Histological and transcriptional characterization of the pancreatic acinar tissue in type 1 diabetes

Abstract

IntroductionDespite a reduced function and volume of the exocrine pancreas in type 1 diabetes, the acinar cells remain understudied in type 1 diabetes research. The hypothesis of this study is that the acinar tissue is altered in subjects with type 1 diabetes compared with subjects without diabetes.Research design and methodsThe cell density, expression of digestive enzymes, and transcriptome of acinar tissue at varying distances from islets were analyzed using histology, immunostaining, and AmpliSeq RNA sequencing of laser capture microdissected tissue. Pancreases examined were from organ donors with or without type 1 diabetes.ResultsWe demonstrate preserved acinar nuclei density and find no support of acinar atrophy in type 1 diabetes. Staining for digestive enzymes (amylase, lipase, and trypsin) demonstrated an evenly distributed expression in the exocrine parenchyma; although occasional amylase-negative regions appeared in tissue that had been formalin-fixed and paraffin-embedded, this phenomenon was not evident in frozen tissue. Gene set enrichment analysis of whole transcriptome data identified transcriptional alterations in type 1 diabetes that were present in the acinar tissue independent of the distance from islets. Among these, the two most enriched gene sets were Myc Targets V2 and Estrogen Response Early.ConclusionTaken together, these new data emphasize the involvement of the entire pancreas in type 1 diabetes pathology. The alteration of the gene sets Myc Targets V2 and Estrogen Response Early is a possible link to the increased incidence of pancreatic cancer in type 1 diabetes.

Altered microvasculature in pancreatic islets from subjects with type 1 diabetes

“…al . [ 12 ]. Briefly, the donors with longstanding T1D were age-, sex- and BMI-matched to non-diabetic donors, and all biopsies were evaluated for immune infiltration by staining for CD45 and synaptophysin.…”

“…al . [ 12 ]). Out of 24 donors examined (12 donors with long-standing T1D and 12 matched controls), 15 donors passed the screening and were included in the study.…”

“…Frozen biopsies were sectioned and consecutive sections were alternately used for immunofluorescence (IF), LCM or immunohistochemistry (IHC), as described in Granlund et al . [ 12 ]. The sections intended for IF were stained for insulin, glucagon and somatostatin ( S1 Table ) and the slides were scanned on a confocal microscope (LSM700, Zeiss, Oberkochen, Germany) and used to locate islets that were microdissected on the consecutive PEN membranes.…”

“…LCM was performed as described in Granlund et al . [ 12 ]. In brief, the frozen sections were thawed and dehydrated after which they were mounted on an Arcturus XT LCM system (Thermo Fisher Scientific, Massachusetts).…”

Pancreas Whole Tissue Transcriptomics Highlights the Role of the Exocrine Pancreas in Patients With Recently Diagnosed Type 1 Diabetes

“…The reduction in pancreas weight and volume in T1D could occur even before beta-cell loss and disease diagnosis ( 40 , 41 ), and might be one of the early T1D predisposing changes in the pancreas. Curiously, recent studies have shown preserved acinar cell size ( 42 ) and density ( 43 ) in the pancreases of donors with T1D, implying that the reduced pancreas volume in T1D could be due to a reduced number of acinar cells rather than acinar atrophy. Interestingly, in the current study, higher expression of core acinar cell genes encoding for digestive enzymes was observed in the pancreas tissue samples from the recent onset T1D patients than from the controls.…”