Neuropeptide Cortistatin Regulates Dermal and Pulmonary Fibrosis in an Experimental Model of Systemic Sclerosis.

INTRODUCTION: Scleroderma, or systemic sclerosis, is a complex connective tissue disorder characterized by autoimmunity, vasculopathy, and progressive fibrosis of the skin and internal organs. Because its aetiology is unknown, the identification of genes/factors involved in disease severity, differential clinical forms, and associated complications is critical for understanding its pathogenesis and designing novel treatments. Neuroendocrine mediators in the skin emerge as potential candidates. We investigated the role played by the neuropeptide cortistatin in a preclinical model of scleroderma. METHODS: Dermal fibrosis was induced by repetitive intradermal injections of bleomycin in wild-type and cortistatin-deficient mice. The histopathological signs and expression of fibrotic markers were evaluated in the skin and lungs. RESULTS: An inverse correlation between cortistatin levels and fibrogenic activation exists in the damaged skin and dermal fibroblasts. Bleomycin-challenged skin lesions of mice that are partially and totally deficient in cortistatin showed exacerbated histopathological signs of scleroderma, characterized by thicker and more fibrotic dermal layer, enlarged epidermis, and increased inflammatory infiltration in comparison to those of wild-type mice. Cortistatin deficiency enhanced dermal collagen deposits, connective tissue growth factor expression, loss of microvessels, and predisposition to suffer severe complications that co-occur with dermal exposition to bleomycin, including pulmonary fibrotic disease and increased mortality. Treatment with cortistatin mitigated these pathological processes. DISCUSSION/CONCLUSION: We identify cortistatin as an endogenous break of skin inflammation and fibrosis. Deficiency in cortistatin could be a marker of poor prognosis of scleroderma and associated complications. Cortistatin-based therapies emerge as attractive candidates to treat severe forms of systemic sclerosis and to manage fibrosis-related side effects of bleomycin chemotherapy in oncologic patients.

Association Between FGF-23 Levels and Risk of Fracture in Women With Systemic Sclerosis.

INTRODUCTION/BACKGROUND: The purpose of this study was to evaluate the association between Fracture Risk Assessment Tool (FRAX) and serum fibroblast grow factor-23 (FGF-23) levels in SSc women patients compared with healthy controls. METHODOLOGY: This cross-sectional study was performed in San Cecilio Hospital, Granada (Spain) from November 2017 to May 2019. Sixty-two women with SSc and 62 age and sex matched healthy controls were included in this study. FGF-23 serum concentration was evaluated by indirect enzyme-linked immunosorbent assay. The FRAX scoring tool was applied using the on-line calculator (www.shef.ac.uk/FRAX). RESULTS: Even though there was no significant difference in FGF-23 levels between SSc women patients and healthy controls (78.2 ± 60.5 vs 80.3 ± 56.3 pg/mL, p = 0.662). FGF-23 levels were positively associated with FRAX index within the study group. CONCLUSIONS: This study shows that FGF-23 status is associated with FRAX index in women with SSc. FGF-23 could be a promising biomarker for detecting risk fracture in SSc women patients.

FGF23-Klotho axis in patients with rheumatoid arthritis.

