Complex Regulation of Pulmonary Inflammation and Fibrosis by CCL18

Abstract

Elevated pulmonary levels of CCL18 have been associated with influx of T lymphocytes, collagen accumulation, and a decline in lung function in pulmonary fibrosis patients. We previously reported that overexpression of CCL18 in mouse lungs triggers selective infiltration of T lymphocytes and moderate lymphocyte-dependent collagen accumulation. We hypothesized that in combination with bleomycin injury, overexpression of CCL18 will worsen the severity of lung inflammation and fibrosis. Mice were infected with a replication-deficient adenovirus encoding CCL18 and then instilled with bleomycin; control mice were challenged with either CCL18 overexpression or bleomycin. Additive effects of CCL18 overexpression and bleomycin injury were observed on pulmonary inflammation, particularly on T-cell infiltration, and increased levels of tumor necrosis factor-␣, interferon-␥, matrix metalloproteinase (MMP)-2, and MMP-9. Despite the additive effect on inflammation, CCL18 overexpression unexpectedly attenuated the bleomycin-induced collagen accumulation. Pulmonary levels of active transforming growth factor-␤1 mirrored the changes in collagen levels. Depletion of T cells with antilymphocyte serum or pharmacological inhibition of MMPs with GM6001 abrogated accumulation of collagen and increases in the levels of tumor necrosis factor-␣, interferon-␥, and active transforming growth factor-␤1. Thus, CCL18-stimulated T-lymphocytic infiltration is by itself mildly profibrotic to a healthy lung, whereas it partially protects against lung fibrosis in an inflammatory profibrotic pulmonary milieu. (Am J Pathol

Splice isoforms of human interleukin-4 are functionally active in mice in vivo

“…2c). In contrast to over-expression of hIL-4d2 or hIL-4, over-expression of an unrelated protein hCCL18, a potent and highly selective chemoattractant of T lymphocytes, [25][26][27] did not change the relative levels of regulatory T cells (Fig. 2c).…”

“…23 A relative increase in IL-4 and a decrease in IL-4d2 have been associated with better survival in patients with severe sepsis. 24 In this study, we used a replication-deficient adenovirus system [25][26][27] for gene delivery to mouse lung to overexpress human IL-4 or IL-4d2 in vivo. We show that hIL-4 and hIL-4d2 partially share functional activities in mice in vivo with their species-specific counterparts, but they differ from each other in that over-expression of hIL-4d2 appears to have a more pronounced pro-inflammatory effect.…”

“…Bronchoalveolar lavage (BAL), pulmonary homogenates, histological and immunohistological analyses, and flow cytometry were all performed as previously described. [25][26][27] Multiplex analyses (Luminex, Austin, TX) of cytokine levels in BAL and lung homogenates were performed in triplicate in each sample from each animal, and the mean values and standard deviations were calculated for the triplicates.…”

“…The adenoviruses were instilled intra-tracheally as previously described in detail. [25][26][27] Fluorescence microscopy of unstained lung sections for GFP was used to confirm infectivity in vivo. Quantitative PCR of lung homogenates was used to confirm over-expression of mRNAs for the delivered cytokines.…”

“…[25][26][27] Briefly, GenBank consensus sequences for these cytokines were used to artificially synthesize (GenScript, Piscataway, NJ) the DNA fragments corresponding to the respective cDNAs. The fragments were subcloned into a shuttle vector, and transferred into a recombinant replication-deficient adenovirus vector (AdV) using RAPAD Ò technology (ViraQuest, North Liberty, IA).…”