ImmunoHorizons最新文献

Human in vitro studies of HIV Nef on TcR proximal signaling have been controversial and have not provided an integrated picture of its impact. Tyrosine (Y) phosphorylation (pY) of Lck and its substrates (CD3ζ, Zap-70) was investigated in vivo, in Nef-expressing transgenic (Tg) thymocytes. In Tg cells, Lck was mis-localized and activated, but the pY-CD3ζ levels were unexpectedly lower, both constitutively and after anti-CD3ε Ab stimulation. Nef also favors the hyperphosphorylation of the Lck Y505 site and the accumulation of doubly phosphorylated (Y394, Y505) Lck. In contrast, after anti-CD3ε+anti-CD4 Ab stimulation, Nef decreased Lck activity and Lck was deprived of its pY partners. In Nef and LckY505F Tg thymocytes, Lck had similar activity but distinct LckY505 levels, Zap-70 pY phosphorylation, and Zap-70 activity, suggesting a different mode of Lck activation. Western blot analysis of Zap-70 with pY site-specific mAb showed modest enhanced levels of Zap-70pY292 and Zap-70pY493 (the latter required for its full activation) constitutively and after anti-CD3ε Ab stimulation, consistent with elevated Tg LATpY and suggesting a semiactive kinase. In fact, phenotypes of Nef Tg mice are very similar to those of mice harboring semiactive Zap-70 mutants. After anti-CD3ε+anti-CD4 stimulation, Tg Zap-70 activity and Zap-70pY493 levels were severely decreased, but Zap-70pY292 and Zap-70pY319 levels were barely affected, suggesting qualitative Lck defect. Rescue of Nef-mediated CD4+ T-cell loss with LckY505F in double (Nef × LckY505F) Tg mice correlated with greatly enhanced levels of Zap-70pY and Zap-70 activity. Thus, Nef impacts Lck in a unique way, triggering it to mis-phosphorylate its substrates.

MK-6194, an interleukin-2 mutein designed to selectively activate regulatory T cells (Tregs), was evaluated for safety, pharmacokinetics (PK), immunogenicity, and pharmacodynamics in healthy participants. In a single ascending dose trial (N = 56), participants received subcutaneous MK-6194 or placebo (3:1 ratio) across dose levels ranging from 1 to 10 mg. In a multiple ascending dose trial (N = 54), participants received subcutaneous MK-6194 or placebo (3:1 ratio) at dose levels ranging from 0.5 to 5 mg every 2 wk (total 3 doses) as well as 5 mg every 4 wk (total 2 doses). Baseline characteristics were comparable between trials, with participants mostly male with a mean age of 36 yr. There were no serious adverse events or dose-limiting toxicities. The most common adverse events were injection site erythema and eosinophil count elevations (with no indication of severe eosinophilia or eosinophilia-related organ damage). PK showed dose-proportionality and repeated doses of MK-6194 did not result in accumulation or time-dependent PK. Immunogenicity was low with no impact on PK or safety. Treg expansion as assessed by flow cytometry and Treg-specific demethylation region analysis was observed in a dose-dependent manner during both trials and expanded within about 8 d postdose up to about 5-fold and returned to baseline by 14 to 29 d postdose. Minimal impact was observed on other lymphocytes including total T lymphocyte and natural killer cell counts. These findings support the further development of MK-6194 as a potential treatment for autoimmune disorders.

To alleviate the contribution of antibody dependent enhancement in DenV pathogenesis, we obtain a DenV neutralizing single domain antibody (sdAb) from an in-house constructed phage display library of camelid VHH. The anti-DenV sdAb specifically reacts with the envelope (E) protein of DenV with a Kd value of 2x108. Molecular dynamic simulations and docking analysis show that the sdAb interacts with the DenV(E) protein via domain II (EDII) and interferes with the virus internalization process. The anti-DenV(E) sdAb potently inhibits the infectivity of a DenV(E) protein expressing pseudovirus as well as that of a virulent DenV in vitro. A mouse adapted DenV2 induces 100% mortality in the infected IFNRKO mice, but the animals injected with the sdAb neutralized virus remain fully protected. Furthermore, the therapeutically administered anti-DenV(E) sdAb slows down the disease progression and enhances the survival of DenV infected animals. In conclusion, we report an anti-DenV(E) sdAb as a potential therapy to manage DenV pathogenesis.

