Recombinant Reg3α Prevents Islet β-Cell Apoptosis and Promotes β-Cell Regeneration

Genetics of constant and severe pain in the NAPS2 cohort of recurrent acute and chronic pancreatitis patients

Recurrent acute and chronic pancreatitis (RAP, CP) are complex, progressive inflammatory diseases with variable pain experiences impacting patient function and quality of life. The genetic variants and pain pathways in patients contributing to most severe pain experiences are unknown. We used previously genotyped individuals with RAP/CP from the North American Pancreatitis Study II (NAPS2) of European Ancestry for nested genome-wide associated study (GWAS) for pain-severity, chronicity, or both. Lead variants from GWAS were determined using FUMA. Loci with p<1e-5 were identified for post-hoc candidate identification. Transcriptome-wide association studies (TWAS) identified loci in cis and trans to the lead variants. Serum from phenotyped individuals with CP from the PROspective Evaluation of Chronic Pancreatitis for EpidEmiologic and Translational StuDies (PROCEED) was assessed for BDNF levels using Meso Scale Discovery Immunoassay. We identified four pain systems defined by candidate genes: 1) Pancreas-associated injury/stress mitigation genes include: REG gene cluster, CTRC, NEURL3 and HSF22. 2) Neural development and axon guidance tracing genes include: SNPO, RGMA, MAML1 and DOK6 (part of the RET complex). 3) Genes linked to psychiatric stress disorders include TMEM65, RBFOX1, and ZNF385D. 4) Genes in the dorsal horn pain-modulating BDNF/neuropathic pathway included SYNPR, NTF3 and RBFOX1. In an independent cohort BDNF was significantly elevated in patients with constant-severe pain. Extension and expansion of this exploratory study may identify pathway- and mechanism-dependent targets for individualized pain treatments in CP patients. PERSPECTIVE: Pain is the most distressing and debilitating feature of chronic pancreatitis. Yet many patients with chronic pancreatitis have little or no pain. The North American Pancreatitis Study II (NAPS2) includes over 1250 pancreatitis patients of all progressive stages with all clinical and phenotypic characteristics carefully recorded. Pain did not correlate well with disease stage, inflammation, fibrosis or other features. Here we spit the patients into groups with the most severe pain and/or chronic pain syndromes and compared them genetically with patients reporting mild or minimal pain. Although some genetic variants associated with pain were expressed in cells (1) of the pancreas, most genetic variants were linked to genes expressed in the nervous system cells associated with (2) neural development and axon guidance (as needed for the descending inhibition pathway), (3) psychiatric stress disorders, and (4) cells regulating sensory nerves associated with BDNF and neuropathic pain. Similar and overlapping genetic variants in systems 2 -4 are also seen in pain syndromes form other organs. The implications for treating pancreatic pain are great in that we can no longer focus on just the pancreas. Furthermore, new treatments designed for pain disorders in other tissues may be effective in some patient with pain syndromes from the pancreas. Further research is needed to replicate and extend these observations so that new, genetics-guided rational treatments can be developed and delivered.

Dysfunctional β-cell autophagy induces β-cell stress and enhances islet immunogenicity

Background

Type 1 Diabetes (T1D) is caused by a combination of genetic and environmental factors that trigger autoimmune-mediated destruction of pancreatic β-cells. Defects in β-cell stress response pathways such as autophagy may play an important role in activating and/or exacerbating the immune response in disease development. Previously, we discovered that β-cell autophagy is impaired prior to the onset of T1D, implicating this pathway in T1D pathogenesis.

Aims

To assess the role of autophagy in β-cell health and survival, and whether defects in autophagy render islets more immunogenic.

Methods

We knocked out the critical autophagy enzyme, ATG7, in the β-cells of mice (ATG7Δβ-cell) then monitored blood glucose, performed glucose tolerance tests, and evaluated bulk islet mRNA and protein. We also assessed MHC-I expression and presence of CD45+ immune cells in ATG7Δβ-cell islets and evaluated how impaired autophagy affects EndoC-βH1 HLA-I expression under basal and IFNα stimulated conditions. Lastly, we co-cultured ATG7Δβ-cell islet cells with diabetogenic BDC2.5 helper T cells and evaluated T cell activation.

