Four Decades After the Discovery of Regenerating Islet-Derived (Reg) Proteins: Current Understanding and Challenges

Regenerating Family Member 3 Alpha Is Predictive of Mortality Following Emergent Large Vessel Occlusion

Regenerating Family Member 3 Alpha (REG3A) is an antimicrobial protein secreted by the intestine and pancreas with additional immunomodulatory properties. Previously, we published that REG3A expression in ischemic stroke patient systemic blood, during mechanical thrombectomy (MT), is significantly associated with inflammatory cytokines and patient function on admission. This paper, however, did not investigate post-acute death rates. Therefore, we investigated plasma REG3A protein expression, during MT, in patients (n = 141) that survived or died within the end of the follow-up after MT. Subjects who died had significantly higher systemic plasma REG3A levels at the time of MT compared to survivors (p = 0.001). Age, sex, time from last known normal, and admission NIHSS were included as predictors to control for confounding variables and were all examined to determine their association in patient mortality. Logistic regression was used to demonstrate that higher odds of death were associated with increased REG3A levels (p = 0.002). REG3A demonstrated acceptable discrimination (AUC (95% CI): 0.669 (0.566-0.772) in predicting mortality. The overall model with age, sex, time from last known normal, and admission NIHSS discriminated well between survivors and those who died (AUC (95% CI): 0.784 (0.703-0.864)). In conclusion, REG3A could be promising as a biomarker to prognosticate stroke outcomes and stratify high-risk groups following acute ischemic stroke.

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.

Urinary complement factor D is increased in primary malignant hypertension: a single-center, cross-sectional study

Kidney injury is one of the detrimental consequences of primary malignant hypertension (pMHTN). There is a paucity of non-invasive biomarkers to enhance diagnosis and elucidate the underlying mechanisms. This study aims to explore urine protein biomarkers for pMHTN associated renal damage. In the discovery phase, urine samples were collected from 8 pMHTN, 19 disease controls (DCs), and 5 healthy controls (HCs). In-gel digestion combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) approach was used for identification of proteins associated with pMHTN. In the validation phase, the differentially expressed proteins were validated by ELISA assay in cohort with 10 pMHTN patients, 37 DCs, and 30 HCs. Compared to DCs and HCs, a specific band between 15 and 25 kDa was found in 7 out of 8 patients with pMHTN. Further LC-MS/MS analysis revealed 5 differentially expressed proteins. ELISA validation demonstrated that urinary complement factor D (CFD) was significantly up regulated in pMHTN. By receiver operating characteristic curve analysis, urinary CFD/Cr showed moderate potential in discriminating pMHTN from DCs (the area under curve: 0.822, 95% CI 0.618-0.962). Urinary CFD may be a potential biomarker for pMHTN with its elevation indicative of the activation of the alternative complement pathway in pMHTN.

Activation of the osteoblastic HIF-1α pathway partially alleviates the symptoms of STZ-induced type 1 diabetes mellitus via RegIIIγ

The hypoxia-inducible factor-1α (HIF-1α) pathway coordinates skeletal bone homeostasis and endocrine functions. Activation of the HIF-1α pathway increases glucose uptake by osteoblasts, which reduces blood glucose levels. However, it is unclear whether activating the HIF-1α pathway in osteoblasts can help normalize glucose metabolism under diabetic conditions through its endocrine function. In addition to increasing bone mass and reducing blood glucose levels, activating the HIF-1α pathway by specifically knocking out Von Hippel‒Lindau (Vhl) in osteoblasts partially alleviated the symptoms of streptozotocin (STZ)-induced type 1 diabetes mellitus (T1DM), including increased glucose clearance in the diabetic state, protection of pancreatic β cell from STZ-induced apoptosis, promotion of pancreatic β cell proliferation, and stimulation of insulin secretion. Further screening of bone-derived factors revealed that islet regeneration-derived protein III gamma (RegIIIγ) is an osteoblast-derived hypoxia-sensing factor critical for protection against STZ-induced T1DM. In addition, we found that iminodiacetic acid deferoxamine (SF-DFO), a compound that mimics hypoxia and targets bone tissue, can alleviate symptoms of STZ-induced T1DM by activating the HIF-1α-RegIIIγ pathway in the skeleton. These data suggest that the osteoblastic HIF-1α-RegIIIγ pathway is a potential target for treating T1DM.

Novel Approach for Pancreas Transcriptomics Reveals the Cellular Landscape in Homeostasis and Acute Pancreatitis

BACKGROUND & AIMS

Acinar cells produce digestive enzymes that impede transcriptomic characterization of the exocrine pancreas. Thus, single-cell RNA-sequencing studies of the pancreas underrepresent acinar cells relative to histological expectations, and a robust approach to capture pancreatic cell responses in disease states is needed. We sought to innovate a method that overcomes these challenges to accelerate study of the pancreas in health and disease.

METHODS

We leverage FixNCut, a single-cell RNA-sequencing approach in which tissue is reversibly fixed with dithiobis(succinimidyl propionate) before dissociation and single-cell preparation. We apply FixNCut to an established mouse model of acute pancreatitis, validate findings using GeoMx whole transcriptome atlas profiling, and integrate our data with prior studies to compare our method in both mouse and human pancreas datasets.

RESULTS

FixNCut achieves unprecedented definition of challenging pancreatic cells, including acinar and immune populations in homeostasis and acute pancreatitis, and identifies changes in all major cell types during injury and recovery. We define the acinar transcriptome during homeostasis and acinar-to-ductal metaplasia and establish a unique gene set to measure deviation from normal acinar identity. We characterize pancreatic immune cells, and analysis of T-cell subsets reveals a polarization of the homeostatic pancreas toward type-2 immunity. We report immune responses during acute pancreatitis and recovery, including early neutrophil infiltration, expansion of dendritic cell subsets, and a substantial shift in the transcriptome of macrophages due to both resident macrophage activation and monocyte infiltration.

CONCLUSIONS

FixNCut preserves pancreatic transcriptomes to uncover novel cell states during homeostasis and following pancreatitis, establishing a broadly applicable approach and reference atlas for study of pancreas biology and disease.

Antibacterial peptide Reg4 ameliorates Pseudomonas aeruginosa-induced pulmonary inflammation and fibrosis

Pseudomonas aeruginosa (P. aeruginosa) is a Gram-negative facultative anaerobe that has become an important cause of severe infections in humans, particularly in patients with cystic fibrosis. The development of efficacious methods or mendicants against P. aeruginosa is still needed. We previously reported that regenerating islet-derived family member 4 (Reg4) has bactericidal activity against Salmonella Typhimurium, a Gram-negative flagellated bacterium. We herein explore whether Reg4 has bactericidal activity against P. aeruginosa. In the P. aeruginosa PAO1-chronic infection model, Reg4 significantly inhibits the colonization of PAO1 in the lung and subsequently ameliorates pulmonary inflammation and fibrosis. Reg4 recombinant protein suppresses the growth motility and biofilm formation capability of PAO1 in vitro. Mechanistically, Reg4 not only exerts bactericidal action via direct binding to the P. aeruginosa cell wall but also enhances the phagocytosis of alveolar macrophages in the host. Taken together, our study demonstrates that Reg4 may provide protection against P. aeruginosa-induced pulmonary inflammation and fibrosis via its antibacterial activity.IMPORTANCEChronic lung infection with Pseudomonas aeruginosa is a leading cause of morbidity and mortality in patients with cystic fibrosis. Due to the antibiotic resistance of Pseudomonas aeruginosa, antimicrobial peptides appear to be a potential alternative to combat its infection. In this study, we report an antimicrobial peptide, regenerating islet-derived 4 (Reg4), that showed killing activity against clinical strains of Pseudomonas aeruginosa PAO1 and ameliorated PAO1-induced pulmonary inflammation and fibrosis. Experimental data also showed Reg4 directly bound to the bacterial cell membrane and enhanced the phagocytosis of host alveolar macrophages. Our presented study will be a helpful resource in searching for novel antimicrobial peptides that could have the potential to replace conventional antibiotics.

The integration of single-cell and bulk RNA-seq atlas reveals ERS-mediated acinar cell damage in acute pancreatitis

BACKGROUND

Acute pancreatitis (AP) is a clinically common acute abdominal disease, whose pathogenesis remains unclear. The severe patients usually have multiple complications and lack specific drugs, leading to a high mortality and poor outcome. Acinar cells are recognized as the initial site of AP. However, there are no precise single-cell transcriptomic profiles to decipher the landscape of acinar cells during AP, which are the missing pieces of jigsaw we aimed to complete in this study.

