Novel Circulating and Tissue Monocytes as Well as Macrophages in Pancreatitis and Recovery

Exploring the mechanism of intestinal bacterial translocation after severe acute pancreatitis: the role of Toll-like receptor 5

Severe acute pancreatitis (SAP)-induced intestinal bacterial translocation and enterogenic infection are among the leading causes of mortality in patients. However, the mechanisms by which SAP disrupted the intestinal barrier and led to bacterial translocation remained unclear. Therefore, we employed multi-omics analysis including microbiome, metabolome, epigenome, transcriptome, and mass cytometry (CyTOF) to identify potential targets, followed by functional validation using transgenic mice. The integrated multi-omics analysis primarily indicated overgrowth of intestinal flagellated bacteria, upregulation of intestinal Toll-like receptor 5 (TLR5) and acute inflammatory response, and increased infiltration of intestinal high-expressing TLR5 lamina propria dendritic cells (TLR5hi LPDC) after SAP. Subsequently, intestinal flagellin-TLR5 signaling was activated after SAP. Intestinal barrier disruption, bacterial translocation, and helper T cells (Th) differentiation imbalance caused by SAP were alleviated in TLR5 knocked out (Tlr5-/-) or conditionally knocked out on LPDC (Tlr5ΔDC) mice. However, TLR5 conditional knockout on intestinal epithelial cells (Tlr5ΔIEC) failed to improve SAP-induced bacterial translocation. Moreover, depletion of LPDC and regulatory T cells (Treg) ameliorated bacterial translocation after SAP. Our findings identify TLR5 on LPDC as a potential novel target for preventing or treating intestinal bacterial translocation caused by SAP.

Identification of Grb2 protein as a potential mediator of macrophage activation in acute pancreatitis based on bioinformatics and experimental verification

Introduction

Macrophage activation is closely associated with Acute pancreatitis (AP). We screened and found that Growth factor receptor bound protein 2 (Grb2) is highly expressed in macrophages during AP. However, the relationship between Grb2 and AP is still poorly understood. In this study, we explored the role of Grb2 in AP.

Methods

We screened for gene affecting macrophage activation in AP by combining transcriptomics with Single-cell RNA-sequence analysis. Next, the expression of Grb2 in M1/M2 macrophage activation was detected by Single-cell RNA-sequence analysis and western blot. Furthermore, the effect of Grb2 on M1/M2 macrophage activation was detected by flow cytometry. The severity of AP was assessed by histological analysis, serum amylase, serum lipase and serum inflammatory factors in vivo. NOD-like receptor thermal protein domain associated protein 3 (Nlrp3) and Nuclear factor kappa-B (NF-kB) signaling pathways were also evaluated.

Results

Grb2 is mainly expressed in macrophages of pancreas in AP and up-regulated in M1 macrophage activation. Inhibiting Grb2 could alleviate AP by preventing M1 macrophage activation through down-regulating Nlrp3 and NF-κB.

Discussion

Inhibition of Grb2 can effectively prevent M1 macrophage activation and alleviate AP. Grb2 may potentially be an effective target of macrophage activation for the treatment of AP.

Annexin A1 regulates inflammatory-immune response and reduces pancreatic and extra- pancreatic injury during severe acute pancreatitis

Severe acute pancreatitis (SAP) poses significant challenges due to its complex pathophysiology, which includes inflammatory-immune responses that cause considerable damage to both the pancreas and other tissues. In this study, we explored the role of Annexin A1 (Anxa1), a glucocorticoid-regulated protein recognized for its anti-inflammatory properties, in regulating inflammation during acute pancreatitis. Using flow cytometry, single-cell RNA sequencing, and gene expression analysis, we examined how Anxa1 expression is regulated in myeloid cells throughout acute pancreatitis, employing various animal models to evaluate the consequences of modulating Anxa1 on injuries induced by SAP. Our findings revealed dynamic regulation of Anxa1 expression in myeloid cells, with mice lacking Anxa1 exhibiting worsened pancreatic injury and heightened systemic inflammation, resulting in significant damage to extra-pancreatic organs such as the lungs, liver, and kidneys. In contrast, treatment with Ac2-26, a synthetic peptide derived from Anxa1, effectively mitigated both pancreatic and extra-pancreatic inflammation and tissue damage. Overall, this study highlights the critical role of Anxa1 in modulating inflammatory responses during acute pancreatitis. Targeting Anxa1 presents a promising therapeutic strategy to mitigate pancreatic injury and prevent systemic complications associated with severe acute pancreatitis.

