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Background Nirmatrelvir/ritonavir, the first severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) protease inhibitor, reduces the risk of hospitalization and death by coronavirus disease 2019 (COVID-19) but has been associated with symptomatic rebound after therapy completion. Methods Six individuals with relapse of COVID-19 symptoms after treatment with nirmatrelvir/ritonavir, 2 individuals with rebound symptoms without prior antiviral therapy and 7 patients with acute Omicron infection (controls) were studied. Soluble biomarkers and serum SARS-CoV-2 nucleocapsid protein were measured. Nasal swabs positive for SARS-CoV-2 underwent viral isolation and targeted viral sequencing. SARS-CoV-2 anti-spike, anti–receptor-binding domain, and anti-nucleocapsid antibodies were measured. Surrogate viral neutralization tests against wild-type and Omicron spike protein, as well as T-cell stimulation assays, were performed. Results High levels of SARS-CoV-2 anti-spike immunoglobulin G (IgG) antibodies were found in all participants. Anti-nucleocapsid IgG and Omicron-specific neutralizing antibodies increased in patients with rebound. Robust SARS-CoV-2–specific T-cell responses were observed, higher in rebound compared with early acute COVID-19 patients. Inflammatory markers mostly decreased during rebound. Two patients sampled longitudinally demonstrated an increase in activated cytokine-producing CD4+ T cells against viral proteins. No characteristic resistance mutations were identified. SARS-CoV-2 was isolated by culture from 1 of 8 rebound patients; Polybrene addition increased this to 5 of 8. Conclusions Nirmatrelvir/ritonavir treatment does not impede adaptive immune responses to SARS-CoV-2. Clinical rebound corresponds to development of a robust antibody and T-cell immune response, arguing against a high risk of disease progression. The presence of infectious virus supports the need for isolation and assessment of longer treatment courses. Clinical trials registration NCT04401436. [ABSTRACT FROM AUTHOR]

In the combination antiretroviral era, there are limited data regarding the pathogenesis of histoplasmosis immune reconstitution inflammatory syndrome (IRIS) in people with human immunodeficiency virus (HIV). We immunologically characterized 10 cases of histoplasmosis, 4 of whom developed histoplasmosis IRIS. CD4+ T cells in histoplasmosis IRIS demonstrated a significant polyfunctional cytokine response to histoplasma antigen. [ABSTRACT FROM AUTHOR]

CD4 expression identifies a subset of mature T cells primarily assisting the germinal center reaction and contributing to CD8+ T-cell and B-cell activation, functions, and longevity. Herein, we present a family in which a novel variant disrupting the translation-initiation codon of the CD4 gene resulted in complete loss of membrane and plasma soluble CD4 in peripheral blood, lymph node, bone marrow, skin, and ileum of a homozygous proband. This inherited CD4 knockout disease illustrates the clinical and immunological features of a complete deficiency of any functional component of CD4 and its similarities and differences with other clinical models of primary or acquired loss of CD4+ T cells. The first inherited loss of any functional component of CD4, including soluble CD4, is clinically distinct from any other congenital or acquired CD4 T-cell defect and characterized by compensatory changes in T-cell subsets and functional impairment of B cells, monocytes, and natural killer cells. [ABSTRACT FROM AUTHOR]

Background Immune reconstitution inflammatory syndrome (IRIS) is an aberrant inflammatory response in individuals with advanced human immunodeficiency virus (HIV) infection, after antiretroviral therapy (ART) initiation. The pathogenesis of Mycobacterium avium complex (MAC)–associated IRIS has not been fully elucidated. Methods We investigated monocyte and CD4+ T-cell responses in vitro, tumor necrosis factor (TNF) expression in tissues, and plasma cytokines and inflammatory markers, in 13 HIV-infected patients with MAC-IRIS and 14 HIV-uninfected patients with pulmonary MAC infection. Results Prior to ART, HIV-infected compared with HIV-uninfected patients, had reduced TNF+ monocytes (P =.013), although similar cytokine (interferon gamma [IFN-γ], TNF, interleukin 2 [IL-2], and interleukin 17 [IL-17])–expressing CD4+ T cells. During IRIS, monocyte cytokine production was restored. IFN-γ+ (P =.027), TNF+ (P =.004), and polyfunctional CD4+ T cells (P = 0.03) also increased. These effectors were T-betlow, and some expressed markers of degranulation and cytotoxic potential. Blockade of cytotoxic T-lymphocyte associated protein 4 and lymphocyte activation gene-3 further increased CD4+ T-cell cytokine production. Tissue immunofluorescence showed higher proportions of CD4+ and CD68+ (monocyte/macrophage) cells expressed TNF during IRIS compared with HIV-uninfected patients. Plasma IFN-γ (P =.048), C-reactive protein (P =.008), and myeloperoxidase (P <.001) levels also increased, whereas interleukin 10 decreased (P =.008) during IRIS. Conclusions Advanced HIV infection was associated with impaired MAC responses. Restoration of monocyte responses and expansion of polyfunctional MAC-specific T-betlow CD4+ T cells with cytotoxic potential after ART initiation may overwhelm existing regulatory and inhibitory mechanisms, leading to MAC-IRIS. [ABSTRACT FROM AUTHOR]

