A monoclonal antibody against kininogen reduces inflammation in the HLA-B27 transgenic rat

The human leukocyte antigen B27 (HLA-B27) transgenic rat is a model of human inflammatory bowel disease, rheumatoid arthritis and psoriasis. Studies of chronic inflammation in other rat models have demonstrated activation of the kallikrein–kinin system as well as modulation by a plasma kallikrein inhibitor initiated before the onset of clinicopathologic changes or a deficiency in high-molecular-mass kininogen. Here we study the effects of monoclonal antibody C11C1, an antibody against high-molecular-mass kininogen that inhibits the binding of high-molecular-mass kininogen to leukocytes and endothelial cells in the HLA-B27 rat, which was administered after the onset of the inflammatory changes. Thrice-weekly intraperitoneal injections of monoclonal antibody C11C1 or isotype IgG(1 )were given to male 23-week-old rats for 16 days. Stool character as a measure of intestinal inflammation, and the rear limbs for clinical signs of arthritis (tarsal joint swelling and erythema) were scored daily. The animals were killed and the histology sections were assigned a numerical score for colonic inflammation, synovitis, and cartilage damage. Administration of monoclonal C11C1 rapidly decreased the clinical scores of pre-existing inflammatory bowel disease (P < 0.005) and arthritis (P < 0.001). Histological analyses confirmed significant reductions in colonic lesions (P = 0.004) and synovitis (P = 0.009). Decreased concentrations of plasma prekallikrein and high-molecular-mass kininogen were found, providing evidence of activation of the kallikrein–kinin system. The levels of these biomarkers were reversed by monoclonal antibody C11C1, which may have therapeutic potential in human inflammatory bowel disease and arthritis

Erosive arthritis and hepatic granuloma formation induced by peptidoglycan polysaccharide in rats is aggravated by prasugrel treatment.

Administration of the thienopyridine P2Y12 receptor antagonist, clopidogrel, increased the erosive arthritis induced by peptidoglycan polysaccharide (PG-PS) in rats or by injection of the arthritogenic K/BxN serum in mice. To determine if the detrimental effects are caused exclusively by clopidogrel, we evaluated prasugrel, a third-generation thienopyridine pro-drug, that contrary to clopidogrel is mostly metabolized into its active metabolite in the intestine. Prasugrel effects were examined on the PG-PS-induced arthritis rat model. Erosive arthritis was induced in Lewis rats followed by treatment with prasugrel for 21 days. Prasugrel treated arthritic animals showed a significant increase in the inflammatory response, compared with untreated arthritic rats, in terms of augmented macroscopic joint diameter associated with significant signs of inflammation, histomorphometric measurements of the hind joints and elevated platelet number. Moreover, fibrosis at the pannus, assessed by immunofluorescence of connective tissue growth factor, was increased in arthritic rats treated with prasugrel. In addition to the arthritic manifestations, hepatomegaly, liver granulomas and giant cell formation were observed after PG-PS induction and even more after prasugrel exposure. Cytokine plasma levels of IL-1 beta, IL-6, MIP1 alpha, MCP1, IL-17 and RANTES were increased in arthritis-induced animals. IL-10 plasma levels were significantly decreased in animals treated with prasugrel. Overall, prasugrel enhances inflammation in joints and liver of this animal model. Since prasugrel metabolites inhibit neutrophil function ex-vivo and the effects of both clopidogrel and prasugrel metabolites on platelets are identical, we conclude that the thienopyridines metabolites might exert non-platelet effects on other immune cells to aggravate inflammation