Mass cytometric analysis of circulating monocyte subsets in a murine model of diabetic gastroparesis

Circulating monocytes (Mo) are precursors to a subset of gastric resident muscularis macrophages. Changes in muscularis macrophages (MMs) result in delayed gastric emptying (DGE) in diabetic gastroparesis. However, the dynamics of Mo in the development of DGE in an animal model are unknown. Using cytometry by time-of-flight and computational approaches, we show a high heterogeneity within the Mo population. In DGE mice, via unbiased clustering, we identified two reduced Mo clusters that exhibit migratory phenotype (Ly6ChiCCR2hi-intCD62LhiLy6GhiCD45RhiMERTKhiintLGALS3intCD14intCX3CR1lowSiglec-Hint-low) resembling classical Mo (CMo-like). All markers enriched in these clusters are known to regulate cell differentiation, proliferation, adhesion, and migration. Trajectory inference analysis predicted these Mo as precursors to subsequent Mo lineages. In gastric muscle tissue, we demonstrated an increase in the gene expression levels of chemokine receptor C-C chemokine receptor type 2 (Ccr2) and its C-C motif ligand 2 (Ccl2), suggesting increased trafficking of classical-Mo. These findings establish a link between two CMo-like clusters and the development of the DGE phenotype and contribute to a better understanding of the heterogenicity of the Mo population.NEW & NOTEWORTHY Using 32 immune cell surface markers, we identified 23 monocyte clusters in murine blood. Diabetic gastroparesis was associated with a significant decrease in two circulating classical monocyte-like clusters and an upregulation of the Ccr2-Ccl2 axis in the gastric muscularis propria, suggesting increased tissue monocyte migration. This study offers new targets by pointing to a possible role for two classical monocyte subsets connected to the Ccr2-Ccl2 axis.

Dietary emulsifier carboxymethylcellulose-induced gut dysbiosis and SCFA reduction aggravate acute pancreatitis through classical monocyte activation

OBJECTIVE

Carboxymethylcellulose (CMC), one of the most common emulsifiers used in the food industry, has been reported to promote chronic inflammatory diseases, but its impact on acute inflammatory diseases, e.g., acute pancreatitis (AP), remains unclear. This study investigates the detrimental effects of CMC on AP and the potential for mitigation through Akkermansia muciniphila or butyrate supplementation.

DESIGN

C57BL/6 mice were given pure water or CMC solution (1%) for 4 weeks and then subjected to caerulein-induced AP. The pancreas, colon, and blood were sampled for molecular and immune parameters associated with AP severity. Gut microbiota composition was assessed using 16S rRNA gene amplicon sequencing. Fecal microbiota transplantation (FMT) was used to illustrate gut microbiota's role in mediating the effects of CMC on host mice. Additional investigations included single-cell RNA sequencing, monocytes-specific C/EBPδ knockdown, LPS blocking, fecal short-chain fatty acids (SCFAs) quantification, and Akkermansia muciniphila or butyrate supplementation. Finally, the gut microbiota of AP patients with different severity was analyzed.

RESULTS

CMC exacerbated AP with gut dysbiosis. FMT from CMC-fed mice transferred such adverse effects to recipient mice, while single-cell analysis showed an increase in classical monocytes in blood. LPS-stimulated C/EBPδ, caused by an impaired gut barrier, drives monocytes towards classical phenotype. LPS antagonist (eritoran), Akkermansia muciniphila or butyrate supplementation ameliorates CMC-induced AP exacerbation. Fecal Akkermansia muciniphila abundance was negatively correlated with AP severity in patients.

CONCLUSIONS

This study reveals the detrimental impact of CMC on AP due to gut dysbiosis, with Akkermansia muciniphila or butyrate offering potential therapeutic avenues for counteracting CMC-induced AP exacerbation. Video Abstract.

Multi-omics profiles reveal immune microenvironment alterations associated with PD-L1 checkpoint in acute pancreatitis in the early phase

BACKGROUND

Acute pancreatitis (AP) initiates as primarily sterile local inflammation that triggers pro-inflammatory response, which is subsequently counterbalanced by an anti-inflammatory response. Immune checkpoints, such as PD-1/PD-L1, play a pivotal role in modulating these responses to prevent excessive immune activation and associated inflammatory damage. This study aimed to investigate the underlying mechanisms of these processes in both murine and human AP.

