The Expression And Role Of Ifnλ1in Systemic Lupus Erythematosus

Background:Systemic lupus erythematosus (SLE) is an autoimmune disease that predominantly affects women and typically has manifestations in multiple organs, such as, kidney, skin, lungs, brain and heart. Immunesystem aberrations, as well as heritable, hormonal, and environmental factors, contribute to the expression of organ damage. Immune complexes, autoantibodies, autoreactive lymphocytes, dendritic cells are all involved in clinical manifestations of SLE. Nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, as well as immunomodulators or immunosuppressive agents, biologic therapies are all slow down the development of SLE.IFN-X1together with IFN-λ2as well as IFN-λ3, which all belong to Type Ⅲ IFN, also referred as IL-29, IL-28A, and IL-28B, respectively, are new members of the IFN super-family. They are expressed by human PBMC and dendritic cells (DCs) upon infection with viruses or stimulation with poly (I:C) and lipopolysaccharide (LPS). They express in all kinds of tissues in a low level detected by PCR, such as, blood, brain, lung, pancreas, ovarian, pituitary, placenta, prostate and testicular. IFN-λ1gene is regulated by virus-activated Interferon Rregulatory Factor (IRF)3and IRF7, resembling that of the IFN-β gene, whereas IFN-λ2/3gene expression is mainly controlled by IRF7, resembling those of IFN-α genes.The intron-exon structure of the IFN-λs family genes more closely resembles that of IL-10. They act through a cell-surface receptor composed of2chains, one being IFN-λ, specific---IFN-λR1,and the second, IL-10R2,being shared among IL-10, IL-22,and IL-26, and induce the activation of the JAK/STAT signaling pathways that variously lead to phosphorylation of STAT1, STAT2, STAT3, STAT4,and STAT5, and then play different kinds of function.IFN-λs exhibit several common features with type Ⅰ IFN, including antiviral, antiproliferative and antitumor activities[1]. IFN-λs exhibited dose-and time-dependent hepatitis C virus (HCV) inhibition. They also inhibited replication of human immunodeficiency virus-1(HIV-1) in macrophages through both extracellular and intracellular antiviral mechanisms. Meantime, replication of hepatitis B virus (HBV) in a human hepatoma cell line was reduced by approximately30%following treatment with a high concentration of IFN-λs. After human cytomegalovirus virus (CMV) infected intestinal epithelial cell (IEC), both IL-28A and IL-29significantly decreased cell proliferation.IFN-λs also possess immuneregulatory function. In mixed lymphocyte reaction (MLR) cultures, IFN-λs treated DCs specifically induced proliferation of CD4+CD25+Foxp3+T cell subset, which showed contact-dependent suppressive activity on T-cell proliferation initiated by fully mature DCs. As well, IFN-λ1was an inhibitor of human Th2responses with an apparent emphasis on the diminution of IL-13secretion. It could significantly diminish levels of IL-13mRNA, the amount of secreted IL-13protein and numbers of IL-13-positive CD3+CD4+cells. Furthermore, IFN-λ1could also specifically upregulate IL-6, IL-8and IL-10secreted by PBMC (mainly monocytes) in a dose-dependent fashion. IFN-λ1also enhanced responses of monocyte induced by low level LPS. What's more, Human macrophages also produced cytokines IL-6, IL-8and IL-10in response to IFN-λ1.With this background, we compared expression of IFN-λ1mRNA in PBMC and serum protein levels in SLE patients with healthy controls. In addition, we determined the correlation of serum IFN-λ1levels with disease activity and clinical manifestations in SLE, and investigated the effect of IFN-λ1on the secretion of the chemokines IP-10, MIG and IL-8.Methods:We determined levels of IFN-λ1mRNA in peripheral blood mononuclear cells (PBMC) and serum protein levels in patients with SLE using real-time polymerase chain reaction (real-time PCR) and enzyme-linked immunoassay (ELISA), compared the IFN-λ1mRNA and IFN-λ1protein expression levels in patients with SLE with healthy control, together with IFN-λ1mRNA and IFN-λ1protein expression levels in patients with active diseases with patients with inactive diseases. Next, we investigated the relationship of IFN-λ1protein expression levels with Systemic Lupus Erythematosus Disease Activity Index, a lot of clinical characteristic, such as, alopecia, mucosal ulcer, malar rash, chest affection, fever, neurological disorder, anemia, thrombocytopenia, leucopenia, renal disease and arthritis, important laboratory values, for example, anti-dsDNA, AnuA, smith, rRNP, AHA antibody, ESR, CRP, C3, C4and24-hour urine protein. Then we detected concentration of IFN-inducible protein-10(IP-10), monokine induced by IFN-y (MIG) and interleukin-8(IL-8) secreted by PBMC under the stimulation of IFN-λ1using ELISA. For identify the probable role of IFN-λ1in the pathogenesis of SLE, we stimulated PBMC of SLE patients with different concentration of IFN-λ1, and observed the secretion of