Malaria is caused by protozoan parasites in the genus Plasmodium. Over time individuals slowly develop clinical immunity to malaria, but this process occurs at variable rates, and the mechanism of protection is not fully understood. We have recently demonstrated that in genetically identical C57BL/6N mice, gut microbiota composition dramatically impacts the quality of the humoral immune response to Plasmodium yoelii and subsequent protection against a lethal secondary challenge with Plasmodium berghei ANKA in C57BL/6N mice. Here, we utilize this genetically identical, gut microbiome-dependent model to investigate how the gut microbiota modulate immunological memory, hypothesizing that the gut microbiome impacts the formation and functionality of immune memory. In support of this hypothesis, P. yoelii hyperparasitemia-resistant C57BL/6N mice exhibit increased protection against P. berghei ANKA-induced experimental cerebral malaria (ECM) compared to P. yoelii hyperparasitemia-susceptible C57BL/6N mice. Despite differences in protection against ECM, P. yoelii-resistant and -susceptible mice accumulate similar numbers of memory B cells (MBCs) and memory T cells. Following challenge with P. berghei ANKA, P. yoelii-resistant mice generated more rapid germinal center reactions; however, P. yoelii-resistant and -susceptible mice had similar titers of P. yoelii- and P. berghei-specific antibodies. In contrast, P. yoelii-resistant mice had an increased number of regulatory T cells in response to secondary challenge with P. berghei ANKA, which may dampen the immune-mediated breakdown of the blood-brain barrier and susceptibility to P. berghei-induced ECM. These findings demonstrate the ability of the gut microbiome to shape immune memory and the potential to enhance resistance to severe malaria outcomes.

Innate immune cells sense microbial danger signals, resulting in dynamic transcriptional reprogramming and rapid inflammatory responses. If not properly regulated, such responses can be detrimental to the host, as is seen in septic shock. A better understanding of the genetic regulation of responses during endotoxemia could provide potential therapeutic insights. However, the majority of animal model studies have been performed using classic inbred laboratory strains of mice, capturing limited genetic diversity. Here, we compared classic inbred C57BL/6 (B6) mice with wild-derived and genetically divergent PWD/PhJ (PWD) mice using in vivo and in vitro models of endotoxemia. Compared with B6 mice, PWD mice were markedly resistant to bacterial lipopolysaccharide (LPS)-induced endotoxic shock. Using LPS stimulation of bone marrow derived dendritic cells (BMDC) and RNA sequencing, we demonstrate that B6 and PWD BMDCs exhibit partially overlapping yet highly divergent transcriptional responses, with B6 skewed toward stereotypical proinflammatory pathway activation, and PWD engaging regulatory or developmental pathways. To dissect genetic regulation of inflammatory responses by allelic variants, we used BMDCs from a sub-consomic strain carrying a ∼50 Mb PWD-derived portion of chromosome 11 on the B6 background. This identified a subset of cis-regulated and a large number of trans-regulated genes. Bioinformatic analyses identified candidate trans regulators encoded in the chromosome 11 locus as transcription factors Irf1, Ncor1, and Srebf1. Our results demonstrate that natural genetic variation controls host survival and transcriptional reprogramming during endotoxemia, suggesting possibilities for prediction of sepsis risk and/or personalized therapeutic interventions.

This study aimed to better understand the importance of CD8 T cell responses in protective immunity to chlamydia. In women evaluated for reinfection at a 3-month follow-up visit after treatment for chlamydia, the presence or magnitude of Chlamydia trachomatis-specific CD8 interferon-gamma (IFN-γ) responses to Momp and Pgp3 peptide pools was not associated with reinfection status, despite having an increased frequency of responses compared to C. trachomatis CD4-specific T cells. However, reinfected women with detectable interferon-gamma (IFN-γ)-producing CD8 T cells had lower C. trachomatis bacterial load compared to women without these CD8 T cell responses. Moreover, the frequency of IFN-γ-producing CD8 T cells was inversely associated with C. trachomatis bacterial load. We further determined that C. trachomatis-specific IFN-γ-producing CD8 T cells were predominately late differentiated effector memory T cells that re-expressed CD45RA (Temra; CCR7-CD45RA+) or effector memory T cells (Tem; CCR7-CD45RA-). Together, these data support the concept that CD8 T cells may contribute to protective immunity against chlamydia in women.

Maresin-1 is a derivative of docosahexaenoic acid with strong anti-inflammatory action in various disease models. However, these effects may not always be beneficial. In instances like cutaneous diseases in which wound healing is important, inflammation is required. In this study, we investigated the effects of maresin-1 on cutaneous wound healing and found that wound healing was significantly delayed in maresin-1-treated mouse skin in the early phase of wound healing on days 1 to 3. Histological analyses revealed that maresin-1 suppressed re-epithelization in the wounded skin. Despite the direct influence of maresin-1 on keratinocyte migration, a comprehensive quantitative polymerase chain reaction analysis revealed that maresin-1-treated wound skin showed a decrease in tumor necrosis factor α, indicating that maresin-1 indirectly suppresses keratinocyte migration mediated by reduced tumor necrosis factor α derived from wounded skin, leading to delayed wound healing.