METHODS

We conducted a comprehensive integration of data from cerulein-induced AP mouse models (CER-AP), utilizing single-cell RNA sequencing and digital spatial profiling for pancreatic samples, as well as single-cell Cytometry by Time Of Flight (CyTOF) for blood samples. Additionally, bulk-RNA sequencing performed on blood samples from AP patients was employed to investigate innate and adaptive immune changes at early stage of the disease.

RESULTS

Across the four analytical approaches, we observed consistent immune cell type distributions. Our integrative analysis revealed a significant imbalance between increased innate immune cells, including neutrophils, macrophages, and monocytes, and decreased adaptive immune cells, including CD4+ and CD8+ T cells, in early-stage AP. Notably, the PD-1/PD-L1 related pathway exhibited substantial alterations, especially in the acinar cells, T cells, B cells, macrophages, and neutrophils at the early stage of disease. Moreover, we observed a significant reduction in PD-L1 expression in the blood and regulatory T cells of CyTOF mice at the CyTOF level.

CONCLUSION

This multi-omics analysis deciphers a distinct imbalance between increased innate immunity and decreased adaptive immunity during the early phase of AP. The PD-L1 checkpoint emerges as a key regulator of immune homeostasis and a critical factor in the pathogenesis of AP.

SIRT5 mediated succinylation of SUCLA2 regulates TCA cycle dysfunction and mitochondrial damage in pancreatic acinar cells in acute pancreatitis

Acute pancreatitis (AP) is a severe inflammatory disorder associated with metabolic reprogramming and mitochondrial dysfunction. This study investigated central carbon metabolism alterations in pancreatic acinar cells during AP, elucidated the molecular mechanisms of tricarboxylic acid (TCA) cycle disorders, and explored the role of protein hypersuccinylation in AP pathogenesis. Using in vitro and in vivo AP models, targeted metabolomics and bioinformatics analyses revealed TCA cycle dysregulation characterized by elevated succinyl-CoA and decreased succinate levels. Colorimetric assays, mass spectrometry, and site-directed mutagenesis demonstrated that SIRT5 downregulation led to SUCLA2 hypersuccinylation at K118, inhibiting succinyl-CoA synthetase activity and triggering a vicious cycle of succinyl-CoA accumulation and SUCLA2 succinylation. Adenovirus-mediated SIRT5 overexpression and SUCLA2 knockdown clarified the SIRT5-SUCLA2 pathway's role in regulating TCA cycle disorders. Protein succinylation levels positively correlated with pancreatic tissue damage and mitochondrial injury severity. Succinylome analysis identified cytochrome c1 (CYC1) as a key hypersuccinylated protein, and the SIRT5-SUCLA2 pathway regulated its succinylation level and electron transport chain complex III activity. Hypersuccinylation induced mitochondrial DNA release, activating the cGAS-STING pathway, contributing to multiple organ dysfunction syndrome. Modulating the SIRT5-SUCLA2 axis attenuated TCA cycle dysregulation, protein hypersuccinylation, mitochondrial damage, and inflammatory responses in AP. These findings reveal novel mechanisms linking the SIRT5-SUCLA2 axis, TCA cycle dysfunction, and protein hypersuccinylation in AP pathogenesis, providing potential therapeutic targets for AP treatment.

CIP2A inhibitors TD52 and Ethoxysanguinarine promote macrophage autophagy and alleviates acute pancreatitis by modulating the AKT-mTOR pathway

BACKGROUND

Acute pancreatitis (AP) is a prevalent and serious condition within the digestive system, with approximately 20 % to 30 % of cases advancing to severe acute pancreatitis (SAP). During the initial phases of SAP, macrophages are activated in response to the substantial amounts of acinar cell contents and damage-associated molecular patterns (DAMPs) resulting from acinar cell destruction. Subsequently, activated macrophages release a significant array of pro-inflammatory factors that exacerbate the progression of SAP. Cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncogenic protein that is intimately linked to immune regulation. While the role of CIP2A in T-cell-mediated specific immune responses has been reported, its function and mechanism in macrophages, a component of non-specific immunity, have not been widely studied. This research fills this knowledge gap by elucidating the critical role of CIP2A in regulating macrophage autophagy and inflammation. This finding not only expands our understanding of CIP2A in immune modulation but also provides a new scientific basis and potential application prospects for targeting CIP2A in the treatment of AP.