Results

We found that all ATG7Δβ-cell mice developed diabetes between 11-15 weeks of age. Gene ontology analysis revealed a significant upregulation of pathways involved in inflammatory processes, response to ER stress, and the ER-associated degradation pathway. Interestingly, we also observed upregulation of proteins involved in MHC-I presentation, suggesting that defective β-cell autophagy may alter the immunopeptidome, or antigen repertoire, and enhance β-cell immune visibility. In support of this hypothesis, we observed increased MHC-I expression and CD45+ immune cells in ATG7Δβ-cell islets. We also demonstrate that HLA-I is upregulated in EndoC β-cells when autophagic degradation is inhibited. This effect was observed under both basal and IFNα stimulated conditions. Conversely, a stimulator of lysosome acidification/function, C381, decreased HLA-I expression. Lastly, we showed that in the presence of islet cells with defective autophagy, there is enhanced BDC2.5 T cell activation.

Conclusions

Our findings demonstrate that β-cell autophagy is critical to cell survival/function. Defective β-cell autophagy induces ER stress, alters pathways of antigen production, and enhances MHC-I/HLA-I presentation to surveilling immune cells. Overall, our results suggest that defects in autophagy make β-cells more susceptible to immune attack and destruction.

Controversial Roles of Regenerating Family Proteins in Tissue Repair and Tumor Development

Background: Over the past 40 years since the discovery of regenerating family proteins (Reg proteins), numerous studies have highlighted their biological functions in promoting cell proliferation and resisting cell apoptosis, particularly in the regeneration and repair of pancreatic islets and exocrine glands. Successively, short peptides derived from Reg3δ and Reg3α have been employed in clinical trials, showing favorable therapeutic effects in patients with type I and type II diabetes. However, continued reports have been limited, presumably attributed to the potential side effects. Methods: This review summarizes extensive research on Reg proteins over the past decade, combined with our own related studies, proposing that Reg proteins exhibit dimorphic effects. Results: The activity of Reg proteins is not as simplistic as previously perceived but shows auto-immunogenicity depending on different pathophysiological microenvironments. The immunogenicity of Reg proteins could recruit immune cells leading to an anti-tumor effect. Such functional diversity is correlated with their structural characteristics: the N-terminal region contributes to autoantigenicity, while the C-type lectin fragment near the C-terminal determines the trophic action. It should be noted that B-cell masking antigens might also reside within the C-type lectin domain. Conclusions: Reg proteins have dual functional roles under various physiological and pathological conditions. These theoretical foundations facilitate the subsequent development of diagnostic reagents and therapeutic drugs targeting Reg proteins.

Inhalation of H2/O2 (66.7 %/33.3 %) mitigates depression-like behaviors in diabetes mellitus complicated with depression mice via suppressing inflammation and preventing hippocampal damage

Diabetes mellitus complicated with depression (DD) is a prevalent psychosomatic disorder. It is characterized by severe cognitive impairment, and associated with high rates of disability and mortality. Although conventional treatment options are available, the efficacy of these regimens in managing DD remains limited. Molecular hydrogen (H2), a selective hydroxyl radical scavenger, has shown therapeutic potential in the treatment of various systemic diseases. This study aims to investigate the therapeutic effects of H2 on DD. A DD mouse model was established through intraperitoneal injection of streptozotocin (STZ, 150 mg/kg) and lipopolysaccharide (LPS, 0.5 mg/kg). Following the induction of DD, the mice were treated with H2/O2 (66.7 %/33.3 %)inhalation for 7 days. Behavioral assessments were conducted by standard behavioral tests, and the levels of inflammatory cytokines in peripheral blood serum and hippocampal tissue were measured using enzyme-linked immunosorbent assay (ELISA). Furthermore, magnetic resonance imaging (MRI) scans and immunofluorescence staining of the hippocampus were performed to evaluate hippocampal structural integrity. The results demonstrated that inhalation of H2/O2 (66.7 %/33.3 %) significantly ameliorated depressive behaviors and symptoms in DD mice, reversed hippocampal volume reduction, decreased inflammatory cytokine levels in peripheral blood serum and hippocampal tissue, and inhibited the activation of A1 astrocytes in the hippocampus. Our study suggests that H2/O2 (66.7 %/33.3 %) inhalation therapy may offer a promising treatment strategy for DD and its associated symptoms.

