Orchestration of an effective T lymphocyte response at infection sites is critical for protection against Mycobacterium tuberculosis (Mtb) infection. However, the local T cell immunity landscape in human tuberculosis is poorly defined. Tuberculous pleural effusion (TPE), caused by Mtb, is characterized by an influx of leukocytes to the pleural space, providing a platform suitable for delineating complex tissue responses to Mtb infection. Using single-cell transcriptomics and T cell receptor sequencing, we analyzed mononuclear cell populations in paired pleural fluid and peripheral blood of TPE patients. While all major cell clusters were present in both tissues, their relative proportions varied significantly by anatomic location. Lineage tracking analysis revealed subsets of CD8 and CD4 T cell populations with distinct effector functions specifically expanded at pleural sites. Granzyme K–expressing CD8 T cells were preferentially enriched and clonally expanded in pleural fluid from TPE, suggesting that they are involved in the pathogenesis of the disease. The findings collectively reveal the landscape of local T cell immunity in tuberculosis.

Significance: Microbes colonizing the infant gut during the first year(s) of life play an important role in immune system development. We show that after birth the (nearly) sterile gut is rapidly colonized by bacteria and their viruses (phages), which often show a strong cooccurrence. Most viruses infecting the infant do not cause clinical signs and their numbers strongly increase after day-care entrance. The infant diet is clearly reflected by identification of plant-infecting viruses, whereas fungi and parasites are not part of a stable gut microbiota. These temporal high-resolution baseline data about the gut colonization process will be valuable for further investigations of pathogenic viruses, dynamics between phages and their bacterial host, as well as studies investigating infants with a disturbed microbiota.

Ferritin, a key regulator of iron homeostasis in macrophages, has been reported to confer host defenses against Mycobacterium tuberculosis (Mtb) infection. Nuclear receptor coactivator 4 (NCOA4) was recently identified as a cargo receptor in ferritin degradation. Here, we show that Mtb infection enhanced NCOA4-mediated ferritin degradation in macrophages, which in turn increased the bioavailability of iron to intracellular Mtb and therefore promoted bacterial growth. Of clinical relevance, the upregulation of FTH1 in macrophages was associated with tuberculosis (TB) disease progression in humans. Mechanistically, Mtb infection enhanced NCOA4-mediated ferritin degradation through p38/AKT1- and TRIM21-mediated proteasomal degradation of HERC2, an E3 ligase of NCOA4. Finally, we confirmed that NCOA4 deficiency in myeloid cells expedites the clearance of Mtb infection in a murine model. Together, our findings revealed a strategy by which Mtb hijacks host ferritin metabolism for its own intracellular survival. Therefore, this represents a potential target for host-directed therapy against tuberculosis.

In this study, we first utilized the single mosquito microbiome analysis, demonstrating a complex three-way interaction among arboviruses, resident microbiota, and the host, which is distinct for different arbovirus–mosquito combinations. Some of the previously described “core virus” increased in the mosquitos receiving viral blood meal, like Guadeloupe mosquito virus and Guadeloupe Culex tymo-like virus, suggesting their potential roles in ZIKV and WNV infection.

Culex modestus mosquitoes are considered to be a potential “bridge” vector, being able to transmit pathogens between birds as well as from birds to mammals, including humans. In Belgium, this mosquito species was considered absent until the finding of one larva in 2018 and subsequent evidence of a large population in 2019 to 2020 described here.