Sea Anemone Membrane Attack Complex/Perforin Superfamily Demonstrates an Evolutionary Transitional State between Venomous and Developmental Functions.

Gene duplication is a major force driving evolutionary innovation. A classic example is generating new animal toxins via duplication of physiological protein-encoding genes and recruitment into venom. While this process drives the innovation of many animal venoms, reverse recruitment of toxins into nonvenomous cells remains unresolved. Using comparative genomics, we find members of the Membrane Attack Complex and Perforin Family (MAC) have been recruited into venom-injecting cells (cnidocytes), in soft and stony corals and sea anemones, suggesting that the ancestral MAC was a cnidocyte expressed toxin. Further investigation into the model sea anemone Nematostella vectensis reveals that three members have undergone Nematostella-specific duplications leading to their reverse recruitment into endomesodermal cells. Furthermore, simultaneous knockdown of all three endomesodermally expressed MACs leads to mis-development, supporting that these paralogs have nonvenomous function. By resolving the evolutionary history and function of MACs in Nematostella, we provide the first proof for reverse recruitment from venom to organismal development.

[L-DEP regimen salvage therapy for refractory primary hemophagocytic lymphohistiocytosis triggered by Epstein-Barr virus infection in 4 children].

Objective: To analyze the efficacy and safety of the L-DEP regimen (asparaginase, liposome doxorubicin, etoposide and methylprednisolone) as a salvage therapy for the refractory primary hemophagocytic lymphohistocytosis triggered by Epstein-Barr virus infection (EBV-pHLH) in children. Methods: In this retrospective case study, clinical and laboratory data before and after L-DEP regimen of 4 children diagnosed with EBV-pHLH in Beijing Children's hospital between January 2016 and June 2022 were collected, and the efficacy and safety of L-DEP regimen for the treatment of EBV-pHLH were analyzed. Results: Among 4 patients, there were 3 females and 1 male with the age ranged from 0.8 to 7.0 years. Two of them showed compound heterozygous mutations of PRF1, one with a heterozygous mutation of UNC13D, one homozygous mutation of ITK. Before the L-DEP therapy, all of them had anemia and a soaring level of soluble CD25, 3 patients had neutropenia and thrombopenia, 3 patients had a high level of ferritin, 3 patients had hypofibrinogenemia and 1 patient had hypertriglyceridemia. After receiving 1 or 2 cycles of L-DEP treatment, three achieved remission, including complete remission (1 case) and partial remission (2 cases), and the other one had no remission. The levels of blood cell counts, soluble CD25, triglyceride, fibrinogen and albumin were recovered gradually in 3 patients who got remission. All four patients underwent hematopoietic stem cell transplantation (HSCT) after L-DEP regimen, and three survived. All patients had no severe chemotherapy related complications. The main side effects were bone marrow suppression, infection and pancreatitis, which recovered after appropriate treatments, apart from one who died from severe infection after urgent HSCT. Conclusion: L-DEP regimen could be served as an effective and safe salvage treatment for refractory pediatric EBV-pHLH, and also provide an opportunity for patients to receive HSCT.

Posttranscriptional Events Orchestrate Immune Homeostasis of CD8+ T Cells.

Maintaining immune homeostasis is instrumental for host health. Immune cells, such as T cells, are instrumental for the eradication of pathogenic bacteria, fungi and viruses. Furthermore, T cells also play a major role in the fight against cancer. Through the formation of immunological memory, a pool of antigen-experienced T cells remains in the body to rapidly protect the host upon reinfection or retransformation. In order to perform their protective function, T cells produce cytolytic molecules, such as granzymes and perforin, and cytokines such as interferon γ and tumor necrosis factor α. Recently, it has become evident that posttranscriptional regulatory events dictate the kinetics and magnitude of cytokine production by murine and human CD8+ T cells. Here, the recent literature regarding the role posttranscriptional regulation plays in maintaining immune homeostasis of antigen-experienced CD8+ T cells is reviewed.

