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Problem: Endometriosis exhibits several immune dysfunctions, including deficient natural killer (NK) cell cytotoxicity. MICA (MHC class I chain-related molecule A) is induced by biological stress and soluble MICA (sMICA) negatively modulates the expression of the activating receptor, NKG2D, reducing NK cells activities. We investigated the involvement of soluble MICA in NK cell-deficient activity in endometriosis., Methods of Study: sMICA levels (serum and peritoneal fluid-PF) were evaluated by ELISA. Circulating NK cell subsets quantification and its NKG2D receptor expression, NK cell cytotoxicity and CD107a, IFN-γ and IL-10 expressions by NK cells stimulated with K562 cells were determined by flow cytometry., Results: We found higher sMICA levels (serum and PF) in endometriosis, especially in advanced and deep endometriosis. Endometriosis presented lower percentages of CD56 dim CD16+ cytotoxic cells and impaired NK cell responses upon stimulation, resulting in lower CD107a and IFN-γ expressions, and deficient NK cell cytotoxicity. NK cell stimulation in the MICA-blocked condition (mimicking the effect of sMICA) showed decreased cytotoxicity in initial endometriosis stages and the emergence of a negative correlation between CD107a expression and sMICA levels., Conclusions: We suggest that soluble MICA is a potential player in endometriosis pathophysiology with involvement in disease progression and severity, contributing to NK cell impaired IFN-γ response and degranulation. NK cell compartment exhibits multiple perturbations, including quantitative deficiency and impaired cytotoxicity, contributing to inadequate elimination of ectopic endometrial tissue., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Despite the high number of individuals infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who develop coronavirus disease 2019 (COVID-19) symptoms worldwide, many exposed individuals remain asymptomatic and/or uninfected and seronegative. This could be explained by a combination of environmental (exposure), immunological (previous infection), epigenetic, and genetic factors. Aiming to identify genetic factors involved in immune response in symptomatic COVID-19 as compared to asymptomatic exposed individuals, we analyzed 83 Brazilian couples where one individual was infected and symptomatic while the partner remained asymptomatic and serum-negative for at least 6 months despite sharing the same bedroom during the infection. We refer to these as "discordant couples". We performed whole-exome sequencing followed by a state-of-the-art method to call genotypes and haplotypes across the highly polymorphic major histocompatibility complex (MHC) region. The discordant partners had comparable ages and genetic ancestry, but women were overrepresented (65%) in the asymptomatic group. In the antigen-presentation pathway, we observed an association between HLA-DRB1 alleles encoding Lys at residue 71 (mostly DRB1*03:01 and DRB1*04:01) and DOB*01:02 with symptomatic infections and HLA-A alleles encoding 144Q/151R with asymptomatic seronegative women. Among the genes related to immune modulation, we detected variants in MICA and MICB associated with symptomatic infections. These variants are related to higher expression of soluble MICA and low expression of MICB. Thus, quantitative differences in these molecules that modulate natural killer (NK) activity could contribute to susceptibility to COVID-19 by downregulating NK cell cytotoxic activity in infected individuals but not in the asymptomatic partners., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Castelli, de Castro, Naslavsky, Scliar, Silva, Andrade, Souza, Pereira, Castro, Mendes-Junior, Meyer, Nunes, Matos, Silva, Wang, Esposito, Coria, Bortolin, Hirata, Magawa, Cunha-Neto, Coelho, Santos, Marin, Kalil, Mitne-Neto, Maciel, Passos-Bueno and Zatz.)

Endometriosis (EDT) is an inflammatory disease characterized by implantation/growth of endometrial tissue, glands, and/or stroma, outside the uterus. Reduced NK cell cytotoxic activity has been implicated in its pathogenesis, together with other immunologic alterations. We investigated the influence of KIR gene polymorphisms and their HLA ligand combinations in deep endometriosis (DE) susceptibility. One hundred sixty women with a histological diagnosis of DE and 202 control women without the disease, who underwent laparoscopy, were enrolled. The DE group was subdivided into initial (I/II; n = 60) and advanced stages (III/IV, n = 100). KIR and HLA class I gene polymorphisms were typed by PCR-SSP and sequence-based-typing (SBT), respectively. We observed a significant association of KIR2DL2, an inhibitory gene of B haplotype, conferring risk for DE in Euro-descendants. Positive associations of Bx haplotype and centromeric AB segments were also found. However, no association with KIR-HLA ligand combination was observed. Our data suggest KIR2DL2 gene to be a relevant factor favoring NK inhibition in DE in Euro-descendants, contributing to the defective NK cytotoxic activity and impaired clearance of ectopic endometrial cells in the disease.

Objective: To assess whether the HLA-G immunomodulatory protein is potentially involved in the pathophysiology of endometriosis or disease progression., Study Design: Cross-sectional observational study of 227 women who underwent laparoscopy, being 146 for endometriosis excision and 81 for elective tubal ligation (control group). Soluble HLA-G (sHLA-G) levels in the serum and peritoneal fluid (PF), as well as the HLA-G protein expression in matched eutopic and ectopic endometrium of women with and without endometriosis were evaluated by ELISA and immunohistochemistry assays, respectively. Women with endometriosis were separated into groups according to the initial (I/II, n = 60) and advanced (III/IV, n = 86) stages of disease. sHLA-G measurement was performed only in women with matched serum and PF samples in both the control (CTRL; n = 77) and endometriosis (EDT; I-II, n = 60; III-IV, n = 83) groups. HLA-G protein expression was evaluated in 26 women with deep endometriosis (I-II, n = 12; III-IV, n = 14) and 22 controls., Results: Higher concentrations of sHLA-G (P = 0.013) in the serum but not in the PF were observed in women with advanced endometriosis compared to the control group. In situ expression of HLA-G protein was also higher in ectopic (P = 0.018) but not in eutopic endometrium of women with advanced endometriosis compared to control group., Conclusion: Our findings suggest that HLA-G upregulation in advanced stages may contribute to the state of immunosuppression in endometriosis as disease progresses., (Copyright © 2019 Elsevier B.V. All rights reserved.)