METHODS

We established AP using a combination of palmitoleic acid with anhydrous ethanol or using caerulein alone. The effects of TD52 and Ethoxysanguinarine (Etho) on SAP were evaluated through serological, histopathological, and tissue inflammation observations. The effect of TD52 on macrophage activation in vitro was examined using primary macrophages (PMs) and RAW264.7 cells.

RESULTS

We found that TD52 and Etho inhibit CIP2A expression while reducing the levels of serum amylase, lipase, and inflammatory cytokines, thereby alleviating the pathological symptoms of SAP. Additionally, TD52 could reduce the infiltration of macrophages into pancreatic tissue. Therefore, we established a model of macrophage inflammatory response mimicking the pathophysiological process of AP and detected changes in inflammation, apoptosis, and autophagy through pre-treatment of macrophages with TD52. The results show that inhibiting CIP2A expression decreases the release of inflammatory cytokines and reduces apoptosis in macrophages. Further exploration revealed that TD52 promoted macrophage autophagy regulation and inhibited the AKT-mTOR pathway to modulate macrophage activation.

CONCLUSION

In summary, our findings indicate that TD52 and Etho can alleviate the severity of SAP. TD52 can block the AKT-mTOR pathway to promote macrophage autophagy, thereby improving SAP. Thus, CIP2A may serve as one of the molecular targets in SAP, highlighting its potential as a therapeutic option.

ATP citrate lyase ablation hampers exocrine regeneration via TLR4/NF-kappaB signaling after acute pancreatitis in mice

BACKGROUND

ATP citrate lyase (Acly) is widely expressed in many tissues, has been proved to be involved in the pathogenesis of many inflammatory diseases. So far, the importance of Acly in acute pancreatitis(AP) has not been clearly determined. The purpose of this study is to clarify whether Acly can evoke inflammatory cascades in the progression of AP and hamper the subsequent regeneration process of pancreas.

METHODS

Experimental pancreatitis in mice with a specific deficiency of Acly in the pancreas and in control mice through repetitive cerulein injections in vivo. The pancreas pathological grading, cell proliferative potential and the formation of acinar-to-ductal metaplasia (ADM) were evaluated. The levels of inflammatory cytokines in plasma were qualified by enzyme-linked immuno sorbent assay (ELISA). Pancreatic malondialdehyde (MDA), superoxide dismutase (SOD) activity and reduced glutathione (GSH) contents were measured for oxidative stress. The infiltration of macrophages and neutrophils, the expression of Toll like receptor 4 (TLR4), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and the activation of nuclear factor kappaB (NF-κB) and cleaved Caspase-3, were measured using immunostaining. The mRNA transcription levels of TLR4, TNF-α, and IL-1β in pancreatic tissues were detected by quantitative real-time PCR as well. Additionally, inhibition of TLR4 signaling by TAK-242 in AP mice with a pancreas-specific deletion of Acly was conducted in vivo.

RESULTS

The results demonstrated that the elimination of pancreatic Acly not only exacerbated the severity of pancreatitis in mice during the initial inflammatory phase, as evidenced by more severe pathological damage, but also impeded the healing process of the exocrine pancreas by enhancing the formation of ADM and decreasing the ability of acinar cells to proliferate. In addition, deficiency of Acly increased the circulating TNF-α, IL-1β and IL-6, the infiltration of macrophages and neutrophils, agumented the activation of nuclear factor kappaB (NF-κB) p65, the expression of TLR4, TNF-α, IL-1β and cleaved Caspase-3, and exacerbated excessive oxidative stress in the pancreas at specific time points of AP mice. However, TLR4 inhibition significantly attenuated the structural and functional damage of the pancreas induced by AP in mice with a pancreas-specific deletion of Acly, as indicated by improvement of the above indexes.

CONCLUSIONS

The present study demonstrated that ablation of pancreatic Acly intensified inflammatory reaction and cell death, and dampened exocrine regeneration following AP, due to the positive regulation of TLR4/NF-κB signaling activation.

