Increased levels of prolactin receptor expression correlate with the early onset of lupus symptoms and increased numbers of transitional-1 B cells after prolactin treatment.

BACKGROUND: Prolactin is secreted from the pituitary gland and other organs, as well as by cells such as lymphocytes. Prolactin has an immunostimulatory effect and is associated with autoimmune diseases that are characterised by abnormal B cell activation, such as systemic lupus erythematosus (SLE). Our aim was to determine if different splenic B cell subsets express the prolactin receptor and if the presence of prolactin influences these B cell subsets and correlates with development of lupus. RESULTS: Using real-time PCR and flow cytometry, we found that different subsets of immature (transitional) and mature (follicular, marginal zone) B cells express different levels of the prolactin receptor and are differentially affected by hyperprolactinaemia. We found that transitional B cells express the prolactin receptor at higher levels compared to mature B cells in C57BL/6 mice and the lupus-prone MRL/lpr and MRL mouse strains. Transitional-1 (T1) B cells showed a higher level of prolactin receptor expression in both MRL/lpr and MRL mice compared to C57BL/6 mice. Hyperprolactinaemia was induced using metoclopramide, which resulted in the development of early symptoms of SLE. We found that T1 B cells are the main targets of prolactin and that prolactin augments the absolute number of T1 B cells, which reflects the finding that this B cell subpopulation expresses the highest level of the prolactin receptor. CONCLUSIONS: We found that all B cell subsets express the prolactin receptor but that transitional B cells showed the highest prolactin receptor expression levels. Hyperprolactinaemia in mice susceptible to lupus accelerated the disease and increased the absolute numbers of T1 and T3 B cells but not of mature B cells, suggesting a primary effect of prolactin on the early stages of B cell maturation in the spleen and a role of prolactin in B cell differentiation, contributing to SLE onset.

Prolactin Increases the Frequency of Follicular T Helper Cells with Enhanced IL21 Secretion and OX40 Expression in Lupus-Prone MRL/lpr Mice.

Systemic lupus erythematosus is characterized by high levels of IgG class autoantibodies that contribute to the pathophysiology of the disease. The formation of these autoantibodies occurs in the germinal centers, where there is cooperation between follicular T helper cells (TFH) and autoreactive B cells. Prolactin has been reported to exacerbate the clinical manifestations of lupus by increasing autoantibody concentrations. The objective of this study was to characterize the participation of prolactin in the differentiation and activation of TFH cells, by performing in vivo and in vitro tests with lupus-prone mice, using flow cytometry and real-time PCR. We found that TFH cells express the long isoform of the prolactin receptor and promoted STAT3 phosphorylation. Receptor expression was higher in MRL/lpr mice and correlative with the manifestations of the disease. Although prolactin does not intervene in the differentiation of TFH cells, it does favor their activation by increasing the percentage of TFH OX40+ and TFH IL21+ cells, as well as leading to high serum concentrations of IL21. These results support a mechanism in which prolactin participates in the emergence of lupus by inducing overactive TFH cells and perhaps promoting dysfunctional germinal centers.

Bone Marrow Mesenchymal Stromal Cells from Clinical Scale Culture: In Vitro Evaluation of Their Differentiation, Hematopoietic Support, and Immunosuppressive Capacities.

The differentiation capacity, hematopoietic support, and immunomodulatory properties of human bone marrow mesenchymal stromal cells (BM-MSCs) make them attractive therapeutic agents for a wide range of diseases. Clinical scale cultures (CSCs) have been used to expand BM-MSCs for their use in cell therapy protocols; however, little is known about the functionality of the expanded cells. The main goal of the present study was to evaluate the functional characteristics of BM-MSCs expanded from CSCs to determine the quality of the cells for cellular therapy protocols. To address this issue, we analyzed the morphology, immunophenotype, differentiation potential (adipogenic, osteogenic and chondrogenic), hematopoietic support, and immunosuppressive capacity of BM-MSCs from short scale cultures (SSCs) and CSCs in a comparative manner. After 12 days of culture in CSCs (HYPERFlask System), BM-MSCs reached cell numbers of 125.52 × 10(6) ± 25.6 × 10(6) MSCs, which corresponded to the number of cells required for transplantation (∼1.7 × 10(6) MSCs/kg for a 70-kg patient). After expansion, BM-MSCs expressed the characteristic markers CD73, CD90, and CD105; however, expansion decreased their differentiation capacity toward the adipogenic, osteogenic, and chondrogenic lineages and their ability to inhibit T-cell proliferation compared with SSCs-MSCs. Importantly, CSCs-MSCs maintained the ability to support the proliferation and expansion of hematopoietic progenitor cells and the capacity to express the molecules, cytokines, and extracellular matrix proteins involved in the regulation of hematopoiesis. Our study highlights the need to evaluate the functional properties of the expanded BM-MSCs for verification of their quality for cell therapy protocols.

Innate immune system cells in atherosclerosis.

Atherosclerosis is a chronic inflammatory disease of the arterial wall characterized by innate and adaptive immune system involvement. A key component of atherosclerotic plaque inflammation is the persistence of different innate immune cell types including mast cells, neutrophils, natural killer cells, monocytes, macrophages and dendritic cells. Several endogenous signals such as oxidized low-density lipoproteins, and exogenous signals such as lipopolysaccharides, trigger the activation of these cells. In particular, these signals orchestrate the early and late inflammatory responses through the secretion of pro-inflammatory cytokines and contribute to plaque evolution through the formation of foam cells, among other events. In this review we discuss how innate immune system cells affect atherosclerosis pathogenesis.