Up-regulated serum levels of TAM receptor tyrosine kinases in a group of Egyptian autistic children

TAM receptor family belongs to receptor tyrosine kinases (TAMRTKs). It includes three receptors; Tyro-3, Axl and Mer. TAMRTKs has a great role in resolution of inflammation due to their role in clearance of apoptotic cells by macrophages. Dysregulated TAM signaling pathways are associated with many autoimmune diseases and chronic inflammatory disorders. Autism may be an autoimmune disease in some patients. This work was the first study that investigated serum levels of the soluble ectodomain shed TAMRTKs in a group of autistic children. Serum levels of TAMRTKs were measured by ELISA in 30 autistic children aged between 3.5 and 11 years and 30 age and sex-matched healthy control children. Serum levels of TAMRTKs were significantly higher in autistic children than healthy control children (P < 0.001). Patients with severe autism had significantly higher serum levels of TAMRTKs than patients with mild to moderate autism (P < 0.01). In addition, there were significant positive correlations between scores of the Childhood Autism Rating Scale (CARS) and serum levels of TAMRTKs in autistic patients, (P < 0.01). In conclusions, serum levels of TAMRTKs were up-regulated in autistic children with significant positive correlations with the degree of the disease severity. This initial report requires further studies to investigate the relationship between TAMRTKs and autism.

Antibody-mediated neutralization of autocrine Gas6 inhibits the growth of pancreatic ductal adenocarcinoma tumors in vivo

Gas6 and its receptors Axl, Mer and Tyro-3 (TAM) are highly expressed in human malignancy suggesting that signaling through this axis may be tumor-promoting. In pancreatic ductal adenocarcinoma (PDAC), Gas6 and the TAM receptor Axl are frequently co-expressed and their co-expression correlates with poor survival. A strategy was devised to generate fully human neutralizing antibodies against Gas6 using XenoMouse® technology. Hybridoma supernatants were selected based on their ability to inhibit Gas6 binding to the receptor Axl and block Gas6-induced Axl phosphorylation in human cells. Two purified antibodies isolated from the screened hybridomas, GMAB1 and GMAB2, displayed optimal cellular potency which was comparable to that of the soluble extracellular domain of the receptor Axl (Axl-Fc). In vivo characterization of GMAB1 was conducted using a pharmacodynamic assay that measured inhibition of Gas6-induced Akt activation in the mouse spleen. Treatment of mice with a single dose (100-1000 µg) of GMAB1 led to greater than 90% inhibition of Gas6-induced phosphorylated Akt (pAkt) for up to 72 hr. Based on the target coverage observed in the PD assay, the efficacy of GMAB1 was tested against human pancreatic adenocarcinoma xenografts. At doses of 50 µg and 150 µg, twice weekly, GMAB1 was able to inhibit 55% and 76% of tumor growth, respectively (p < 0.001 for both treatments vs. control Ig). When combined with gemcitabine, GMAB1 significantly inhibited tumor growth compared to either agent alone (p < 0.001). Together, the data suggest that Gas6 neutralization may be important as a potential strategy for the treatment of PDAC.