Effective control of Staphylococcus aureus lung infection despite tertiary lymphoid structure disorganisation.

BACKGROUND: Tertiary lymphoid structures (TLS) are triggered by persistent bronchopulmonary infection with Staphylococcus aureus, but their roles remain elusive. The present study sought to examine the effects of B- and/or T-cell depletion on S. aureus infection and TLS development (lymphoid neogenesis) in mice. METHODS: C57Bl/6 mice were pre-treated with 1) an anti-CD20 monoclonal antibody (mAb) (B-cell depletion) or 2) an anti-CD4 and/or an anti-CD8 mAb (T-cell depletion) or 3) a combination of anti-CD20, anti-CD4 and anti-CD8 mAbs (combined B- and T-cell depletion) or 4) isotype control mAbs. After lymphocyte depletion, mice were infected by intratracheal instillation of agarose beads containing S. aureus (106 CFU per mouse). 14 days later, bacterial load and lung inflammatory cell infiltration were assessed by cultures and immunohistochemistry, respectively. RESULTS: 14 days after S. aureus-bead instillation, lung bacterial load was comparable between control and lymphocyte-depleted mice. While TLS were observed in the lungs of infected mice pre-treated with control mAbs, these structures were disorganised or abolished in the lungs of lymphocyte-depleted mice. The absence of CD20+ B-lymphocytes had no effect on CD3+ T-lymphocyte infiltration, whereas CD4+/CD8+ T-cell depletion markedly reduced CD20+ B-cell infiltration. Depletion of CD4+ or CD8+ T-cells separately had limited effect on B-cell infiltration, but led to the absence of germinal centres. CONCLUSION: TLS disorganisation is not associated with loss of infection control in mice persistently infected with S. aureus.

Risk stratification in patients with pulmonary arterial hypertension at the time of listing for lung transplantation.

BACKGROUND: It is unknown whether pulmonary arterial hypertension (PAH) risk stratification instruments could be helpful to support the decision to list a patient for lung transplantation (LT). Our aim was to evaluate contemporary risk assessment tools in a cohort of PAH patients listed for LT. METHODS: Consecutive PAH patients (without pulmonary veno-occlusive disease or unrepaired congenital heart disease) listed for LT at the French Pulmonary Hypertension Reference Center between January 2006 and December 2018 were included. At the time of listing, risk stratification was assessed using the ESC/ERS criteria, the REVEAL Lite 2 score and the COMPERA 2.0 method. The primary end point was overall survival after LT listing. Secondary outcome measures were mortality on waiting list and posttransplant survival. RESULTS: One hundred and two patients were enrolled (mean age 38 ± 13 years, 69% females). Overall survival after listing was 72%, 58% and 46% at 1, 3 and 5 years respectively. Survival after LT listing was lower in "high-risk" patients according to the ESC/ERS criteria (p = 0.0001) and the REVEAL Lite 2 score (p = 0.04). The COMPERA 2.0 method discriminated post-listing survival of patients at high-risk, intermediate-high and intermediate-low risk (p = 0.04). The proportion of patients requiring urgent transplantation and extracorporeal life support as a bridge to transplantation was higher in the "high-risk" patients. Posttransplant survival was significantly lower in "high-risk" patients according to the ESC/ERS criteria (p = 0.0004). CONCLUSIONS: High-risk PAH patients at the time of LT listing have poor outcomes, suggesting that LT should be considered earlier in the course of PAH remaining refractory to triple combination therapy with a parenteral prostacyclin.