The 17-ß-oestradiol inhibits osteoclast activity by increasing the cannabinoid CB2 receptor expression.

Bone is a highly metabolically active tissue and its formation and resorption is at the base of bone remodelling. The critical importance of a balanced bone remodelling is demonstrated by human diseases, i.e. osteoporosis, in which a net increase in bone resorption is responsible of skeleton weakening and fracture risk. Oestrogens display anti-resorptive properties on bone metabolism. Indeed, the so-called post-menopausal osteoporosis occurs after interruption of gonad function and benefits from hormonal replacement treatment. Recently, an important role for the endocannabinoid system in the regulation of skeletal remodelling in human has also been shown. In particular, we showed that CB2 stimulation is able to reduce the number of human OCs in vitro. Here, we provide unprecedented evidence that 17-ß-oestradiol administration inhibits activity and formation of human OCs in vitro, demonstrating that oestrogens are able to induce an increase of CB2 expression probably through the recruitment of a putative oestrogens responsive element in the CB2 encoding for gene.

The cannabinoid receptor type 2 Q63R variant increases the risk of celiac disease: implication for a novel molecular biomarker and future therapeutic intervention.

Celiac disease (CD) is a chronic inflammatory disease of the small bowel that occurs with the ingestion of gluten, found in several grains products. Although HLA-DQ2 variant is required for the gluten-derived peptide gliadin presentation by antigen-presenting cells to T-cells, non-HLA genetic factors account for the majority of heritable risk. Several genome-wide association studies have identified susceptibility loci for CD on chromosome 1. Cells of the immune system express the cannabinoid receptor type 2 (CB2), a plasma-membrane receptor activated by both endogenous and exogenous cannabinoids. Consistent data evidence that CB2 is linked to a variety of immune functional events and that, in the course of an inflammatory process, an increased number of receptors becomes available for activation. The cannabinoid receptor type 2 gene (CNR2; GeneID1269) maps on 1p36.11. In order to investigate the possible involvement of CB2 in CD establishment, immunohistochemistry toward CB2 receptor and CD4+ cells in small bowel biopsies from celiac children and association analysis, through TaqMan assay, of a CNR2 common missense variant, rs35761398 (CAA/CGG), resulting in the aminoacidic substitution of Glutamine at codon 63 with Arginine (Q63R), in a cohort of 327 South Italian children have been performed. We observed in this study that CB2 is up-regulated in CD small bowel biopsies and CNR2 rs35761398 is significantly associated with CD (χ(2) = 37.064; d.f. 1; p = 1.14 × 10(-9)). Our findings suggest a role of CB2 in CD. The Q63R variant, increasing more than six-fold the risk for CD susceptibility, might eventually represent a novel molecular biomarker for CD risk stratification. Indeed, we provide here further evidence that CB2 receptor plays a critical role in autoimmunity susceptibility and indicates that it represents a molecular target to pharmacologically modulate the immune components in CD.

CNR2 functional variant (Q63R) influences childhood immune thrombocytopenic purpura.

Immune thrombocytopenic purpura is an acquired autoimmune disorder that is the most common cause of thrombocytopenia in children. The endocannabinoid system is involved in immune regulation. We evaluated a common missense variant (CAA/CGG; Q63R) of the gene encoding the cannabinoid receptor type 2 (GeneID 1269) in 190 children with immune thrombocytopenic purpura and 600 healthy controls. The allelic frequencies and genotype distribution of the polymorphism in the patients were significant compared to control samples (P=0.006 and P=0.0001, respectively). Interestingly, when acute and chronic immune thrombocytopenic purpura patients were analyzed separately with respect to controls, a significant overrepresentation of the RR genotype and of the R allele was observed only for the chronic form (P=0.00021 and P=0.011, respectively). The relative odds ratio suggested the risk of developing chronic form was more than double in immune thrombocytopenic purpura children homozygous for the variant (odds ratio=2.349, 95% CI: 1.544-3.573; P<0.001).

Beta-spectrinBari: a truncated beta-chain responsible for dominant hereditary spherocytosis.

We describe a beta-spectrin variant, named beta-spectrin Bari, characterized by a truncated chain and associated with hereditary spherocytosis. The clinical phenotype consists of a moderately severe hemolytic anemia, splenomegaly, and spherocytes and acanthocytes in the blood smear. The occurrence of the truncated protein, that represents about 8% of the total beta-spectrin occurring on the membrane, results in a marked spectrin deficiency. The altered protein is due to a single point mutation at position -2 (A->G) of the acceptor splice site of intron 16 leading to an aberrant beta-spectrin message skipping exons 16 and 17 indistinguishable from that reported for beta-spectrin Winston-Salem. We provide evidence that the mutated gene is transcribed but its mRNA is less abundant than either its normal counterpart or beta-spectrin Winston-Salem mRNA. Our findings are an example of how mutations in different splice sites, although causing the same truncating effect, result in clearly different clinical pictures.

HNF-1ß mutation affects PKD2 and SOCS3 expression causing renal cysts and diabetes in MODY5 kindred.

BACKGROUND: Maturity onset diabetes of young (MODY) type 5 is a form of non-insulin-dependent diabetes mellitus associated with renal cysts. It is an autosomal dominant disorder caused by mutations in the gene encoding hepatocyte nuclear factor-1ß (HNF-1ß). METHODS: We performed molecular screening of HNF-1ß in a 13-year-old patient and his affected father, and analyzed polycystic kidney disease 2 (PKD2) gene and suppressor of cytokine signaling 3 (SOCS3) expression in lymphoblastoid cell lines and lymphocytes from both patients. RESULTS: We found a novel HNF-1ß frameshift mutation (c.C1304del) that results in a truncated protein (p.I434IfsX1). The genetic change is localized in the transactivated protein domain. CONCLUSIONS: We demonstrated that this novel HNF-1ß mutation strongly influences the expression of both PKD2, responsible for the formation of the renal cysts, and SOCS3, which is associated with early diabetes onset.

The endovanilloid/endocannabinoid system: a new potential target for osteoporosis therapy.

Human osteoclasts express functional TRPV1 channels, CB1/CB2 cannabinoid receptors and endocannabinoid/endovanilloid synthetic/catabolic enzymes. Pharmacologic manipulation of this system can modulate osteoclast activity. Here, through multidisciplinary approaches, we demonstrate that enzymes and receptors of the endocannabinoid/endovanilloid system are differently expressed in osteoclasts from menopausal women without or with osteoporosis. We report that in osteoclasts from osteoporotic patients, TRPV1 channels are upregulated and, if persistently stimulated with resiniferatoxin, become clustered to the plasma membrane while inducing a massive over-expression of CB2 receptors. By providing new evidence for a critical functional cross-talk between CB2 and TRPV1 receptors in osteoporosis, we speculate that TRPV1 desensitization, or its enhanced trafficking, together with TRPV1 agonist-induced CB2 receptor overexpression, might be critical to minimize calcium entry in osteoclasts, which could be in turn responsible of cell over-activation and higher bone resorption. Our data pave the way to the use of TRPV1 agonist together with CB2 agonists or CB1 antagonists in osteoporosis.