Chronic immunosuppressive therapies are crucial in organ transplantation but can increase the risk of opportunistic infections and cancer over time. We investigated immune status changes in 10 kidney transplant patients and 11 age-matched healthy adults using broad in vitro stimulation of subject-derived peripheral blood mononuclear cells followed by mass cytometry by time of flight over 6 mo. Overall, the immune cells of transplant patients exhibited increased CD8+ T cell activation and differentiation compared with healthy donors, with elevated CD8+ CD57+, MIP-1β, and interferon γ production (P < 0.05, P < 0.05, and P < 0.01, respectively). CD107a and granzyme B expression were increased in CD8+ T cells and CD56bright natural killer cells (P < 0.05 and P < 0.01, respectively), while T regulatory cells had decreased interleukin-10 production (P < 0.05). These changes indicated a proinflammatory environment influenced by induction therapy and ongoing maintenance drugs. Additionally, transplant recipients displayed signs of immune modulation, including decreased tumor necrosis factor α, interferon γ, and MIP-1β expression in γδT cells (P < 0.05 and P < 0.01), and reduced interleukin-17 and granulocyte-macrophage colony-stimulating factor expression in CD8+ T memory cell subsets (P < 0.05). The diverse functional changes underscore the importance of comprehensive immune status profiling for optimizing individual treatment strategies and developing better immunosuppressants that specifically target activated cell populations.

Chikungunya (CHIKV) and dengue (DENV) are mosquito-borne viruses that cause severe epidemics, often in remote regions. A limitation to our understanding of these pathogens is the difficulty of performing assays of the cellular immune response. To fill this gap, we developed a novel miniaturized automated system capable of processing 250 μl of whole blood for high-throughput cellular analysis. In a field study with a pediatric cohort in Msambweni, Kenya, known for previous exposure to CHIKV and/or DENV, we processed 133 whole blood samples using our system under three conditions: no stimulation, and stimulation with CHIKV or DENV peptide pools. These samples underwent CyTOF or flow cytometry analysis to evaluate virus-specific memory T cell responses and phenotypes. CyTOF analysis of 81 participant samples revealed significant cytokine responses to CHIKV and DENV, particularly IFNγ (P < 0.01 and P < 0.0001, respectively) and TNF-α (P < 0.0001) by γδ T cells. Additionally, a significant TNF-α response was observed in the CD8+ TEMRA memory subset to DENV, albeit to a lesser degree than in γδ T cells. To confirm our CyTOF findings, we employed flow cytometry on the remaining 40 samples using a targeted panel, validating significant TNF-α (P < 0.0001 and P < 0.01) and IFN-γ (P < 0.05) responses by γδ T cells to CHIKV and DENV, respectively. Our study demonstrates that our innovative automated system enables detailed assessment of immune function, particularly beneficial in pediatric populations and resource-limited settings with limited sample volumes. This approach holds promise for advancing our understanding of cellular immune responses to various viral and infectious diseases.

Neurogenic bowel dysfunction (NBD) is common after spinal cord injury (SCI). Gut-associated lymphoid tissue (GALT), an organized structure within the mucosal immune system, is important for the maintenance of gut homeostasis and body health and serves as the first line barrier/defense against diet antigens, commensal microbiota, pathogens, and toxins in mucosal areas. The current study examined gene expression levels along six segments of anorectal tissue using real-time polymerase chain reaction (RT-PCR) in uninjured rats (28-day sham surgical controls) and at both 28- and 42-days post-T9 contusion injury. Consistent with our previous report of functional regional differences in the ano-rectum, we demonstrate the existence of GALTs located primarily within the segment at 3-4.5 cm from the rectal dentate line (termed rectal GALTs-rGALTs) in shams with upregulated gene expression levels of multiple biomarkers, including B cell and T cell-related genes, major histocompatibility complex (MHC) class II molecules, and germinal center (GC)-related genes, which was further confirmed by histologic examination. In the same rectal tissue segment following T9 SCI, inflammation-related genes were upregulated at 28 days post-injury (DPI) indicating that microbial infection and inflammation of rGALTs modified structure and function of rGALTs, while at 42 DPI rGALTs exhibited resolution of inflammation and impaired structure/function for extrafollicular B cell responses. Taken together, our data suggest that rGALTs exists in rat rectum for homeostasis of gut microbiota/barrier. SCI induces microbial infection and inflammation in rectal tissues containing rGALTs, which could contribute to development of SCI-related gut microbiome dysbiosis, NBD, and systemic diseases.