OBJECTIVES: We aimed to compare serum Klotho and fibroblast growth factor-23 (FGF-23) levels between rheumatoid arthritis (RA) patients and healthy controls. Possible association between FGF-23 and soluble Klotho with different characteristic of the disease as well as their potential role as surrogate markers of cardiovascular disease (CVD) were studied. METHODS: Sixty-three patients with RA recruited at Vega-Baja Hospital, Orihuela (Spain) from November 2016 to May 2018 and sixty-five age- and sex-matched healthy controls were included in this study. Serum Klotho and FGF-23 were analysed using ELISA. RESULTS: Patients had higher serum levels of Klotho than healthy controls (p˂0.0001). They were positively associated with the presence of anticitrullinated peptide antibody and rheumatic factor (p<0.05). Klotho serum levels were higher in RA patients treated with biologic agents than in those undergoing conventional therapy (p=0.008). However, no association with carotid intima media thickness was found. Although no significant differences in serum FGF-23 levels between patients and controls were found (p=0.43), FGF-23 levels were positively associated with low-density lipoprotein (LDL-c) level (p<0.05) and smoking (p=0.008) in patients with RA. CONCLUSIONS: The increased serum Klotho levels in RA patients, especially in those undergoing biologic therapy, may indicate a potential implication in the pathogenesis of the disease. Although levels of FGF-23 were related to LDL-c levels, the FGF-23-Klotho axis does not seem to be related to subclinical arteriosclerosis in RA.

Adrenomedullin protects from experimental autoimmune encephalomyelitis at multiple levels.

Adrenomedullin is a neuropeptide known for its cardiovascular activities and anti-inflammatory effects. Here, we investigated the effect of adrenomedullin in a model of experimental autoimmune encephalomyelitis (EAE) that mirrors chronic progressive multiple sclerosis. A short-term systemic treatment with adrenomedullin reduced clinical severity and incidence of EAE, the appearance of inflammatory infiltrates in spinal cord and the subsequent demyelination and axonal damage. This effect was exerted at multiple levels affecting both early and late events of the disease. Adrenomedullin decreased the presence/activation of encephalitogenic Th1 and Th17 cells and down-regulated several inflammatory mediators in peripheral lymphoid organs and central nervous system. Noteworthy, adrenomedullin inhibited the production by encephalitogenic cells of osteopontin and of Granulocyte Macrophage Colony-Stimulating Factor (GM-CSF), two critical cytokines in the development of EAE. At the same time, adrenomedullin increased the number of IL-10-producing regulatory T cells with suppressive effects on the progression of EAE. Furthermore, adrenomedullin generated dendritic cells with a semi-mature phenotype that impaired encephalitogenic responses in vitro and in vivo. Finally, adrenomedullin regulated glial activity and favored an active program of neuroprotection/regeneration. Therefore, the use of adrenomedullin emerges as a novel multimodal therapeutic approach to treat chronic progressive multiple sclerosis.

IL2/IL21 region polymorphism influences response to rituximab in systemic lupus erythematosus patients.

To determine whether the IL2/IL21 region, a general autoimmunity locus, contributes to the observed variation in response to rituximab in patients with systemic lupus erythematosus as well as to analyze its influence in a cohort including other autoimmune diseases. rs6822844 G/T polymorphism at the IL2-IL21 region was analyzed by TaqMan assay in 84 systemic lupus erythematosus (SLE) and 60 different systemic autoimmune diseases Spanish patients receiving rituximab. Six months after the first infusion patients were classified, according to the EULAR criteria, as good responders, partial responders and non-responders. A statistically significant difference was observed in GG genotype frequency between responder (total and partial response) (83.56%) and non-responder (45.45%) SLE patients (p=0.010, odds ratio (OR)=6.10 [1.28-29.06]). No association with the response was evident in the group of patients with autoimmune diseases other than lupus. Furthermore, when both groups of patients were pooled in a meta-analysis, a reduced statistical significance of the association was observed (p=0.024, OR=3.53 [1.06-11.64]). Our results show for a first time that IL2-IL21 region seems to play a role in the response to rituximab in SLE patients but not in other autoimmune diseases.

Cortistatin, a new antiinflammatory peptide with therapeutic effect on lethal endotoxemia.

