Severe chemotherapy-induced gastrointestinal toxicity (CIGT) following 5-fluorouracil (5-FU) therapy is highly prevalent and negatively affects therapy. The underpinning mechanism of this response is an increase in pro-inflammatory cytokine expression via the Toll-Interleukin-1 Receptor (TIR) pathway. Our immune genetic studies have shown genetic variability in IL1B, TNFA and TLR2 can predict the risk of severe CIGT. However, there are no matching diagnostic phenotypic markers to predict CIGT risk in patients. This study aimed to determine if the pro-inflammatory secretory response (IL-1β and TNF-α) from isolated peripheral mononuclear blood cells (PBMCs) can act as a diagnostic phenotypic marker to predict the incidence of CIGT in participants following 5-FU-based therapy; and if IL1B, TNFA, TLR4 and TLR2 genotypes are associated with IL-1β and TNF-α secretory responses.
Eighteen participants (eight with severe CIGT) with prior involvement in our immune genetic studies were recruited, with their CIGT data, demographics and treatment parameters and genetic variability in IL1B, TNFA, TLR4 and TLR2 known. Ex vivo quantification of TLR2 and TLR4 agonist-induced stimulation of IL-1β and TNF-α secretion from PBMCs was determined by enzyme-linked immunosorbent assay (ELISA). Delta and fold changes in secretion were determined, with these parameters compared between the two participant groups, severe CIGT and no/mild CIGT, using t-tests. In addition, the association between IL1B, TNFA, TLR4 and TLR2 genotypes and IL-1β and TNF-α secretion was also examined using t-tests.
There were no differences in IL-1β and TNF-α secretion between the participants with no/mild versus severe CIGT. There was a decreased expression of TLR4 stimulated IL-1β secretion in participants with the IL1B rs1143627 (-31 T>C) and 16944 (-511 C>T) genotypes (P = 0.045).
This study is ongoing. Further participants are being recruited to expand the study cohort to 46, allowing a two-fold change between IL-1β and TNF-α to be adequately detected.