Surfactant protein D inhibits lipopolysaccharide-induced monocyte chemoattractant protein-1 expression in human renal tubular epithelial cells: Implication for tubulointerstitial fibrosis

Division of Nephrology, Department of Medicine, Renmin Hospital of Wuhan University, Wuhan, China.
Clinical & Experimental Immunology (Impact Factor: 3.04). 03/2012; 167(3):514-22. DOI: 10.1111/j.1365-2249.2011.04521.x
Source: PubMed


Surfactant protein D (SP-D), a member of the C-type lectin (collectin) protein family, plays a critical role in innate host defence against various microbial pathogens and in the modulation of inflammatory responses in the lung. However, little is known about its expression and biological function in the kidney. In this work, we studied SP-D expression in human kidney and cultured human renal proximal tubular epithelial cells (HK-2), and examined the effect of SP-D on proinflammatory cytokine production after lipopolysaccharide (LPS) stimulus. We observed the expression of both SP-D mRNA and protein in human kidney and in-vitro HK-2 cells by immunohistochemistry, Western blot analysis, reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR. To explore the potential role of SP-D in the pathogenesis of tubulointerstitial fibrosis in kidney infection, we examined the production of monocyte chemoattractant protein-1 (MCP-1) in HK-2 cells after LPS treatment. Results showed that the level of MCP-1 in the conditioned medium increased significantly when HK-2 cells were cultured with LPS (>0·1 µg/ml) for 8 h. Of interest, LPS treatment inhibited SP-D expression in HK-2 cells. Furthermore, over-expression of SP-D reduced significantly the LPS-induced expression of MCP-1 in transfected cells. These findings suggest that SP-D in the kidney functions as an anti-inflammatory factor in renal tubular epithelial cells and may modulate tubulointerstitial fibrosis in kidney.

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    ABSTRACT: Objective: To analyze the etiopathogenic role of genetic polymorphisms and serum levels of surfactant protein-D (SP-D) in primary Sjögren syndrome (pSS). Methods: We analyzed 210 consecutive patients with pSS. SFTPD genotyping (M11T polymorphism rs721917) was analyzed by sequence-based typing and serum SP-D by ELISA. Results: Thirty-two patients (15%) had the Thr11/Thr11 genotype, 80 (38%) the Met11/Met11 genotype, and 96 (46%) the Met11/Thr11 genotype; 2 patients could not be genotyped. Patients carrying the Thr11/Thr11 genotype had a higher prevalence of renal involvement (13% vs 1% and 4% in comparison with patients carrying the other genotypes, p = 0.014). Serum SP-D levels were analyzed in 119 patients (mean 733.94 ± 49.88 ng/ml). No significant association was found between serum SP-D levels and the SP-D genotypes. Higher mean values of serum SP-D were observed in patients with severe scintigraphic involvement (851.10 ± 685.69 vs 636.07 ± 315.93 ng/ml, p = 0.038), interstitial pulmonary disease (1053.60 ± 852.03 vs 700.36 ± 479.33 ng/ml, p = 0.029), renal involvement (1880.64 ± 1842.79 vs 716.42 ± 488.01 ng/ml, p = 0.002), leukopenia (899.83 ± 661.71 vs 673.13 ± 465.88 ng/ml, p = 0.038), positive anti-Ro/SS-A (927.26 ± 731.29 vs 642.75 ± 377.23 ng/ml, p = 0.006), and positive anti-La/SS-B (933.28 ± 689.63 vs 650.41 ± 428.14 ng/ml, p = 0.007), while lower mean values of serum SP-D were observed in patients with bronchiectasis (489.49 vs 788.81 ng/ml, p = 0.019). Conclusion: In pSS, high SP-D levels were found in patients with severe glandular involvement, hypergammaglobulinemia, leukopenia, extraglandular manifestations, and positive anti-Ro/La antibodies. The specific association between SP-D levels and pulmonary and renal involvements may have pathophysiological implications.
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