Cortistatin is a recently discovered cyclic neuropeptide related to somatostatin that has emerged as a potential endogenous antiinflammatory factor based on its production by and binding to immune cells. Because human septic shock involves excessive inflammatory cytokine production, we investigated the effect of cortistatin on the production of inflammatory mediators and its therapeutic action in various murine models of endotoxemia. Cortistatin down-regulated the production of inflammatory mediators by endotoxin-activated macrophages. The administration of cortistatin protected against lethality after cecal ligation and puncture, or injection of bacterial endotoxin or Escherichia coli, and prevented the septic shock-associated histopathology, such as infiltration of inflammatory cells and intravascular disseminated coagulation in various target organs. The therapeutic effect of cortistatin was mediated by decreasing the local and systemic levels of a wide spectrum of inflammatory mediators, including cytokines, chemokines, and acute phase proteins. The combined use of cortistatin and other antiinflammatory peptides was very efficient treating murine septic shock. This work provides the first evidence of cortistatin as a new immunomodulatory factor with the capacity to deactivate the inflammatory response. Cortistatin represents a potential multistep therapeutic agent for human septic shock, to be used in combination with other immunomodulatory agents or as a complement to other therapies.

The PTPN22 C1858T variant as a risk factor for rheumatoid arthritis and systemic lupus erythematosus but not for systemic sclerosis in the Colombian population.

OBJECTIVES: C1858T single nucleotide polymorphism in PTPN22 encoding the R620W allele variant of Lyp-PTPN22 (a protein phosphatase negatively regulating T-cell activation) has been associated with autoimmunity. This work has investigated the possible association between PTPN22 C1858T (rs2476601) polymorphism and rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) in a Colombian population. METHODS: A case-control study included 1,042 samples from 413 RA, 94 SLE and 101 SSc patients and 434 healthy controls. The TaqMan allele discrimination assay was used for genotyping. RESULTS: The case-control study provided robust evidence of association between allele 1858T and RA (p=5E-05), as well as between 1858T and SLE (p=0.004). These observations were confirmed for both diseases by meta-analysis (p=2E-04, pooled OR 1.9; 1.3-2.7 95% CI for RA; p<0.0001, pooled OR 2.8, 1.8-4.5 95% CI for SLE). No significant association was observed between 1858T and SSc (p=0.98, OR 1.11, 0.46-2.65 95% CI). CONCLUSIONS: The study suggested that the PTPN22 1858T variant influences RA and SLE genetic background but not that of SSc in the Colombian population.

Protective role of cortistatin in pulmonary inflammation and fibrosis.

BACKGROUND AND PURPOSE: Acute lung injury (ALI), acute respiratory distress syndrome (ARDS) and pulmonary fibrosis remain major causes of morbidity, mortality and a healthcare burden in critically ill patient. There is an urgent need to identify factors causing susceptibility and for the design of new therapeutic agents. Here, we evaluate the effectiveness of the immunomodulatory neuropeptide cortistatin to regulate pulmonary inflammation and fibrosis in vivo. EXPERIMENTAL APPROACH: ALI/ARDS and pulmonary fibrosis were induced experimentally in wild-type and cortistatin-deficient mice by pulmonary infusion of the bacterial endotoxin LPS or the chemotherapeutic drug bleomycin, and the histopathological signs, pulmonary leukocyte infiltration and cytokines, and fibrotic markers were evaluated. KEY RESULTS: Partially deficient mice in cortistatin showed exacerbated pulmonary damage, pulmonary inflammation, alveolar oedema and fibrosis, and subsequent increased respiratory failure and mortality when challenged to LPS or bleomycin, even at low doses. Treatment with cortistatin reversed these aggravated phenotypes and protected from progression to severe ARDS and fibrosis, after high exposure to both injury agents. Moreover, cortistatin-deficient pulmonary macrophages and fibroblasts showed exaggerated ex vivo inflammatory and fibrotic responses, and treatment with cortistatin impaired their activation. Finally, the protective effects of cortistatin in ALI and pulmonary fibrosis were partially inhibited by specific antagonists for somatostatin and ghrelin receptors. CONCLUSION AND IMPLICATIONS: We identified cortistatin as an endogenous inhibitor of pulmonary inflammation and fibrosis. Deficiency in cortistatin could be a marker of poor prognosis in inflammatory/fibrotic pulmonary disorders. Cortistatin-based therapies could emerge as attractive candidates to treat severe ALI/ARDS, including SARS-CoV-2-associated ARDS.