Bone marrow mesenchymal stem cell-derived exosomal miR-181a-5p promotes M2 macrophage polarization to alleviate acute pancreatitis through ZEB2-mediated RACK1 ubiquitination

As a common digestive disease, acute pancreatitis (AP) often threatens the life of patients. Bone marrow mesenchymal stem cells (BMSCs) derived exosomes have exhibited some benefits for AP. However, the mechanism remains unclear and deserves to be further investigated. The characteristics of BMSCs-exosomes (BMSCs-Exos) were identified. The abundance of genes and proteins was evaluated using quantitative real-time PCR (RT-qPCR), western blot, enzyme-linked immunosorbent assay (ELISA) and IF assay. Cell apoptosis and CD206-positive cells were measured by flow cytometry. The interactions among miR-181a-5p, Zinc finger E-box binding homeobox 2 (ZEB2) and Receptor for Activated C Kinase 1 (RACK1) were verified using dual luciferase reporter assay, RNA immunoprecipitation (RIP), coimmunoprecipitation (Co-IP). BMSCs-Exos effectively improved AP injury through restraining AR42J cell apoptosis and promoting M2 macrophage polarization, which was realized due to BMSCs-Exos harboring an abundance of miR-181a-5p. Further experiments validated miR-181a-5p silenced ZEB2 and ZEB2 reduced RACK1 expression through mediating RACK1 ubiquitination. ZEB2 knockdown decreased AR42J cell apoptosis and induced M2 macrophage polarization to alleviate AP injury, whereas RACK1 downregulation abolished these phenomena. BMSCs-Exos harboring miR-181a-5p suppressed AR42J cell apoptosis and promoted M2 macrophage polarization to delay AP progression through ZEB2-mediated RACK1 ubiquitination.

A causal relationship between distinct immune features and acute or chronic pancreatitis: results from a mendelian randomization analysis

OBJECTIVES

This study aimed to thoroughly examining the causal link between immune traits and four types of pancreatitis, using mendelian randomization.

METHODS

Data on 731 immune traits were collected from the genome-wide association study (GWAS) database as exposure. Information regarding acute pancreatitis (AP), alcohol-induced acute pancreatitis (AAP), chronic pancreatitis (CP), and alcohol-induced chronic pancreatitis (ACP) were acquired from the FinnGen Consortium as outcomes. Mendelian randomization (MR) using inverse variance weighting (IVW) evaluated the links between immune traits and pancreatitis. We evaluated the robustness of the IVW results through sensitivity analyses and validated them using meta-analysis with AP and CP data from the UK Biobank in the GWAS catalog.

RESULTS

A total of 36 immune traits showed significant associations with susceptibility of four types of pancreatitis, including AP (7 traits), AAP (8 traits), CP (14 traits), and ACP (7 traits). Twenty characteristics were found to be potential risk factors for pancreatitis, identified in B Cells (5 traits), conventional dendritic cells (cDCs, 2 traits), maturation stage of T cells (2 traits), monocytes (2 traits), myeloid cells (2 traits), T cells, B cells, natural killer cells (TBNK, 2 traits), and regulatory T cells (Treg cells, 5 traits). Multiple sensitivity analyses confirmed the validity of the findings. Meta-analysis confirmed a solid causal relationship between CX3CR1 on CD14- CD16-of monocyte panel and the susceptibility of CP.

CONCLUSIONS

Our MR study identified immune traits causally linked to acute and chronic pancreatitis, offering new insights for early clinical intervention and immune cell-targeted therapies.

Prognostic significance and gene co-expression network of CD16A and FGL2 in gliomas

Introduction

The CD16A protein encoding gene FcγRIIIa (FCGR3A) and its potential ligand Fibrinogen-like protein 2 (FGL2) are involved in various cell physiological activities on the extracellular surface. Aberrant expression of these genes has been linked to tumorigenesis.

Methods

To assess the prognostic significance of FCGR3A and FGL2 transcription expression in glioma and explore their roles in glioma initiation and progression, we utilized multiple online databases, including TCGA, GEPIA, CGGA, cBioPortal, TISCH, LinkedOmics, Ivy Glioblastoma Atlas Project, and Human Protein Atlas.