Reduced expression of central innate defense molecules in pancreatic biopsies from subjects with Type 1 diabetes

AIMS/HYPOTHESIS

Defensins play a crucial role in the innate immune system's first defense against microbial threats. However, little is known about the defensin system in the pancreas, especially in relation to Type 1 diabetes. We explore the expression of defensins in different disease stages of Type 1 diabetes and correlated obtained findings to the degree of inflammation, providing new insights into the disease and the innate immune system.

MATERIAL AND METHODS

Pancreases from non-diabetic human organ donors of different age groups and donors with Type 1 diabetes with different disease duration were examined. Sections from head, body and tail of the pancreas were stained for eight different defensins and for immune cells; CD3+, CD45+, CD68+ and NES+ (granulocytes).

RESULTS

In non-diabetic adult controls the level of expression for defensins Beta-1,Alpha-1, Cathelicidin and REG3A correlated with the level of inflammation. In contrast, individuals with Type  1 diabetes exhibit a reduction or absence of several central defensins regardless of the level of inflammation in their pancreas. The expression of Cathelicidin is present in neutrophils and macrophages but not in T-cells in subjects with Type 1 diabetes.

CONCLUSIONS

Obtained findings suggest a pancreatic dysfunction in the innate immune system and the bridging to the adaptive system in Type 1 diabetes. Further studies on the role of the local innate immune system in Type 1 diabetes is needed.

Reg2 treatment is protective but the induced Reg2 autoantibody is destructive to the islets in NOD mice

Regenerating family protein 2 (Reg2) is a trophic factor which stimulates β-cell replication and resists islet destruction. However, Reg2 also serves as an islet autoantigen, which makes it complicated to judge the effectiveness in treating diabetes. How Reg2 treatment behaves in non-obese diabetic (NOD) mice is to be investigated. NOD mice were treated with recombinant Reg2 protein, Complete Freund's adjuvant (CFA) + PBS and CFA+Reg2 vaccinations, CFA+PBS- and CFA+Reg2-immunized antisera, and single chain variable fragment (scFv)-Reg2 and mIgG2a-Reg2 antibodies. Glycemic level, bodyweight, serum Reg2 antibody titer, glucose tolerance, and insulin secretion were determined. Islet morphological characteristics, insulitis, cell apoptosis, islet cell components, and T cell infiltration were analyzed by histological examinations. The autoantigenicity of constructed Reg2C and Reg2X fragments was determined in healthy BALB/c mice, and the bioactivity in stimulating cell proliferation and survival was assessed in insulinoma MIN6 cells. Reg2 administration alleviated diabetes in NOD mice with improved glucose tolerance and insulin secretion but elevated serum Reg2 autoantibodies. Histomorphometry showed reduced inflammatory area, TUNEL signal and CD8 + T cell infiltration, and increased β-cell proportion in support of the islet-protective effect of Reg2 treatment. CFA+PBS and CFA+Reg2 immunizations prevented diabetic onset and alleviated insulitis while injections of the antisera offered mild protections. Antibody treatments accelerated diabetic onset without increasing the overall incidence. Reg2C fragment depletes antigenicity, but reserves protective activity in streptozotocin (STZ)-treated MIN6 cells. In conclusion, Reg2 treatment alleviates type 1 diabetes (T1D) by preserving islet β-cells, but induces Reg2 autoantibody production which poses a potential risk of accelerating diabetic progression.

Identification of eight genomic protective alleles for mitochondrial diabetes by Kinship-graph convolutional network

AIMS

Nearly 85% of maternally inherited diabetes and deafness (MIDD) are caused by the m.3243A>G mutation in the mitochondrial DNA. However, the clinical phenotypes of MIDD may also be influenced by the nuclear genome, this study aimed to investigate nuclear genome variants that influence clinical phenotypes associated with m.3243A>G mutation in MIDD based on whole-genome sequencing of the patients belonging to pedigrees.

MATERIALS AND METHODS

We analyzed a whole-genome sequencing (WGS) dataset from blood samples of 38 MIDD patients with the m.3243A > G mutation belonging to 10 pedigrees, by developing a Kinship-graph convolutional network approach, called Ki-GCN, integrated with the conventional genome-wide association study (GWAS) methods.

RESULTS

We identified eight protective alleles in the nuclear genome that have protective effects against the onset of MIDD, related deafness, and also type 2 diabetes. Based on these eight protective alleles, we constructed an effective logistic regression model to predict the early or late onset of MIDD patients.