Investigation of the IL23R gene in a Spanish rheumatoid arthritis cohort.

Recently, a genome-wide association study identified the interleukin-23 receptor gene (IL23R) as an inflammatory bowel disease (IBD) associated gene. Given the involvement of IL23R in T-cell regulation, we decided to test whether this gene is associated with rheumatoid arthritis (RA). Eight IL23R gene polymorphisms (rs1,004,819, rs7,517,847, rs10,489,629, rs11,209,026, rs1,343,151, rs10,889,677, rs11,209,032, and rs1,495,965) were selected among the 10 most associated SNPs from the IBD study. A total of 322 RA patients and 342 healthy controls were genotyped for the selected SNPs using a Taqman 5' allelic discrimination assay. We did not find statistically significant differences when we compared allele and genotype frequencies between RA patients and controls for none of the IL23R gene polymorphisms under study. We did not observe significant differences when RA patients were stratified according to their clinical and demographic features. We conclude that the IL23R gene does not seem to be associated with RA predisposition in a Spanish population.

The neuropeptide cortistatin attenuates experimental autoimmune myocarditis via inhibition of cardiomyogenic T cell-driven inflammatory responses.

BACKGROUND AND PURPOSE: Myocarditis is an inflammatory and autoimmune cardiovascular disease that causes dilated myocardiopathy and is responsible for high morbidity and mortality worldwide. Cortistatin is a neuropeptide produced by neurons and cells of the immune and vascular systems. Besides its action in locomotor activity and sleep, cortistatin inhibits inflammation in different experimental models of autoimmune diseases. However, its role in inflammatory cardiovascular disorders is unexplored. Here, we investigated the therapeutic effects of cortistatin in a well-established preclinical model of experimental autoimmune myocarditis (EAM). EXPERIMENTAL APPROACH: We induced EAM by immunization with a fragment of cardiac myosin in susceptible Balb/c mice. Cortistatin was administered i.p. starting 7, 11 or 15 days after EAM induction. At day 21, we evaluated heart hypertrophy, myocardial injury, cardiac inflammatory infiltration and levels of serum and cardiac inflammatory cytokines, cortistatin and autoantibodies. We determined proliferation and cytokine production by heart draining lymph node cells in response to cardiac myosin restimulation. KEY RESULTS: Systemic injection of cortistatin during the effector phase of the disease significantly reduced its prevalence and signs of heart hypertrophy and injury (decreased the levels of brain natriuretic peptide) and impaired myocardial inflammatory cell infiltration. This effect was accompanied by a reduction in self-antigen-specific T-cell responses in lymph nodes and in the levels of cardiomyogenic antibodies and inflammatory cytokines in serum and myocardium. Finally, we found a positive correlation between cardiac and systemic cortistatin levels and EAM severity. CONCLUSIONS AND IMPLICATIONS: Cortistatin emerges as a new candidate to treat inflammatory dilated cardiomyopathy.

Signaling mechanisms of vasoactive intestinal peptide in inflammatory conditions.

The vasoactive intestinal peptide (VIP) is a neuropeptide belonging to the secretin/glucagon family of peptides, which exerts a wide spectrum of immunological functions controlling the homeostasis of immune system through different receptors expressed in various immunocompetent cells. In the last decade, VIP has emerged as a potent anti-inflammatory factor, which exerts its function by regulating the production of both anti- and pro-inflammatory mediators. In this sense, VIP has been proposed as a promising candidate, alternative to other existing treatments, for treating acute and chronic inflammatory and autoimmune diseases, such as septic shock, rheumatoid arthritis, multiple sclerosis and Crohn's disease. The present work reviews the involvement of the specific receptors and or different transduction pathways and transcription factors in the anti-inflammatory action of VIP, and their implication on its therapeutic effect on inflammatory/autoimmune disorders.