Results

Our analysis revealed that FCGR3A and FGL2 expression was significantly correlated with clinical variables such as age, tumor type, WHO grade, histology, IDH-1 mutation, and 1p19q status. A strong correlation was also observed between the transcriptional expression levels of FCGR3A and FGL2. High expression of both genes predicted poor prognosis in primary and recurrent glioma patients, particularly those with lower grade gliomas. Cox regression analysis further confirmed that elevated expression of FCGR3A and FGL2 were independent prognostic factors for shorter overall survival in glioma patients. Gene co-expression network analysis suggested that FCGR3A, FGL2, and their co-expressed genes were involved in inflammatory activities and tumor-related signaling pathways. Additionally, tissue microarrays from glioma patients at Tiantan Hospital showed significantly higher FCGR3A protein expression in high-grade gliomas compared to low-grade gliomas.

Discussion

In conclusion, our findings suggest that FCGR3A and FGL2 could serve as promising prognostic biomarkers and potential therapeutic targets for glioma patients.

Altered immune cell in human severe acute pancreatitis revealed by single-cell RNA sequencing

Background

Severe acute pancreatitis (SAP) is characterized by inflammation, with inflammatory immune cells playing a pivotal role in disease progression. This study aims to understand variations in specific immune cell subtypes in SAP, uncover their mechanisms of action, and identify potential biological markers for predicting Acute Pancreatitis (AP) severity.

Methods

We collected peripheral blood from 7 untreated SAP patients and employed single-cell RNA sequencing for the first time to construct a transcriptome atlas of peripheral blood mononuclear cells (PBMCs) in SAP. Integrating SAP transcriptomic data with 6 healthy controls from the GEO database facilitated the analysis of immune cell roles in SAP. We obtained comprehensive transcriptomic datasets from AP samples in the GEO database and identified potential biomarkers associated with AP severity using the "Scissor" tool in single-cell transcriptomic data.

Results

This study presents the inaugural construction of a peripheral blood single-cell atlas for SAP patients, identifying 20 cell subtypes. Notably, there was a significant decrease in effector T cell subsets and a noteworthy increase in monocytes compared to healthy controls. Moreover, we identified a novel monocyte subpopulation expressing high levels of PPBP and PF4 which was significantly elevated in SAP. The proportion of monocyte subpopulations with high CCL3 expression was also markedly increased compared to healthy controls, as verified by flow cytometry. Additionally, cell communication analysis revealed insights into immune and inflammation-related signaling pathways in SAP patient monocytes. Finally, our findings suggest that the subpopulation with high CCL3 expression, along with upregulated pro-inflammatory genes such as S100A12, IL1B, and CCL3, holds promise as biomarkers for predicting AP severity.

Conclusion

This study reveals monocytes' crucial role in SAP initiation and progression, characterized by distinct pro-inflammatory features intricately linked to AP severity. A monocyte subpopulation with elevated PPBP and CCL3 levels emerges as a potential biomarker and therapeutic target.

Podoplanin expressing macrophages and their involvement in tertiary lymphoid structures in mouse models of Sjögren's disease

Tertiary lymphoid structures (TLSs) are formed in tissues targeted by chronic inflammation processes, such as infection and autoimmunity. In Sjögren's disease, the organization of immune cells into TLS is an important part of disease progression. Here, we investigated the dynamics of tissue resident macrophages in the induction and expansion of salivary gland TLS. We induced Sjögren's disease by cannulation of the submandibular glands of C57BL/6J mice with LucAdV5. In salivary gland tissues from these mice, we analyzed the different macrophage populations prior to cannulation on day 0 and on day 2, 5, 8, 16 and 23 post-infection using multicolored flow cytometry, mRNA gene analysis, and histological evaluation of tissue specific macrophages. The histological localization of macrophages in the LucAdV5 induced inflamed salivary glands was compared to salivary glands of NZBW/F1 lupus prone mice, a spontaneous mouse model of Sjögren's disease. The evaluation of the dynamics and changes in macrophage phenotype revealed that the podoplanin (PDPN) expressing CX3CR1+ macrophage population was increased in the salivary gland tissue during LucAdV5 induced inflammation. This PDPN+ CX3CR1+ macrophage population was, together with PDPN+CD206+ macrophages, observed to be localized in the parenchyma during the acute inflammation phase as well as surrounding the TLS structure in the later stages of inflammation. This suggests a dual role of tissue resident macrophages, contributing to both proinflammatory and anti-inflammatory processes, as well as their possible interactions with other immune cells within the inflamed tissue. These macrophages may be involved with lymphoid neogenesis, which is associated with disease severity and progression. In conclusion, our study substantiates the involvement of proinflammatory and regulatory macrophages in autoimmune pathology and underlines the possible multifaceted functions of macrophages in lymphoid cell organization.

