Fc Gamma Receptor CD64 Modulates the Inhibitory Activity of Infliximab

Abstract

BackgroundTumor necrosis factor (TNF) is an important cytokine in the pathogenesis of inflammatory bowel disease (IBD). Anti-TNF antibodies have been successfully implemented in IBD therapy, however their efficacies differ among IBD patients. Here we investigate the influence of CD64 Fc receptor on the inhibitory activity of anti-TNFs in cells of intestinal wall.MethodsIntestinal cell lines, monocytes/macrophages and peripheral blood mononuclear cells (PBMCs) were used as models. The efficacies of adalimumab, infliximab and certolizumab-pegol were assessed by RT-PCR for target genes. Protein levels and localizations were examined by Western blotting and immunofluorescence. Antibody fragments were obtained by proteolytic digestion, immunoprecipitation and protein chip analysis. Knock-down of specific gene expression was performed using siRNAs.ResultsInfliximab had limited efficacy towards soluble TNF in cell types expressing Fc gamma receptor CD64. Both adalimumab and infliximab had lower efficacies in PBMCs of IBD patients, which express elevated levels of CD64. Infliximab-TNF complexes were more potent in activating CD64 in THP-1 cells than adalimumab, which was accompanied by distinct phospho-tyrosine signals. Blocking Fc parts and isolation of Fab fragments of infliximab improved its efficacy. IFN-γ-induced expression of CD64 correlated with a loss of efficacy of infliximab, whereas reduction of CD64 expression by either siRNA or PMA treatment improved inhibitory activity of this drug. Colonic mRNA expression levels of CD64 and other Fc gamma receptors were significantly increased in the inflamed tissues of infliximab non-responders.ConclusionsCD64 modulates the efficacy of infliximab both in vitro and ex vivo, whereas the presence of this receptor has no impact on the inhibitory activity of certolizumab-pegol, which lacks Fc fragment. These data could be helpful in both predicting and evaluating the outcome of anti-TNF therapy in IBD patients with elevated systemic and local levels of Fc receptors.

Neutrophil CD64 Expression in Crohn’s Disease following Anti-TNF-α Therapy

“…CD64 positive neutrophils have been shown to infiltrate the colonic lamina propria in active CD [17], and FcγRIA mRNA expression has been shown to be significantly elevated in ileal and rectal tissue subjects with the disease. In IBD patients, who were refractory to anti-TNFα therapy, CD64 mRNA expression remained up-regulated even in post-treatment colonic biopsy specimens [24]. A correlation between the CD64 expression of the peripheral neutrophils and FcγRIA expression in the ileal mucosa has been demonstrated, thereby suggesting that CD64 expression can a marker for mucosal treatment response [13].…”

Update on the mechanisms of action of anti‑TNF-α antibodies and their clinical implications in inflammatory bowel disease

“…It is not clear, however, whether this is a cause or a consequence of unresponsiveness to IFX. 47 Nevertheless, it is reasonable to hypothesize that the upregulation of some types of Fc receptors is linked to decreased efficacy of anti-TNF-α therapy in a proportion of IBD patients.…”

Recombinant H22(scFv) blocks CD64 and prevents the capture of anti-TNF monoclonal antibody

“…8 To elucidate whether H22(scFv), which lacks an Fc part, would also lead to increased receptor activation, IFN-g-stimulated HL-60 cells were incubated with H22(scFv) alone, adalimumab alone, or pre-incubated with H22(scFv) followed by addition of adalimumab. While adalimumab strongly induced phosphorylation of the receptor, no significant CD64 activation could be detected for H22(scFv).…”

“…7 However, some patients do not respond to anti-TNF therapy, and recently this was shown to correlate with the increased expression of CD64 on monocytes and macrophages in non-responding IBD patients. 8 The lower response was dependent on interactions between the Fcg domain of the full-length anti-TNF mAbs and CD64. For example, when the two anti-TNF mAbs infliximab (Remicade Ò ) and adalimumab (Humira Ò ) are captured by CD64 via the Fcg domain, this induces a pro-inflammatory downstream signaling cascade, which counteracts the positive effects from neutralizing TNF.…”

“…Preblocking the Fcg receptors with purified IgG1 Fcg domains improved the efficacy of these mAbs under laboratory conditions. 8 However, this approach is unsuitable in the clinic because the low-affinity Fcg receptors CD32 and CD16 will also be blocked, thus inducing immunosuppression by inhibiting antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). 9,10 This is of particular concern because anti-TNF therapy can already induce moderate immunosuppression, so further compromising the immune system would be highly undesirable.…”