METHODS

A single-cell sequencing dataset was used to identify the cell types in pancreas of AP mice and to depict the transcriptomic maps in acinar cells. The pathways' activities were evaluated by gene sets enrichment analysis (GSEA) and single-cell gene sets variation analysis (GSVA). Pseudotime analysis was performed to describe the development trajectories of acinar cells. We also constructed the protein-protein interaction (PPI) network and identified the hub genes. Another independent single-cell sequencing dataset of pancreas samples from AP mice and a bulk RNA sequencing dataset of peripheral blood samples from AP patients were also analyzed.

RESULTS

In this study, we identified genetic markers of each cell type in the pancreas of AP mice based on single-cell sequencing datasets and analyzed the transcription changes in acinar cells. We found that acinar cells featured acinar-ductal metaplasia (ADM), as well as increased endocytosis and vesicle transport activity during AP. Notably, the endoplasmic reticulum stress (ERS) and ER-associated degradation (ERAD) pathways activated by accumulation of unfolded/misfolded proteins in acinar cells could be pivotal for the development of AP.

CONCLUSION

We deciphered the distinct roadmap of acinar cells in the early stage of AP at single-cell level. ERS and ERAD pathways are crucially important for acinar homeostasis and the pathogenesis of AP.

Evidence that the loss of colonic anti-microbial peptides may promote dysbiotic Gram-negative inflammaging-associated bacteria in aging mice

Introduction: Aging studies in humans and mice have played a key role in understanding the intestinal microbiome and an increased abundance of "inflammaging" Gram-negative (Gn) bacteria. The mechanisms underlying this inflammatory profile in the aging microbiome are unknown. We tested the hypothesis that an aging-related decrease in colonic crypt epithelial cell anti-microbial peptide (AMP) gene expression could promote colonic microbiome inflammatory Gn dysbiosis and inflammaging. Methods: As a model of aging, C57BL/6J mice fecal (colonic) microbiota (16S) and isolated colonic crypt epithelial cell gene expression (RNA-seq) were assessed at 2 months (mth) (human: 18 years old; yo), 15 mth (human: 50 yo), and 25 mth (human: 84 yo). Informatics examined aging-related microbial compositions, differential colonic crypt epithelial cell gene expressions, and correlations between colonic bacteria and colonic crypt epithelial cell gene expressions. Results: Fecal microbiota exhibited significantly increased relative abundances of pro-inflammatory Gn bacteria with aging. Colonic crypt epithelial cell gene expression analysis showed significant age-related downregulation of key AMP genes that repress the growth of Gn bacteria. The aging-related decrease in AMP gene expressions is significantly correlated with an increased abundance in Gn bacteria (dysbiosis), loss of colonic barrier gene expression, and senescence- and inflammation-related gene expression. Conclusion: This study supports the proposed model that aging-related loss of colonic crypt epithelial cell AMP gene expression promotes increased relative abundances of Gn inflammaging-associated bacteria and gene expression markers of colonic inflammaging. These data may support new targets for aging-related therapies based on intestinal genes and microbiomes.

Immune cell-intrinsic Ah receptor facilitates the expression of antimicrobial REG3G in the small intestine

The intestinal epithelial layer is susceptible to damage by chemical, physiological and mechanical stress. While it is essential to maintain the integrity of epithelium, the biochemical pathways that contribute to the barrier function have not been completely investigated. Here we demonstrate an aryl hydrocarbon receptor (AHR)-dependent mechanism facilitating the production of the antimicrobial peptide AMP regenerating islet-derived protein 3 gamma (REG3G), which is essential for intestinal homeostasis. Genetic ablation of AHR in mice impairs pSTAT3-mediated REG3G expression and increases bacterial numbers of Segmented filamentous bacteria (SFB) and Akkermansia muciniphila in the small intestine. Studies with tissue-specific conditional knockout mice revealed that the presence of AHR in the epithelial cells of the small intestine is not required for the production of REG3G through the phosphorylated STAT3-mediated pathway. However, immune-cell-specific AHR activity is necessary for normal expression of REG3G in all regions of the small intestine. A diet rich in broccoli, capable of inducing AHR activity, increases REG3G production when compared to a semi-purified diet that is devoid of ligands that can potentially activate the AHR, thus highlighting the importance of AHR in antimicrobial function. Overall, these data suggest that homeostatic antimicrobial REG3G production is increased by an AHR pathway intrinsic to the immune cells in the small intestine.

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.

Hyperinsulinemia acts via acinar insulin receptors to initiate pancreatic cancer by increasing digestive enzyme production and inflammation

The rising pancreatic cancer incidence due to obesity and type 2 diabetes is closely tied to hyperinsulinemia, an independent cancer risk factor. Previous studies demonstrated reducing insulin production suppressed pancreatic intraepithelial neoplasia (PanIN) pre-cancerous lesions in Kras-mutant mice. However, the pathophysiological and molecular mechanisms remained unknown, and in particular it was unclear whether hyperinsulinemia affected PanIN precursor cells directly or indirectly. Here, we demonstrate that insulin receptors (Insr) in KrasG12D-expressing pancreatic acinar cells are dispensable for glucose homeostasis but necessary for hyperinsulinemia-driven PanIN formation in the context of diet-induced hyperinsulinemia and obesity. Mechanistically, this was attributed to amplified digestive enzyme protein translation, triggering of local inflammation, and PanIN metaplasia in vivo. In vitro, insulin dose-dependently increased acinar-to-ductal metaplasia formation in a trypsin- and Insr-dependent manner. Collectively, our data shed light on the mechanisms connecting obesity-driven hyperinsulinemia and pancreatic cancer development.

EXTL3-Associated Immunoskeletal Dysplasia with Neurodevelopmental Abnormalities: A Lethal Phenotype

Background: Immunoskeletal dysplasia with neurodevelopmental abnormalities (ISDNA) caused by Exostosin-Like Glycosyltransferase 3 (EXTL3) biallelic mutations is a very rare syndrome with only 16 cases reported in the literature. Skeletal dysplasia, neurodevelopmental delay, immunodeficiency, liver, and kidney cysts are the most common findings of this syndrome. Case Presentation: Here, we report on a patient who exhibited a lethal phenotype with clinical characteristics of this syndrome and had a homozygous pathogenic mutation in EXTL3 gene. Conclusions: ISDNA should be kept in mind in the differential diagnosis of patients presenting with neuro-immuno-skeletal dysplasia phenotype.

Association of inflammation-related markers and diabetic retinopathy severity in the aqueous humor, but not serum of type 2 diabetic patients

Diabetic retinopathy (DR) is a frequent microvascular complication of diabetes mellitus, and inflammatory pathways have been linked to its pathogenesis. In this retrospective, observational pilot study, we aimed to compare the concentrations of four inflammation-related proteins, ZAG, Reg-3a, elafin and RBP-4, in the serum and aqueous humor of healthy controls and diabetic patients with different stages of DR. The concentrations of VEGF-A, IL-8, IL-6 were determined in parallel as internal controls. In the serum, we did not find significant differences in the concentrations of target proteins. In the aqueous humor, higher levels of ZAG, RBP-4, Reg-3a and elafin were observed in advanced nonproliferative DR (NPDR)/ proliferative DR (PDR) compared to controls. The levels of ZAG and RBP-4 were also higher in advanced NPDR/PDR than in nonapparent DR. Normalization of target protein concentrations to the aqueous humor total protein demonstrates that a spill-over from serum due to breakage of the blood-retina barrier only partially accounts for increased inflammation related markers in later stages. In conclusion, we found elevated levels of Reg-3a, RBP-4, elafin and ZAG in advanced stages of diabetic retinopathy. Higher levels of pro-inflammatory proteins, Reg-3a and RBP-4, might contribute to the pathogenesis of diabetic retinopathy, as the parallel increased concentrations of anti-inflammatory molecules elafin and ZAG might indicate a compensatory mechanism.

Antimicrobial overproduction sustains intestinal inflammation by inhibiting Enterococcus colonization

Loss of antimicrobial proteins such as REG3 family members compromises the integrity of the intestinal barrier. Here, we demonstrate that overproduction of REG3 proteins can also be detrimental by reducing a protective species in the microbiota. Patients with inflammatory bowel disease (IBD) experiencing flares displayed heightened levels of secreted REG3 proteins that mediated depletion of Enterococcus faecium (Efm) from the gut microbiota. Efm inoculation of mice ameliorated intestinal inflammation through activation of the innate immune receptor NOD2, which was associated with the bacterial DL-endopeptidase SagA that generates NOD2-stimulating muropeptides. NOD2 activation in myeloid cells induced interleukin-1β (IL-1β) secretion to increase the proportion of IL-22-producing CD4+ T helper cells and innate lymphoid cells that promote tissue repair. Finally, Efm was unable to protect mice carrying a NOD2 gene variant commonly found in IBD patients. Our findings demonstrate that inflammation self-perpetuates by causing aberrant antimicrobial activity that disrupts symbiotic relationships with gut microbes.