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.

Network dynamics and therapeutic aspects of mRNA and protein markers with the recurrence sites of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease that typically manifests late patient presentation and poor outcomes. Furthermore, PDAC recurrence is a common challenge. Distinct patterns of PDAC recurrence have been associated with differential activation of immune pathway-related genes and specific inflammatory responses in their tumour microenvironment. However, the molecular associations between and within cellular components that underpin PDAC recurrence require further development, especially from a multi-omics integration perspective. In this study, we identified stable molecular associations across multiple PDAC recurrences and utilised integrative analytics to identify stable and novel associations via simultaneous feature selection. Spatial transcriptome and proteome datasets were used to perform univariate analysis, Spearman partial correlation analysis, and univariate analyses by Machine Learning methods, including regularised canonical correlation analysis and sparse partial least squares. Furthermore, networks were constructed for reported and new stable associations. Our findings revealed gene and protein associations across multiple PDAC recurrence groups, which can provide a better understanding of the multi-layer disease mechanisms that contribute to PDAC recurrence. These findings may help to provide novel association targets for clinical studies for constructing precision medicine and personalised surveillance tools for patients with PDAC recurrence.

Ferroptosis exacerbates hyperlipidemic acute pancreatitis by enhancing lipid peroxidation and modulating the immune microenvironment

Abnormal activation of ferroptosis worsens the severity of acute pancreatitis and intensifies the inflammatory response and organ damage, but the detailed underlying mechanisms are unknown. Compared with other types of pancreatitis, hyperlipidemic acute pancreatitis (HLAP) is more likely to progress to necrotizing pancreatitis, possibly due to peripancreatic lipolysis and the production of unsaturated fatty acids. Moreover, high levels of unsaturated fatty acids undergo lipid peroxidation and trigger ferroptosis to further exacerbate inflammation and worsen HLAP. This paper focuses on the malignant development of hyperlipidemic pancreatitis with severe disease combined with the core features of ferroptosis to explore and describe the mechanism of this phenomenon and shows that the activation of lipid peroxidation and the aberrant intracellular release of many inflammatory mediators during ferroptosis are the key processes that regulate the degree of disease development in patients with HLAP. Inhibiting the activation of ferroptosis effectively reduces the intensity of the inflammatory response, thus reducing organ damage in patients and preventing the risk of HLAP exacerbation. Additionally, this paper summarizes the key targets and potential therapeutic agents of ferroptosis associated with HLAP deterioration to provide new ideas for future clinical applications.

The role of Interleukin-22 in severe acute pancreatitis

Severe acute pancreatitis (SAP) begins with premature activation of enzymes, promoted by the immune system, triggering a potential systemic inflammatory response that leads to organ failure with increased mortality and a bleak prognosis. Interleukin-22 (IL-22) is a cytokine that may have a significant role in SAP. IL-22, a member of the IL-10 cytokine family, has garnered growing interest owing to its potential tissue-protective properties. Recently, emerging research has revealed its specific effects on pancreatic diseases, particularly SAP. This paper provides a review of the latest knowledge on the role of IL-22 and its viability as a therapeutic target in SAP.

Qing Xia Jie Yi Formula granules alleviated acute pancreatitis through inhibition of M1 macrophage polarization by suppressing glycolysis

ETHNOPHARMACOLOGICAL RELEVANCE

Herbal formulas from Traditional Chinese Medicine are common and well-established practice for treating acute pancreatitis (AP) patients. However, little is known about their bioactive ingredients and mechanisms, such as their targets and pathways to inhibit inflammation.

AIM OF THE STUDY

This study aimed to evaluate the effect of Qing Xia Jie Yi Formula (QXJYF) granules on AP and discuss the molecular mechanisms involved.

