Myeloid Zfhx3 deficiency protects against hypercapnia-induced suppression of host defense against influenza A virus
S. Marina Casalino-Matsuda, Fei Chen, Francisco J. Gonzalez-Gonzalez, Hiroaki Matsuda, Aisha Nair, Hiam Abdala-Valencia, G.R. Scott Budinger, Jin-Tang Dong, Greg J. Beitel, Peter H.S. Sporn
S. Marina Casalino-Matsuda, Fei Chen, Francisco J. Gonzalez-Gonzalez, Hiroaki Matsuda, Aisha Nair, Hiam Abdala-Valencia, G.R. Scott Budinger, Jin-Tang Dong, Greg J. Beitel, Peter H.S. Sporn
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Research Article Immunology Pulmonology

Myeloid Zfhx3 deficiency protects against hypercapnia-induced suppression of host defense against influenza A virus

Abstract

Hypercapnia, elevation of the partial pressure of CO2 in blood and tissues, is a risk factor for mortality in patients with severe acute and chronic lung diseases. We previously showed that hypercapnia inhibits multiple macrophage and neutrophil antimicrobial functions and that elevated CO2 increases the mortality of bacterial and viral pneumonia in mice. Here, we show that normoxic hypercapnia downregulates innate immune and antiviral gene programs in alveolar macrophages (AMØs). We also show that zinc finger homeobox 3 (Zfhx3) — a mammalian ortholog of zfh2, which mediates hypercapnic immune suppression in Drosophila — is expressed in mouse and human macrophages. Deletion of Zfhx3 in the myeloid lineage blocked the suppressive effect of hypercapnia on immune gene expression in AMØs and decreased viral replication, inflammatory lung injury, and mortality in hypercapnic mice infected with influenza A virus. To our knowledge, our results establish Zfhx3 as the first known mammalian mediator of CO2 effects on immune gene expression and lay the basis for future studies to identify therapeutic targets to interrupt hypercapnic immunosuppression in patients with advanced lung disease.

Authors

S. Marina Casalino-Matsuda, Fei Chen, Francisco J. Gonzalez-Gonzalez, Hiroaki Matsuda, Aisha Nair, Hiam Abdala-Valencia, G.R. Scott Budinger, Jin-Tang Dong, Greg J. Beitel, Peter H.S. Sporn

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Figure 5

Myeloid Zfhx3 deficiency prevents hypercapnia-induced increases in viral replication and suppression of antiviral gene and protein expression in IAV-infected mice.

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Myeloid Zfhx3 deficiency prevents hypercapnia-induced increases in viral...
(A–E) Zfhx3+/+ and Zfhx3–/– mice were preexposed to normoxic hypercapnia (10% CO2/21% O2, HC) for 3 days, or air as control, before being infected intratracheally with 30 (A, B, D, and E) or 300 (C) pfu IAV (A/WSN/33) per animal; n = 6–10 per group. Viral titers in homogenized lung tissue determined by plaque assay at 4 dpi (A). Expression of viral NS1 protein (magenta) assessed in lung tissue sections from mice sacrificed 4 dpi (B). Ifn1b, Rsad2, and viral ns1 transcript expression in lung tissue sections from mice infected with IAV 300 pfu 1 dpi was detected by RNAscope (C). AMØs from IAV-infected mice were obtained by BAL 1 dpi and cultured under normocapnic (5% CO2/95% air, NC) or hypercapnic (15% CO2/21% O2/64% N2, HC) conditions for 18 hours, after which viral titers in culture supernatants were determined by plaque assay (D) or assessed for viral NS1 (magenta) and M2 (green) protein expression by immunofluorescence microscopy (E). Nuclei were stained with DAPI (blue) (B, C, and E). In A and D, differences were analyzed by 1-way ANOVA plus Sidak’s multiple-comparison test; *P < 0.05, **P < 0.01. Scale bars: 50 μm (B) and 10 μm (C and E).