Studies On The Association Between HLA-A, B, Cw, DR, DQ Alleles And Variations In Serum Leptin Levels In Patients With Psoriasis Vulgaris In Northern Chinese Han

Psoriasis vulgaris is a chronic skin disorder characterized by infiltration of inflammatory elements, keratinocyte hyperproliferation and altered differentiation. It is affecting about 0. 123% of the Chinese Han population. Although the pathogenesis of psoriasis is not fully understood, many studies showed that genetic, immunological and environmental factors predispose to psoriasis. Recent use of genome scans has provided evidence of a susceptibility locus in the human leukocyte antigen ( HLA) regeion.As one of the important marker of human cell surface, HLA is the most complicated human dominant polymorphic genetic system because of its highly complicated polymorphism. It differs significantly in different regions and races, which can be regarded as the best sign of colony genetic character and used for investigating disease susceptibility group distribution and disease association study. It plays an important role in antigen recognition, presentation, immune response and regulation. HLA genes locate in human chromosome 6p21. 3 region. HLA class I gene spans approximately 1500 kb, encoding transplantation antigen. This region consists of a large number of immunologically relevant genes, including loci HLA -A, B, C, D, E, F, G, H, I, J, L, K. HLA -A, B, C genes have similar configuration, spanning approximately 4000 - 5000 bps. The class I gene consists of genes encoding α chain and β2m chain. HLAclass II gene spans approximately 1000 kb, and consists of several immunologi-cally relevant genes, too. These genes include HLA - DR, HLA - DQ and HLA -DP, which has similar configuration. DR region consists of 1 a gene, 4 0 genes in which 2 (3 genes are pseudogenes. ^ gene is polymorphic, while a gene is conservative. The polymorphism of class II molecules present in region J31. The speciality of HLA - DR comes from the highly polymorphic DRB1 locus alleles. DNA typing for HLA locus is necessary for disease and HLA association research.Many studies showed that different HLA alleles have increased frequencies among patients with psoriasis vulgaris in different racial or ethnic populations, especially HLA class I and class II specifities. At present, there was not a systematic report about HLA polymorphism for psoriasis vulgaris in the north of China.And we attempt to lead - in a new concept, leptin, to dermatological sphere. Leptin is a 16 kd peptide hormone secreted from adipocytes and encoded by obesity gene ( ob gene). The human ob gene was cloned and mapped to chromosome 7q32 in 1994. Subsequent studies by others have identified its product, leptin, a protein of 167 amino acids. Initial studies showed that when combined with its receptors, leptin controls many physiological and metabolic functions, including the regulation of body weight, endocrine functions, blood pressure, reproduction, and immunity. The role of leptin in the modulation of the immune response and inflammation has recently received particular attention. Recent studies suggested that leptin might play an important role in immunomodulation apart from its variety of important biological activities. Leptin modulates the immune response by stimulating the proliferation of natural T lymphocytes and memory T lymphocytes, promoting the synthesis of type 1 cytokines and inhibiting that of type 2 cytokines. These immunological changes are also observed in psoriasis vulgaris. Whether leptin plays any role in the pathogenesis of psoriasis vulgaris has never been studied so far.It is necessary to investigate the association between psoriasis vulgaris and HLA trying to discover the rule in immune genetics. It is helpful to explore the pathogenesis of different clinical menifestation. With this mind, we try to inves-tigate HLA class I and class II alleles association with psoriasis vulgaris in Northern Chinese Han population, typing was performed by polymerase chain reaction amplification with sequence - specific primers (PCR - SSP).It is tempting to speculate that psoriasis, an autoimmune skin disease, might be correlated to leptin. So, in our present study, we evaluated the serum levels of leptin by radioimmunoassay (RIA) in patients with psoriasis vulgaris compared with those in normal controls, and investigated whether any different clinical typing, familial history, disease activity or severity of psoriasis vulgaris correlate with different leptin levels.Methods1. SubjectsDNA extracted from the following 2 groups:(1) 91 patients met with psoriasis vulgaris diagnostic criterion. 