IP-10(IFN-inducible protein-10), MIG (monokine induced by IFN-y) and IL-8, also explored the dosage-concentration relationship of IFN-λ1with secretion of IP-10,MIG and IL-8. Furthermore, we investigated the effect of IFN-λ1on the secretion of IP-10,MIG and IL-8stimulated by LPS.Results:1. SLE patients had significantly higher IFN-λ1mRNA level than did normal controls (p=0.012). IFN-λ1protein levels in patients with SLE displayed significant elevation compared with normal controls (p=0.000), indicating that IFN-λ1probably participated in the pathogenesis of SLE.2. Significant differences were viewed in IFN-λ1mRNA and protein levels between patients with active (SLEDAI score≥6) and those with inactive disease (SLEDAI score<6)(p<.0001, p=0.028), in the meantime, patients with active disease displayed higher IFN-λ1mRNA and serum protein levels compared with normal controls (p<0.0001, p<.0001), however, we didn't observe the differences of IFN-λ1mRNA and protein levels between patients with inactive disease and normal controls. Thus, we speculated that IFN-λ1probably was associated with disease activity in SLE.3. Serum IFN-λ1protein levels were positively correlated with SLEDAI, anti-dsDNA antibody and CRP (r=0.4103, p=0.007; r=0.8339, p<0.0001; r=0.3760, p=0.0141). There was a negative correlation between serum IFN-λ1levels and complement C3(r=-0.5863, p=0.008). No significant correlations were found between serum IFN-λ1levels and anti-AnuA, smith, rRNP, AHA antibody, ESR, C4and24-hour urine protein.4. Serum IFN-λ1level were significantly higher in patients with renal disease and arthritis compared with patients without these manifestations together with normal controls (p=0.0368, p<0.0001; p=0.0097, p=0.0028), meantime, patients in the absence of renal disorder had higher serum IFN-λ1level compared with normal controls as well (p=0.0258), but patients without arthritis didn't show significant higher serum IFN-λ1level than normal controls (data not shown), illustrating that IFN-λ1probably acted in the development of renal disorder and arthritis in SLE. There were no significant differences in serum IFN-λ1protein levels between patients in the presence of alopecia, mucosal ulcer, malar rash, chest affection, fever, neurological disorder, anemia, thrombocytopenia, leucopenia and patients in the absence of the above-mentioned clinical manifestations.5. In both SLE patients and normal controls, IFN-λ1-stimulated PBMC emerged higher levels of chemokines IP-10(p=0.039,0.028) and MIG (p=0.009,0.038) in comparison with positive control LPS, and about the secretion of IL-8, the same result was observed in normal controls (p=0.049). Moreover, at50ng/ml IFN-λ1, the generation levels of chemokines IP-10and MIG in SLE patients were more than normal controls (p=0.02; p=0.031), and the secretion levels of IL-8were lower in SLE patients than normal controls (p=0.007). Meanwhile, in patients with SLE, IFN-λ1induced less secretion of chemokine IL-8than LPS (p=0.016), but it had the ability to stimulate more IL-8production than medium (p=0.002). Thus, through the above observation, we can acquire the conclusion that in patients with SLE, IFN-λ1was capable of inducing the production of chemokines IP-10, MIG and IL-8which participate in the pathogenesis of SLE by their special mechanism. With respect to the dose-response curves for IFN-λ1inducing IP-10, MIG and IL-8, finding that in SLE patients, both10ng/ml and50ng/ml IFN-λ1had effects on the secretion of IP-10(p=0.033,0.005) and stimulated more IP-10than normal controls (p=0.024,0.047). IFN-λ1displayed its effects at the three different concentration on MIG secretion with dose-dependent relation (p=0.043,0.016,0.001), and the secretion levels of MIG were higher compared with normal controls (p=0.033,0.029,0.031). Compared with other two concentration,10ng/ml IFN-λ1had the most obvious effect in the secretion of IL-8, and stimulated more IL-8secretion than normal controls (p=0.008,0.018).6. At100ng/ml LPS, only50ng/ml IFN-λ1showed a synergistic effect on the chemokine IP-10response (p=0.016). With regard to chemokine MIG, different concentration of IFN-λ1all played an assistant role in the effect of LPS (p=0.047,0.013,0.038). Both10ng/ml and100ng/ml IFN-λ1manifested this synergistic effect on the secretion of chemokine IL-8when100ng/ml LPS were used (p<0.001, p=0.002).Conclusions:In conclusion, this preliminary study demonstrated that IFN-λ1perhaps played a part in the pathogenesis of SLE and had a positive association with disease activity, meanwhile, it was likely refer to the development of renal disease as well as arthritis in SLE. Furthermore, we observed that IFN-λ1probably played an important role in the pathogenesis of SLE by inducing production of chemokines IP-10, MIG and IL-8which attended the progression of SLE. The present study of IFN-λ1may offer new insight for future studies on pathogenesis of SLE and novel research targets for SLE therapy.