Octreotide may improve pharyngocutaneous fistula healing through downregulation of cystatins: a pilot study

Abstract

ObjectivePharyngocutaneous fistula (PCF) and salivary leaks are well known complications of head and neck surgery. The medical management of PCF has included the use of octreotide without a well-defined understanding of its therapeutic mechanism. We hypothesized that octreotide induces alterations in the saliva proteome and that these alterations may provide insight into the mechanism of action underlying improved PCF healing. We undertook an exploratory pilot study in healthy controls that involved collecting saliva before and after a subcutaneous injection of octreotide and performing proteomic analysis to determine the effects of octreotide.Materials and MethodsFour healthy adult participants provided saliva samples before and after subcutaneous injection of octreotide. A mass-spectrometry based workflow optimized for the quantitative proteomic analysis of biofluids was then employed to analyze changes in salivary protein abundance after octreotide administration.ResultsThere were 3,076 human, 332 S. mitis, 102 G. haemolyans and 42 G. adiacens protein groups quantified in saliva samples. A paired statistical analysis was performed using the generalized linear model (glm) function in edgeR. There were and ∼300 proteins that had a p<0.05 between the pre-and post-octreotide groups ∼50 proteins with an FDR-corrected p<0.05 between pre-and post-groups. These results were visualized using a volcano plot after filtering on proteins quantified by 2 more or unique precursors. Both human and bacterial proteins were among the proteins altered by octreotide treatment. Notably, four isoforms of the human cystatins, belonging to a family of cysteine proteases, that had significantly lower abundance after treatment.ConclusionThis pilot study demonstrated octreotide-induced downregulation of cystatins. By downregulation of cystatins in the saliva, there is decreased inhibition of cysteine proteases such as Cathepsin S. This results in increased cysteine protease activity that has been linked to enhanced angiogenic response, cell proliferation and migration that have resulted in improved wound healing. These insights provide first steps at furthering our understanding of octreotide’s effects on saliva and reports of improved PCF healing.

The Management of Salivary Fistulas

“…19 Others have articulated in case reports the use of octreotide (a synthetic analog of somatostatin) in the setting of fistula management. [20][21][22] The mechanism of this has yet to be fully elucidated, though there is emerging evidence that octreotide may induce changes in the salivary proteome that may be more favorable for wound healing.…”