Increased toxicity of amylin (Islet Amyloid Polypeptide) in beta cells induced by photochemical internalization

• Published in: Photodiagnosis and photodynamic therapy 2018-09, Vol.23, p.218-220
• Main Authors: Rinku, Singh, Hals, Ingrid, Høgset, Anders, Grill, Valdemar, Gederaas, Odrun A.
• Format: Article
• Language: English
• Subjects: Amylin; Animals; Cell Survival; Diabetes Mellitus, Type 2; Dose-Response Relationship, Drug; Insulin - biosynthesis; Insulin-Secreting Cells - drug effects; Islet amyloid polypeptide (IAPP); Islet Amyloid Polypeptide - pharmacology; meso-tetraphenylchlorin disulfonate (TPCS2a); Photochemical internalization (PCI); Photochemotherapy - methods; Photosensitizing Agents - pharmacology; Porphyrins - pharmacology; Rats; Type 2 diabetes
• ISSN: 1572-1000; 1873-1597
• DOI: 10.1016/j.pdpdt.2018.06.017

•PCI technology can be a tool to induce endosomal rupture in clonal beta cells.•Exposure to human amylin and PCI together exerted toxic effects in beta cells.•Exposure to rat amylin and PCI together had no effect on beta cells.•Results are compatible with intracellular toxic effects of human amylin. Amylin and oligomers formed from amylin are implicated in demise of beta cells in type 2 diabetes. However, whether putative toxicity is exerted intra or extracellularly is unclear. Use of photochemical internalization (PCI) technique may give clues for impact of intracellular toxicity. (a) To optimize the concentration and exposure set up of the photosensitizing compound meso-disulfonated tetraphenyl chlorin TPCS2a (Amphinex®) for use in insulin producing beta cells and (b) to utilize the photosensitizing technique to probe for intracellular effects in beta cells by amylin. The titration of TPCS2a and blue light exposure was evaluated by MTT assay. The insulin producing INS-1 832/13 beta cells were incubated with the photosensitizing agent TPCS2a prior to exposure of amylin. Viability and function were further evaluated by standard biochemical techniques. A protocol was developed for use in INS-1 832/13 cells in which the optimal concentration of TPCS2a was found to be 4ng/ml. Using this protocol human amylin (10 μM, 8 h) in combination with TPCS2a (4 ng/ml, 18 h) and blue light exposure (60 s) exerted toxic effects above those by TPCS2a and illumination alone as measured by MTT (15 ± 3.6%, n = 6, p