Early hematopoietic cell transplantation for familial hemophagocytic lymphohistiocytosis in a regional treatment network in Japan.

Familial hemophagocytic lymphohistiocytosis (FHLH) is a fatal hyperinflammation syndrome arising from the genetic defect of perforin-mediated cytolysis. Curative hematopoietic cell transplantation (HCT) is needed before development of central nervous system (CNS) disease. We studied treatment outcomes of 13 patients (FHLH2 n = 11, FHLH3 n = 2) consecutively diagnosed from 2011 to 2022 by flow cytometric screening for non-myeloablative HCT in a regional treatment network in Kyushu, Japan. One patient with a novel PRF1 variant escaped screening, but all patients with FHLH2 reached diagnosis and 8 of them received HCT until 3 and 9 months of age, respectively. The earliest HCT was conducted 65 days after birth. Three pretransplant deaths occurred in newborns with liver failure at diagnosis. Ten posttransplant patients have remained disease-free, 7 of whom had no neurological involvement. Time from first etoposide infusion to HCT was shorter in patients without CNS disease or bleeding than in patients with those factors (median [range] days: 62 [50-81] vs. 122 [89-209], p = 0.016). Six of 9 unrelated patients had a PRF1 c.1090_1091delCT variant. These results suggest that the critical times to start etoposide and HCT are within 3 months after birth and during etoposide control, respectively. Newborn screening may increase the percentage of disease-free survivors without complications.

New Insights into Interactions between Mushroom Aegerolysins and Membrane Lipids.

Aegerolysins are a family of proteins that recognize and bind to specific membrane lipids or lipid domains; hence they can be used as membrane lipid sensors. Although aegerolysins are distributed throughout the tree of life, the most studied are those produced by the fungal genus Pleurotus. Most of the aegerolysin-producing mushrooms code also for proteins containing the membrane attack complex/perforin (MACPF)-domain. The combinations of lipid-sensing aegerolysins and MACPF protein partners are lytic for cells harboring the aegerolysin membrane lipid receptor and can be used as ecologically friendly bioinsecticides. In this work, we have recombinantly expressed four novel aegerolysin/MACPF protein pairs from the mushrooms Heterobasidion irregulare, Trametes versicolor, Mucidula mucida, and Lepista nuda, and compared these proteins with the already studied aegerolysin/MACPF protein pair ostreolysin A6-pleurotolysin B from P. ostreatus. We show here that most of these new mushroom proteins can form active aegerolysin/MACPF cytolytic complexes upon aegerolysin binding to membrane sphingolipids. We further disclose that these mushroom aegerolysins bind also to selected glycerophospholipids, in particular to phosphatidic acid and cardiolipin; however, these interactions with glycerophospholipids do not lead to pore formation. Our results indicate that selected mushroom aegerolysins show potential as new molecular biosensors for labelling phosphatidic acid.

Late Onset of Primary Hemophagocytic Lymphohistiocytosis (HLH) with a Novel Constellation of Compound Heterozygosity Involving Two Missense Variants in the PRF1 Gene.

Hemophagocytic lymphohistiocytosis (HLH) is a rare but in most cases life-threatening immune-mediated disease of the hematopoietic system frequently associated with hematologic neoplasms. Here, we report on a case in which we detected a novel constellation of two missense variants affecting the PRF1 gene, leading to de novo primary HLH. Diagnostics included a comprehensive clinical work-up and standard methods of hematopathology as well as extended molecular genomics based on polymerase chain reaction (PCR) reactions and the calculation of three-dimensional molecule reconstructions of PRF1. Subsequently, a comprehensive review of the literature was performed, which showed that this compound heterozygosity has not been previously described. The patient was a 20-year-old female. Molecular diagnostics revealed two heterozygous missense variants in the PRF1 gene (A91V and R104C) on exon 2. Apart from the finding of two inconclusive genetic variants, all clinical criteria defined by the HLH study group of Histiocyte Society were met at initial presentation. The final diagnosis was made in cooperation with the Consortium of German HLH-reference centers. Here, chemotherapy did not lead to sufficient sustained disease control. Therefore, the decision for allogenic hematopoietic stem cell transplantation (alloHSCT) was made. Hitherto, the duration of response was 6 months. Due to severe and unmanageable hepatic graft-versus-host disease (GvHD), the patient died. We report on a novel constellation of a compound heterozygosity containing two missense variants on exon 2 of the PRF1 gene. To the authors' best knowledge, this is the first presentation of a primary HLH case harboring this genomic constellation with late-onset clinical manifestation.