Analysis of Systemic Sclerosis-associated Genes in a Turkish Population.

OBJECTIVE: To evaluate the genetic background of systemic sclerosis (SSc) in the Turkish population. METHODS: There were 354 cases and 718 unaffected controls from Turkey genotyped for the most relevant SSc genetic markers (IRF5-rs10488631, STAT4-rs3821236, CD247-rs2056626, DNASE1L3-rs35677470, IL12A-rs77583790, and ATG5-rs9373839). Association tests were conducted to identify possible associations. RESULTS: Except for ATG5, all the analyzed genes showed either significant associations (IRF5: p = 1.32E-05, OR 1.76; CD247: p = 2.20E-03, OR 0.75) or trends of association (STAT4: p = 0.066, OR 1.21; IL12A: p = 0.079, OR 4.07; DNASE1L3: p = 0.097, OR 1.41) with the overall disease or with specific phenotypes. CONCLUSION: The genetic component of SSc seems to be similar between Turks and Europeans.

Vitamin D receptor GATG haplotype association with atherosclerotic disease in patients with rheumatoid arthritis.

INTRODUCTION: An association between the vitamin D receptor (VDR) GAT haplotype and coronary artery disease (CAD) in type-2 diabetes has recently been described. Since cardiovascular mortality in rheumatoid arthritis (RA) is comparable to that observed for patients with type-2 diabetes, we aimed to determine if VDR GAT haplotype is also associated with atherosclerotic disease in RA. MATERIAL AND METHODS: 591 Northern Spanish RA patients were genotyped for 4 VDR polymorphisms (rs731236 A/G; rs7975232 A/C; rs1544410C/T; rs2228570 G/A). Atherosclerotic disease was established by the presence of carotid plaques in carotid ultrasound. RESULTS: VDR rs7975232 AA genotype was increased in RA patients with plaques (p = 0.045, OR = 1.46 [1.01-2.18]). More importantly, the frequency of carotid plaques was significantly increased in RA patients who carried the GATG haplotype (p = 0.009, OR = 1.56 [1.09-2.42]). CONCLUSION: Our results suggest a potential VDR GATG haplotype association with atherosclerotic disease in RA patients.

Stimulation of the mitogen-activated protein kinase pathway antagonizes TRAIL-induced apoptosis downstream of BID cleavage in human breast cancer MCF-7 cells.

We studied the role of the mitogen-activated protein kinase (MAPK) pathway in the regulation of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis in breast tumor MCF-7 cells. We found that addition of a protein kinase C (PKC) activator to MCF-7 cultures prevented TRAIL-induced apoptosis, by inhibiting a step downstream of both caspase-8 activation and BID cleavage. TRAIL-induced translocation of Bax from cytosol to mitochondria, release of cytochrome c from mitochondria and activation of caspase-9 were all inhibited by PKC activation. PKC-mediated prevention of mitochondrial apoptotic events and apoptosis was found to be dependent on the MAPK pathway. Since TRAIL is a ligand of potential use in antineoplastic clinical trials, our findings may provide relevant information in cancer therapy.

Thymidylate synthase inhibition triggers glucose-dependent apoptosis in p53-negative leukemic cells.

Chemotherapeutic drugs that inhibit the synthesis of DNA precursor thymidine triphosphate cause apoptosis, although the mechanism underlying this process remains rather unknown. Here, we describe thymineless death of human myeloid leukemia U937 cells treated with the thymidylate-synthase inhibitor 5'-fluoro- 2'-deoxyuridine (FUdR). This apoptotic process was shown to be independent of p53, reactive oxygen species generation and CD95 activation. Caspases were activated downstream of cytochrome c but upstream of mitochondrial depolarization. Furthermore, FUdR-induced apoptosis required the presence of glucose in the culture medium at a step upstream of the release of cytochrome c from mitochondria.

