CD72 is a Negative Regulator of B Cell Responses to Nuclear Lupus Self-antigens and Development of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is the prototypic systemic autoimmune disease characterized by production of autoantibodies to various nuclear antigens and overexpression of genes regulated by IFN-I called IFN signature. Genetic studies on SLE patients and mutational analyses of mouse models demonstrate crucial roles of nucleic acid (NA) sensors in development of SLE. Although NA sensors are involved in induction of anti-microbial immune responses by recognizing microbial NAs, recognition of self NAs by NA sensors induces production of autoantibodies to NAs in B cells and production of IFN-I in plasmacytoid dendritic cells. Among various NA sensors, the endosomal RNA sensor TLR7 plays an essential role in development of SLE at least in mouse models. CD72 is an inhibitory B cell co-receptor containing an immunoreceptor tyrosine-based inhibition motif (ITIM) in the cytoplasmic region and a C-type lectin like-domain (CTLD) in the extracellular region. CD72 is known to regulate development of SLE because CD72 polymorphisms associate with SLE in both human and mice and CD72−/− mice develop relatively severe lupus-like disease. CD72 specifically recognizes the RNA-containing endogenous TLR7 ligand Sm/RNP by its extracellular CTLD, and inhibits B cell responses to Sm/RNP by ITIM-mediated signal inhibition. These findings indicate that CD72 inhibits development of SLE by suppressing TLR7-dependent B cell response to self NAs. CD72 is thus involved in discrimination of self-NAs from microbial NAs by specifically suppressing autoimmune responses to self-NAs.

Distribution of SDF1-3'A polymorphisms in three different ethnic groups from Brazil

A mutation described as a G-to-A transition has been reported in SDF-1 gene (SDF1-3'A), being prevalent in all ethnic groups, except in Africans. This mutation is associated with the onset of AIDS progression. Our aim was to identify the frequency of this allele in different groups from Brazil: Tiriyó and Waiampi Amerindian tribes (Asian ancestry); selected blood donors from Joinville (German descendents); and from Salvador (predominance of African and Portuguese mixture). SDF1-3'A was screened by PCR/RFLP with MspI enzyme. Our results showed a high allelic frequency in Tiriyó tribe (0.24) and Joinville population (0.21), and a frequency of 0.17 and 0.05 in the Salvador population and in the Waiampi tribe, respectively. There was no statistical difference among the allelic frequencies in the studied ethnic groups, except in the Waiampi. Due to the great genetic diversity among Brazilian population and the lack of studies on SDF1-3'A allele, our study of this allelic frequency in these different Brazilian ethnic groups could be important to identification of biomarker for therapeutic support in progression to AIDS and a molecular marker for analysis of evolutionary relationships among human populations.

Advancement in developing a new class of anti-AIDS drugs: HIV entry inhibitors / 中国药理学通报

Process of HIV fusion with target cells, mediated by the HIV envelope glycoprotein surface subunit gp120 and the transmembrane subunit gp41, is an important step for drug intervention. The membrane fusion events leading to HIV entry into the target cell are initiated by the binding of gp120 to CD4 and subsequently to a co-receptor, CXCR4 or CCR5. Consequently, gp41 undergoes conformational changes, resulting in the fusion between the viral and cellular membranes or between the infected and uninfected cells. Therefore, gp120 and gp41 on the virions and CD4 and coreceptors on the target cells may serve as targets for development of a new class of anti-HIV drugs, HIV entry inhibitors, with a mechanism of action different from those mediated by reverse transcriptase inhibitors (RTIs) and protease inhibitors (PIs), the two classes of antiretroviral drugs approved by FDA for clinical application. The successful development of a peptidic anti-HIV drug T-20, which is targeted to the HIV gp41, implies that HIV entry inhibitors are milestone in the current anti-HIV therapy. Application of the HIV entry inhibitors alone or in combination with the RTIs and PIs will increase the efficacy and reduce the toxicity of these anti-HIV drugs and will save lives of AIDS patients who fail to response to the current antiretroviral drugs. The advancement in the study and development of the HIV entry inhibitors was reviewed here in detail