Objective: IL-15 has been postulated to play an important role in HIV-1 infection, yet there are conflicting reports regarding its expression levels in these patients. We sought to measure the level of IL-15 in a large, well characterised cohort of HIV-1 infected patients and correlate this with well known markers of inflammation, including CRP, D-dimer, sCD163 and sCD14. Design and Methods: IL-15 levels were measured in 501 people (460 patients with HIV-1 infection and 41 uninfected controls). The HIV-1 infected patients were divided into 4 groups based on viral load: <50 copies/ml, 51–10,000 copies/ml, 10,001–100,000 copies/ml and >100,000 copies/ml. The Mann Whitney test (non-parametric) was used to identify significant relationships between different patient groups. Results: IL-15 levels were significantly higher in patients with viral loads >100,000 copies/ml (3.02 ± 1.53 pg/ml) compared to both uninfected controls (1.69 ± 0.37 pg/ml, p<0.001) or patients with a viral load <50 copies/ml (1.59 ± 0.40 pg/ml (p<0.001). There was a significant correlation between HIV-1 viremia and IL-15 levels (Spearman r = 0.54, p<0.001) and between CD4+ T cell counts and IL-15 levels (Spearman r = -0.56, p<0.001). Conclusions: IL-15 levels are significantly elevated in HIV-1 infected patients with viral loads >100,000 copies/ml compared to uninfected controls, with a significant direct correlation noted between IL-15 and HIV-1 viremia and an inverse correlation between IL-15 levels and CD4+ T cell counts. These data support a potential role for IL-15 in the pathogenesis of HIV-associated immune activation. [ABSTRACT FROM AUTHOR]

Idiopathic CD4(+) lymphopenia (ICL) is a rare syndrome characterized by low peripheral CD4(+) T-cell counts that can lead to serious opportunistic infections. The pathogenesis of ICL remains unclear, and whether effector sites are also lymphopenic is unknown. In this study, rectosigmoid mucosal biopsy specimens from patients with ICL and healthy controls were evaluated. Significant T-cell lymphopenia was observed in the mucosal tissue of patients with ICL by flow cytometry and immunohistochemistry, compared with healthy controls. Functional capacity of T cells, assessed by production of interferon γ and interleukin 17, was preserved in the mucosa of patients with ICL. In contrast to T lymphocytes, the frequency of myeloid cells (neutrophils and macrophages) was elevated in the colonic mucosa of patients with ICL. Despite the observed mucosal abnormalities, plasma levels of intestinal fatty acid binding protein, a marker of enterocyte turnover and other inflammatory biomarkers, including interleukin 6, C-reactive protein, and tumor necrosis factor, were not elevated in patients with ICL, compared with healthy controls, whereas soluble CD14 levels were minimally elevated. These data suggest that patients with ICL, despite gut mucosal lymphopenia and local tissue inflammation, have preserved enterocyte turnover and T-helper type 17 cells with minimal systemic inflammation. These observations highlight differences from patients with human immunodeficiency virus infection, with or without AIDS, and may partially explain their distinct clinical prognosis. [ABSTRACT FROM AUTHOR]

Background. Elite controllers maintain high CD4+ T-cell counts and suppress plasma human immunodeficiency virus (HIV) viremia in the absence of antiretroviral therapy (ART). It is unclear whether levels of biomarkers associated with coagulation, monocyte activation, and inflammation, which are linked to HIV-associated mortality, differ among elite controllers, ART recipients with suppressed viremia (plasma HIV type 1 RNA load, <50 copies/mL), and HIV-negative controls.Methods. A total of 68 elite controllers, 68 ART recipients with suppressed viremia, and 35 HIV-negative participants were evaluated. Levels of biomarkers in cryopreserved plasma were measured by enzyme-linked immunosorbent assay and electrochemiluminescence-based assay. Cryopreserved peripheral blood mononuclear cells were used to assess monocyte phenotype and function and interferon-inducible gene expression (IFIG). Nonparametric testing was used to compare median values among groups.Results. CD4+ T-cell counts were similar between elite controllers and HIV-negative controls but significantly lower in ART recipients with suppressed viremia. Levels of C-reactive protein and interleukin 6 were higher and IFIG upregulated in both HIV-positive groups, compared with HIV-negative controls. D-dimer and soluble tissue factor levels were significantly elevated in elite controllers, compared with those in ART recipients with suppressed viremia and HIV-negative controls (P < .01). Monocytes from elite controllers (and ART recipients with suppressed viremia) expressed lower CCR2 and higher CX3CR1 levels than monocytes from HIV-negative controls. In addition, elite controllers had a significantly higher proportion of CD14++CD16+ monocytes, compared with HIV-negative controls.Conclusion. Elite controllers maintain control of plasma HIV viremia and have evidence of an activated innate immune response. [ABSTRACT FROM PUBLISHER]