Daphnetin attenuates intestinal inflammation, oxidative stress, and apoptosis in ulcerative colitis via inhibiting REG3A-dependent JAK2/STAT3 signaling pathway

Daphnetin is a natural coumarin compound with anti-inflammatory, anti-oxidant, and anti-apoptotic effects, which has been previously demonstrated to ameliorate DSS-induced ulcerative colitis (UC). However, the molecular mechanism involved in the daphnetin-mediated pathological process of UC remains unclarified. The current study used DSS-induced mice and LPS-challenged Caco-2 cells as UC models. Bodyweight, disease activity index (DAI) score, and colon length were used to evaluate the severity of colitis. The histological changes in colon tissues were observed using H&E and PAS staining. Protein levels were detected by western blot. The malondialdehyde (MDA) and superoxide dismutase (SOD) activities were used to assess oxidative stress. Inflammatory responses were evaluated by detecting the levels of inflammatory cytokines (IFN-r, IL-1β, IL-6, and TNF-α) using flow cytometry. CCK-8 and TUNEL assay were employed to determine cell growth and cell death, respectively. The results showed that daphnetin could ameliorate the severity of colitis and attenuate the damage to intestinal structure in DSS-induced mice. Compared with the DSS group, the expression of ZO-1, occludin, and anti-apoptotic protein (BCL-2) was increased while the level of pro-apoptotic proteins (Bax and cleaved caspase 3) was decreased in DSS + daphnetin group. The activity of MDA and SOD, as well as the levels of inflammatory cytokines were substantially suppressed by daphnetin. In consistency, in vitro assays indicated that daphnetin protected Caco-2 cells from LPS-stimulated viability impairment, apoptosis, oxidative stress, and inflammation. Furthermore, daphnetin suppressed the activity of JAK2/STAT signaling in LPS-induced Caco-2 cells in a REG3A-dependent manner. REG3A overexpression abated the ameliorative effects of daphnetin while JAK2/STAT signaling inhibition functioned synergically with daphnetin in LPS-stimulated Caco-2 cells. Collectively, this study deepened the understanding of the therapeutic effects of daphnetin on UC and uncovered for the first time that daphnetin functioned through REG3A-activated JAK2/STAT3 signaling in UC, which may provide novel insights for the treatment of UC.

Reg family proteins contribute to inflammation and pancreatic stellate cells activation in chronic pancreatitis

Chronic pancreatitis (CP) is a disease characterized by the inflammation and destruction of pancreatic tissue, leading to the replacement of functional tissue with fibrotic tissue. The regenerating gene (Reg) family proteins have recently been implicated in the repair and regeneration of inflamed pancreatic tissue, though the exact mechanisms of their involvement in the pathogenesis of CP are not yet fully understood. To investigate the role of Reg family proteins in CP, we generated global knockout mice (Reg^-/-) for Reg1-3 (Reg1,2,3a,3b,3d,3g) genes using the CRISPR/Cas9 system. We then investigated the effect of Reg family protein deficiency in a genetic model of CP (X-SPINK1) mice by knocking out Reg1-3 genes. We examined pancreatic morphology, inflammatory cytokines expression, and activation of pancreatic stellate cells (PSCs) at different ages. Reg^-/- mice showed no abnormalities in general growth and pancreas development. Deficiency of Reg1-3 in CP mice led to a reduction in pancreatic parenchymal loss, decreased deposition of collagen, and reduced expression of proinflammatory cytokines. Additionally, Reg proteins were found to stimulate PSCs activation. Overall, our study suggests that Reg1-3 deficiency can lead to the remission of CP and Reg family proteins could be a potential therapeutic target for the treatment of CP.

Tuft cells mediate commensal remodeling of the small intestinal antimicrobial landscape

Succinate produced by the commensal protist Tritrichomonas musculis (T. mu) stimulates chemosensory tuft cells, resulting in intestinal type 2 immunity. Tuft cells express the succinate receptor SUCNR1, yet this receptor does not mediate antihelminth immunity nor alter protist colonization. Here, we report that microbial-derived succinate increases Paneth cell numbers and profoundly alters the antimicrobial peptide (AMP) landscape in the small intestine. Succinate was sufficient to drive this epithelial remodeling, but not in mice lacking tuft cell chemosensory components required to detect this metabolite. Tuft cells respond to succinate by stimulating type 2 immunity, leading to interleukin-13-mediated epithelial and AMP expression changes. Moreover, type 2 immunity decreases the total number of mucosa-associated bacteria and alters the small intestinal microbiota composition. Finally, tuft cells can detect short-term bacterial dysbiosis that leads to a spike in luminal succinate levels and modulate AMP production in response. These findings demonstrate that a single metabolite produced by commensals can markedly shift the intestinal AMP profile and suggest that tuft cells utilize SUCNR1 and succinate sensing to modulate bacterial homeostasis.

Breast density and estradiol are associated with distinct different expression patterns of metabolic proteins in normal human breast tissue in vivo

Background

Breast density and exposure to sex steroids are major risk factors for breast cancer. The local microenvironment plays an essential role in progression of breast cancer. Metabolic adaption is a major hallmark of cancer. Whether proteins from the extracellular space regulating metabolism are affected in breast cancer, dense breasts or by estrogen exposure are not yet fully elucidated.

Methods

Women with breast cancer, postmenopausal women with normal breast tissue with varying breast density or premenopausal women with breasts exposed to high levels of estradiol were included in the study. Microdialysis was used to collect proteins from the extracellular space in vivo in 73 women; 12 with breast cancer, 42 healthy postmenopausal women with different breast densities, and 19 healthy premenopausal women. Breast density was determined as lean tissue fraction (LTF) using magnetic resonance imaging. Data were evaluated in a murine breast cancer model. We quantified a panel of 92 key proteins regulating metabolism using proximity extension assay.

Results

We report that 29 proteins were upregulated in human breast cancer. In dense breasts 37 proteins were upregulated and 17 of these were similarly regulated as in breast cancer. 32 proteins correlated with LTF. In premenopausal breasts 19 proteins were up-regulated and 9 down-regulated. Of these, 27 correlated to estradiol, a result that was confirmed for most proteins in experimental breast cancer. Only two proteins, pro-cathepsin H and galanin peptide, were similarly regulated in breast cancer, dense- and estrogen exposed breasts.

Conclusions

Metabolic proteins may be targetable for breast cancer prevention. Depending on risk factor, this may, however, require different approaches as breast density and estradiol induce distinct different expression patterns in the breast. Additionally, metabolic proteins from the extracellular space may indeed be further explored as therapeutic targets for breast cancer treatment.

Antimicrobial protein REG3A regulates glucose homeostasis and insulin resistance in obese diabetic mice

Innate immune mediators of pathogen clearance, including the secreted C-type lectins REG3 of the antimicrobial peptide (AMP) family, are known to be involved in the regulation of tissue repair and homeostasis. Their role in metabolic homeostasis remains unknown. Here we show that an increase in human REG3A improves glucose and lipid homeostasis in nutritional and genetic mouse models of obesity and type 2 diabetes. Mice overexpressing REG3A in the liver show improved glucose homeostasis, which is reflected in better insulin sensitivity in normal weight and obese states. Delivery of recombinant REG3A protein to leptin-deficient ob/ob mice or wild-type mice on a high-fat diet also improves glucose homeostasis. This is accompanied by reduced oxidative protein damage, increased AMPK phosphorylation and insulin-stimulated glucose uptake in skeletal muscle tissue. Oxidative damage in differentiated C2C12 myotubes is greatly attenuated by REG3A, as is the increase in gp130-mediated AMPK activation. In contrast, Akt-mediated insulin action, which is impaired by oxidative stress, is not restored by REG3A. These data highlight the importance of REG3A in controlling oxidative protein damage involved in energy and metabolic pathways during obesity and diabetes, and provide additional insight into the dual function of host-immune defense and metabolic regulation for AMP.

Relevance of biomarkers indicating gut damage and microbial translocation in people living with HIV

The intestinal barrier has the daunting task of allowing nutrient absorption while limiting the entry of microbial products into the systemic circulation. HIV infection disrupts the intestinal barrier and increases intestinal permeability, leading to microbial product translocation. Convergent evidence has shown that gut damage and an enhanced level of microbial translocation contribute to the enhanced immune activation, the risk of non-AIDS comorbidity, and mortality in people living with HIV (PLWH). Gut biopsy procedures are invasive, and are not appropriate or feasible in large populations, even though they are the gold standard for intestinal barrier investigation. Thus, validated biomarkers that measure the degree of intestinal barrier damage and microbial translocation are needed in PLWH. Hematological biomarkers represent an objective indication of specific medical conditions and/or their severity, and should be able to be measured accurately and reproducibly via easily available and standardized blood tests. Several plasma biomarkers of intestinal damage, i.e., intestinal fatty acid-binding protein (I-FABP), zonulin, and regenerating islet-derived protein-3α (REG3α), and biomarkers of microbial translocation, such as lipopolysaccharide (LPS) and (1,3)-β-D-Glucan (BDG) have been used as markers of risk for developing non-AIDS comorbidities in cross sectional analyses and clinical trials, including those aiming at repair of gut damage. In this review, we critically discuss the value of different biomarkers for the estimation of gut permeability levels, paving the way towards developing validated diagnostic and therapeutic strategies to repair gut epithelial damage and to improve overall disease outcomes in PLWH.