Cordyceps sinensis extract protects against acute kidney injury by inhibiting perforin expression in NK cells via the STING/IRF3 pathway.

Acute kidney injury (AKI) is associated with immune cell activation and inflammation. However, the putative pathogenic mechanisms of this injury have not been thoroughly investigated. Natural killer (NK) cells play an important role in immune regulation; however, whether NK cells regulate AKI remains unclear. Cordyceps sinensis (CS), a modern Chinese patented medicine preparation, has been widely used in treating patients with chronic kidney disease (CKD) owing to its anti-inflammatory effects and maintenance of immune homeostasis. Whether 2'-deoxyadenosine, a major active component in CS, can ameliorate renal AKI by regulating immunity, particularly in NK cells, has not been reported. This study is the first to demonstrate how NK cells promote AKI by releasing perforin, interferon-gamma (IFN-γ) and other inflammatory factors in vivo and in vitro. Differential gene expression between AKI and normal tissues was assessed using bioinformatic analyses. Quantitative real-time PCR, western blotting, and immunohistochemical staining were used to detect target protein mRNA and protein expression. Levels of inflammatory factors were measured using enzyme-linked immunosorbent assay. We found the high doses of the 2'-deoxyadenosine treatment significantly alleviated FA-induced renal damage in vivo, and alleviated the NK cells of renal injury by activating the STING/IRF3 pathway to inhibit perforin release in vitro. The results showed that 2'-deoxyadenosine could mitigate AKI by downregulating the activity of NK cells (by decreasing the expressions of perforin and IFN-γ) and inhibiting the stimulator of interferon genes and phosphorylated IFN regulatory factor 3. This may provide valuable evidence supporting the clinical use of CS in treating patients with AKI.

Interleukin-36gamma Mediates the In Vitro Activation of CD8+ T Cells from Patients Living with Chronic Human Immunodeficiency Virus-1 Infection.

Interleukin-36 (IL-36) signaling plays an important role in promoting CD8+ T cell-mediated antitumor immune responses. The role of IL-36 signaling in CD8+ T cells that are involved in host immune responses during human immunodeficiency virus-1 (HIV-1) infection has not been characterized. Sixty-one patients living with chronic HIV-1 infection and 23 controls were enrolled in this study. The levels of IL-36 cytokine family members were measured by enzyme-linked immunosorbent assay. Purified CD8+ T cells were stimulated with recombinant IL-36gamma (1 or 10 ng/mL). The expression of inhibitory receptors, the secretion of cytotoxic molecules and interferon-gamma, and the mRNA levels of apoptosis-related ligands were assessed to evaluate the effect of IL-36gamma on CD8+ T cell function in vitro. There were no significant differences in IL-36alpha, IL-36beta, or IL-36 receptor antagonist levels between patients living with chronic HIV-1 infection and controls. Plasma IL-36gamma levels were reduced in patients living with chronic HIV-1 infection. Perforin, granzyme B, and granulysin secretion, as well as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and Fas ligand (FasL) mRNA expression, but not programmed death-1 (PD-1) or cytotoxic T lymphocyte-associated protein-4 (CTLA-4) expression was downregulated in CD8+ T cells from patients living with chronic HIV-1 infection. The addition of both 1 and 10 ng/mL IL-36gamma enhanced perforin, granzyme B, granulysin, and interferon-gamma secretion by CD8+ T cells without affecting PD-1/CTLA-4 or TRAIL/FasL mRNA expression in CD8+ T cells from patients living with chronic HIV-1 infection. The addition of 1 ng/mL IL-36gamma also promoted perforin and granzyme B secretion by HIV-1-specific CD8+ T cells from patients living with chronic HIV-1 infection. The reduced IL-36gamma levels in patients living with chronic HIV-1 infection might be insufficient for the activation of CD8+ T cells, leading to CD8+ T cell exhaustion.