49 was male and 42 was female, age from 7-70 years. Of the patients, 39 cases with family history of psoriasis, 72 had type I psoriasis (onset at below 40 years of age) and 19 had type II psoriasis (onset at age 40 or older).(2) An age - , sex - and body mass index ( BMI) - matched normal control group of 102 healthy blood donors was enrolled. In the control group, all persons and their family members have not family history of psoriasis.In this study were all unrelated Northern Chinese Han.2. MaterialsHLA -A, B, Cw, DRB1 and DQB1 SSPtray was provided by Biotest, Germany. Taq (5 U/|xl) and agarose were provided by TaKaRa Biotechnology Co. , Ltd. Leptin RIA kit was provided by Beijing Beifang Biological Technologies Research Institute.3. Methods(1) Genomic DNA was extracted from the peripheral blood lymphocytes with improved carbamidine hydrochloride method.(2) HLA typing was performed using Biotest HLA - A, B, Cw, DRB1 and DQB1 SSPtray following the manufacturer's instructions.(3) Serum leptin level was measured by RIA. Standard leptin or sera from patients with psoriasis vulgaris or normal controls were mixed with 125 iodine labelled leptin and its anti - recombinant human leptin rabbit serum, then incubated for 24 hours at 4°C. Thereafter the bound leptin was precipitated by adding immunoprecipitator after 15 min incubation at 22 Tl, the tubes were centrifuged for 15 min at 2,000 rpm. After removing the supernatant, the pellet was counted in Packard 5000 gamma counter. Radioactivity of the precipitate ( B or Bo) was then obtained. A standard curve was plotted according to the combination rate (B/ Bo% ) and the leptin levels of the patients' sera were deduced from the combination rates based on the standard curve.4. Statistical analysisThe gene frequencies were estimated using the computer package Biotest, Germany. HLA - A, B, Cw, DRB1 and DQB1 alleles were compared between patients and normal controls by \ - test and Fisher's exact test using computer package SPSS 11.5. Relative risk( RR) was calculated using SPSS, too. Significance was taken as Pc <0.05.Results of serum leptin level were expressed as mean ± standard deviation .( X ± SD) and were analyzed statistically by using two independent samples test, or Kendall's correlation analysis. A P value less than 0.05 was considered statistically significant.Results1. HLA class I and II alleles and psoriasis vulgaris in Northern Chinese HanThe gene frequencies of A*OlOx, A*300x, B*570x, Cw*0602, Cw'060x , DRB1 '0701/0702 and DQB1 '0201 were higher in patients with psoriasis vulgaris than that in normal controls. At the same time, the gene frequency of Cw* 040x was lower in patients with psoriasis vulgaris, the differentia was significantly (Pc<0.05).2. HLA alleles and male and female patients with psoriasis vulgarisThe gene frequencies of HLA - B *570x and Cw*0602 were higher only in. o .female patients with psoriasis vulgaris than that in female controls. In male patients with psoriasis vulgaris, the gene frequencies of A*300x and DQB1 *0201 were higher than that in male controls, the differentia was significantly (Pc <0. 05).3. HLA alleles and type I and type II psoriasis vulgarisThe gene frequencies of HLA - A * OlOx, A' 300x, B * 570x, Cw * 0602, Cw'060x, DRB1 * 0701/0702 and DQB1 '0201 were more prevalent in the patients with type I psoriasis than in controls, and HLA - B*51, Cw*040x, DQB1 *0301 alleles were less prevalent ( Pc <0.05) in the patients with type I psoriasis, too.To compare with controls, the gene frequencies of HLA - B * 370x and Cw * 060x were higher in the patients with type II psoriasis, but Cw * 060x was only significantly ( Pc < 0.05).4. HLA alleles and patients with or without family history of psoriasis vulgarisHLA - A' 300x, Cw * 060x, DRB1 * 0701/0702 and DQB1' 0201 alleles were positively associated with patients with family history of psoriasis vulgaris ( Pc < 0.05). To compare with controls, the gene frequencies of HLA - B * 07, B*51 and DRB1 * 15 were lower in the patients with family history, but there were not significantly ( Pc > 0.05).HLA - B * 570x, Cw * 0602 and Cw * 060x alleles were positively associated with psoriasis vulgaris patients without family history of psoriasis ( Pc < 0. 05) , and HLA - DQB1 * 050x allele was negatively associated with the patients ( Pc < 0.05).5. Serum leptin levels and psoriasis vulgarisThe serum leptin levels in patients with psoriasis vulgaris (7.63 ±4.44 ng/ ml) were significantly (P <0.001) higher when compared with those in normal controls (5.03 ±2.72 ng/ml). Further more, there was a significant difference in the serum leptin levels between the male and female subjects (P <0.001). The serum leptin levels were significantly higher in female and male patients with psoriasis vulgaris than in normal female and male controls, respectively (P...