Alterations in the pH of pancreatic juice are associated with chymotrypsin C inactivation and lithostathine precipitation in chronic pancreatitis patients: a proteomic approach

BACKGROUND

The progression of chronic pancreatitis (CP), an inflammatory disease of the pancreas, causes pancreatic stones to form within the pancreatic ductal lumen/parenchyma, which occurs via protein plug formation. Pain is the most common symptom that necessitates clinical attention, and pain relief is the therapeutic goal for these patients. Endoscopic therapy and surgery are complimentary forms of therapy for pain relief. This study was envisaged to clarify the mechanism by which protein plug/soft stones form in pancreatic ducts prior to undergoing calcification.

METHODS

Protein plugs were obtained from twenty CP patients undergoing therapeutic ERCP for stone removal. Pancreatic juice was obtained from five CP patients without stones. Proteins were isolated by TCA/acetone precipitation, SDS PAGE and 2-D gel electrophoresis to determine the protein profile. Protein spots from the 2-D gel were excised and subjected to matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) for identification. The effect of altered pH and elevated concentrations of trypsin on pancreatic juice protein was assessed by SDS‒PAGE to determine the protein profile. Differentially expressed protein bands were excised and subjected to MALDI-TOF. In silico analysis was performed by docking lithostathine with the calcite molecule using AutoDock Vina and PyMOL to clarify their interaction during stone formation.

RESULTS

Twenty-three and twenty-nine spots from 2D gels of protein plugs and pancreatic juice, respectively, revealed that lithostathine (Reg1A) was the only protein in the protein plugs, whereas digestive enzymes and lithostathine were identified in pancreatic juice. Altered pH levels and increased trypsin concentrations in the pancreatic juice caused a protein to degrade via an unknown mechanism, and this protein was identified as chymotrypsin C (CTRC) by MALDI-TOF. Docking studies showed that the binding affinity of calcite was higher with the cleaved lithostathine, explaining the deposition of calcium that was observed around the protein plugs after calcified stones were formed through precipitation.

CONCLUSION

Our results suggest that chymotrypsin C (CTRC) is degraded in an acidic environment, leading to the precipitation of lithostathine in the ductal lumen.

Down-regulating Interleukin-22/Interleukin-22 binding protein axis promotes inflammation and aggravates diet-induced metabolic disorders

The prevalence of metabolic diseases has become a severe public health problem. Previously, we reported that Interleukin-22 (IL-22) was independently associated with type 2 diabetes mellitus and cardiovascular disease, and could protect endothelial cells from glucose- and lysophosphatidylcholine-induced injury. The activity of IL-22 is strongly regulated by IL-22-binding protein (IL-22BP). The aim of this investigation was to determine the effect of IL-22/IL-22BP axis on glucolipid metabolism. Serum IL-22 and IL-22BP expression in metabolic syndrome (MetS) patients and healthy controls was examined. IL-22BP-knockout (IL-22ra2^-/-) and wild-type (WT) mice were fed with control diet (CTD) and high-fat diet (HFD) for 12 weeks. The IL-22 related pathway expression, the glucolipid metabolism, and inflammatory markers in mice were examined. Serum IL-22 and IL-22BP levels were found significantly increased in MetS patients (p < 0.001). IL-22BP deficiency down-regulated IL-22-related pathway, aggravated glucolipid metabolism disorder, and promoted inflammation in mice. Collectively, this work deepens the understanding of the relationship between IL-22/IL-22BP axis and metabolism disorders, and identified that down-regulation of IL-22/IL-22BP axis promotes metabolic disorders in mice.

Local problems need global solutions: The metabolic needs of regenerating organisms

The vast majority of species that belong to the plant or animal kingdom evolved with two main strategies to counter tissue damage-scar formation and regeneration. Whereas scar formation provides a fast and cost-effective repair to exit life-threatening conditions, complete tissue regeneration is time-consuming and requires vast resources to reinstall functionality of affected organs or structures. Local environments in wound healing are widely studied and findings have provided important biomedical applications. Less well understood are organismic physiological parameters and signalling circuits essential to maintain effective tissue repair. Here, we review accumulated evidence that positions the interplay of local and systemic changes in metabolism as essential variables modulating the injury response. We particularly emphasise the role of lipids and lipid-like molecules as significant components long overlooked.

BefA, a microbiota-secreted membrane disrupter, disseminates to the pancreas and increases β cell mass

Microbiome dysbiosis is a feature of diabetes, but how microbial products influence insulin production is poorly understood. We report the mechanism of BefA, a microbiome-derived protein that increases proliferation of insulin-producing β cells during development in gnotobiotic zebrafish and mice. BefA disseminates systemically by multiple anatomic routes to act directly on pancreatic islets. We detail BefA's atomic structure, containing a lipid-binding SYLF domain, and demonstrate that it permeabilizes synthetic liposomes and bacterial membranes. A BefA mutant impaired in membrane disruption fails to expand β cells, whereas the pore-forming host defense protein, Reg3, stimulates β cell proliferation. Our work demonstrates that membrane permeabilization by microbiome-derived and host defense proteins is necessary and sufficient for β cell expansion during pancreas development, potentially connecting microbiome composition with diabetes risk.

Identification of regenerating island-derived protein 3E in dogs

Regenerating islet-derived protein (REG) 1A (aka pancreatic stone protein) and REG3A (aka pancreatitis-associated protein) are upregulated in humans with sepsis, pancreatitis, and gastrointestinal diseases, but little is known about this protein family in dogs. Our aim was to identify REG1 and REG3 family members in dogs. REG-family genes were computationally annotated in the canine genome and proteome, with verification of gene expression using publicly available RNA-seq data. The presence of the protein in canine pancreatic tissue and plasma was investigated with Western blot and immunohistochemistry, using anti-human REG1A and REG3A antibodies. Protein identity was confirmed with mass spectrometry. Two members of the REG3 subfamily were found in the canine genome, REG3E1 and REG3E2, both encoding for the same 176 AA protein, subsequently named REG3E. Anti-human REG3A antibodies demonstrated cross-reactivity with the canine REG3E protein in pancreas homogenates. In canine plasma, a protein band of approximately 17 kDa was apparent. Mass spectrometry confirmed this protein to be the product of the two annotated REG3E genes. Strong immunoreactivity to anti-human REG3A antibodies was found in sections of canine pancreas affected with acute pancreatitis, but it was weak in healthy pancreatic tissue. Recombinant canine REG3E protein underwent a selective trypsin digestion as described in other species. No evidence for the presence of a homolog of REG1A in dogs was found in any of the investigations. In conclusion, dogs express REG3E in the pancreas, whose role as biomarker merits further investigations. Homologs to human REG1A are not likely to exist in dogs.