HIV infection and the associated chronic immune activation alter T cell homeostasis leading to CD4 T cell depletion and CD8 T cell expansion. The mechanisms behind these outcomes are not totally defined and only partially explained by the direct cytopathic effect of the virus. In this manuscript, we addressed the impact of lymphopenia and chronic exposure to IFN-α on T cell homeostasis. In a lymphopenic murine model, this interaction led to decreased CD4 counts and CD8 T cell expansion in association with an increase in the Signal Transducer and Activator of Transcription 1 (STAT1) levels resulting in enhanced CD4 T cell responsiveness to IFN-α. Thus, in the setting of HIV infection, chronic stimulation of this pathway could be detrimental for CD4 T cell homeostasis. [ABSTRACT FROM AUTHOR]

HIV infection is characterized by a brisk immune activation that plays an important role in the CD4 depletion and immune dysfunction of patients with AIDS. The mechanism underlying this activation is poorly understood. In the current study, we tested the hypothesis that this activation is the net product of two distinct pathways: the inflammatory response to HIV infection and the homeostatic response to CD4 T cell depletion. Using ex vivo BrdU incorporation of PBMCs from 284 patients with different stages of HIV infection, we found that CD4 proliferation was betterpredicted by the combination of CD4 depletion and HIV viral load (R[sup2] = 0.375, p < 0.001) than by either parameter alone (CD4 T cell counts, R[sup2] = 0.202, P < 0.001; HIV viremia, R[sup2] = 0.302, P < 0.001). Interestingly, CD8 T cell proliferation could be predicted by HIV RNA levels alone (R[sup2] = 0.334, P < 0.001) and this predictive value increased only slightly (R[sup2] = 0.346, P < 0.001) when CD4 T cell depletion was taken into account. Consistent with the hypothesis that CD4 T cell proliferation is driven by IL-7 as a homeostatic response to CD4 T cell depletion, levels of phosphorylated STAT-5 were found to be elevated in naive subsets of CD4 and CD8 T cells from patients with HIV infection and in the central memory subset of CD4 T cells. Taken together these data demonstrate that at least two different pathways lead to immune activation of T cells in patients with HIV infection and these pathways differentially influence CD4 and CD8 T cell subsets. [ABSTRACT FROM AUTHOR]

Intermittent administration of interleukin (IL)-2 produces significant and sustained increases in CD4[SUP+] T lymphocyte count in human immunodeficiency virus (HIV)-infected subjects but can be associated with dose-limiting toxicities. The primary objective of this study was to determine whether concomitant administration of prednisone could decrease these toxicities. HIV-seropositive adults receiving highly active antiretroviral therapy (HAART) were randomized to receive either (1) intermittent subcutaneous IL-2 and placebo, (2) intermittent subcutaneous IL-2 and prednisone, (3) intermittent prednisone, or (4) intermittent placebo. Prednisone decreased levels of proinflammatory cytokines during IL-2 cycles but, despite induction of expression of CD25, blunted increases in IL-2-associated CD4[SUP+] T lymphocyte count. Whereas intermittent administration of IL-2 reduced basal proliferation of CD4[SUP+] T cells, this effect was inhibited by prednisone, suggesting that prednisone potentially interferes with IL-2's long-term effects on survival of T lymphocytes. [ABSTRACT FROM AUTHOR]

IL-2 has been used in culture of primary T cells to maintain cell proliferation.Wehave previously reported that IL-27 inhibits HIV-1 replication in primary T cells in the presence of IL-2. To gain a better understanding of the mechanisms involved in this inhibitory effect, we attempted to investigate in detail the effects of IL-27 and IL-2 using several cell lines. Unexpectedly, IL-27 did not inhibit HIV-1 in T cell lines, whereas IL-2 inhibited HIV-1 replication in the human T cell lymphotrophic virus (HTLV)-1-transformed T cell lines, MT-2, MT-4, SLB-1, and ATL-2. No effects were seen in HTLV-1-negative cell lines. Utilizing MT-2 cells, we demonstrated that IL-2 treatment inhibited HIV-1 syncytia-inducing ability and dose-dependently decreased supernatant p24 antigen levels by >90%. Using real time PCR and Western blot analysis, we observed that IL-2 treatment induced the host restriction factor, APOBEC3G with accumulation into the lower molecular mass active form as characterized by FPLC. Further analysis revealed that the virus recovered from IL-2-treated MT-2 cells had impaired replication competency. This was found to be due to incorporation of APOBEC3G into the virion despite the presence of Vif. These findings demonstrate a novel role for IL-2 in regulating production of infectious HIV-1 virions in HTLV-1-infected cells through the induction of APOBEC3G. [ABSTRACT FROM AUTHOR]

The article examines the interleukin-7 (IL-7)/IL-7 receptor α system in a large cohort of HIV-infected patients, including a subset treated with intermittent IL-2. Predictors of CD127 expression were determined using multivariate regression models. CD127 expression on T-cells is low in HIV-infected patients despite antiretroviral therapy.