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A new paradigm of islet adaptations in human pregnancy: insights from immunohistochemistry and proteomics.

ABSTRACT: Pregnancy induces significant physiological changes to support foetal growth, including critical adaptations in pancreatic islets for glucose homeostasis. This study elucidates these adaptations in human islets using immunohistochemistry, with a focus on α- and β-cell metrics, prolactin receptor (PRLR), and serotonin 2B receptor (5-HT2B) expression during pregnancy. Utilising formalin-fixed paraffin-embedded (FFPE) pancreatic tissue sections from pregnant and non-pregnant donors, we employed laser capture microdissection (LCM) to isolate islets followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) for proteomic analysis. We observed a 1.9-fold increase in islet area, with α-cell and β-cell areas expanding by 4.3-fold and 1.9-fold, respectively, driven by cell number rather than hypertrophy. Notably, PRLR expression was upregulated in α-cells but not β-cells, and 5-HT2B receptors were absent in β-cells. Proteomic profiling revealed minimal changes in protein expression, suggesting nuanced islet adaptations during pregnancy. Key differentially expressed proteins included cathepsin Z, cyclin-dependent kinase 5, and laminin subunit alpha 4. Our findings highlight the distinct molecular mechanisms of human islets compared to rodent models, underscoring the necessity of human-based studies for advancing understanding of islet adaptations in pregnancy.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Pancreatic Islet, Exocrine Pancreas

SUBMITTER: Simon Davis

LAB HEAD: Roman Fischer

PROVIDER: PXD055852 | Pride | 2025-06-30

REPOSITORIES: Pride

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			Action	DRS
	Pancreas-LCM.gg_matrix.tsv	Tabular
	Pancreas-LCM.log.txt	Txt
	Pancreas-LCM.pg_matrix.tsv	Tabular
	Pancreas-LCM.pr_matrix.tsv	Tabular
	Pancreas-LCM.stats.tsv	Tabular

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Project description:ABSTRACT:Pregnancy requires a higher functional beta cell mass and this is associated with profound changes in the gene expression profile of pancreatic islets. Taking Tph1 as a sensitive marker for pregnancy-related islet mRNA expression in female mice, we previously identified prolactin receptors and placental lactogen as key signalling molecules. Since beta cells from male mice also express prolactin receptors, the question arose whether male and female islets have the same phenotypic resilience at the mRNA level during pregnancy. We addressed this question in vitro, by using islet tissue culture with placental lactogen and in vivo, by transplanting male or female islets into female acceptor mice. Additionally, the islet mRNA expression of pregnant prolactin receptor deficient mice was compared with that of their pregnant wild-type littermates. When cultured with placental lactogen, or transplanted in female recipients that became pregnant (day 12.5), male islets induced the ‘islet pregnancy gene signature’, which we defined as the 12 highest induced genes in non-transplanted female islets at day 12.5 of pregnancy. In addition, serotonin immunoreactivity was also induced in these male transplanted islets at day 12.5 of pregnancy. In order to investigate the importance of prolactin receptors in these mRNA changes we used a prolactin receptor deficient mouse model. For the 12 genes of the signature, which are highly induced in control pregnant mice, no significant induction of mRNA transcripts was found at day 9.5 of pregnancy. Together, our results support the key role of placental lactogen as a circulating factor that can trigger the pregnancy mRNA profile in male and female beta cells. The data obtained from the normal islets of pregnant mice (day12.5) was already described in Schraenen et al. 2010 (PMID: 20886204 and PMID: 20938637). Islets and islet grafts were isolated from non-prengant and pregnant mice for RNA extraction and hybridization on Affymetrix microarrays. For every condition, at least 3 biological replicates were used.

Project description:Expression of CD40 in non-hematopoietic cells has been linked to inflammation. We presented evidence that CD40, a T-cell costimulatory molecule, is expressed in human Î²-cells and the engagement of CD40 in insulinoma cells activated the NFKB and ERK1/2 pathways. CD40 activation in human islets cells induced secretion of IL-8, MCP-1 and MIP-1 Î², which is abrogated by inhibitors of NFkB and ERK1/2 inhibitors. In this study, we have studied gene expression mediated by CD40-CD40L interaction in islet cells. This approach identified 90 genes and transcripts exhibiting at least a 1.7 fold increase in their expression intensity after treatment with soluble CD40L. A significant number of genes were related to inflammation and oxidative stress. We have a strong overexpression of CXCL1 (GroÎ±), CXCL2 (Mif2) and CXCL3; chemokines belonging to CXC family structurally related to Il-8. 11 genes were selected from this group and further quantified by Real Time PCR, including CXCL1. Activation of islet cells with CD40L induced the secretion of CXCL1 in a NFKB dependent manner. Engagement of CD40 in islet cells did not induce apoptosis, neither Î²-cell death and did not enhanced TNF-Î± mediated cell death as observed in insulinoma cells. CD40 activation in insulinoma cells, results in ERK1/2 dependent phsophorylation of synapsin I, a protein associated with the exocytosis machinery in neurons and Î²-cells. However, treatment of islets with soluble CD40L did not affect glucose induced insulin secretion. It has been reported that ductal cells always present in human islet preparations express CD40 constitutively (ref). We found that CD40-CD40L interaction in ductal cells, unlike in Î²-cells, induces secretion of diabetogenic cytokines IFNÎ³ and TNF-Î±. Furthermore, incubation of islets containing ductal cells with CD40L decreased Î²-cells viability as assessed by measurement of their mitochondrial membrane potential Experiment Overall Design: We isolated islet cells from three patients. Part of islet cells from each patient has been treated with CD40L. We compared gene expression in treated cells vs untreated for each patient using dye-swap.

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A new paradigm of islet adaptations in human pregnancy: insights from immunohistochemistry and proteomics.

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