While tuberculosis (TB) is a risk factor in HIV-1-infected individuals, the mechanisms by which Mycobacterium tuberculosis (Mtb) worsens HIV-1 pathogenesis remain scarce. We showed that HIV-1 infection is exacerbated in macrophages exposed to TB-associated microenvironments due to tunneling nanotube (TNT) formation. To identify molecular factors associated with TNT function, we performed a transcriptomic analysis in these macrophages, and revealed the up-regulation of Siglec-1 receptor. Siglec-1 expression depends on Mtb-induced production of type I interferon (IFN-I). In co-infected non-human primates, Siglec-1 is highly expressed by alveolar macrophages, whose abundance correlates with pathology and activation of IFN-I/STAT1 pathway. Siglec-1 localizes mainly on microtubule-containing TNT that are long and carry HIV-1 cargo. Siglec-1 depletion decreases TNT length, diminishes HIV-1 capture and cell-to-cell transfer, and abrogates the exacerbation of HIV-1 infection induced by Mtb. Altogether, we uncover a deleterious role for Siglec-1 in TB-HIV-1 co-infection and open new avenues to understand TNT biology.

Background: Efficacy of COVID-19 convalescent plasma (CCP) in COVID-19 pneumonia is uncertain. Early transfusion of high antibody titre CCP may be beneficial, especially in case of underlying immunosuppression. Methods: The CORIPLASM study was a multicentric, open-label, Bayesian randomised clinical trial evaluating the efficacy of CCP in patients with moderate COVID-19 pneumonia, including patients with underlying immunosuppression. Patients hospitalised with COVID-19 for less than 9 days were assigned to receive 2 plasma units/day over 2 days (CCP) or usual care (UC) alone. Primary outcomes were the proportion of patients with a WHO-Clinical Progression Score (CPS) >= 6 on the 10-point scale on day 4 and survival without ventilation or additional immunomodulatory treatment by day 14. Main analysis was conducted on the whole population and a planned subgroup analysis was performed according to immunosuppression status. Findings: A total of 120 patients were recruited between April 16, 2020, and April 21, 2021, and assigned to CCP (n=60) or UC (n=60) with a 28 day-follow-up. The median time from symptoms onset to randomisation (days) was 7.0 [interquartile range (IQR) 5.0-9.0] and 7.0 [IQR 4.0-8.5] in CCP and UC, respectively. Thirteen (22%) patients with CCP had a WHO-CPS >= 6 at day 4 versus 8 (13%) with UC, adjusted odds ratio (aOR) 1.88 [95% confidence interval (CI), 0.71 to 5.24]. By d14, 19 (31.6%) patients with CCP and 20 (33.3%) patients with UC had ventilation, additional immunomodulatory treatment or had died. Cumulative incidence of death was 3 (5%) with CCP and 8 (13%) with UC at d14 (aHR 0.40 [95%CI 0.10 -1.53]), and 7 (12%) with CCP and 12 (20%) with UC at day 28 (aHR 0.51 [95% CI 0.20-1.32]). Subgroup analysis indicated that CCP might be associated with a lower mortality in patients with underlying immunosuppression (HR 0.37 [95% CI 0.14-0.97]). Serious adverse events were noted in 30 (50%) and 26 (43%) patients with CCP or UC, respectively. Interpretation: CCP treatment did not improve early outcomes in patients with mild-to-moderate form COVID-19 pneumonia but was associated with reduced mortality in the subgroup of immunosuppressed patients. Trial registration: clinicaltrials.gov Identifier: NCT04345991