ERG mediates the inhibition of NK cell cytotoxicity through the HLX/STAT4/Perforin signaling pathway, thereby promoting the progression of myocardial infarction

This study aimed to investigate the role of ERG in the HLX/STAT4/Perforin signaling axis, impacting natural killer (NK) cell cytotoxicity and myocardial infarction (MI) progression. NK cell cytotoxicity was assessed via co-culture and 51Cr release assays. Datasets GSE34198 and GSE97320 identified common differentially expressed genes in MI. NK cell gene expression was analyzed in MI patients and healthy individuals using qRT-PCR and Western blotting. ERG's regulation of HLX and STAT4's regulation of perforin were studied through computational tools (MEM) and ChIP experiments. HLX's influence on STAT4 was explored with the MG132 proteasome inhibitor. Findings were validated in a mouse MI model. ERG, a commonly upregulated gene, was identified in NK cells from MI patients and mice. ERG upregulated HLX, leading to STAT4 proteasomal degradation and reduced Perforin expression. Consequently, NK cell cytotoxicity decreased, promoting MI progression. ERG mediates the HLX/STAT4/Perforin axis to inhibit NK cell cytotoxicity, fostering MI progression. These results provide vital insights into MI's molecular mechanisms. (AU)

ERG mediates the inhibition of NK cell cytotoxicity through the HLX/STAT4/Perforin signaling pathway, thereby promoting the progression of myocardial infarction

This study aimed to investigate the role of ERG in the HLX/STAT4/Perforin signaling axis, impacting natural killer (NK) cell cytotoxicity and myocardial infarction (MI) progression. NK cell cytotoxicity was assessed via co-culture and 51Cr release assays. Datasets GSE34198 and GSE97320 identified common differentially expressed genes in MI. NK cell gene expression was analyzed in MI patients and healthy individuals using qRT-PCR and Western blotting. ERG's regulation of HLX and STAT4's regulation of perforin were studied through computational tools (MEM) and ChIP experiments. HLX's influence on STAT4 was explored with the MG132 proteasome inhibitor. Findings were validated in a mouse MI model. ERG, a commonly upregulated gene, was identified in NK cells from MI patients and mice. ERG upregulated HLX, leading to STAT4 proteasomal degradation and reduced Perforin expression. Consequently, NK cell cytotoxicity decreased, promoting MI progression. ERG mediates the HLX/STAT4/Perforin axis to inhibit NK cell cytotoxicity, fostering MI progression. These results provide vital insights into MI's molecular mechanisms. (AU)

Kill rates by immune cells: Ratio-dependent, or mass action?

We describe a cell-based fixed-lattice model to simulate immune cell and tumor cell interaction involving MHC recognition, and FasL vs perforin lysis. We are motivated by open questions about the mechanisms behind observed kill rates of tumor cells by different types of effector cells. These mechanisms play a big role in the effectiveness of many cancer immunotherapies. The model is a stochastic cellular automaton on a hexagonal grid.

Low Percentage of Perforin-Expressing NK Cells during Severe SARS-CoV-2 Infection: Consumption Rather than Primary Deficiency.

