phagocytes remain incompletely understood. In this study, we investigated the role of perforin-2 (Mpeg1) in antifungal immunity. We found that Mpeg1 -/- mice generated on a mixed C57BL/6J-DBA/2 background exhibited enhanced survival, reduced lung fungal burden, and greater neutrophil fungal killing activity compared to wild-type C57BL/6J (B6) mice, suggesting that perforin-2 may impair antifun…

Perforin-2 is dispensable for host defense against Aspergillus fumigatus and Candida albicans.

UNLABELLED: Myeloid phagocytes are essential for antifungal immunity against pulmonary Aspergillus fumigatus and systemic Candida albicans infections. However, the molecular mechanisms underlying fungal clearance by phagocytes remain incompletely understood. In this study, we investigated the role of Perforin-2 (Mpeg1) in antifungal immunity. We found that Mpeg1-/- mice generated on a mixed C57BL/6J-DBA/2 background exhibited enhanced survival, reduced lung fungal burden, and greater neutrophil fungal killing activity compared to wild-type C57BL/6J (B6) mice, suggesting that Perforin-2 may imp…

Immunohistochemical study of perforin and apoptosis stimulation fragment ligand (FasL)in active vitiligo.

Several studies demonstrated a major pathological role of melanocyte-specific cytotoxic CD8+ T cells in the pathogenesis of vitiligo. It has been suggested that apoptosis, rather than necrosis, is the mechanism of melanocyte depletion in vitiligo. The aim of this study was to evaluate the expression and distribution of perforin and apoptosis stimulation fragment ligand (FasL) in the epidermis and dermis of the perilesional and non-lesional skin of vitiligo patients in comparison to controls, to assess their possible role in mediating apoptosis in vitiligo. Twenty patients with active non-segme…

Maternal- and Fetal-Encoded Perforin-2 Limits Placental Infection by a Bloodborne Pathogen.

Placental immune responses are highly regulated to strike a balance between protection and tolerance. For relatively mild infections, protection encompasses both the mother and fetus; however, during worsening conditions, protection becomes exclusively reserved for the mother. Previously, we and others have shown that the host factor perforin-2 plays a central role in protecting mice and cells against infection. In this study, we analyzed perforin-2 activity in the mouse placenta to determine whether perforin-2 plays a similarly protective role. We show that perforin-2 is critical for inhibiti…

Identification and co-localization of perforin-like (TgPLP1) protein in Toxoplasma gondii bradyzoites.

For the first time, we show here that perforin-like (TgPLP1) is expressed in bradyzoites of Toxoplasma gondii. An immunofluorescence assay (IFA) and immunohistochemistry (IHC) revealed that TgPLP1 is expressed in T. gondii-encysted and in vitro-induced bradyzoites, TgPLP1 is distributed in micronemes in a manner similar to its distribution in tachyzoites. To shed light on the function of TgPLP1 in bradyzoites, quantitative PCR revealed that the expression level of TgPLP1 gene decreased over time during differentiation into bradyzoites in vitro. This finding suggests that TgPLP1 may play a role…

Adult hemophagocytic lymphohistiocytosis with severe pulmonary hypertension and a novel perforin gene mutation.

Adult hemophagocytic lymphohistiocytosis (HLH) is a rare and deadly hyperinflammatory syndrome presenting both diagnostic and therapeutic challenges. HLH may be primary, due to an underlying genetic abnormality, and/or secondary to infection, malignancy, or rheumatologic conditions. We describe a case of HLH-associated severe pulmonary hypertension paralleling Epstein-Barr virus (EBV) reactivation in a 52-year-old male in whom a novel perforin missense mutation was found (PRF1 1517C>T). Although intolerant of standard therapy (HLH-2004 protocol), a 6-week course of anti-CD52 (alemtuzumab) was …

Perforin-dependent CD4+ T-cell cytotoxicity contributes to control a murine poxvirus infection.

CD4(+) T cells are generally regarded as helpers and regulators of the immune response. Although cytolytic CD4(+) T cells have been described, whether those generated during the course of a viral infection play a role in virus control remains unknown. Here we show that during acute infection with ectromelia virus, the mouse homolog of the human virus of smallpox, large numbers of CD4(+) T cells in the draining lymph node and liver of resistant mice have a cytotoxic phenotype. We also show that these cells kill targets in vivo in a perforin-dependent manner and that mice with specific deficienc…