Elevated serum levels of decoy receptor 3 are associated with disease severity in patients with hemorrhagic fever with renal syndrome

Hemorrhagic fever with renal syndrome (HFRS) is an acute viral infectious disease characterized by fever, hemorrhage and renal failure. HFRS has become a serious public health problem in China. Unfortunately, the pathogenesis of HFRS has not been completely clarified. The aim of this study is to investigate the changes of decoy receptor 3 (DcR3) and to further explore its potential roles in HFRS. The levels of serum DcR3 were measured by sandwich ELISA. We found serum DcR3 levels increased significantly, which reached peak value during the oliguric phase and in the critical group. Moreover, serum DcR3 levels were closely related to the levels of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and parameters reflecting kidney injury including BUN, creatinine (Cr) and proteinuria. This study indicates that high levels of serum DcR3 have associations with the disease stages, severity and degree of kidney damage. Meanwhile, our results suggest that DcR3 may play a dual role in HFRS pathogenesis. First, DcR3 is involved in the inflammatory cascade response resulting in capillary permeability and kidney injury in the early stage. Secondly, HTNV infection induced DcR3 expression at the convalescent phase may act as a feed-back mechanism in anti-inflammatory response. Thus, a study of DcR3 is essential for a better understanding of HFRS pathogenesis.

Over-expression of the decoy receptor 3 (DcR3) gene in peripheral blood mononuclear cells (PBMC) derived from silicosis patients

Dysregulation of apoptosis, particularly in the Fas/Fas ligand (FasL) pathway, is considered to be involved in the pathogenesis of autoimmune diseases such as systemic lupus erythematosus (SLE). Recently, a soluble decoy receptor, termed decoy receptor 3 (DcR3), that binds FasL and inhibits FasL-induced apoptosis, has been identified. Silicosis is clinically characterized not only by respiratory disorders but by immunological abnormalities. We have found that serum soluble Fas (sFas) levels are elevated in silicosis patients and that sFas message is dominantly expressed in PBMC derived from these patients. This study examined DcR3 gene expression in PBMC derived from patients with silicosis, SLE, or progressive systemic sclerosis (PSS), and compared it with that in healthy volunteers (HV). The relative expression level of the DcR3 gene was examined in PBMC derived from 37 patients with silicosis without clinical symptoms of autoimmune disease, nine patients with SLE, 12 patients with PSS, and 28 HV using the semiquantitative multiplex-reverse transcriptase-polymerase chain reaction (MP-RT-PCR). The correlation between the relative expression level of the DcR3 gene and multiple clinical parameters for respiratory disorders and immunological abnormalities in individuals with silicosis was analysed. The DcR3 gene was significantly over-expressed in cases of silicosis or SLE when compared with HV. In addition, the DcR3 relative expression level was positively correlated with the serum sFas level in silicosis patients. It is unclear, however, whether over-expression of the DcR3 gene in silicosis is caused by chronic silica exposure, merely accompanies the alteration in Fas-related molecules, or precedes the clinical onset of autoimmune abnormalities. It will be necessary to study these patients further, establish an in vitro model of human T cells exposed recurrently to silica compounds, and resolve whether the increase in DcR3 mRNA expression is a cause or consequence of disease.