Preconditioning of microglia by α-synuclein strongly affects the response induced by toll-like receptor (TLR) stimulation.

In recent years, it has become accepted that α-synuclein (αSyn) has a key role in the microglia-mediated neuroinflammation, which accompanies the development of Parkinson's disease and other related disorders, such as Dementia with Lewy Bodies and Alzheimer's disease. Nevertheless, the cellular and molecular mechanisms underlying its pathological actions, especially in the sporadic forms of the diseases, are not completely understood. Intriguingly, several epidemiological and animal model studies have revealed a link between certain microbial infections and the onset or progression of sporadic forms of these neurodegenerative disorders. In this work, we have characterized the effect of toll-like receptor (TLR) stimulation on primary murine microglial cultures and analysed the impact of priming cells with extracellular wild-type (Wt) αSyn on the subsequent TLR stimulation of cells with a set of TLR ligands. By assaying key interleukins and chemokines we report that specific stimuli, in particular Pam3Csk4 (Pam3) and single-stranded RNA40 (ssRNA), can differentially affect the TLR2/1- and TLR7-mediated responses of microglia when pre-conditioned with αSyn by augmenting IL-6, MCP-1/CCL2 or IP-10/CXCL10 secretion levels. Furthermore, we report a skewing of αSyn-primed microglia stimulated with ssRNA (TLR7) or Pam3 (TLR2/1) towards intermediate but at the same time differential, M1/M2 phenotypes. Finally, we show that the levels and intracellular location of activated caspase-3 protein change significantly in αSyn-primed microglia after stimulation with these particular TLR agonists. Overall, we report a remarkable impact of non-aggregated αSyn pre-sensitization of microglia on TLR-mediated immunity, a phenomenon that could contribute to triggering the onset of sporadic α-synuclein-related neuropathologies.

Analysis of the interferon gamma (rs2430561, +874T/A) functional gene variant in relation to the presence of cardiovascular events in rheumatoid arthritis.

OBJECTIVE: Rheumatoid arthritis (RA) is a chronic inflammatory disease associated with increased cardiovascular (CV) morbidity and mortality. Since interferon-gamma (IFN-γ) has a direct effect on inflammation, in this study we assessed the potential association of the IFNG functional gene variant rs2430561 with CV disease in patients with RA. METHODS: One thousand six hundred and thirty-five patients fulfilling the 1987 American College of Rheumatology classification criteria for RA were genotyped for the IFNG (rs2430561, +874T/A) gene polymorphism using TaqMan genotyping assay. Patients were stratified according to the presence of CV events or not. Logistic regression models to explain the presence of CV disease according to the IFNG rs2430561 allele distribution were performed. The potential influence of this variant in the development of subclinical atherosclerosis was also analyzed in a subgroup of patients with no history of CV events to determine carotid artery intima-media thickness (IMT) (n = 286) and presence of carotid plaques. Levels of the cytokine were determined in a subgroup of patients by ELISA. RESULTS: Adjusted logistic regression model disclosed that presence of the minor allele A was not associated with increased risk of suffering CV events in RA patients. Besides, differences did not achieve statistical significance regarding carotid IMT and presence of carotid plaques in RA patients carrying IFNG rs2430561 variant allele. Levels of IFN-γ were higher in patients who had suffered CV events compared to patients who did not. CONCLUSION: Our results do not support a role of IFNG rs2430561 (+874T/A) functional gene variant in the development of CV disease in RA patients.

NPSR1 gene is associated with reduced risk of rheumatoid arthritis.

