Tuberculosis (TB) is the leading infectious cause of death in the world. Cheaper and more accessible TB treatment monitoring methods are needed. Here, we evaluated white blood cell (WBC) absolute counts, lymphocyte, and monocyte proportions during TB treatment, and characterized their association with treatment failure. This multicentered prospective cohort study was based in Bangladesh, Georgia, Lebanon, Madagascar, and Paraguay. Adult, non-immunocompromised patients with culture-confirmed pulmonary TB were included and followed up after two months of treatment and at the end of therapy. Blood counts were compared to treatment outcome using descriptive statistics, logistic regression, and Receiver Operating Characteristic (ROC) analyses. Between December 2017 and August 2020, 198 participants were enrolled, and 152 completed treatment, including 28 (18.5%) drug-resistant patients. The rate of cure at the end of treatment was 90.8% (138/152). WBC absolute counts decreased, and lymphocyte proportions increased throughout treatment. In multivariate analyses, baseline high WBC counts and low lymphocyte proportions were associated with positive sputum culture results at the end of treatment (WBC > 11,450 cells/mm³: p = 0.048; lymphocytes 11,450 cells/mm³ and lymphocytes <16.0%: p = 0.024). High WBC counts and low lymphocyte proportions at baseline are significantly associated with the risk of TB treatment failure.

Secondary bacterial infections contribute to the excess morbidity and mortality of influenza A virus (IAV) infection. Disruption of lung integrity and impaired antibacterial immunity during IAV infection participate in colonization and dissemination of the bacteria out of the lungs. One key feature of IAV infection is the profound alteration of lung myeloid cells, characterized by the recruitment of deleterious inflammatory monocytes. We herein report that IAV infection causes a transient decrease of lung conventional dendritic cells (cDCs) (both cDC1 and cDC2) peaking at day 7 post-infection. While triggering emergency monopoiesis, IAV transiently altered the differentiation of cDCs in the bone marrow, the cDC1-biaised pre-DCs being particularly affected. The impaired cDC differentiation during IAV infection was independent of type I interferons (IFNs), IFN-γ, TNFα and IL-6 and was not due to an intrinsic dysfunction of cDC precursors. The alteration of cDC differentiation was associated with a drop of local and systemic production of Fms-like tyrosine kinase 3 ligand (Flt3-L), a critical cDC differentiation factor. Overexpression of Flt3-L during IAV infection boosted the cDC progenitors’ production in the BM, replenished cDCs in the lungs, decreased inflammatory monocytes’ infiltration and lowered lung damages. This was associated with partial protection against secondary pneumococcal infection, as reflected by reduced bacterial dissemination and prolonged survival. These findings highlight the impact of distal viral infection on cDC genesis in the BM and suggest that Flt3-L may have potential applications in the control of secondary infections. Secondary bacterial infections constitute a leading cause of mortality during influenza epidemics and pandemics. Acute infections trigger the mobilization of myeloid cells from the bone marrow (BM) to the infected tissues, a process referred to as emergency myelopoiesis. Influenza infection leads to a profound alteration in the pulmonary myeloid cell compartment characterized by the recruitment of inflammatory myeloid cells. The consequences of IAV infection on BM myelopoiesis have yet to be described in detail. Here, we report that influenza infection leads to reduced number of conventional dendritic cells (cDC) in the lungs (with a peak at day 7) and severely impairs DC differentiation in the BM, for the benefit of monopoiesis. The altered cDC differentiation was independent of pro-inflammatory cytokines and was not due to an intrinsic dysfunction of cDC precursors. Defective DC differentiation during influenza was associated with a decrease in the production of the key cDC differentiation factor, Fms-like tyrosine kinase 3 ligand (Flt3-L). Overexpression of Flt3-L during influenza enhanced the number of BM cDC progenitors and restored lung cDC compartment. This phenomenon was associated with a lowered number of lung inflammatory monocytes and reduced lung damages. Importantly, Flt3-L overexpression partially protected against secondary pneumococcal infection characterized by reduced bacterial loads, improved pathological outcomes and prolonged survival. Our results provide new clues as to how influenza infection influences the differentiation of cDCs, and highlight the potential therapeutic value of Flt3-L in a disease in desperate need of better treatments.

The Syrian conflict has damaged key infrastructure and indirectly affected almost all parts of the Middle East and Europe, with no end in sight. Exhausting conditions created by the Syrian crisis a...

Identification of MDR and XDR TB cases among refugees and migrant workers in Lebanon has important implications for TB control with ramifications beyond the country.