Toll-like receptor 3, 7/8 and 9 function is impaired in hepatitis C patients with rapid fibrosis post liver transplant.

Background: Toll like receptors (TLRs) are critical to innate immune antiviral responses. Hepatitis C (HCV) alters TLR function to evade immune clearance. Whether TLRs play a role in rapid HCV recurrence and fibrosis progression post liver transplant is unknown. Method(s): Peripheral blood mononuclear cells (PBMCs) from 73 HCV post liver transplant patients and 53 non-HCV post transplant controls (matched for sex, race and time post transplant) were stimulated with TLR subclass-specific ligands LPS (TLR4), P3C (TLR2), PIC (TLR3), R848 (TLR7/8) and CpG (TLR9) for 24 hrs. Production of interleukin 6 (IL-6), tumour necrosis factor (TNFalpha) and interferon alpha (IFNalpha) was then measured by analyzing cell culture supernatants using enzyme-linked immunosorbent assay and compared between groups using Mann Whitney test. Rate of fibrosis progression was calculated using post transplant liver biopsies graded by Metavir scoring (F0-4; R = fibrosis stage/ year post transplant). Rapid fibrosis was defined as >0.4 units/yr, dichotomized about the median observed rate (0.4). Result(s): 28 of 73 (38%) HCV post liver transplant patients had rapid fibrosis progression. PBMCs from HCV subjects produced greater amounts of IL-6 at baseline (p = 0.03) and in response to TLR3 stimulation (p = 0.02) compared with controls. In contrast, PBMCs from HCV rapid-fibrosers produced less IL-6 in response to TLR3 (p = 0.007) and TLR9 stimulation (p = 0.02), and less IFNalpha in response to TLR7/8 stimulation compared with HCV slow-fibrosers (p = 0.02). We confirmed these findings in a prospective cohort of 16 patients who had PBMCs collected and liver biopsy 1 yr post transplant. 8 (50%) had fibrosis progression (F1 or greater). Rapid fibrosers produced less IL-6 in response to TLR3 (p = 0.05) and TLR9 stimulation (p = 0.06) and less IFNalpha in response to TLR7/8 stimulation (p = 0.01). Additionally, rapid fibrosers produced less TNFalpha in response to TLR3 stimulation (p = 0.009). Conclusio