The involvement of complement (C) in inflammatory diseases has driven the search for agents capable of inhibiting dysregulated complement activation. Many of these reagents inhibit the C3 convertases during the early stages of the cascade. However, a drawback of total systemic C inhibition, particularly in longterm treatment of chronic disease, is potentiation of infection and immune complex disease due to an inability to opsonize complexes and foreign cells and to lyse pathogens. Recent identification of a C5-binding protein in the salivary gland of the soft tick Ornithodoros moubata has enabled development of a terminal pathway-specific reagent, OmCI, with potential to ameliorate disease while leaving key physiological processes unaffected. Here we demonstrated that OmCI has broad cross-species activity. When given intravenously to rodents, OmCI totally ablated complement hemolytic activity, which gradually restored as C5 was resynthesized. The circulating half-life of OmCI was 30 h, demonstrating a much slower clearance than other small, biological agents. Using C5-sufficient and C5-deficient mice we showed that prolonged half-life was due to binding to plasma C5. Surface plasmon resonance analysis of C5 binding to OmCI confirmed a high binding affinity with a slow dissociation rate. OmCI was effective in preventing experimental autoimmune myasthenia gravis induced by passive transfer in normal Lewis rats. OmCI ablated clinical disease, reduced C3 and C9 deposition at the neuro-muscular junction, and effected a marked reduction in cellular infiltration at this site. These data offer exciting prospects for targeted treatment of complement-mediated diseases without the detrimental inhibition of the opsonic roles of complement.

Fungal peritonitis is an important complication in peritoneal dialysis patients; either continuous or recurrent peritonitis may enhance peritoneal damage. Even when the peritoneal dialysis catheter is removed in patients with fungal peritonitis, peritoneal fibrosis can progress and evolve into encapsular peritoneal sclerosis. It is unclear why fungal infections are worse than bacterial in these respects. Zymosan is a cell wall component of yeast that strongly activates the complement system. In this study, we compared the effects of zymosan and bacterial LPS on peritoneal inflammation in a rat peritoneal injury model induced by mechanical scraping. Intraperitoneal administration of zymosan, but not LPS or vehicle, caused markedly enhanced peritonitis with massive infiltration of cells and deposition of complement activation products C3b and membrane attack complex on day 5. In rats administered zymosan and sacrificed on days 18 or 36, peritoneal inflammation persisted with accumulation of ED-1-positive cells, small deposits of C3b and membrane attack complex, exudation of fibrinogen, and capillary proliferation in subperitoneal tissues. When zymosan was administered daily for 5 days after peritoneal scrape, there was even greater peritoneal inflammation with peritoneal thickening, inflammatory cell accumulation, and complement deposition. Inhibition of systemic complement by pretreatment with cobra venom factor or local inhibition by i.p. administration of the recombinant complement regulator Crry-Ig reduced peritoneal inflammation in zymosan-treated rats. Our results show that yeast components augment inflammation in the injured peritoneum by causing complement activation within the peritoneal cavity. Local anticomplement therapy may therefore protect from peritoneal damage during fungal infection of the peritoneum.

Despite its vital role in innate immunity, complement is involved in a number of inflammatory pathologies and has therefore become a therapeutic target. Most agents generated for anti-complement therapy have short half-lives in plasma, or have been of mouse or human origin, thereby limiting their use either to murine models of disease or to short-term therapy. Here we describe the generation of a long-acting rat therapeutic agent based on the rat complement inhibitor, Crry. Characterisation of various soluble forms of Crry demonstrated that the amino-terminal four short-consensus repeat domains were required for full regulatory and C3b-binding activities. Fusion of these domains to rat IgG2a Fc generated an effective complement inhibitor (rCrry-Ig) with a circulating half-life prolonged from 7 min for Crry alone to 53 h for rCrry-Ig. Systemic administration of rCrry-Ig over 5 weeks generated a weak immune response to the recombinant agent, however this was predominantly IgM in nature and did not neutralise Crry function or cause clearance of the agent from plasma. Administration of rCrry-Ig completely abrogated clinical disease in a rat model of myasthenia gravis whereas soluble Crry lacking the immunoglobulin Fc domain caused a partial response. rCrry-Ig not only ablated clinical disease, but also prevented C3 and C9 deposition at the neuromuscular junction and inhibited cellular infiltration at this site. The long half-life and low immunogenicity of this agent will be useful for therapy in chronic models of inflammatory disease in the rat.

This study was initiated to explore the effect of recombinant rat Crry linked to the Fc portion of rat IgG2a (Crry-Ig) on the induction of experimental autoimmune anterior uveitis (EAAU) and on established disease. EAAU was induced in Lewis rats by immunization with bovine melanin associated antigen (MAA). MAA sensitized animals received Crry-Ig, rat IgG2a (isotype control) or PBS separately before the onset of EAAU or after the onset of clinical disease. Administration of Crry-Ig suppressed the induction of EAAU while all animals injected with IgG2a or PBS developed the normal course of EAAU. Treatment with Crry-Ig resulted in suppression of ocular complement activation as well as the functional activity of complement in the peripheral blood. At the peak of EAAU, levels of IFN-γ, IP-10, ICAM-1 and LECAM-1 were significantly reduced within the eyes of Crry-Ig treated Lewis rats. Importantly, administration of Crry-Ig even after the onset of EAAU resulted in a sharp decline in the disease activity and early resolution of EAAU. Collectively, the evidence presented here demonstrate that inhibition of complement by Crry-Ig results in low levels of inflammatory molecules - C3 activation products, MAC, cytokines, chemokines and adhesion molecules in the eye. Down-regulation of these molecules affects the infiltration and recruitment of inflammatory cells to the eye resulting in inhibition of EAAU.

The objective of this study was to examine the effect of daily probiotic supplementation upon the immune profile of healthy participants by the assessment of ex vivo cytokine production. Twenty healthy adult volunteers received a multi-strain probiotic supplement consisting of two strains of Lactobacillus acidophilus (CUL60 and CUL21), Bifidobacterium lactis (CUL34) and Bifidobacterium bifidum (CUL20) and fructooligosaccharide for 12 weeks. Blood samples were collected at baseline, 6 and 12 weeks. Peripheral blood mononuclear cells (PBMCs) were isolated and cultured ex vivo in the presence or absence of lipopolysaccharide and cytokine production was assessed. Postintervention, a significant decrease in the production of interleukin-6 and interleukin-1β was apparent when PBMCs were incubated in the presence of lipopolysaccharide, whilst a significant increase in IL-10 and transforning growth factor-β production was seen when the cells were incubated without an additional stimulus. This preliminary study demonstrates the potential of a multi-strain probiotic supplement to alter the immune response as demonstrated by changes in ex vivo cytokine production. Such results demonstrate the potential benefit of probiotic supplementation for healthy individuals and warrants further investigation.