The clinical significance of posttranslational modification of autoantigens.

Posttranslational modifications (PTMs) are defined as covalent modifications occurring in a specific protein amino acid in a time- and signal-dependent manner. Under physiological conditions, proteins are posttranslationally modified to carry out a large number of cellular events from cell signaling to DNA replication. However, an absence, deficiency, or excess in PTMs of a given protein can evolve into a target to trigger autoimmunity, since PTMs arise in the periphery and may not occur in the thymus; hence, proteins with PTMs never tolerize developing thymocytes. Consequently, when PTMs arise during cellular responses, such as inflammation, these modified self-antigens can be taken up and processed by the antigen-presenting cells (APCs). Autoreactive T cells, which recognize peptides presented by APCs, can then infiltrate into host tissue where the modified antigen serves to amplify the autoimmune response, eventually leading to autoimmune pathology. Furthermore, a PTM occurring in an amino acid residue can induce changes in the net charge of the protein, leading to conformational modifications in the tertiary and quaternary structure of the protein, especially interaction with human leukocyte antigen (HLA) molecules. Molecular mimicry (MM) was until now the prevailing hypothesis explaining generation of autoimmunity; nevertheless, experimental animal models need inflammation via infection or other immunogens to ensure autoimmunity; MM alone is not sufficient to develop autoimmunity. PTMs could arise as an additive factor to MM, which is required to start an autoimmune response. PTMs have been found to be present in different pathologic conditions such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), antiphospholipid syndrome, and primary biliary cirrhosis. The aim of the present review is to expose protein posttranslational modifications and the evidence suggesting their role in the generation of autoimmunity.

The distribution of CD56(dim) CD16+ and CD56(bright) CD16- cells are associated with prolactin levels during pregnancy and menstrual cycle in healthy women.

PROBLEM: The pregnancy and menstrual cycle (MC) are the main physiologic events linked to the human reproduction. An adequate neuroendocrine axis is mandatory for the homeostasis in both events. To analyze the distribution of NK, T, Treg cells, expression of their receptors and to associate with hormone levels in pregnant and MC in healthy women. METHOD OF STUDY: We studied two groups of healthy women: 13 pregnant women followed up at 1st, 2nd and 3rd trimesters and 11 women in the 5th and 21st day of the MC. The distribution of NK, T, Treg cells population, expression of their receptors and hormone levels were quantified. RESULTS: In pregnant women, we found an association of NK cells CD56(dim) CD16(+) with prolactin levels. This finding was also was observed for CD56(brigthCD16-) being statistical significant during 1st trimester for both subpopulations. During MC, correlation of CD56(dim) CD16(+) , CD56(bright) CD16(-) cells with prolactin in follicular and luteal phase was found. CONCLUSION: This is the first report where these cell subpopulations have been analyzed prospectively. Even we can argue the random effect for the small number of women is interesting that prolactin showed the more consistent correlation with CD56(dim) CD16(+) , CD56(brigth) CD16(-) cells during both events studied.

IL-17 increased in the third trimester in healthy women with term labor.

INTRODUCTION: The function, peripheral blood expression, and physiologic importance of IL-17 is not well established. Detection of IL-17 in sera and plasma samples from patients with pre-eclampsia has been reported with inconsistent results. To establish the l levels of the IL-17 at peripheral level, we studied prospectively a cohort of 13 healthy pregnant women. OBJECTIVE: To evaluate the changes in serum levels of IL-17 in healthy pregnant women in a prospective cohort. MATERIAL AND METHODS: Thirteen healthy pregnant women were prospectively followed to evaluate serum levels of IL-17. Each patient was evaluated at each trimester. IL-17 levels were measured by ELISA. The statistical analysis was done using repeated measures anova and Bonferroni's multiple comparison test. RESULTS: IL-17 levels were significantly increased from first trimester with a mean of 14.61 up to 31.78 pg/mL at third trimester (P < 0.05), but when detectable, they were almost identical range in all trimesters. CONCLUSIONS: We propose that IL-17 levels in healthy women are present with very similar range levels during the whole pregnancy but the average is increased during the third trimester maybe as a part of the complex network of cytokines as a result of implantation, fetal development, and labor process itself.

Inhibitors of MAPK pathway ERK1/2 or p38 prevent the IL-1{beta}-induced up-regulation of SRP72 autoantigen in Jurkat cells.

Phosphorylation is the most important post-translational event at a cellular level that is regulated by protein kinases. MAPK is a key player in the important cellular signaling pathway. It has been hypothesized that phosphorylation might have a role in the induction of break tolerance against some autoantigens such as SRP72. The aim of this study was to explore the pathways of phosphorylation and overexpression of the SRP72 polypeptide, using an in vitro model of Jurkat cells stimulated by recombinant human (rh)IL-1ß in the presence of MAPK inhibitors. We used Jurkat cells as a substrate stimulated with rhIL-1ß in the presence of MAPK inhibitors at different concentrations in a time course in vitro experiment by immunoprecipitation, immunoprecipitation-Western blotting, and real time PCR. Our results showed that rhIL-1ß causes up-regulation of protein expression and phosphorylation of SRP72 in Jurkat cells. Inhibitors of the MAPK pathway ERK1/2 or p38α/ß down-regulate the expression of SRP72 autoantigen in Jurkat cells stimulated by rhIL-1ß. Our results highlight the importance of studying the pathways of activation and overexpression of autoantigens. It will be necessary to perform careful research on various kinases pathways, including MAPK in dermatomyositis and other rheumatic diseases, to help to explain the routes of activation and inhibition of autoantigens. The understanding of this process may help to develop new therapies to prevent and control the loss of tolerance toward own normal proteins.