Genetic defects in the ability to deliver effective perforin have been reported in patients with hemophagocytic lymphohistiocytosis. We tested the hypothesis that a primary perforin deficiency might also be causal in severe SARS-CoV-2 infection. We recruited 54 volunteers confirmed as being SARS-CoV-2-infected by RT-PCR and admitted to intensive care units or non-intensive care units and age- and sex-matched healthy controls. Compared with healthy controls, the percentage of perforin-expressing CD3-CD56+ NK cells quantified by flow cytometry was low in COVID-19 patients (69.9 ± 17.7 versus 78.6 ± 14.6%, p = 0.026). There was no correlation between the proportions of perforin-positive NK cells and T8 lymphocytes. Moreover, the frequency of NK cells producing perforin was neither linked to disease severity nor predictive of death. Although IL-6 is known to downregulate perforin production in NK cells, we did not find any link between perforin expression and IL-6 plasma level. However, we unveiled a negative correlation between the degranulation marker CD107a and perforin expression in NK cells (r = -0.488, p = 10-4). PRF1 gene expression and the frequency of NK cells harboring perforin were normal in patients 1 y after acute SARS-CoV-2 infection. A primary perforin defect does not seem to be a driver of COVID-19 because NK perforin expression is 1) linked neither to T8 perforin expression nor to disease severity, 2) inversely correlated with NK degranulation, and 3) normalized at distance from acute infection. Thus, the cause of low frequency of perforin-positive NK cells appears, rather, to be consumption.

Local Low-dose Anti-PD-L1 Antibodies Improve Antitumor Effects in Oral Squamous Cell Carcinoma.

BACKGROUND/AIM: Immune checkpoint inhibitors are highly effective for treating recurrent and metastatic head and neck cancers. However, they require systemic administration and are associated with immune-related adverse events (irAEs). Reducing therapeutic antibody doses to prevent irAEs is challenging. MATERIALS AND METHODS: Mouse buccal mucosa squamous cell carcinoma cells (Sq-1979) were transplanted into the backs of mice to induce tumors. The antitumor efficacy and tumor immunohistological environment in tumor-bearing mice were compared after administering a standard dose of programmed death-ligand 1 (PD-L1) antibodies systemically (200 mg/body) or 1/10th of the standard dose (20 mg/body) directly to tumors. Mice received four doses of antibody administered in 3-day intervals. Tumor reduction rates and antitumor efficacies were evaluated 21 days after initiating treatment. CD8+T cell counts and PD-L1, PD-1, perforin, and granzyme B levels; CD25 and Foxp3 expression levels; and tumor Tregs were assessed in the resected subcutaneous tumors. RESULTS: The antitumor efficacies in the local low-dose and systemic standard-dose groups were compared with that of the control group. The efficacies of the two treatment groups were similar, and both treatment groups revealed significant antitumor effects compared to the control group. Perforin and granzyme B levels were higher in the local low-dose group (p<0.05). CONCLUSION: Local low-dose administration of anti-PD-L1 antibodies exhibits antitumor efficacy similar to systemic standard-dose administration suggesting that local low-dose administration is useful for treating oral squamous cell carcinoma.

Hyperactivation and enhanced cytotoxicity of reduced CD8+ gamma delta T cells in the intestine of patients with Crohn's disease correlates with disease activity.

BACKGROUND AND AIMS: We aimed to investigate the immune characteristics of intestinal CD8+ gamma delta T (CD8+ γδ T) cells in Crohn's disease (CD) and their correlation with disease activity. METHODS: The study cohorts included 21 CD patients and 21 healthy individuals. CD8+ γδ T cells were isolated from human ileal mucosa for detection by flow cytometry. The activation or inhibition status of cells was detected by detecting the expression of activation marker HLA-DR and the immunosuppressive molecule PD-1 on cells. The cytotoxicity of cells was assessed by detecting the expression of cytotoxic molecules (Perforin, Granzyme B, and TRAIL) in cells. Ratios of investigated cells were calculated as prediction factors by receiver operating characteristic curve (ROC) analysis. RESULTS: The study revealed a reduction in intestinal CD8+ γδT cells among active CD patients, with a more pronounced reduction observed in moderately active patients compared to mildly active patients. Moreover, active CD patients exhibited heightened activation levels in their intestinal CD8+ γδT cells, whereas the activation was comparatively weakened in moderately active patients compared with mildly active patients. Additionally, the cytotoxicity of intestinal CD8+ γδT cells was enhanced solely in mildly active patients, while it was impaired in moderately active patients compared with mildly active patients. Furthermore, HLA-DR+ CD8+ γδT cell ratio, CD8+ γδT ratio, and CD8+ γδT count were identified as indicators in the diagnosis of active CD. Meanwhile, the ratios of Granzyme B+ CD8+ γδT cell and Perforin+ CD8+ γδT cell were identified as indicators that distinguish mildly moderately active CD cases. CONCLUSIONS: Intestinal CD8+ γδT was reduced in active CD patients, but their activation and cytotoxicity were enhanced. However, with increased disease activity, intestinal CD8+ γδ T cells became dysfunctional. CD-specific perturbations observed in various phenotypic markers in CD8+ γδ T cells can be used as indicators to assist in diagnosing CD patients.