The effects of REG4 expression on chemoresistance of ovarian cancer

Although ovarian cancer usually responds well to platinum- and taxane-based first-line chemotherapy, most patients develop recurrence and chemoresistance. Regenerating gene 4 (REG4) is a secretory protein involved in cell differentiation and proliferation. We found higher REG4 expression in ovarian cancer than in normal tissues (p < .05). Regenerating gene 4 expression was negatively associated with overall, progression-free or post-progression survival rates of patients with ovarian cancer receiving platinum or paclitaxel treatment (p < .05) according to a Kaplan-Meier plotter. Regenerating gene 4 overexpression resulted in either cisplatin or paclitaxel resistance, and apoptosis resistance in CAOV3 ovarian cancer cells (p < .05). REG4-transfected ovarian cancer cells showed stronger migration and invasion treated with cisplatin or paclitaxel (p < .05). Additionally, cisplatin or paclitaxel exposure led to the overexpression of phosphorylated phosphoinositide 3-kinase (p-PI3K), p-Akt, phosphorylated mammalian target of rapamycin (p-mTOR), glutathione S-transferase-π, survivin, and B-cell lymphoma 2 in REG4 transfectants compared with control cells (p < .05). These findings suggested that REG4 expression was up-regulated in ovarian cancer, and associated with poor survival and chemotherapy resistance. REG4 promoted the occurrence, development, and chemotherapy resistance of ovarian cancer by regulating cell proliferation, apoptosis, migration, and invasion, and PI3K/Akt/m-TOR signalling pathways. IMPACT STATEMENTWhat is already known on this subject? REG4 mRNA expression is up-regulated in many digestive cancers. High REG4 expression was associated with an adverse prognosis, high tumour and nodal stages, poor differentiation, and hepatic and peritoneal metastases of digestive cancers. REG4 expression conferred cancer cells with increased resistance to chemoradiotherapy, especially 5-FU-based treatment, by activating the MAPK/Erk/Bim signalling pathway.What do the results of this study add? REG4 was highly expressed in ovarian cancer. The expression of p-PI3K, p-AKT, p-mTOR, GST-π, survivin, and Bcl-2 was increased in REG4-overexpressing cells. High REG4 expression was significantly associated with inferior OS, PFS, and PPS rates in patients with ovarian cancer receiving platinum chemotherapy. REG4 mediated cisplatin and paclitaxel resistance in CAOV3 ovarian cancer cells. The percentage of apoptotic cells was markedly lower in REG4-transfected compared to mock-transfected cells after cisplatin or paclitaxel treatment.What are the implications of these findings for clinical practice and/or further research? This study aimed to evaluate the prognostic significance of REG4 expression in ovarian cancer treated with platinum and paclitaxel, to explore REG4 chemoresistance mechanisms to platinum and paclitaxel, and to provide a scientific experimental basis for the clinical treatment and outcome evaluation of ovarian cancer. In order to provide comprehensive clinical treatment of ovarian cancer, it is helpful to improve our understanding of multi-drug resistance and identify new cancer diagnostic biomarkers.

Fetal Programming of the Endocrine Pancreas: Impact of a Maternal Low-Protein Diet on Gene Expression in the Perinatal Rat Pancreas

In rats, the time of birth is characterized by a transient rise in beta cell replication, as well as beta cell neogenesis and the functional maturation of the endocrine pancreas. However, the knowledge of the gene expression during this period of beta cell expansion is incomplete. The aim was to characterize the perinatal rat pancreas transcriptome and to identify regulatory pathways differentially regulated at the whole organ level in the offspring of mothers fed a regular control diet (CO) and of mothers fed a low-protein diet (LP). We performed mRNA expression profiling via the microarray analysis of total rat pancreas samples at embryonic day (E) 20 and postnatal days (P) 0 and 2. In the CO group, pancreas metabolic pathways related to sterol and lipid metabolism were highly enriched, whereas the LP diet induced changes in transcripts involved in RNA transcription and gene regulation, as well as cell migration and apoptosis. Moreover, a number of individual transcripts were markedly upregulated at P0 in the CO pancreas: growth arrest specific 6 (Gas6), legumain (Lgmn), Ets variant gene 5 (Etv5), alpha-fetoprotein (Afp), dual-specificity phosphatase 6 (Dusp6), and angiopoietin-like 4 (Angptl4). The LP diet induced the downregulation of a large number of transcripts, including neurogenin 3 (Neurog3), Etv5, Gas6, Dusp6, signaling transducer and activator of transcription 3 (Stat3), growth hormone receptor (Ghr), prolactin receptor (Prlr), and Gas6 receptor (AXL receptor tyrosine kinase; Axl), whereas upregulated transcripts were related to inflammatory responses and cell motility. We identified differentially regulated genes and transcriptional networks in the perinatal pancreas. These data revealed marked adaptations of exocrine and endocrine in the pancreas to the low-protein diet, and the data can contribute to identifying novel regulators of beta cell mass expansion and functional maturation and may provide a valuable tool in the generation of fully functional beta cells from stem cells to be used in replacement therapy.

Reg-1α, a New Substrate of Calpain-2 Depending on Its Glycosylation Status

Reg-1α/lithostathine, a protein mainly associated with the digestive system, was previously shown to be overexpressed in the pre-clinical stages of Alzheimer’s disease. In vitro, the glycosylated protein was reported to form fibrils at physiological pH following the proteolytic action of trypsin. However, the nature of the protease able to act in the central nervous system is unknown. In the present study, we showed that Reg-1α can be cleaved in vitro by calpain-2, the calcium activated neutral protease, overexpressed in neurodegenerative diseases. Using chemical crosslinking experiments, we found that the two proteins can interact with each other. Identification of the cleavage site using mass spectrometry, between Gln⁴ and Thr⁵, was found in agreement with the in silico prediction of the calpain cleavage site, in a position different from the one reported for trypsin, i.e., Arg¹¹-Ile¹² peptide bond. We showed that the cleavage was impeded by the presence of the neighboring glycosylation of Thr⁵. Moreover, in vitro studies using electron microscopy showed that calpain-cleaved protein does not form fibrils as observed after trypsin cleavage. Collectively, our results show that calpain-2 cleaves Reg-1α in vitro, and that this action is not associated with fibril formation.

Mitoribosome insufficiency in β cells is associated with type 2 diabetes-like islet failure

Genetic variations in mitoribosomal subunits and mitochondrial transcription factors are related to type 2 diabetes. However, the role of islet mitoribosomes in the development of type 2 diabetes has not been determined. We investigated the effects of the mitoribosomal gene on β-cell function and glucose homeostasis. Mitoribosomal gene expression was analyzed in datasets from the NCBI GEO website (GSE25724, GSE76894, and GSE76895) and the European Nucleotide Archive (ERP017126), which contain the transcriptomes of type 2 diabetic and nondiabetic organ donors. We found deregulation of most mitoribosomal genes in islets from individuals with type 2 diabetes, including partial downregulation of CRIF1. The phenotypes of haploinsufficiency in a single mitoribosomal gene were examined using β-cell-specific Crif1 (Mrpl59) heterozygous-deficient mice. Crif1^beta+/− mice had normal glucose tolerance, but their islets showed a loss of first-phase glucose-stimulated insulin secretion. They also showed increased β-cell mass associated with higher expression of Reg family genes. However, Crif1^beta+/− mice showed earlier islet failure in response to high-fat feeding, which was exacerbated by aging. Haploinsufficiency of a single mitoribosomal gene predisposes rodents to glucose intolerance, which resembles the early stages of type 2 diabetes in humans.

Disruptions in the mitochondrial protein synthesis machinery give rise to metabolic disturbances that lay the foundation for type 2 diabetes. As physiological glucose levels rise, the energy-generating machinery of the mitochondria responds with increased activity, which stimulates insulin secretion. Many proteins responsible for mitochondrial metabolism are produced by ribosomes within this cellular organelle. Researchers led by Hyun Jin Kim and Minho Shong at Chungnam National University, Daejon, South Korea, have determined that mutations affecting a mitochondrial ribosomal protein called CRIF1 can lead to impaired insulin release. Mice with reduced CRIF1 were initially healthy, but as they aged, exhibited signs of impaired pancreatic function similar to those seen in patients with early-stage diabetes. This process was accelerated by consumption of a high-fat diet, and the researchers propose that this mechanism may be directly relevant to human disease.

Regenerating islet-derived protein 3α: A promising therapy for diabetes. Preliminary data in rodents and in humans

The aim of our study was to test the hypothesis that administration of Regenerating islet-derived protein 3α (Reg3α), a protein described as having protective effects against oxidative stress and anti-inflammatory activity, could participate in the control of glucose homeostasis and potentially be a new target of interest in the treatment of type 2 diabetes. To that end the recombinant human Reg3α protein was administered for one month in insulin-resistant mice fed high fat diet. We performed glucose and insulin tolerance tests, assayed circulating chemokines in plasma and measured glucose uptake in insulin sensitive tissues. We evidenced an increase in insulin sensitivity during an oral glucose tolerance test in ALF-5755 treated mice vs controls and decreased the pro-inflammatory cytokine C-X-C Motif Chemokine Ligand 5 (CXCL5). We also demonstrated an increase in glucose uptake in skeletal muscle. Finally, correlation studies using human and mouse muscle biopsies showed negative correlation between intramuscular Reg3α mRNA expression (or its murine isoform Reg3γ) and insulin resistance. Thus, we have established the proof of concept that Reg3α could be a novel molecule of interest in the treatment of T2D by increasing insulin sensitivity via a skeletal muscle effect.

