Genetics and systemic lupus erythematosus

Immunological and Clinical Characteristics of Systemic Lupus Erythematosus: A Series from Morocco

Systemic Lupus Erythematosus (SLE) is a complex autoimmune disease with a high female predominance. To date, studies about SLE in Morocco are few. This retrospective study describes the clinical and immunological features in a series of 50 SLE Moroccan patients in University Hospital Center of Rabat, Morocco, between December 2011 and December 2013. All patients were screened for antinuclear antibodies (ANA) and anti-DNA antibodies by indirect immunofluorescence, followed by identification of anti-extractable nuclear antigen antibodies by ELISA. The female to male ratio was 6.1:1. Mean age was 31.72 years. The main clinical manifestations were arthritis (82%), mucocutaneous manifestations (80%), renal manifestations (50%), and hematological features (46%). Of the mucocutaneous features, the highest frequencies were observed in the malar rash (68%) and photosensitivity (60%). Of the hematological features, lymphopenia was most frequently observed in 30% of patients, followed by hemolytic anemia in 16% and leucopenia and thrombocytopenia in 8%. Central nervous system was involved in 10%. ANA were found in 88%, anti-DNA antibodies in 56%, and anti-Sm antibodies in 50%. Anti-SSA, anti-SSB, anti-Sm/RNP, and anti-Scl70 antibodies were detected in 38%, 10%, 48%, and 8%, respectively. Our data show that, in our patients, the main clinical and immunological features of SLE remain comparable to patients from other Arab countries.

Genetics of transfusion recipient alloimmunization: can clues from susceptibility to autoimmunity pave the way?

The search for genetic determinants of alloimmunization in sickle cell disease transfusion recipients was based on two premises: i) that polymorphisms responsible for stronger immune and/or inflammatory responses and hemoglobin β(S) mutation were co-selected by malaria; and ii) that stronger responder status contributes to development of lupus. We found a marker of alloimmunization in the gene encoding for Ro52 protein, also known as Sjögren syndrome antigen 1 (SSA1) and TRIM21. Surprisingly, the nature of the association was opposite of that with lupus; the same variant of a polymorphism (rs660) that was associated with lupus incidence was also associated with induction of tolerance to red blood cell antigens during early childhood. The dual function of Ro52 can explain this apparent contradiction. We propose that other lupus/autoimmunity susceptibility loci may reveal roles of additional molecules in various aspects of alloimmunization induced by transfusion as well as during pregnancy.

Mechanisms of tissue injury in lupus nephritis

Systemic lupus erythematosus is a prototypic autoimmune disease characterized by autoantibody production and immune complex formation/deposition in target organs such as the kidney. Resultant local inflammation then leads to organ damage. Nephritis, a major cause of morbidity and mortality in patients with lupus, occurs in approximately 50% of lupus patients. In the present review, we provide an overview of the current research and knowledge concerning mechanisms of renal injury in both lupus-prone mouse models and human lupus patients.

Selective small antigenic structures are capable of inducing widespread autoimmunity which closely mimics the humoral fine specificity of human SLE

Recent data have suggested that autoantibodies in lupus can progress from simple immunity against a few antigenic structures to a complex response against multiple autoantigens. Our aim was to determine whether these diverse epitope patterns can indeed be generated by antigenic challenge with a single, small structure. Rabbits were immunized with either a 60 kDa Ro peptide commonly antigenic in human systemic lupus erythematosus (SLE) (Ro 274-289) or one which is rarely a humoral target (Ro 500-515). Rabbits immunized with the antigenic peptide (Ro 274-289) not only developed antibodies to multiple epitopes of 60 kDa Ro and La, as has been described, but also produced non-cross-reactive antibodies to the common spliceosomal proteins Sm B' and D1, and nRNP A and C. Rabbits immunized with the Ro 274-289 peptide also mount a progressive, diversified immune response to the sequential antigenic regions of these proteins (60 kDa Ro, Sm B' and D1, nRNP A and C), which is nearly identical to that seen in human SLE. Animals immunized with the nonantigenic peptide Ro 500-515 develop antibodies only to 60 kDa Ro. These results demonstrate that loss of tolerance to select single, small antigenic structures can begin a cascade which virtually recreates, at the epitope level, the humoral autoimmune specificity seen in human SLE.