NFIL3 contributes to cytotoxic T lymphocyte-mediated killing.

Cytotoxic T lymphocytes (CTLs) are key effectors of the adaptive immune system that recognize and eliminate virally infected and cancerous cells. In naive CD8+ T cells, T-cell receptor (TCR) engagement drives a number of transcriptional, translational and proliferation changes over the course of hours and days leading to differentiation into CTLs. To gain a better insight into this mechanism, we compared the transcriptional profiles of naive CD8+ T cells to those of activated CTLs. To find new regulators of CTL function, we performed a selective clustered regularly interspaced short palindromic repeats (CRISPR) screen on upregulated genes and identified nuclear factor IL-3 (NFIL3) as a potential regulator of cytotoxicity. Although NFIL3 has established roles in several immune cells including natural killer, Treg, dendritic and CD4+ T cells, its function in CD8+ CTLs is less well understood. Using CRISPR/Cas9 editing, we found that removing NFIL3 in CTLs resulted in a marked decrease in cytotoxicity. We found that in CTLs lacking NFIL3 TCR-induced extracellular signal-regulated kinase phosphorylation, immune synapse formation and granule release were all intact while cytotoxicity was functionally impaired in vitro. Strikingly, NFIL3 controls the production of cytolytic proteins as well as effector cytokines. Thus, NFIL3 plays a cell intrinsic role in modulating cytolytic mechanisms in CTLs.

Involvement of M1-Activated Macrophages and Perforin/Granulysin Expressing Lymphocytes in IgA Vasculitis Nephritis.

We investigated the polarisation of CD68+ macrophages and perforin and granulysin distributions in kidney lymphocyte subsets of children with IgA vasculitis nephritis (IgAVN). Pro-inflammatory macrophage (M)1 (CD68/iNOS) or regulatory M2 (CD68/arginase-1) polarisation; spatial arrangement of macrophages and lymphocytes; and perforin and granulysin distribution in CD3+ and CD56+ cells were visulaised using double-labelled immunofluorescence. In contrast to the tubules, iNOS+ cells were more abundant than the arginase-1+ cells in the glomeruli. CD68+ macrophage numbers fluctuated in the glomeruli and were mostly labelled with iNOS. CD68+/arginase-1+ cells are abundant in the tubules. CD56+ cells, enclosed by CD68+ cells, were more abundant in the glomeruli than in the tubuli, and co-expressed NKp44. The glomerular and interstitial/intratubular CD56+ cells express perforin and granulysin, respectively. The CD3+ cells did not express perforin, while a minority expressed granulysin. Innate immunity, represented by M1 macrophages and CD56+ cells rich in perforin and granulysin, plays a pivotal role in the acute phase of IgAVN.

Cell softness renders cytotoxic T lymphocytes and T leukemic cells resistant to perforin-mediated killing.

