Transforming growth factor-β1 (TGF-β1) exerts broad anti-inflammatory and immunosuppressive effects and plays a key role in self-tolerance. Complete knockout of TGF-β1 in mice results in autoimmunity and multi-organ inflammatory syndrome. The aim of the present study was to determine TGF-β1 serum levels in healthy individuals and in patients with typical systemic or organ-specific autoimmune disorders such as systemic lupus erythematosus (SLE) and Hashimoto's thyroiditis (HT) in an attempt to elucidate the importance of TGF-β1 in human autoimmunity. Serum concentrations of TGF-β1 were determined using an enzyme-linked immunosorbent assay in a group of 53 patients with SLE (87% women) and 123 with HT (95% women). Results were compared with those from 66 healthy controls (HC; 80% women). Significantly lower levels of serum TGF-β1 were found in patients with SLE and HT than those found in HC (mean ± SD: SLE: 8.7 ± 2.5 ng/mL; HT: 18.74 ± 8.2 ng/mL; HC: 33.01 ± 2.4.8 ng/mL; SLE versus HC: p0.05). Our data demonstrate that altered TGF-β1 levels are associated with the presence of autoimmune disorders, and that TGF-β1 concentrations seem to be more profoundly depressed in systemic autoimmune diseases than in autoimmune thyroid disorders. Autoimmunity may have been triggered as a result of a decreased immunosuppressive effect induced by depressed TGF-β1 levels in patients with SLE and Hashimoto's thyroiditis.

We aimed to analyze serum pro-inflammatory profiles of female rheumatoid arthritis (RA) patients and compare them with healthy women to establish the relative importance of pro-inflammatory cytokines in RA and their relation with different treatment regimens. Levels of six cytokines were determined by ELISA assays. A supervised dimensionality reducing approach (PLS-DA Analysis) was applied. All of the cytokines assayed were significantly elevated in the sera of RA female patients than healthy controls with fold change: 21-fold for IL-6; 6.1-fold for IL-17A; 2.5-fold for IL-23; 2.3-fold for IL-18; 1.94-fold for TNF-α; 1.7-fold for IL-12p40. According to the results of the PLS-DA analysis, IL-17A, IL-18, and TNF-α were of higher importance rank compared to IL-23 and IL-12p40. Women in the early stage of RA displayed significantly elevated IL-17A levels than those with longer disease duration: 8.04 pg/ml [8.04–175.3] vs 4.64 pg/ml [2.95–13.31], p = 0.007. IL-6 serum levels were related to higher disease activity. We have demonstrated altered cytokine production within female RA patients on different treatment regimens. Those on Tocilizumab therapy showed elevated IL-6 levels and decreased IL-17A versus the rest of the patients’ subgroups. In conclusion, our data support the pivotal role of IL-18 in addition to IL-6, IL-17A, and TNF-α as the hierarchical cytokines in the pathogenesis of RA, particularly valid for women. Therapy with biological agents targeting IL-18 in addition to the Th17 axis may be an adequate approach in RA patients.

The aim of this study was to evaluate the possible association of IL12B gene polymorphisms with serum levels of IL-12p40, IL-23 and genetic susceptibility to rheumatoid arthritis (RA) in the Bulgarian population. Genotyping for IL12Bpro (rs17860508) and IL12B A/C − 3ʹ UTR (rs3212227) polymorphisms was performed by polymerase chain reaction (PCR)-based methods in 125 RA patients and 239 healthy controls. The IL-23 and IL-12p40 serum levels were measured by enzyme-linked immunosorbent assay (ELISA). An association was established between the rs17860508 polymorphism and RA susceptibility in Bulgarian population with an increased frequency of rs17860508 minor allele-2 and homozygous genotype-22 in RA patients. The rs17860508 risk RA genotype-22 was also significantly correlated to elevated serum IL-23 in RA patients. Although, there was no association between the rs3212227 and genetic predisposition to RA, significantly increased serum levels of both Il-12p40 and IL-23 were observed in RA patients with the rs3212227 AA genotype. Furthermore, the distribution of haplotypes and genotype combination in our cohort indicated increased RA risk in individuals carrying the rs17860508/rs3212227 2/A haplotype or 2.2/AC+CC combination, while 1/A haplotype or 1.1/AA combination may be protective for RA. In conclusion, our study demonstrates a functional effect of IL12B polymorphisms on IL-12p40 and IL-23 cytokine levels in RA patients and suggests a leading role for IL12B rs17860508 in the genetic predisposition to RA, while IL12B rs3212227 significantly modify the RA risk in Bulgarian population.

In this study, we analyzed the putative association between the -308 G/A polymorphism in the promoter region of the tumor necrosis factor (TNF) α gene (rs1800629) and chronic inflammatory arthritis in the Bulgarian population. A case-control study was carried out on 58 patients with ankylosing spondylitis (AS), 108 rheumatoid arthritis (RA) patients and 177 healthy subjects. -308 G/A TNF-α genotypes of patients and controls were determined by restriction fragment length polymorphism polymerase chain reaction (RFLP-PCR). No significant association between the rs1800629 polymorphism and RA risk in the study cohort was observed. However, there were significant differences in the genotype and allele frequencies of the -308 G/A TNF-α polymorphism between AS patients and the healthy subjects. In logistic regression analysis, the presence of the TNF-α -308A allele in the genotype (AA + AG vs. GG) was associated with a 3.298 times lower risk of developing AS. In addition, in AS, there were associations for age at disease onset ( 4; OR = 0.152) and response to anti-TNF treatment (OR = 2.25) under a dominant model (AA + AG vs. GG). In conclusion, our results suggested that the promoter polymorphism -308 G/A in the TNF-α gene had no significant effect on RA development, but could play a role in AS development and in determining the age of disease onset, disease severity and therapeutic outcome of AS in the Bulgarian patients who participated in our study.