Gastric Cancer Pre-Stage Detection and Early Diagnosis of Gastritis Using Serum Protein Signatures

Background: A gastric cancer (GC) diagnosis relies on histopathology. Endoscopy rates are increasing. Helicobacter pylori infection is a major GC risk factor. In an effort to elucidate abundant blood biomarkers, and potentially reduce the number of diagnostic surgical interventions, we investigated sera and biopsies from a cohort of 219 H. pylori positive and negative patients diagnosed with GC, gastritis, and ulcers. This allowed the comparative investigation of the different gastroduodenal diseases, and the exclusion of protein changes resulting from bacterial infection or inflammation of the gastric mucosa when searching for GC-dependent proteins. Methods: High-definition mass spectrometry-based expression analysis of tryptically digested proteins was performed, followed by multivariate statistical and network analyses for the different disease groups, with respect to H. pylori infection status. Significantly regulated proteins differing more than two-fold between groups were shortlisted, and their role in gastritis and GC discussed. Results: We present data of comparative protein analyses of biopsies and sera from patients suffering from mild to advanced gastritis, ulcers, and early to advanced GC, in conjunction with a wealth of metadata, clinical information, histopathological evaluation, and H. pylori infection status. We used samples from pre-malignant stages to extract prospective serum markers for early-stage GC, and present a 29-protein marker panel containing, amongst others, integrin β-6 and glutathione peroxidase. Furthermore, ten serum markers specific for advanced GC, independent of H. pylori infection, are provided. They include CRP, protein S100A9, and kallistatin. The majority of these proteins were previously discussed in the context of cancer or GC. In addition, we detected hypoalbuminemia and increased fibrinogen serum levels in gastritis. Conclusion: Two protein panels were suggested for the development of multiplex tests for GC serum diagnostics. For most of the elements contained in these panels, individual commercial tests are available. Thus, we envision the design of multi-protein assays, incorporating several to all of the panel members, in order to gain a level of specificity that cannot be achieved by testing a single protein alone. As their development and validation will take time, gastritis diagnosis based on the fibrinogen to albumin serum ratio may be a quick way forward. Its determination at the primary/secondary care level for early diagnosis could significantly reduce the number of referrals to endoscopy. Preventive measures are in high demand. The protein marker panels presented in this work will contribute to improved GC diagnostics, once they have been transferred from a research result to a practical tool.

Single-Cell Transcriptome Analysis Reveals the Role of Pancreatic Secretome in COVID-19 Associated Multi-organ Dysfunctions

The SARS-CoV-2 infection affects the lungs, heart, kidney, intestine, olfactory epithelia, liver, and pancreas and brings forward multi-organ dysfunctions (MODs). However, mechanistic details of SARS-CoV-2-induced MODs are unclear. Here, we have investigated the role of pancreatic secretory proteins to mechanistically link COVID-19 with MODs using single-cell transcriptome analysis. Secretory proteins were identified using the Human Protein Atlas. Gene ontology, pathway, and disease enrichment analyses were used to highlight the role of upregulated pancreatic secretory proteins (secretome). We show that SARS-CoV-2 infection shifts the expression profile of pancreatic endocrine cells to acinar and ductal cell-specific profiles, resulting in increased expression of acinar and ductal cell-specific genes. Among all the secretory proteins, the upregulated expression of IL1B, AGT, ALB, SPP1, CRP, SERPINA1, C3, TFRC, TNFSF10, and MIF was mainly associated with disease of diverse organs. Extensive literature and experimental evidence are used to validate the association of the upregulated pancreatic secretome with the coagulation cascade, complement activation, renin-angiotensinogen system dysregulation, endothelial cell injury and thrombosis, immune system dysregulation, and fibrosis. Our finding suggests the influence of an upregulated secretome on multi-organ systems such as nervous, cardiovascular, immune, digestive, and urogenital systems. Our study provides evidence that an upregulated pancreatic secretome is a possible cause of SARS-CoV-2-induced MODs. This finding may have a significant impact on the clinical setting regarding the prevention of SARS-CoV-2-induced MODs.

Metaproteomic profiling of fungal gut colonization in gnotobiotic mice

BACKGROUND

Eukaryotic microbes can modulate mammalian host health and disease states, yet the molecular contribution of gut fungi remains nascent. We previously showed that mice exclusively colonised with fungi displayed increased sensitivity to allergic airway inflammation and had fecal metabolite profiles similar to germ-free mice. This marginal effect on the host metabolome suggested that fungi do not primarily use metabolites to modulate the host immune system.

METHODS

To describe functional changes attributed to fungal colonisation, we performed mass spectrometry-based analyses of feces (Label-Free Quantitative; LFQ) and the small intestine (labeling with Tandem Mass Tag; TMT) of gnotobiotic mice colonised with defined consortia of twelve bacterial species, five fungal species, or both. We also evaluated the effect of microbiome perturbances on the metaproteome by analysing feces from mouse pups treated with an antibiotic or antifungal.

RESULTS

We detected 6675 proteins in the mice feces, of which 3845 had determined LFQ levels. Analysis of variance showed changes in the different gnotobiotic mouse groups; specifically, 46% of 2860 bacterial, 15% of 580 fungal, and 76% of 405 mouse quantified proteins displayed differential levels. The antimicrobial treatments resulted in lasting changes in the bacterial and fungal proteomes, suggesting that the antimicrobials impacted the entire community. Fungal colonisation resulted in changes in host proteins functional in innate immunity as well as metabolism, predicting specific roles of gut fungi on host systems during early developmental stages. Several of the detected fungal proteins (3% of 1492) have been previously reported as part of extracellular vesicles and having immunomodulating properties. Using an isobaric labelling TMT approach for profiling low abundant proteins of the jejunal tissue, we confirmed that the five fungal species differentially impacted the host intestinal proteome compared to the bacterial consortium. The detected changes in mouse jejunal proteins (4% of 1514) were mainly driven by metabolic proteins.

CONCLUSIONS

We used quantitative proteomic profiling of gnotobiotic conditions to show how colonisation with selected fungal species impacts the host gut proteome. Our results suggest that an increased abundance of certain gut fungal species in early life may affect the developing intracellular attributes of epithelial and immune cells.

Effects of hyperinsulinemia on pancreatic cancer development and the immune microenvironment revealed through single-cell transcriptomics

BACKGROUND

Hyperinsulinemia is independently associated with increased risk and mortality of pancreatic cancer. We recently reported that genetically reduced insulin production resulted in ~ 50% suppression of pancreatic intraepithelial neoplasia (PanIN) precancerous lesions in mice. However, only female mice remained normoglycemic, and only the gene dosage of the rodent-specific Ins1 alleles was tested in our previous model. Moreover, we did not delve into the molecular and cellular mechanisms associated with modulating hyperinsulinemia.

METHODS

We studied how reduced Ins2 gene dosage affects PanIN lesion development in both male and female Ptf1a^CreER;Kras^LSL-G12D mice lacking the rodent-specific Ins1 gene (Ins1^-/-). We generated control mice having two alleles of the wild-type Ins2 gene (Ptf1a^CreER;Kras^LSL-G12D;Ins1^-/-;Ins2^+/+) and experimental mice having one allele of Ins2 gene (Ptf1a^CreER;Kras^LSL-G12D;Ins1^-/-;Ins2^+/-). We then performed thorough histopathological analyses and single-cell transcriptomics for both genotypes and sexes.

RESULTS

High-fat diet-induced hyperinsulinemia was transiently or modestly reduced in female and male mice, respectively, with only one allele of Ins2. This occurred without dramatically affecting glucose tolerance. Genetic reduction of insulin production resulted in mice with a tendency for less PanIN and acinar-to-ductal metaplasia (ADM) lesions. Using single-cell transcriptomics, we found hyperinsulinemia affected multiple cell types in the pancreas, with the most statistically significant effects on local immune cell types that were highly represented in our sampled cell population. Specifically, hyperinsulinemia modulated pathways associated with protein translation, MAPK-ERK signaling, and PI3K-AKT signaling, which were changed in epithelial cells and subsets of immune cells.

CONCLUSIONS

These data suggest a potential role for the immune microenvironment in hyperinsulinemia-driven PanIN development. Together with our previous work, we propose that mild suppression of insulin levels may be useful in preventing pancreatic cancer by acting on multiple cell types.

Frederick Banting's observations leading to the potential for islet neogenesis without transplantation

On 31 October 1920, Sir Frederick Banting, while preparing for a medical student lecture on diabetes, a topic that he knew little about, learned how pancreatic stones resulted in the formation of new islets of Langerhans. He then scribbled down a potential research study of tying off the ducts of the pancreas and collecting the secretions to improve diabetes. These secretions became known as insulin. A century later, 60 different oral medications and 20 different insulins are available for the treatment of diabetes, yet none stimulate new islet formation. One hundred years later, after the discovery of insulin, more than a dozen research teams from around the world have demonstrated that similar studies to Banting's pancreatic ligation studies have resulted in upregulation of the REG gene. There are now more than 200 publications on the role of Reg gene proteins and shorter Reg peptides in initiating new islet formation islet from exocrine pancreatic ducts and protecting against inflammation to islets resulting in islet death. Human data through Phase 2b in both type 1 and 2 diabetes patients with diabetes for an average of 20 years have demonstrated that the use of a shorter bioactive Reg peptide can generate new endogenous insulin production, resulting in significant reductions in hemoglobin A1C and increases in stimulated C-peptide. The observations of Frederick Banting, one century ago, may now lead to the generation of therapeutics that form new islets without the need for transplantation.