OBJECTIVE: Neuropeptide S receptor 1 (NPSR1) is a G protein-coupled receptor involved in immune response and is associated with several inflammatory diseases. We investigated the possible contribution of several polymorphisms in the intronic region of NPSR1 to rheumatoid arthritis (RA). METHODS: Genotyping of 7 single-nucleotide polymorphisms (SNP) was performed in a total of 1232 patients with RA and 983 healthy controls of Spanish white origin by real-time polymerase chain reaction technology, using the TaqMan 5'-allele discrimination assay. RESULTS: One out of the 7 SNP analyzed (rs740347) was associated with RA [p after Bonferroni correction (p(BNF)) = 1.2 × 10(-3), OR 0.73]. An association was also observed with rheumatoid factor-positive and shared epitope-positive RA (p(BNF) = 0.011, OR 0.73; p(BNF) = 0.037, OR 0.75, respectively). CONCLUSION: Our results show that variations in the NPSR1 intronic region are associated with low risk in patients with RA, supporting other evidence that this locus represents a common genetic factor in inflammatory diseases.

Association of the FCGR3A-158F/V gene polymorphism with the response to rituximab treatment in Spanish systemic autoimmune disease patients.

Rituximab is being used as treatment for systemic autoimmune diseases. The objective of this study was to determine whether the genetic variant in the Fc gamma-receptor III a (FCGR3A) gene, 158F/V, contributes to the observed variation in response to rituximab in patients with systemic autoimmune diseases. DNA samples from 132 Spanish patients with different systemic autoimmune diseases receiving rituximab were genotyped for FCGR3A-158F/V (rs396991) gene polymorphism using the TaqMan(®) allelic discrimination technology. Six months after infusion with rituximab we evaluated the response to the drug: 61% of the patients showed a complete response, partial 27% and 12% did not respond to the treatment. A statistically significant difference was observed in V allele frequency between responder (38%) and nonresponder (16%) patients (p=0.01; odds ratio [OR]=3.24, 95% confidence interval [CI] 1.17-11.1). Rituximab was also more effective in V allele carriers (94%) than in homozygous FF patients (81%): p=0.02; OR=3.96, 95% CI 1.10-17.68. These results suggest that FCGR3A-158F/V (rs396991) gene polymorphism play a role in the response to rituximab in autoimmune diseases. Validation of these findings in independent cohorts is warranted.

Association between -174 interleukin-6 gene polymorphism and biological response to rituximab in several systemic autoimmune diseases.

Rituximab has become a pivotal treatment for systemic autoimmune diseases. The aim of this study was to determine whether the genetic variant -174 IL-6 contributes to differences in the response to rituximab in patients with systemic autoimmune diseases, including systemic lupus erythematosus (SLE), inflammatory myopathies, anti-neutrophil cytoplasmic antibody-mediated vasculitis, systemic sclerosis, Sjöegren's syndrome, rheumatoid arthritis, and autoimmune hemolytic anemia. DNA samples from 144 Spanish patients with different systemic autoimmune diseases receiving rituximab were genotyped for -174 IL-6 (rs1800795) gene polymorphism using the TaqMan(®) allelic discrimination technology. Six months after the first infusion with rituximab, we evaluated the response to the drug: 60.4% of the patients showed a complete response, partial 27.8%, and 11.8% did not respond to the treatment. The CC genotype frequency was significantly increased in nonresponders with respect to responders (23.5% vs. 7.1%, respectively; p=0.049; odds ratio (OR)=4.03, 95% confidence intervals (CI) 0.78-16.97). According to the genotype distribution, rituximab was effective in 69.2% of the CC carriers, 91.9% of the CG carriers, and 88.4% of the GG carriers. A similar trend was observed when SLE patients were analyzed separately (27.3% carried CC homozygosis in nonresponders and 6.9% in responders; p=0.066; OR=5.10, 95% CI 0.65-31.73). Rituximab was effective in 62.5% of the CC carriers, 88.9% of the GC carriers, and 90% of the GG carriers. These results suggest that -174 IL-6 (rs1800795) gene polymorphism plays a role in the response to rituximab in systemic autoimmune diseases. Validation of these findings in independent cohorts is warranted.