European Journal of Immunology最新文献

Inborn deficiencies of the alternative pathway (AP) of the complement system have been associated with life-threatening infections, mainly by encapsulated bacteria. Complete factor D (FD) deficiencies have been reported in only seven families in the literature. We report two new cases of biochemically and genetically confirmed complete FD deficiency, including the first in a Down syndrome patient. The index cases respectively suffered from severe H. influenza and N. meningitidis infections. Their FD activity was undetectable but was restored by adding recombinant human FD. FD levels were undetectable in the plasma of both patients using ELISA. Genetic analysis of the CFD gene identified a homozygous missense variant p.M40R in one patient, and compound heterozygous variants—a nonsense mutation p.Cys148* and a splice site variant c.212+2T>G—in the other. Patients with Down syndrome are more susceptible to infections, but this case highlights the importance of investigating the complement system, particularly the AP, even in those with Down syndrome or other secondary immune deficiencies. A familial study should follow if a congenital deficiency is found. The natural history of patients with inherited complete FD deficiency underscores the necessity of preventive measures against encapsulated bacteria for those receiving therapeutic MASP-3 or FD inhibitors.

Intracellular cytokine labeling combined with high-parametric flow cytometry offers substantial promise in elucidating the nuanced effector functions of cells. However, the establishment of complex multicolor panels is often laborious and the importance of validation processes may be underestimated in research practice. This raises the risk of prematurely translating multicolor panels into in vivo studies. Alternatively, researchers may resort to animal disease models to procure cytokine-producing cells. Both scenarios raise ethical concerns as they entail the potential for unnecessary animal suffering without yielding novel insights into immunobiology. Here, we perform multicolor panel optimization and validation without the need for stressful animal testing. We designed two spectral flow cytometry panels for cytokine expression analyses across mouse immune and joint cells. Animal testing was replaced by stimulated co-cultures of T cells, splenocytes, and fibroblast-like synoviocytes. These cultures were used for multicolor labeling experiments. Our method proved suitable for validating the two cytometry panels, as it provided a complex cellular environment in which a variety of cytokine-producing populations were identified. In summary, we here present a blueprint for the quality control of single-cell cytokine assays by cell culture and further introduce multicolor panels that can be employed for studies on inflammatory or infectious diseases.

Immunosenescence, age-related immune dysregulation, reduces immunity upon vaccinations and infections. Cytomegalovirus (CMV) infection results in declining naïve (T_naïve) and increasing terminally differentiated (T_emra) T cell populations, further aggravating immune aging. Both immunosenescence and CMV have been speculated to hamper the formation of protective T-cell immunity against novel or emerging pathogens. The SARS-CoV-2 pandemic presented a unique opportunity to examine the impact of age and/or CMV on the generation of de novo SARS-CoV-2-specific CD8⁺ T cell responses in 40 younger (22–40 years) and 37 older (50–66 years) convalescent individuals. Heterotetramer combinatorial coding combined with phenotypic markers were used to study 35 SARS-CoV-2 epitope-specific CD8⁺ T cell populations directly ex vivo. Neither age nor CMV affected SARS-CoV-2-specific CD8⁺ T cell frequencies, despite reduced total CD8⁺ T_naïve cells in older CMV^- and CMV⁺ individuals. Robust SARS-CoV-2-specific central memory CD8⁺ T (T_cm) responses were detected in younger and older adults regardless of CMV status. Our data demonstrate that immune aging and CMV status did not impact the SARS-CoV-2-specific CD8⁺ T cell response. However, SARS-CoV-2-specific CD8⁺ T cells of older CMV^- individuals displayed the lowest stem cell memory (T_scm), highest T_emra and PD1⁺ populations, suggesting that age, not CMV, may impact long-term SARS-CoV-2 immunity.

Tumor immune escape refers to the process by which cancer cells evade detection and destruction by the immune system. Glycosylation, a post-translational modification that is altered in almost all cancer types, plays a crucial role in this process by modulating immune responses. This review examines our current understanding of how aberrant tumor glycosylation contributes to a tolerogenic microenvironment, focusing on specific glycosylation signatures—fucosylation, truncated O-glycans, and sialylation—and the immune receptors involved. Additionally, the clinical significance of tumor glycosylation is discussed, emphasizing its potential in developing novel therapeutic approaches aimed at improving immune system recognition and targeting of cancer cells. The review underscores the importance of ongoing research in this area to identify effective strategies for countering tumor immune escape and enhancing the efficacy of cancer treatments.

Bacteriophages (phages) are emerging as a viable adjunct to antibiotics for the treatment of multidrug-resistant (MDR) bacterial infections. While intravenous phage therapy has proven successful in many cases, clinical outcomes remain uncertain due to a limited understanding of host response to phages. In this study, we conducted a comprehensive examination of the interaction between clinical-grade phages used to treat MDR Escherichia coli and Klebsiella pneumoniae infections, and human peripheral blood immune cells. Using whole transcriptome as well as proteomic approaches, we identified a strong inflammatory response to E. coli phage vB_EcoM-JIPh_Ec70 (herein, JIPh_Ec70) that was absent upon exposure to K. pneumoniae phage JIPh_Kp127. We confirmed that JIPh_Ec70's DNA recognition by the STING pathway was principally responsible for the activation of NF-kB and the subsequent inflammatory response. We further show that monocytes and neutrophils play a dominant role in phage uptake, primarily through complement-mediated phagocytosis. Significant differences in complement-mediated phagocytosis of JIPh_Kp127 and JIPh_Ec70 were observed, suggesting that reduced recognition, phagocytosis, and immunogenicity all contribute to the significantly decreased response to JIPh_Kp127. Our findings contribute to the progress of our understanding of the innate immune response to therapeutic phages and offer potential insights into how to improve the safety and effectiveness of phage therapy.

Young females are at high risk of acquiring HIV-1 infections and an imbalance in the vaginal microbiome enhances susceptibility to HIV-1 infection. More insights into the underlying mechanisms could open up new strategies to prevent HIV-1 acquisition and dissemination. Here, we investigated the effect of anaerobic bacteria associated with bacterial vaginosis (BV) on HIV-1 transmission by two distinct dendritic cell (DC) subsets, that is, inflammatory monocyte-derived DCs (moDCs) and primary CD1c⁺ DCs. Notably, in contrast to other BV-associated microbiota, Prevotella timonensis enhanced uptake of HIV-1 by both moDCs and CD1c⁺ DCs and the increased uptake was independent of cellular HIV-1 (co-)receptors. Imaging flow cytometry analyses showed that HIV-1 did not co-localise with P. timonensis but was internalized into tetraspanin-positive compartments known to be involved in HIV-1 transmission. P. timonensis bacteria enhanced HIV-1 transmission by CD1c⁺ DCs, but not by moDCs, and the enhanced transmission was independent of viral infection. Our study strongly suggests that mucosal DC subsets have distinct functions in BV-associated HIV-1 susceptibility, and underscores the importance of early diagnosis and targeted treatment of vaginal dysbiosis to reduce the risk of HIV-1 acquisition.