Antimicrobial protein REG3A and signaling networks are predictive of stroke outcomes

Regenerating Family Member 3 Alpha (REG3A) is a multifunctional protein with antimicrobial activity, and primarily secreted by the intestine and pancreas. Studies have shown an increased expression of REG3A in systemic inflammatory responses to acute injury and infection, but studies investigating REG3A during the pathogenesis of ischemic stroke are limited. The aims of this study were to examine the associations between arterial expression of REG3A and other arterial inflammatory proteins implicated in stroke pathogenesis, as well as associations between REG3A and markers of poor outcome for ischemic stroke. The University of Kentucky Blood and Clot Thrombectomy Registry and Collaboration (BACTRAC) protocol (clinicaltrials.gov NCT03153683) utilizes thrombectomy to isolate intracranial arterial blood (i.e. distal to thrombus) and systemic arterial blood (i.e. carotid). Samples were analyzed by Olink Proteomics for N = 42 subjects. Statistical analyses of plasma proteins included 2-sample t-tests, spearman and biserial correlations, and robust regression models to elucidate network signaling and association to clinical outcomes. Results indicated that levels of systemic REG3A were positively correlated with inflammatory proteins interleukin IL6 (R = 0.344, p = 0.030) and IL17C (R = 0.468, p = 0.002). 2-sided t- tests examining differences of systemic REG3A within quartiles of NIHSS admission score depicted significant differences between quartiles. Those with NIHSS scores corresponding to moderate and moderate-severe neurofunctional deficits had significantly higher levels of systemic REG3A compared to those with NIHSS scores corresponding to mild and mild-moderate neurofunctional deficits (p = 0.016). STRING analyses of proteins in each robust regression model demonstrated substantial networking between REG3A and other systemic proteins highly relevant to ischemic stroke. The present study provides novel data on systemic REG3A in the context of ischemic stroke. These results demonstrate the influential role of REG3A regarding surrogate functional and radiographic outcomes of stroke severity. Additionally, they provide novel insight into the role of REG3A and related proteins during the complex neuroinflammatory process of ischemic stroke. These data provide a foundation for future studies to investigate REG3A and related networking proteins as potential biomarkers with prognostic potential, as well as potential therapeutic targets.

Temporal overexpression of IL-22 and Reg3γ differentially impacts the severity of experimental autoimmune encephalomyelitis

IL-22 is an alpha-helical cytokine which belongs to the IL-10 family of cytokines. IL-22 is produced by RORγt+ innate and adaptive lymphocytes, including ILC3, γδ T, iNKT, Th17 and Th22 cells and some granulocytes. IL-22 receptor is expressed primarily by non-haematopoietic cells. IL-22 is critical for barrier immunity at the mucosal surfaces in the steady state and during infection. Although IL-22 knockout mice were previously shown to develop experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis (MS), how temporal IL-22 manipulation in adult mice would affect EAE course has not been studied previously. In this study, we overexpressed IL-22 via hydrodynamic gene delivery or blocked it via neutralizing antibodies in C57BL/6 mice to explore the therapeutic impact of IL-22 modulation on the EAE course. IL-22 overexpression significantly decreased EAE scores and demyelination, and reduced infiltration of IFN-γ+IL-17A+Th17 cells into the central nervous system (CNS). The neutralization of IL-22 did not alter the EAE pathology significantly. We show that IL-22-mediated protection is independent of Reg3γ, an epithelial cell-derived antimicrobial peptide induced by IL-22. Thus, overexpression of Reg3γ significantly exacerbated EAE scores, demyelination and infiltration of IFN-γ+IL-17A+ and IL-17A+GM-CSF+Th17 cells to CNS. We also show that Reg3γ may inhibit IL-2-mediated STAT5 signalling and impair expansion of Treg cells in vivo and in vitro. Finally, Reg3γ overexpression dramatically impacted intestinal microbiota during EAE. Our results provide novel insight into the role of IL-22 and IL-22-induced antimicrobial peptide Reg3γ in the pathogenesis of CNS inflammation in a murine model of MS.

A genome-scale CRISPR screen reveals factors regulating Wnt-dependent renewal of mouse gastric epithelial cells

An ability to safely harness the powerful regenerative potential of adult stem cells for clinical applications is critically dependent on a comprehensive understanding of the underlying mechanisms regulating their activity. Epithelial organoid cultures accurately recapitulate many features of in vivo stem cell-driven epithelial renewal, providing an excellent ex vivo platform for interrogation of key regulatory mechanisms. Here, we employed a genome-scale clustered, regularly interspaced, short palindromic repeats (CRISPR) knockout (KO) screening assay using mouse gastric epithelial organoids to identify modulators of Wnt-driven stem cell-dependent epithelial renewal in the gastric mucosa. In addition to known Wnt pathway regulators, such as Apc, we found that KO of Alk, Bclaf3, or Prkra supports the Wnt independent self-renewal of gastric epithelial cells ex vivo. In adult mice, expression of these factors is predominantly restricted to non-Lgr5-expressing stem cell zones above the gland base, implicating a critical role for these factors in suppressing self-renewal or promoting differentiation of gastric epithelia. Notably, we found that Alk inhibits Wnt signaling by phosphorylating the tyrosine of Gsk3β, while Bclaf3 and Prkra suppress regenerating islet-derived (Reg) genes by regulating the expression of epithelial interleukins. Therefore, Alk, Bclaf3, and Prkra may suppress stemness/proliferation and function as novel regulators of gastric epithelial differentiation.

Myocardial Accumulations of Reg3A, Reg3γ and Oncostatin M Are Associated with the Formation of Granulomata in Patients with Cardiac Sarcoidosis

Cardiac sarcoidosis (CS) is a poorly understood disease and is characterized by the focal accumulation of immune cells, thus leading to the formation of granulomata (GL). To identify the developmental principles of fatal GL, fluorescence microscopy and Western blot analysis of CS and control patients is presented here. CS is visualized macroscopically by positron emission tomography (PET)/ computed tomography (CT). A battery of antibodies is used to determine structural, cell cycle and inflammatory markers. GL consist of CD68⁺, CD163⁺ and CD206⁺ macrophages surrounded by T-cells within fibrotic areas. Cell cycle markers such as phospho-histone H3, phospho-Aurora and Ki67 were moderately present; however, the phosphorylated ERM (ezrin, radixin and moesin) and Erk1/2 proteins, strong expression of the myosin motor protein and the macrophage transcription factor PU.1 indicate highly active GL. Mild apoptosis is consistent with PI3 kinase and Akt activation. Massive amounts of the IL-1R antagonist reflect a mild activation of stress and inflammatory pathways in GL. High levels of oncostatin M and the Reg3A and Reg3γ chemokines are in accordance with macrophage accumulation in areas of remodeling cardiomyocytes. We conclude that the formation of GL occurs mainly through chemoattraction and less by proliferation of macrophages. Furthermore, activation of the oncostatin/Reg3 axis might help at first to wall-off substances but might initiate the chronic development of heart failure.

Mechanisms and regulation of IL-22-mediated intestinal epithelial homeostasis and repair

AIMS

Ulcerative colitis and Crohn's disease, collectively known as inflammatory bowel disease (IBD), are chronic inflammatory disorders of the intestine for which key elements in disease initiation and perpetuation are defects in epithelial barrier integrity. Achieving mucosal healing is essential to ameliorate disease outcome and so new therapies leading to epithelial homeostasis and repair are under investigation. This study was designed to determine the mechanisms by which IL-22 regulates intestinal epithelial cell function.

MAIN METHODS

Human intestinal organoids and resections, as well as mice were used to evaluate the effect of IL-22 on stem cell expansion, proliferation and expression of mucus components. IL-22 effect on barrier function was assessed in polarized T-84 cell monolayers. Butyrate co-treatments and organoid co-cultures with immune cells were performed to monitor the impact of microbial-derived metabolites and inflammatory environments on IL-22 responses.

KEY FINDINGS

IL-22 led to epithelial stem cell expansion, proliferation, barrier dysfunction and anti-microbial peptide production in human and mouse models evaluated. IL-22 also altered the mucus layer by inducing an increase in membrane mucus but a decrease in secreted mucus and goblet cell content. IL-22 had the same effect on anti-microbial peptides and membrane mucus in both healthy and IBD human samples. In contrast, this IL-22-associated epithelial phenotype was different when treatments were performed in presence of butyrate and organoids co-cultured with immune cells.