Mechanical force contributes to perforin pore formation at immune synapses, thus facilitating the cytotoxic T lymphocytes (CTL)-mediated killing of tumor cells in a unidirectional fashion. How such mechanical cues affect CTL evasion of perforin-mediated autolysis remains unclear. Here we show that activated CTLs use their softness to evade perforin-mediated autolysis, which, however, is shared by T leukemic cells to evade CTL killing. Downregulation of filamin A is identified to induce softness via ZAP70-mediated YAP Y357 phosphorylation and activation. Despite the requirements of YAP in both cell types for softness induction, CTLs are more resistant to YAP inhibitors than malignant T cells, potentially due to the higher expression of the drug-resistant transporter, MDR1, in CTLs. As a result, moderate inhibition of YAP stiffens malignant T cells but spares CTLs, thus allowing CTLs to cytolyze malignant cells without autolysis. Our findings thus hint a mechanical force-based immunotherapeutic strategy against T cell leukemia.

Immunohistochemical expression of perforin in adult systemic lupus erythematosus associated macrophage activation syndrome: Clinicohematological correlation and literature review.

OBJECTIVE: To study the bone marrow (BM) immunohistomorphological characteristics in adult systemic lupus erythematosus (SLE) associated macrophage activation syndrome (SLE-MAS). MATERIALS AND METHODS: Immunohistochemical (IHC) expression of CD3, CD8, perforin (PFN), and CD163 was studied on BM trephine biopsies from 30 cytopenic adult SLE cases (male: female = 1:5, age; 24 years, range; 19-32) and compared them with ten age matched controls. Clinicopathological parameters were compared among the cases likely (L) or unlikely (U) to have MAS using probability scoring criteria. The best cut off laboratory parameters to discriminate between the two were obtained through receiver operator curve (ROC) analysis. RESULTS: MAS occurred in 12/30 (40%) cases and was more commonly associated with prior immunosuppressive therapy (p = .07), ≥ 3 system involvement (p = .09), lower fibrinogen (p < .01), increased triglyceride (p = .002), increased BM hemophagocytosis (p = .002), and higher MAS score [185 (176-203) vs. 105 (77-119), p < .01] than MAS-U subgroup. Although PFN+CD8+ T lymphocytes significantly decreased among cases than controls (p < .05), it was comparable between MAS-L and MAS-U subgroups. Fibrinogen (< 2.4 g/L, AUC; 0.93, p < .01), hemophagocytosis score (> 1.5, AUC; 0.71, p = .03), and an MAS probability score of ≥ 164 (AUC; 1, p < .01) discriminated MAS from those without MAS. CONCLUSION: We noted a decrease in perforin mediated CD8 + T cell cytotoxicity in SLE. Immunohistochemical demonstration of the same along with histiocytic hemophagocytosis on BM biopsy may be useful adjunct in early diagnosis and management of MAS in SLE.

ERG mediates the inhibition of NK cell cytotoxicity through the HLX/STAT4/Perforin signaling pathway, thereby promoting the progression of myocardial infarction.

This study aimed to investigate the role of ERG in the HLX/STAT4/Perforin signaling axis, impacting natural killer (NK) cell cytotoxicity and myocardial infarction (MI) progression. NK cell cytotoxicity was assessed via co-culture and 51Cr release assays. Datasets GSE34198 and GSE97320 identified common differentially expressed genes in MI. NK cell gene expression was analyzed in MI patients and healthy individuals using qRT-PCR and Western blotting. ERG's regulation of HLX and STAT4's regulation of perforin were studied through computational tools (MEM) and ChIP experiments. HLX's influence on STAT4 was explored with the MG132 proteasome inhibitor. Findings were validated in a mouse MI model.ERG, a commonly upregulated gene, was identified in NK cells from MI patients and mice. ERG upregulated HLX, leading to STAT4 proteasomal degradation and reduced Perforin expression. Consequently, NK cell cytotoxicity decreased, promoting MI progression. ERG mediates the HLX/STAT4/Perforin axis to inhibit NK cell cytotoxicity, fostering MI progression. These results provide vital insights into MI's molecular mechanisms.