CXCR3 ligands contribute to Th1-induced inflammation but not to homing of Th1 cells into the lung.

Th1 cells are implicated in numerous pulmonary inflammatory disorders, and adoptive transfer of alloreactive Th1 cells mediates lung injury and inflammation in mice. In response to Th1-mediated immune injury, CXCR3 ligands IP10 and MIG are markedly induced. Because Th1 cells express high levels of CXCR3, their recruitment and activity may be influenced by CXCR3 ligands. To examine the role of CXCR3 ligands, the authors inhibited CXCR3-ligand interaction by 2 approaches: (1) antibody ablation of CXCR3 ligands IP10 (CXCL10/interferon-gamma -inducible 10-kDa protein) and MIG (CXCL9/monokine-induced by interferon-gamma), and (2) use of cxcr3(-/-) mice. Antibody neutralization of IP10 and MIG reduced Th1-cell mediated lung inflammation but did not alter Th1-cell influx in the lung. In contrast, a lack of CXCR3 on host cells had no effect on Th1 cells influx or acute inflammation. In vitro, ablation of endogenous IP10 and MIG inhibited antigen-mediated Th1-cell proliferation. These results suggest that the influx of alloreactive Th1 cells into the lung does not require CXCR3 ligands, but that these chemokines do affect Th1-cell proliferation and activity within the affected tissue. Other CXCR3(+) leukocytes do not contribute to acute alloimmune injury.

Plasticity of airway epithelial cell transcriptome in response to flagellin.

Airway epithelial cells (AEC) are critical components of the inflammatory and immune response during exposure to pathogens. AECs in monolayer culture and differentiated epithelial cells in air-liquid interface (ALI) represent two distinct and commonly used in vitro models, yet differences in their response to pathogens have not been investigated. In this study, we compared the transcriptional effects of flagellin on AECs in monolayer culture versus ALI culture using whole-genome microarrays and RNA sequencing. We exposed monolayer and ALI AEC cultures to flagellin in vitro and analyzed the transcriptional response by microarray and RNA-sequencing. ELISA and RT-PCR were used to validate changes in select candidates. We found that AECs cultured in monolayer and ALI have strikingly different transcriptional states at baseline. When challenged with flagellin, monolayer AEC cultures greatly increased transcription of numerous genes mapping to wounding response, immunity and inflammatory response. In contrast, AECs in ALI culture had an unexpectedly muted response to flagellin, both in number of genes expressed and relative enrichment of inflammatory and immune pathways. We conclude that in vitro culturing methods have a dramatic effect on the transcriptional profile of AECs at baseline and after stimulation with flagellin. These differences suggest that epithelial responses to pathogen challenges are distinctly different in culture models of intact and injured epithelium.

Lipopolysaccharide binding protein promoter variants influence the risk for Gram-negative bacteremia and mortality after allogeneic hematopoietic cell transplantation.

Lipopolysaccharide binding protein (LBP) function is dependent on circulating LBP levels. Disturbance of LBP transcription regulation may influence the risk for clinical events. In a nested case-control study using a single nucleotide polymorphism haplotype tagging (tagSNP) approach, we assessed whether genetic variation in the LBP gene influences the risk for Gram-negative (GN) bacteremia after allogeneic hematopoietic cell transplantation (HCT), then validated the association in a prospective cohort by correlating genetic variation with basal serum LBP levels and mortality. Presence of the tagSNP 6878 C allele among patients was associated with a 2-fold higher risk for GN bacteremia (odds ratio = 2.15; 95% confidence interval [CI], 1.31-3.52, P = .002). TagSNP 6878 was in strong linkage disequilibrium with 3 SNPs in the LBP promoter, one of which was SNP 1683 (r(2) = 0.8), located in a CAAT box that regulates LBP promoter efficiency. SNP 1683 was associated with higher median basal serum LBP levels (TT 8.07 microg/mL; TC 10.40 microg/mL; CC 17.39 microg/mL; P = .002), and a 5-fold increase in GN bacteremia related mortality after HCT (hazard ratio = 4.83; 95% CI, 1.38-16.75, P = .013). These data suggest that transcriptional regulation of the LBP gene contributes to the risk for developing GN bacteremia and death after HCT.

Genetic variation in bactericidal/permeability-increasing protein influences the risk of developing rapid airflow decline after hematopoietic cell transplantation.

Innate immunity is involved in the biology of graft versus host disease and common airway diseases. We screened 15 genes in this pathway using a linkage disequilibrium-based approach to identify potential candidate genes that may be involved in the development of airflow obstruction after hematopoietic cell transplantation. Sixty-nine single-nucleotide polymorphisms were selected for assessment in a discovery cohort (n = 363). Significant associations were validated in a validation cohort (n = 209). Expression of the candidate gene was demonstrated by detecting gene transcript and protein in malignant and normal small airway epithelial cells. In the discovery cohort, 133 patients developed significant airflow decline. Four patient and donor bactericidal/permeability-increasing (BPI) haplotypes were associated with a 2-fold to 3-fold increased risk of developing significant airflow decline (P values, .004-.038). This association was confirmed in the validation cohort, which had 66 patients with significant airflow decline, with 9 significant haplotypes (P values, .013-.043). BPI gene transcript and protein were detected in airway epithelial cells. These results suggest mutations in the BPI gene significantly influence the risk of developing rapid airflow decline after hematopoietic cell transplantation and may represent a novel therapeutic target for this form of airway disease.