CONCLUSIONS

There are protective alleles in the nuclear genome that are associated with the onset-age of MIDD patients and might also provide protective effects on the deafness derived from MIDD patients.

Tumor-suppressive effect of Reg3A in COAD is mediated by T cell activation in nude mice

Regenerating family protein 3 A (Reg3A) is highly expressed in a variety of organs and inflammatory tissues, and is closely related to tumorigenesis and cancer progression. However, clinical statistics show that high expression of Reg3A is associated with better prognosis in colorectal cancer (CRC) patients, suggesting a tumor-suppressive effect. The precise action and underlying mechanism of Reg3A in CRC remain controversial. The present study sought to investigate the relationship among Reg3A expression, CRC development, and immune cell alteration in patients using the TCGA, GEPIA, PrognoScan, TIMER and TISIDB databases. Reg3A-overexpressing LoVo cell line (LoVo-Reg3A), a representative of colon adenocarcinoma (COAD), was constructed and the action of Reg3A was assessed in a xenograft nude mouse model. Our bioinformatical analyses revealed that Reg3A upregulation is highly associated with CRC, along with increased frequency of immune cell infiltration. In the xenograft nude mice, Reg3A overexpression offered a tumor-suppressive effect by inhibiting cell proliferation and promoting apoptosis. The result of RNA-seq suggested a positive regulation of leukocytes and an upregulation of T cells in LoVo-Reg3A tumor tissue. CD4+ and CD8+ T cells in tumors, splenic Reg3A-reactive IFN-γ+/CD4+ T cells, and serum TNF-α, IFN-γ and IL-17 were significantly increased by Reg3A overexpression. In the ex vivo co-culture experiment, elevated cytotoxic effect, increased proportion of CD3ε+ T cells, and upregulated expressions of TNF-α, IFN-γ and IL-17 were detected in the PBMCs isolated from LoVo-Reg3A cell-xenografted nude mice. In conclusion, high expression of Reg3A could activate and recruit T cells in COAD leading to the cytotoxic tumor-suppressive effect.

Talin-1 inhibits Smurf1-mediated Stat3 degradation to modulate β-cell proliferation and mass in mice

Insufficient pancreatic β-cell mass and reduced insulin expression are key events in the pathogenesis of diabetes mellitus (DM). Here we demonstrate the high expression of Talin-1 in β-cells and that deficiency of Talin-1 reduces β-cell proliferation, which leads to reduced β-cell mass and insulin expression, thus causing glucose intolerance without affecting peripheral insulin sensitivity in mice. High-fat diet fed exerbates these phenotypes. Mechanistically, Talin-1 interacts with the E3 ligase smad ubiquitination regulatory factor 1 (Smurf1), which prohibits ubiquitination of the signal transducer and activator of transcription 3 (Stat3) mediated by Smurf1, and ablation of Talin-1 enhances Smurf1-mediated ubiquitination of Stat3, leading to decreased β-cell proliferation and mass. Furthermore, haploinsufficiency of Talin-1 and Stat3 genes, but not that of either gene, in β-cell in mice significantly impairs glucose tolerance and insulin expression, indicating that both factors indeed function in the same genetic pathway. Finally, inducible deletion Talin-1 in β-cell causes glucose intolerance in adult mice. Collectively, our findings reveal that Talin-1 functions as a crucial regulator of β-cell mass, and highlight its potential as a therapeutic target for DM patients.

Reg3γ: current understanding and future therapeutic opportunities in metabolic disease

Regenerating family member gamma, Reg3γ (the mouse homolog of human REG3A), belonging to the antimicrobial peptides (AMPs), functions as a part of the host immune system to maintain spatial segregation between the gut bacteria and the host in the intestine via bactericidal activity. There is emerging evidence that gut manipulations such as bariatric surgery, dietary supplementation or drug treatment to produce metabolic benefits alter the gut microbiome. In addition to changes in a wide range of gut hormones, these gut manipulations also induce the expression of Reg3γ in the intestine. Studies over the past decades have revealed that Reg3γ not only plays a role in the gut lumen but can also contribute to host physiology through interaction with the gut microbiota. Herein, we discuss the current knowledge regarding the biology of Reg3γ, its role in various metabolic functions, and new opportunities for therapeutic strategies to treat metabolic disorders.