Changes in Toll-like Receptor (TLR)-2 and TLR4 Expression and Function but Not Polymorphisms Are Associated with Acute Anterior Uveitis

To investigate the expression and polymorphisms of Toll-like receptor (TLR)-2 and -4 in the peripheral neutrophils and monocytes of patients with acute anterior uveitis (AAU). Nine patients with active AAU and nine age- and sex-matched healthy control subjects were studied. TLR2 and -4 protein expression on CD16(+) neutrophils and CD14(+) monocytes were studied by flow cytometry. TLR function was investigated by whole-blood stimulation with lipopolysaccharide and peptidoglycan for TLR4 and -2 activation, respectively. Proinflammatory cytokine production in response to TLR stimulation was determined by multiplex cytokine bead arrays of the culture supernatant. TLR2 and -4 genotypes were determined by RFLP-PCR. A significant reduction in the levels of TLR2 expression was observed on the neutrophils and monocytes of patients with active AAU compared with that of healthy control subjects (P < 0.05). IL-6 and IFN-gamma production stimulated by TLR4 activation was significantly reduced in patients with AAU, compared with that in healthy control subjects (P < 0.05). In contrast, significantly increased production of IL-1beta in response to TLR2 stimulation was observed in patients with AAU (P < 0.05). There was no correlation between the TLR2 or -4 genotypes and the observed differential functional responses to TLR stimulation. There is a selective perturbation in the expression and function of TLR2 and -4, which could be consistent with a state of endotoxin tolerance, in patients with active AAU. The results support a role for microbial triggers and TLRs in the pathogenesis of AAU.