TNF superfamily member 14 drives post-influenza depletion of alveolar macrophages, enabling secondary pneumococcal pneumonia
Christina Malainou, Christin Peteranderl, Maximiliano Ruben Ferrero, Ana Ivonne Vazquez-Armendariz, Ioannis Alexopoulos, Katharina Franz, Klara Knippenberg, Julian Better, Mohammad Estiri, Cheng-Yu Wu, Hendrik Schultheis, Judith Bushe, Maria-Luisa del Rio, Jose Ignacio Rodriguez-Barbosa, Klaus Pfeffer, Stefan Günther, Mario Looso, Achim Dieter Gruber, István Vadász, Ulrich Matt, Susanne Herold
Christina Malainou, Christin Peteranderl, Maximiliano Ruben Ferrero, Ana Ivonne Vazquez-Armendariz, Ioannis Alexopoulos, Katharina Franz, Klara Knippenberg, Julian Better, Mohammad Estiri, Cheng-Yu Wu, Hendrik Schultheis, Judith Bushe, Maria-Luisa del Rio, Jose Ignacio Rodriguez-Barbosa, Klaus Pfeffer, Stefan Günther, Mario Looso, Achim Dieter Gruber, István Vadász, Ulrich Matt, Susanne Herold
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Research Article Cell biology Infectious disease

TNF superfamily member 14 drives post-influenza depletion of alveolar macrophages, enabling secondary pneumococcal pneumonia

Abstract

Secondary bacterial infection, often caused by Streptococcus pneumoniae, is one of the most frequent and severe complications of influenza A virus–induced (IAV-induced) pneumonia. Phenotyping of the pulmonary immune cell landscape after IAV infection revealed a substantial depletion of the tissue-resident alveolar macrophage (TR-AM) population at day 7, which was associated with increased susceptibility to S. pneumoniae outgrowth. To elucidate the molecular mechanisms underlying TR-AM depletion, and to define putative targets for treatment, we combined single-cell transcriptomics and cell-specific PCR profiling in an unbiased manner, using in vivo models of IAV infection and IAV and S. pneumoniae coinfection. The TNF superfamily 14 (TNFSF14) ligand/receptor axis was revealed as the driving force behind post-influenza TR-AM death during the early infection phase, enabling the transition to pneumococcal pneumonia, whereas intrapulmonary transfer of genetically modified TR-AMs and antibody-mediated neutralization of specific pathway components alleviated disease severity. With mainly neutrophilic expression and high abundance in the bronchoalveolar fluid of patients with severe virus-induced acute respiratory distress syndrome, TNFSF14 emerged as a key determinant of virus-driven lung injury. Targeting the TNFSF14-mediated intercellular communication network in the virus-infected lung can, therefore, improve host defense, minimizing the risk of subsequent bacterial pneumonia and ameliorating the disease outcome.

Authors

Christina Malainou, Christin Peteranderl, Maximiliano Ruben Ferrero, Ana Ivonne Vazquez-Armendariz, Ioannis Alexopoulos, Katharina Franz, Klara Knippenberg, Julian Better, Mohammad Estiri, Cheng-Yu Wu, Hendrik Schultheis, Judith Bushe, Maria-Luisa del Rio, Jose Ignacio Rodriguez-Barbosa, Klaus Pfeffer, Stefan Günther, Mario Looso, Achim Dieter Gruber, István Vadász, Ulrich Matt, Susanne Herold

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Figure 3

IAV infection leads to increased expression of the TNFSF14 ligand/receptor axis.

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IAV infection leads to increased expression of the TNFSF14 ligand/recept...
(A) Fold change of TNFSF receptor genes in mock-infected, day 3–infected, and day 7–infected TR-AMs (n = 5–6; data were pooled from 3 experiments). (B) TR-AM Tnfrsf14 and Ltbr gene expression over the course of the IAV infection (n = 3–6; data were pooled from 2 experiments). (C) TR-AM Tnfrsf14 and Ltbr gene expression after ex vivo iBALF treatment (n = 5; data are representative of 3 experiments). (D and E) TR-AM TNFRSF14 (D) and LTβR (E) expression (n = 7–11; data were pooled from 6 experiments). (F) Fold change of TNFSF ligand genes in mock-infected, day 3–infected, and day 7–infected TR-AMs (n = 5–6, data were pooled from 3 independent experiments). (G) IHC analysis for TNFSF14 expression after mock (PBS) or IAV infection. Scale bar: 25 μm (n = 6–8; data were pooled from 2 experiments). (H) Tnfsf14 gene expression in the lungs of IAV-infected animals (n = 7–8; data were pooled from 3 experiments). (I) BALF TNFSF14 measured by ELISA (n = 4–15; data were pooled from 7 experiments). (J) Soluble TNFSF14 in the BALF of patients with severe viral pneumonia (n = 8–17 per group; data were pooled from 3 experiments). (K) Caspase 3/-7 activity after iBALF treatment of naive WT TR-AMs, following anti-LTβR or anti-TNFRSF14 blocking (n = 15–28; data were pooled from 6 experiments). (L) Caspase 3/-7 activity after iBALF treatment of naive WT, Tnfrsf14–/–, and Ltbr–/– TR-AMs (n = 6–9; data were pooled from 4 experiments). (M) TR-AM numbers for WT, Tnfrsf14–/–, and Ltbr–/– mice on days 0 and 7 p.i. (n = 5–13; data were pooled from 12 experiments, WT controls including values are depicted in Figure 1J). (N) Body weight of WT, Tnfsf14–/–, and Ltbr–/– mice over the course of IAV infection (n = 5 per group; data were pooled from 3 experiments and represent the mean ± SEM). *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001, by unpaired, 2-tailed Student’s t test (G), 1-way, with Tukey’s post hoc test (D, E, H, and K), 2-way ANOVA with Tukey’s post hoc test (B, C, L–N [comparison of weight loss among the 3 groups at each time point after infection]), and Kruskal-Wallis test followed by Dunn′s post hoc comparison test (I). For the heatmaps in A and F, a 2-tailed Student’s t test was performed for the log2 fold-change values of each gene in the compared groups.