SIGNIFICANCE

Our data indicate that IL-22 promotes epithelial regeneration, innate defense and membrane mucus production, strongly supporting the potential clinical utility of IL-22 as a mucosal healing therapy in IBD.

Role of the β-Catenin/REG Iα Axis in the Proliferation of Sessile Serrated Adenoma/Polyps Associated with Fusobacterium nucleatum

Although sessile serrated adenoma/polyps (SSA/Ps) may arise through a pathway different from the traditional adenoma–carcinoma sequence, details of SSA/P tumorigenesis still remain unclear. Fusobacterium nucleatum (Fn) is frequently detected in colorectal cancer (CRC) tissues and may play a pivotal role in colorectal carcinogenesis. Here, we investigated the relationship between Fn and the β-catenin/REG Iα axis in SSA/Ps and their involvement in the proliferation of these lesions. Fn was detected in SSA/Ps by fluorescence in situ hybridization using a Fn-targeted probe, and expression of β-catenin, REG Iα and Ki67 was examined using immunohistochemistry. Sixteen of 30 SSA/P lesions (53.3%) were positive for Fn. Eighteen SSA/P lesions (60%) showed β-catenin immunoreactivity in the tumor cell nuclei. A significant majority of Fn-positive lesions showed nuclear expression of β-catenin (87.5%) and higher REG Iα scores and Ki67 labeling indices relative to Fn-negative lesions. The SSA/P lesions expressing β-catenin in nuclei had significantly higher REG Iα scores and Ki67 labeling indices than those expressing β-catenin on cytomembranes. The REG Iα score was positively correlated with the Ki67 labeling index in SSA/P lesions. The treatment with Wnt agonist SKL2001 promoted nuclear β-catenin translocation and enhanced REG Ia expression in Caco2 cells. Fn may play a role in the proliferation of SSA/P lesions through promotion of β-catenin nuclear translocation and REG Iα expression.

Blood Biomarkers of Intestinal Epithelium Damage Regenerating Islet-derived Protein 3α and Trefoil Factor 3 Are Persistently Elevated in Patients with Alcoholic Hepatitis

BACKGROUND

Heavy alcohol consumption disrupts gut epithelial integrity, leading to increased permeability of the gastrointestinal tract and subsequent translocation of microbes. Regenerating islet-derived protein 3α (REG3α) and Trefoil factor 3 (TFF3) are mainly secreted to the gut lumen by Paneth and Goblet cells, respectively, and are functionally linked to gut barrier integrity. Circulating levels of REG3α and TFF3 have been identified as biomarkers for gut damage in several human diseases. We examined whether plasma levels of REG3α and TFF3 were dysregulated and correlated with conventional markers of microbial translocation (MT) and pro-inflammatory mediators in heavy drinkers with and without alcoholic hepatitis (AH).

METHODS

Cross-sectional and longitudinal studies were performed to monitor plasma levels of REG3α and TFF3 in 79 AH patients, 66 heavy drinkers without liver disease (HDC), and 46 healthy controls (HC) at enrollment and at 6- and 12-month follow-ups. Spearman correlation was used to measure the relationships of REG3α and TFF3 levels with MT, disease severity, inflammation, and effects of abstinence from alcohol.

RESULTS

At enrollment, AH patients had significantly higher levels of REG3α and TFF3 than HDC and HC. The elevated REG3α levels were positively correlated with the 30-day fatality rate. Plasma levels of REG3α and TFF3 in AH patients differentially correlated with conventional MT markers (sCD14, sCD163, and LBP) and several highly up-regulated inflammatory cytokines/chemokines/growth factors. At follow-ups, although REG3α and TFF3 levels were decreased in AH patients with alcohol abstinence, they did not fully return to baseline levels.

CONCLUSIONS

Circulating levels of REG3α and TFF3 were highly elevated in AH patients and differentially correlated with AH disease severity, MT, and inflammation, thereby serving as potential biomarkers of MT and gut epithelial damage in AH patients.

Bioactive potential of natural biomaterials: identification, retention and assessment of biological properties

Biomaterials have had an increasingly important role in recent decades, in biomedical device design and the development of tissue engineering solutions for cell delivery, drug delivery, device integration, tissue replacement, and more. There is an increasing trend in tissue engineering to use natural substrates, such as macromolecules native to plants and animals to improve the biocompatibility and biodegradability of delivered materials. At the same time, these materials have favourable mechanical properties and often considered to be biologically inert. More importantly, these macromolecules possess innate functions and properties due to their unique chemical composition and structure, which increase their bioactivity and therapeutic potential in a wide range of applications. While much focus has been on integrating these materials into these devices via a spectrum of cross-linking mechanisms, little attention is drawn to residual bioactivity that is often hampered during isolation, purification, and production processes. Herein, we discuss methods of initial material characterisation to determine innate bioactivity, means of material processing including cross-linking, decellularisation, and purification techniques and finally, a biological assessment of retained bioactivity of a final product. This review aims to address considerations for biomaterials design from natural polymers, through the optimisation and preservation of bioactive components that maximise the inherent bioactive potency of the substrate to promote tissue regeneration.

Human Lectins, Their Carbohydrate Affinities and Where to Find Them

Lectins are a class of proteins responsible for several biological roles such as cell-cell interactions, signaling pathways, and several innate immune responses against pathogens. Since lectins are able to bind to carbohydrates, they can be a viable target for targeted drug delivery systems. In fact, several lectins were approved by Food and Drug Administration for that purpose. Information about specific carbohydrate recognition by lectin receptors was gathered herein, plus the specific organs where those lectins can be found within the human body.

Protective and anti-inflammatory role of REG1A in inflammatory bowel disease induced by JAK/STAT3 signaling axis

Regenerating islet-derived protein 1-alpha (REG1A) was abnormally upregulated in a series of gastrointestinal inflammatory disorders. However, the potential biological function and underlying regulatory mechanisms of the increased REG1A in inflammatory bowel disease (IBD) pathogenesis remain to be fully elucidated. In this study, we uncovered that REG1A was substantially increased in the inflamed colorectal tissues of IBD patients. And the aberrantly expressed REG1A in intestinal epithelial cells (IEC) prominently inhibited inflammatory responses, promoted cell proliferation and suppressed epithelial apoptosis. Mechanically, IL-6 and IL-22 markedly activated REG1A transcription through triggering JAK/STAT3 signaling pathway. In addition, overexpression of REG1A in mice by systematic delivery of REG1A lentivirus remarkably alleviated DSS-induced inflammatory injury and maintained the integrity of intestinal mucosal barrier. Taken together, our data demonstrated that the novel proliferative factor REG1A controlled by IL-6/IL-22-JAK-STAT3 signaling may provide a promising therapeutic target for patients with IBD.

Re-expression of REG family and DUOXs genes in CRC organoids by co-culturing with CAFs

Organoids derived from epithelial tumors have recently been utilized as a preclinical model in basic and translational studies. This model is considered to represent the original tumor in terms of 3D structure, genetic and cellular heterogeneity, but not tumor microenvironment. In this study, we established organoids and paired cancer-associated fibroblasts (CAFs) from surgical specimens of colorectal carcinomas (CRCs), and evaluated gene expression profiles in organoids with and without co-culture with CAFs to assess interactions between tumor cells and CAFs in tumor tissues. We found that the expression levels of several genes, which are highly expressed in original CRC tissues, were downregulated in organoids but re-expressed in organoids by co-culturing with CAFs. They comprised immune response- and external stimulus-related genes, e.g., REG family and dual oxidases (DUOXs), which are known to have malignant functions, leading tumor cells to proliferative and/or anti-apoptotic states and drug resistant phenotypes. In addition, the degree of differential induction of REG1 and DUOX2 in the co-culture system varied depending on CAFs from each CRC case. In conclusion, the co-culture system of CRC organoids with paired CAFs was able to partially reproduce the tumor microenvironment.

Reg3β: A Potential Therapeutic Target for Tissue Injury and Inflammation-Associated Disorders

Since regenerating islet-derived 3β (Reg3β) was first reported, various studies have been conducted to explore the involvement of Reg3β in a gamut of maladies, such as diabetes, pancreatitis, pancreatic ductal adenocarcinoma, and extrapancreatic maladies such as inflammatory bowel disease, acute liver failure, and myocardial infarction. Surprisingly, there is currently no systematic review of Reg3β. Therefore, we summarize the structural characteristics, transcriptional regulation, putative receptors, and signaling pathways of Reg3β. The exact functional roles in various diseases, especially gastrointestinal and liver diseases, are also discussed. Reg3β plays multiple roles in promoting proliferation, inducing differentiation, preventing apoptosis, and resisting bacteria. The present review may provide new directions for the diagnosis and treatment of gastrointestinal, liver, and pancreatic diseases.