SAT-148 TLR AGONISTS EXACERBATE COMPLEMENT-ASSOCIATED KIDNEY DISEASE AND THE DEVELOPMENT OF AAV THERAPY IN A MOUSE MODEL OF KNOWN HUMAN CFH MUTATION

Abstract

Atypical haemolytic uremic syndrome (aHUS) is commonly associated with complement factor H (CFH) mutation. CFH is a liver-secreted glycoprotein and a negative regulator of the alternative complement pathway. aHUS patients rapidly progress to acute kidney injury (AKI) due to complement-mediated renal insult. CFH mutation is predisposing, and additional infections are required to exacerbate disease. However, the role of infection in triggering disease remains elusive. Recombinant Adeno-Associated Virus (rAAV) have shown immense therapeutic potential and AAV8, in particular, transduce murine hepatocyte potently.The aim of the study is to evaluate whether lipopolysaccharide (LPS) induces acute kidney injury in CFH mutant mice and to assess the therapeutic potential of a liver-mediated AAV therapy. C57BL/6 mice carrying a single nucleotide polymorphism in CFH resembling human aHUS was generated by N-Ethyl-N-Nitrosourea mutagenesis. Homozygous (HOM), heterozygous (HET) and wildtype (WT) mice were treated with LPS via intraperitoneal injection. Renal function, histology and C3 immunofluorescence were assessed post-treatment. Serum and liver CFH levels were also measured. A rAAV8 containing a liver-specific promoter and functional CFH has been administered intravenously into susceptible CFH mutant mice. Hepatic vector transduction was assessed by assessing the vector copy number and a therapeutic outcome was evaluated by renal function, serum CFH levels and C3 deposition in kidney. Homozygous mice showed spontaneous deposition of glomerular C3 and had minimal serum concentrations of CFH compared to WT and heterozygous mice. Following LPS treatment, homozygous mice showed significantly higher levels of proteinuria (3.1±0.2mg/16h) and serum creatinine (28.3±3umol/L) compared to heterozygous (1.3±0.4mg/16h, 20.3±2umol/L, p<0.01 and p<0.05 respectively) and WT mice (1.2±0.2mg/16h, 17.6±1.6umol/L, p<0.01 and p<0.05 respectively). LPS-treated homozygous mice exhibited significantly more glomerulosclerosis, tubular damage and interstitial inflammation than heterozygous and WT mice (p<0.01). Furthermore, rAAV therapy successfully delivered CFH into the liver of CFH-mutant mice demonstrated by higher level of vector copy number (VCN) from liver tissue for gene therapy mice compared with saline treated mice. Mice homozygous for the aHUS-associated CFH mutation develop glomerular C3 deposition and are sensitive to LPS, developing acute kidney injury and renal histological damage. This suggests a significant role for infection in triggering aHUS in susceptible individuals. Gene therapy using rAAV has potential to treat genetic kidney diseases.