People living with HIV (PLWH) have an increased risk for developing tuberculosis after M. tuberculosis infection, despite anti-retroviral therapy (ART). To delineate the underlying mechanisms, we conducted single cell transcriptomics on bronchoalveolar lavage cells from PLWH on ART and HIV uninfected healthy controls infected with M. tuberculosis ex vivo. We identify an M1-like proinflammatory alveolar macrophage subset that sequentially acquires TNF signaling capacity in controls but not in PLWH. Cell-cell communication analyses reveal interactions between M1-like macrophages and effector memory T cells within TNF superfamily, chemokine, and costimulatory networks in the airways of controls. These interaction networks were lacking in PLWH infected with M. tuberculosis, where anti-inflammatory M2-like alveolar macrophages and T regulatory cells dominated along with dysregulated T cell signatures. Our data support a model in which impaired TNF-TNFR signaling, M2-like alveolar macrophages and aberrant macrophage-T cell crosstalk, lead to ineffective immunity to M. tuberculosis in PLWH on ART.
© 2025. The Author(s).

Mucosal antigen-specific T cells are pivotal for pathogen clearance and immune modulation in respiratory infections. Dysregulated T cell responses exacerbate coronavirus disease 2019 severity, marked by cytokine storms and respiratory failure. Despite extensive description in peripheral blood, the characteristics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific T cells in the lungs remain elusive. Here we conducted integrated single-cell profiling of SARS-CoV-2-specific T cells in 122 bronchoalveolar lavage fluid (BALF) and 280 blood samples from 159 patients, including 27 paired BALF and blood samples from 24 patients. SARS-CoV-2-specific T cells were robustly elicited in BALF irrespective of prior vaccination, correlating with diminished viral loads, lessened systemic inflammation and improved respiratory function. SARS-CoV-2-specific T cells in BALF exhibited profound activation, along with proliferative and multi-cytokine-producing capabilities and a glycolysis-driven metabolic signature, which were distinct from those observed in peripheral blood mononuclear cells. After viral clearance, these specific T cells maintained a polyfunctional tissue-resident memory phenotype, highlighting their critical roles in infection control and long-term protection.
© 2025. The Author(s).

Abstract People living with HIV (PLWH) have an increased risk for developing tuberculosis (TB) after infection with Mycobacterium tuberculosis (Mtb), despite anti-retroviral therapy (ART). To delineate the underlying mechanisms, we conducted single cell transcriptomics on bronchoalveolar lavage (BAL) cells from PLWH on ART and HIV uninfected healthy controls (HC) infected with Mtb ex vivo. We identified an M1-like proinflammatory alveolar macrophage (AM) subset that sequentially acquired TNF signaling capacity in HC but not in PLWH. Cell-cell communication analyses revealed robust interactions between M1-like AMs and effector memory T cells within TNF superfamily, chemokine, and costimulatory networks in the airways of HC. These interaction networks were lacking in PLWH infected with Mtb, where anti-inflammatory M2-like AMs and T regulatory cells dominated along with dysregulated T cell signatures. Our data support a model in which impaired TNF-TNFR signaling, and aberrant AM-T cell crosstalk, lead to ineffective immunity to Mtb in PLWH on ART.

The DNA-binding peptide LL37 is a suspected autoantigen in psoriasis. It can be found in neutrophil extracellular traps (NETs) which have been suggested to play a role in the pathogenesis of the disease. Citrullination, the conversion of peptidyl-arginine into peptidyl-citrulline, can be implicated in the formation of NETs. We hypothesized that citrullination increases LL37 immunogenicity and that NETs are a source of LL37.
We aimed to characterize cytokine responses of B cells and T cells to native and citrullinated LL37 (citLL37) and determine the prevalence and composition of circulating NETs in patients with psoriasis and healthy blood donors (HDs).
Mononuclear cells (MNCs) and serum were isolated from 20 HDs and 20 patients with psoriasis. The MNCs were stimulated with native LL37 and citLL37 and the proportion of cytokine-positive B cells and T cells was determined by flow cytometry. Circulating antibodies against native LL37 and citLL37 as well as circulating NETs were measured by ELISA, as was the content of LL37, citLL37, and IgG in the NETs.
CitLL37, but not native LL37, induced IFN-γ-production by T cells and B cells from psoriasis patients, as well as IL-10-production by the patients' CD4+ T cells. Serum from 40% of patients and 55% of HDs contained circulating NETs, of which 63% and 27%, respectively, contained LL37. Only two patients had NETs containing citLL37 and IgG antibodies were found in NETs from three patients and one HD. Post-hoc analysis of the cytokines produced by B cells and T cells after stimulation with citLL37 revealed two clusters of patients consisting of 10 high-responders and 9 low-responders. The high-responders were those that had circulating NETs in combination with an earlier age of onset of the disease.
Citrullinated but not native LL37 elicits IFN-γ-responses by T cells and B cells from psoriasis patients, particularly those with circulating NETs and early disease onset, suggesting a role of citLL37 as an autoantigen in this subgroup of patients.
Copyright © 2023 Martín Monreal, Kvist-Hansen, Massarenti, Steffensen, Loft, Hansen, Ødum, Skov and Nielsen.

There is great need for vaccines against tuberculosis (TB) more efficacious than the licensed BCG. Our goal was to identify new vaccine benchmarks by identifying immune responses that distinguish individuals able to eradicate the infection (TB-resisters) from individuals with latent infection (LTBI-participants). TB-resisters had higher frequencies of circulating CD8+ glucose monomycolate (GMM)+ Granzyme-B+ T cells than LTBI-participants and higher proportions of polyfunctional conventional and nonconventional T cells expressing Granzyme-B and/or PD-1 after ex vivo M. tuberculosis stimulation of blood mononuclear cells. LTBI-participants had higher expression of activation markers and cytokines, including IL10, and IFNγ. An exploratory analysis of BCG-recipients with minimal exposure to TB showed absence of CD8+GMM+Granzyme-B+ T cells, lower or equal proportions of Granzyme-B+PD-1+ polyfunctional T cells than TB-resisters and higher or equal than LTBI-participants. In conclusion, high Granzyme-B+PD-1+ T cell responses to M. tuberculosis and, possibly, of CD8+GMM+Granzyme-B+ T cells may be desirable for new TB vaccines.
© 2023 The Authors.