While antiretroviral therapy (ART) has proven effective in suppressing viremia and disease progression among people living with human immunodeficiency virus (HIV; PLWH), suboptimal CD4+ T cell reconstitution remains a major obstacle in nearly 30% of ART-treated individuals. Epidemiological studies demonstrate that obesity, or a body mass index (BMI) ≥ 30 kg/m2, is positively correlated with greater CD4+ T cell recovery in PLWH on ART. Leptin is a known immunomodulator that is produced in proportion to fat mass and is increased in obese individuals, including PLWH. We hypothesized that CD4+ T cells from obese PLWH have increased cell proliferation and cytokine production compared to cells from lean PLWH, potentially modulated by differential effects of leptin signaling. To test this hypothesis, peripheral blood mononuclear cells from obese and lean PLWH with long-term virologic suppression on the same ART regimen were pretreated with recombinant leptin and then stimulated with anti-CD3/CD28 or PMA/ionomycin to measure Ki67 expression, leptin receptor (LepR) surface expression and cytokine production. In the absence of leptin, Ki67 expression and IL-17A production were significantly higher in CD4+ T cells from obese compared to lean PLWH. However, LepR expression was significantly lower on CD4+ T cells from obese compared to lean PLWH. After leptin treatment, Ki67 expression was significantly increased in CD4+ T cells from obese PLWH compared to the lean participants. Leptin also increased IL-17A production in CD4+ T cells from obese healthy controls. In contrast, leptin decreased IL-17A production in CD4+ T cells from both obese and lean PLWH. Combined, these results demonstrate that obesity is associated with greater CD4+ T cell proliferation among PLWH, and that higher circulating leptin levels in obesity may contribute to improved CD4+ T reconstitution in PLWH initiating ART.
Copyright © 2022 Fuseini, Smith, Nochowicz, Simmons, Hannah, Wanjalla, Gabriel, Mashayekhi, Bailin, Castilho, Hasty, Koethe and Kalams.

Inflammatory bowel disease (IBD), which main clinical manifestations include abdominal pain and diarrhea occurring repeatedly, is a kind of autoimmune disease. It has been reported in preceding studies that mesenchymal stem cells (MSCs) can reduce inflammation by regulating the function of immune cells. But studies about the interaction between MSCs and adaptive immune cells, especially in IBD models, are insufficient. Therefore, the objective of this research was to estimate the therapeutic effects of MSCs from human umbilical cord blood (hUCB-MSCs) in an IBD model of rodent and to clarify the therapeutic mechanisms of hUCB-MSCs. Dextran sulfate sodium (DSS) was used to induce colitis in rodent. Mice with colitis were treated with intraperitoneal infusions of hUCB-MSCs and evaluated for mortality and diverse disease symptoms containing weight reduction, diarrhea, and bloody stools. The levels of histopathologic severity and generation of regulatory T cells (Treg) were also determined. Treatment with hUCB-MSCs ameliorated the clinical and histopathologic severity of acute and chronic colitis in mice. Furthermore, T cell infiltration into the inflamed colon was significantly decreased (p = 0.0175), and Foxp3+ cells were substantially higher in the hUCB-MSC group than that of the DSS group. Our results suggest that hUCB-MSCs are able to alleviate inflammation via adding Foxp3+ Tregs in an IBD model of mouse. As a result, these findings suggest the opportunity of hUCB-MSC being applied to patients with IBD.
Copyright © 2020 Li, Ma, Zhang, Xu and Zhang.

SLAMF6 is a homotypic receptor of the Ig-superfamily whose exact role in immune modulation has remained elusive. Its constitutive expression on resting and activated T cells precludes it from being a bona fide exhaustion marker. By breeding Pmel-1 mice with SLAMF6 -/- mice, we generated donors for T cells lacking SLAMF6 and expressing a transgenic TCR for gp100-melanoma antigen. Activated Pmel-1xSLAMF6 -/- CD8+ T cells displayed improved polyfunctionality and strong tumor cytolysis. T-bet was the dominant transcription factor in Pmel-1 x SLAMF6 -/- cells, and upon activation, they acquired an effector-memory phenotype. Adoptive transfer of Pmel-1 x SLAMF6 -/- T cells to melanoma-bearing mice resulted in lasting tumor regression in contrast to temporary responses achieved with Pmel-1 T cells. LAG-3 expression was elevated in the SLAMF6 -/- cells, and the addition of the LAG-3-blocking antibody to the adoptive transfer protocol improved the SLAMF6 -/- T cells and expedited the antitumor response even further. The results from this study support the notion that SLAMF6 is an inhibitory immune receptor whose absence enables powerful CD8+ T cells to eradicate tumors.
© 2020, Hajaj et al.

CD3+ and CD8+ lymphocytes are well known prognostic markers in primary ovarian cancer. In contrast, the predictive value of the immune infiltrate concerning treatment response and the involvement of immune heterogeneity between primary and metastatic lesions are poorly understood. In this study, the immune infiltrate of 49 primary tumors and 38 corresponding lesions in the omentum (n = 23) and the peritoneum (n = 15) was immunohistochemically analyzed and correlated with clinicopathological factors and platinum-sensitivity. Immune heterogeneity was observed between paired primary and metastatic lesions for all immune cell phenotypes. The stromal immune infiltrate was higher in the omental lesions than in the primary tumors, which was reflected by CD45 (p=0.007), CD3 (p=0.005), CD8 (p=0.012), and PD-1 (programmed cell-death protein 1) (p=0.013). A higher stromal infiltrate of both CD45+ and CD3+ cells in the omental lesions was associated with the detection of lymph node metastasis (CD45, p=0.018; CD3, p=0.037). Platinum-sensitive ovarian cancers revealed a higher intratumoral CD8+ infiltrate in the peritoneal lesions compared to the primary tumors (p=0.045). In contrast, higher counts of stromal PD-1+ cells in the peritoneal lesions have been associated with reduced platinum-sensitivity (p=0.045). Immune heterogeneity was associated with platinum response and might represent a selection marker for personalized therapy.

FCRL5+ atypical memory B cells (atMBCs) expand in many chronic human infections, including recurrent malaria, but studies have drawn opposing conclusions about their function. Here, in mice infected with Plasmodium chabaudi, we demonstrate expansion of an antigen-specific FCRL5+ population that is distinct from previously described FCRL5+ innate-like murine subsets. Comparative analyses reveal overlapping phenotypic and transcriptomic signatures between FCRL5+ B cells from Plasmodium-infected mice and atMBCs from Plasmodium-exposed humans. In infected mice, FCRL5 is expressed on the majority of antigen-specific germinal-center-derived memory B cells (MBCs). Upon challenge, FCRL5+ MBCs rapidly give rise to antibody-producing cells expressing additional atypical markers, demonstrating functionality in vivo. Moreover, atypical markers are expressed on antigen-specific MBCs generated by immunization in both mice and humans, indicating that the atypical phenotype is not restricted to chronic settings. This study resolves conflicting interpretations of atMBC function and suggests FCRL5+ B cells as an attractive target for vaccine strategies.
Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.