The combination of polymorphisms within interferon-gamma receptor 1 and receptor 2 associated with the risk of systemic lupus erythematosus.

Genetic factors seem to play a significant role in susceptibility to systemic lupus erythematosus (SLE). We previously described the amino acid polymorphism (Val14Met) within the IFN-gamma receptor 1 (IFN-gammaRI), and that the frequency of the Metl4 allele in SLE patients was significantly higher than that of the healthy control population [Tanaka et al. (1999) Immunogenetics 49, 266-271]. We also found an amino acid polymorphism (Gln64Arg) within IFN-gamma receptor 2 (IFN-gammaR2). Since the IFN-gamma receptor is a complex consisting of IFN-gammaR1 and IFN-gammaR2, we searched for the particular combination of two kinds of amino acid polymorphisms found within the IFN-gamma receptor which plays a prominent role in susceptibility to SLE. The greatest risk of the development of SLE was detected in the individuals who had the combination of IFNGR1 Met14/Val14 genotype and IFNGR2 Gln64/Gln64 genotype.

Selective DNA-binding activity of interleukin-10-stimulated STAT molecules in human monocytes.

It has been demonstrated that interferon-gamma (IFN-gamma) and interleukin-10 (IL-10) have various reverse effects on macrophages; however, the molecular mechanism of this difference has not been fully understood. In this study, we analyzed the binding activity of IL-10- and IFN-gamma-activated STAT molecules to two kinds of GAS-motif sequences. IL-10-activated STAT1 could bind to the GAS-motif sequence in the promoter region of the Fcgamma receptor, but not to that in the promoter region of the COX-2 gene, whereas IFN-gamma-activated STAT1 and STAT5 could bind to both sequences. IL-10 inhibited IFN-gamma-induced STAT activation without newly synthesized protein. We further demonstrated that aspirin, but not dexamethasone, suppressed IFN-gamma-induced STAT activation. Taken together, these results suggest that IL-10-activated STAT1 has a specificity in binding to the GAS-motif sequences, whereas IFN-gamma-activated STAT1 and STAT5 have a broader spectrum in binding to the GAS-motif sequences. This may explain the difference between IL-10 and IFN-gamma in biological activity, and the inhibitory effect of IL-10 on IFN-gamma activities.

Two polymorphisms within interleukin-3 (hIL3) gene detected by mismatch PCR/RFLP.

Two alleles of IL-3 have been reported to GenBank (GenBank M14743, M20137). The sequence difference between these two alleles is at the first nucleotide of the 27th codon (the 131st nucleotide from the initiation site): thymine and cytosine, and leading the amino acid difference: proline and serine (Pro27Ser). The other allelism, thymine and cytosine, was also observed at position -16 of the IL-3 upstream promotor region (GenBank L10616, M60870). We clarified that these substitutions were frequent polymorphisms in the Japanese population by using the mismatch-PCR (polymerase chain reaction)/RFLP (restriction fragment length polymorphism) method.

MAP kinase pathways as a route for regulatory mechanisms of IL-10 and IL-4 which inhibit COX-2 expression in human monocytes.

Mitogen-activated protein kinases (MAPKs) are activated by various extracellular stimuli and play an important role in regulating the expression of proinflammatory molecules in monocytes/macrophages. We first questioned whether MAPK activation in involved in cyclooxygenase (COX)-2 expression in lipopolysaccharide (LPS)-stimulated human monocytes. LPS induced the expression of COX-2 protein and COX-2 mRNA as well as the phosphorylation and activation of extracellular signal-regulated protein kinase (ERK)2 and p38 MAPK in monocytes. The induction of COX-2 mRNA, COX-2 protein, and prostaglandin (PG)E2 by LPS was inhibited by the specific inhibitors of ERK and p38 MAPK, suggesting that the activation of ERK2 and p38 MAPK is involved in COX-2 expression in LPS-stimulated monocytes. Since we previously showed that interleukin (IL)-10 and IL-4 similarly inhibited COX-2 expression in LPS-stimulated monocytes, we next questioned whether these cytokines regulate the phosphorylation and activation of ERK2 and p38 MAPK in LPS-stimulated monocytes. Interestingly, LPS-induced phosphorylation and activation of ERK2 was significantly inhibited by IL-4 and IL-10, while that of p38 MAPK was inhibited by IL-10, but not IL-4. These results suggest that the mechanisms of inhibition by IL-10 and IL-4 of the LPS-induced expression of proinflammatory molecules could be ascribed to the regulatory effects of both cytokines on MAPK activation.

Polymorphisms within the interleukin-10 receptor cDNA gene (IL10R) in Japanese patients with systemic lupus erythematosus.

OBJECTIVE: To assess the association between polymorphisms within the interleukin-10 receptor cDNA gene (IL10R) and systemic erythematosus (SLE) in Japanese people. METHOD: We examined the IL-10 receptor genotype of 109 SLE patients and 102 healthy subjects by the reverse transcription-polymerase chain reaction-restriction fragment length polymorphism (RT-PCR-RFLP) method. RESULTS: There was no difference in the IL10R genotype frequencies of these two groups. CONCLUSION: The IL10R genotype does not determine susceptibility to SLE in Japanese people.