CXCR3 chemokine ligands during respiratory viral infections predict lung allograft dysfunction

Abstract

Community-acquired respiratory viruses (CARV) can accelerate the development of lung allograft dysfunction, but the immunologic mechanisms are poorly understood. The chemokine receptor CXCR3 and its chemokine ligands, CXCL9, CXCL10 and CXCL11 have roles in the immune response to viruses and in the pathogenesis of bronchiolitis obliterans syndrome, the predominant manifestation of chronic lung allograft rejection. We explored the impact of CARV infection on CXCR3/ligand biology and explored the use of CXCR3 chemokines as biomarkers for subsequent lung allograft dysfunction. Seventeen lung transplant recipients with CARV infection had bronchoalveolar lavage fluid (BALF) available for analysis. For comparison, we included 34 BALF specimens (2 for each CARV case) that were negative for infection and collected at a duration posttransplant similar to a CARV case. The concentration of each CXCR3 chemokine was increased during CARV infection. Among CARV infected patients, a high BALF concentration of either CXCL10 or CXCL11 was predictive of a greater decline in forced expiratory volume in 1 s, 6 months later. CXCR3 chemokine concentrations provide prognostic information and this may have important implications for the development of novel treatment strategies to modify outcomes after CARV infection.

Figure 1

CXCR3 chemokine ligand alterations in BALF during CARV. (A) Concentrations of CXCL9, CXCL10, and CXCL11 in BALF were all elevated at the time of CARV diagnosis as compared to BALF collected from a time matched bronchoscopy in control subjects (P=0.006, P=0.003, and P=0.01; respectively). (B) At the time of CARV diagnosis, concentrations of CXCL9, CXCL10, and CXCL11 were similar in CARV cases with and without lower respiratory tract infection (LRTI) (P values all non-significant). (C) At the time of the last bronchoscopy prior to a CARV diagnosis or matched control bronchoscopy, there were no differences in CXCL9, CXCL10, or CXCL11 BALF concentrations (P values all non-significant). (D) Among CARV cases, the levels of CXCL9, CXCL10, and CXCL11 were increased at the time of CARV diagnosis as compared to the last bronchoscopy prior to CARV diagnosis (P=0.007, P=0.002, and P=0.04, respectively).

Figure 2

Representative immunohistochemistry from CARV infected human lung allografts. A) Case of Influenza LRTI demonstrating CXCL9, CXCL10, and CXCL11 expression by allograft hyperplastic bronchial epithelial cells, as well as by peribronchial mononuclear cells. CXCR3 was expressed by peribronchial infiltrating lymphocytes, as well as by bronchial hyperplastic bronchial epithelial cells. Examples of isotype control antibody demonstrate no significant nonspecific staining. B) Representative example of parainfluenza infection in a lung transplant recipient without lower respiratory tract symptoms, but with histopathologic evidence of bronchial epithelial reserve cell hyperplasia. CXCL9, CXCL10, and CXCL11 were expressed by these hyperplastic epithelial cells and by subepithelial mononuclear cells, as was CXCR3 (not shown). C) Representative example of RSV LRTI with strong expression of CXCR3 by hyperplastic bronchial epithelial cells and infiltrating mononuclear cells. Similar expression was seen for CXCL9, CXCL10, and CXCL11 (not shown). A representative low power view of RSV LRTI incubated with isotype control antibody (mouse IgG) demonstrates no nonspecific staining.

Figure 3

FEV1 changes in 6 months by high and low concentration groups for CXCL9, CXCL10, and CXCL11. (A) For CXCL9, the median change in FEV1 was not significantly different for high (−13.4, IQR −15.8 to 4.0) and low (−5.9%, IQR −22.5 to 15.4) concentration groups (p=0.19). (B) For CXCL10, the median FEV1 declined in the high concentration group (−14.9%, IQR −43.2 to −10.7), and increased slightly in the low concentration group (3.0%, IQR −10.8 to 5.5), and this difference was statistically significant (p=0.04). Similarly, for CXCL11, the median FEV1 declined in the high concentration group (−14.9%, IQR −63.6 to −10.7) and increased slightly in the low concentration group (3.0%, IQR −10.8 to 5.5), and this difference was significant (p=0.01).