Rabbit Anti-Human LYN (a.a. 263-491) Polyclonal antibody

Leishmania major causes cutaneous leishmaniasis. An antileishmanial vaccine for humans is unavailable. In this study, we report development of two attenuated L. major strains-5ASKH-HP and LV39-HP-by continuous culture (high passage) of the corresponding virulent strains (low passage). Both avirulent strains showed similar changes in proteome profiles when analyzed by surface-enhanced laser desorption ionization mass spectrometry. Liquid chromatography-mass spectrometry and microarray characterization of 5ASKH strains revealed substantially altered gene and protein expression profiles, respectively. Both virulent and avirulent L. major strains grew comparably in culture, but the avirulent strain survived significantly less in BALB/c-derived peritoneal macrophages. Both attenuated strains failed to infect BALB/c mice and elicited IFN-gamma, but not IL-4 and IL-10, responses. 5ASKH-HP parasites failed to induce significant infection even in severely immunocompromised- SCID or inducible NO synthase-, CD40-, or IL-12-deficient mice, indicating attenuation. The avirulent strain induced less IL-10, but higher IL-12, in macrophages. The avirulent strain failed to reduce CD40 relocation to the detergent-resistant membrane domain and to inhibit CD40-induced phosphorylation of the kinases Lyn and protein kinase C-13 and MAPKs MKK-3/6 and p38MAPK or to upregulate MEK-1/2 and ERK-1/2 in BALB/c-derived peritoneal macrophages. The virulent and the avirulent strains reciprocally modulated CD40-induced Ras-mediated signaling through PI-3K and Raf-1. Avirulent 5ASKH-primed BALB/c mice were protected against virulent L. major challenge infection. The loss of virulence accompanied by substantially altered proteome profiles and the elicitation of host-protective immune responses indicate plausibly irreversible attenuation of the L. major strain and its potential use as a vaccine strain.

Maintenance of self-tolerance of auto-reactive lymphocytes is a fundamental mechanism to prevent the onset of autoimmune diseases. Deciphering the mechanisms involved in the deregulations leading to tolerance disruption and autoimmunity is still a major area of interest to identify new therapeutic targets and options. Ca2+ signaling plays a major role in B cell normal development and is therefore finely tuned by B cell receptor (BCR)-dependent and independent pathways. Developmental changes in the characteristics of BCR-dependent Ca2+ signals as well as the modulation of basal intracellular concentration ([Ca2+](i)) contribute strongly to self-tolerance maintaining mechanisms responsible for the physical or functional elimination of autoreactive B cells such as clonal deletion, receptor editing, and anergy. Implication of Ca2+ signals in B tolerance mechanisms mainly occurs through the specific activation of transcriptional programs depending on the amplitude, shape, and duration of Ca2+ signals. A large number of studies reported Ca2+ signaling defects in autoimmune pathology such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and primary Sj gren's syndrome (pSS). However, the precise nature of the molecular events responsible for these deregulations is not fully understood. Moreover, the demonstration of a direct correlation between Ca2+ signaling defects and tolerance disruption is still lacking. The recent identification of proteins involved in B cell Ca2+ signals such as ORAI, stromal interaction molecule and transient receptor potential is opening new horizons for understanding Ca2+ signaling defects observed in autoimmune diseases and for proposing potentially new therapeutic solutions. This review aims to present an overview of the developmental evolution of BCR dependent Ca2+ signaling and to place this signaling pathway in the context of mechanisms involved in tolerance maintenance and breakdown.