Pretransplant lung function, respiratory failure, and mortality after stem cell transplantation.

RATIONALE: The role of pulmonary function before stem cell transplant as a potential risk factor for the development of early post-transplant respiratory failure and mortality is controversial. METHODS: We conducted a retrospective analysis of the pretransplant pulmonary function of 2,852 patients who received their transplant between 1990 and 2001. MEASUREMENTS: Pretransplant FEV(1), FVC, total lung capacity (TLC), diffusing capacity of carbon monoxide (DL(CO)), and the alveolar-arterial oxygen tension difference P(A-a)O(2) were measured and assessed for association with development of early respiratory failure and mortality in Cox proportional hazard logistic models. MAIN RESULTS: In multivariate analyses, progressive decrease of all lung function parameters was associated with a stepwise increase in risk of developing early respiratory failure and mortality when assessed in independent models. On the basis of a significant correlation between FEV(1) and FVC (r = 0.81), FEV(1) and TLC (r = 0.61), and FVC and TLC (r = 0.80), and a lack of correlation between FEV(1) and DL(CO), we developed a pretransplant lung function score based on pretransplant FEV(1) and DL(CO) to determine the extent of pulmonary compromise before transplant. Multivariate analysis indicated that higher pretransplant lung function scores are associated with a significant increased risk for developing early respiratory failure (category II hazard ratio [HR], 1.4; category III HR, 2.2; category IV HR, 3.1; p < 0.001) and death (category II HR, 1.2; category III HR, 2.2; category IV HR, 2.7; p < 0.005). CONCLUSIONS: These results suggest that not only does compromised pretransplant lung function contribute to the risk for development of early respiratory failure and mortality but this risk may be estimated before transplant by grading the extent of FEV(1) and DL(CO) compromise.

Comparison of lung function after myeloablative and 2 Gy of total body irradiation-based regimens for hematopoietic stem cell transplantation.

Lung function decline is a well-recognized occurrence after myeloablative hematopoietic stem cell transplantation (HCT) that has not been studied after nonmyeloablative conditioning regimens. We examined the lung function of patients before and after 2-Gy total body irradiation-based nonmyeloablative and myeloablative preparative regimens. Before HCT, at day 100, and 1 year after HCT, nonmyeloablative patients had lower 1-second forced expiratory volume (FEV1), forced vital capacity, total lung capacity, residual volume, and carbon monoxide diffusion capacity. However, after transplantation, the risk for experiencing a >20% per year decrease of FEV 1 was significantly lower for nonmyeloablative than myeloablative patients >50 years of age (odds ratio, 0.3; 95% confidence interval, 0.1-0.8; P = .01). Lower pretransplantation FEV 1 was associated with a higher mortality rate for both groups, with the highest mortality risk among patients with a pretransplantation FEV 1 <60% (nonmyeloablative: hazard ratio, 3.9; 95% confidence interval, 1.9-8.0; myeloablative: hazard ratio, 7.2; 95% confidence interval, 2.5-21.2). These results suggest that despite having worse lung function, patients who receive the 2-Gy total body irradiation-based nonmyeloablative regimen will likely experience less pulmonary toxicity than patients who receive a myeloablative regimen, and this may have important clinical implications when deciding on a conditioning regimen for patients >50 years of age with compromised pretransplantation lung function.

Airflow obstruction after myeloablative allogeneic hematopoietic stem cell transplantation.

Despite advances in the management of myeloablative allogeneic hematopoietic stem cell transplants, airflow obstruction (AFO) remains a significant complication. We conducted a 12-year study to examine the recent epidemiology of AFO and its associated mortality. Using the rate of percent predicted FEV1 decline after transplant, we defined AFO as a more than 5% per year decline in percent predicted FEV1 with the lowest post-transplant FEV1/FVC ratio less than 0.8. New obstruction was more frequent than previous estimates (26% overall, 32% among patients with chronic graft-versus-host disease [GVHD]) and was significantly associated with older age at transplant, lower pretransplant FEV1/FVC ratio, history of both acute and chronic GVHD, and respiratory viral infection within the first 100 days after transplant. AFO was associated with significant attributable mortality rates of 9% at 3 years, 12% at 5 years, and 18% at 10 years after transplant, which were much higher for the subpopulation of patients with chronic GVHD (22% at 3 years, 27% at 5 years, and 40% at 10 years). These results suggest that the incidence of AFO may have been underestimated previously, and its presence significantly increases the mortality of long-term survivors of myeloablative allogeneic hematopoietic stem cell transplant patients.

Trafficking of Th1 cells to lung: a role for selectins and a P-selectin glycoprotein-1-independent ligand.

Trafficking of lymphocytes to lung is a critical component of pulmonary immune defense and surveillance. Selectins, expressed on vascular endothelium, regulate T lymphocyte emigration into tissues, such as skin, but the role of the selectins in trafficking of T cells to lung has not been well characterized. Here, we used a model of lung inflammation induced by adoptive transfer of alloreactive Th1 cells to analyze the role of P- and E-selectin in Th1 cell trafficking to lung in vivo. We found that both P- and E-selectin play an important role in Th1 lymphocyte migration to lung. We confirmed that the Th1 cells express P-selectin glycoprotein ligand-1, which was functional in binding to P- and E-selectin in vitro. However, our studies reveal that a ligand distinct from P-selectin glycoprotein-1 also binds these selectins in vitro and appears to play a physiologic role in in vivo emigration of Th1 lymphocytes into the lung.