MATERIALS AND METHODS

Major compounds in QXJYF granules were identified using UPLC-quadrupole-Orbitrap mass spectrometry (UPLC-Q-Orbitrap MS). The effect of QXJYF granules on experimental AP models both in vitro and in vivo, and detailed mechanisms were clarified. Two AP models were induced in mice by intraperitoneally injections of caerulein or L-arginine, and QXJYF granules were used to treat AP mice in vivo. Histological evaluation of pancreas and lung, serum amylase and lipase levels, serum inflammatory cytokines, inflammatory cell infiltration and macrophage phenotype were assessed. Bone marrow derived macrophages (BMDMs) were cultured and treated with QXJYF granules in vitro. BMDM phenotype and glycolysis levels were measured. Lastly, clinical effect of QXJYF granules on AP patients was verified. Predicted severe AP (pSAP) patients eligible for inclusion were assessed for enrollment.

RESULTS

Nine major compounds were identified in QXJYF granules. Data showed that QXJYF granules significantly alleviated AP severity both in caerulein and L-arginine-induced AP models in vivo, pancreatic injury and inflammatory cell infiltration, systematic inflammation, lung injury and inflammatory cell infiltration were all improved after QXJYF treatment. QXJYF granules significantly reduced M1 macrophages during AP both in vivo and in vitro; besides, the mRNA expression levels of M1 genes such as inos, Tnfα, Il1β and Il6 were significantly lower after QXJYF treatment in M1 macrophages. Mechanistically, we found that HK2, PFKFB3, PKM, LDHα levels were increased in M1 macrophages, but significantly decreased after QXJYF treatment. Clinical data indicated that QXJYF granules could significantly reduce CRP levels and shorten the duration of organ failure, thereby reducing the incidence of SAP and preventing pSAP patients from progressing to SAP.

CONCLUSION

QXJYF granules alleviated AP through the inhibition of M1 macrophage polarization by suppressing glycolysis.

Bioinformatics and Machine Learning Methods Identified MGST1 and QPCT as Novel Biomarkers for Severe Acute Pancreatitis

Severe acute pancreatitis (SAP) is a life-threatening gastrointestinal emergency. The study aimed to identify biomarkers and investigate molecular mechanisms of SAP. The GSE194331 dataset from GEO database was analyzed using bioinformatics. Differentially expressed genes (DEGs) associated with SAP were identified, and a protein-protein interaction network (PPI) was constructed. Machine learning algorithms were used to determine potential biomarkers. Gene set enrichment analysis (GSEA) explored molecular mechanisms. Immune cell infiltration were analyzed, and correlation between biomarker expression and immune cell infiltration was calculated. A competing endogenous RNA network (ceRNA) was constructed, and biomarker expression levels were quantified in clinical samples using RT-PCR. 1101 DEGs were found, with two modules most relevant to SAP. Potential biomarkers in peripheral blood samples were identified as glutathione S-transferase 1 (MGST1) and glutamyl peptidyltransferase (QPCT). GSEA revealed their association with immunoglobulin regulation, with QPCT potentially linked to pancreatic cancer development. Correlation between biomarkers and immune cell infiltration was demonstrated. A ceRNA network consisting of 39 nodes and 41 edges was constructed. Elevated expression levels of MGST1 and QPCT were verified in clinical samples. In conclusion, peripheral blood MGST1 and QPCT show promise as SAP biomarkers for diagnosis, providing targets for therapeutic intervention and contributing to SAP understanding.

Mitochondrial (mt)DNA-cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling promotes pyroptosis of macrophages via interferon regulatory factor (IRF)7/IRF3 activation to aggravate lung injury during severe acute pancreatitis

BACKGROUND

Macrophage proinflammatory activation contributes to the pathology of severe acute pancreatitis (SAP) and, simultaneously, macrophage functional changes, and increased pyroptosis/necrosis can further exacerbate the cellular immune suppression during the process of SAP, where cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) plays an important role. However, the function and mechanism of cGAS-STING in SAP-induced lung injury (LI) remains unknown.

METHODS

Lipopolysaccharide (LPS) was combined with caerulein-induced SAP in wild type, cGAS -/- and sting -/- mice. Primary macrophages were extracted via bronchoalveolar lavage and peritoneal lavage. Ana-1 cells were pretreated with LPS and stimulated with nigericin sodium salt to induce pyroptosis in vitro.

RESULTS

SAP triggered NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation-mediated pyroptosis of alveolar and peritoneal macrophages in mouse model. Knockout of cGAS/STING could ameliorate NLRP3 activation and macrophage pyroptosis. In addition, mitochondrial (mt)DNA released from damaged mitochondria further induced macrophage STING activation in a cGAS- and dose-dependent manner. Upregulated STING signal can promote NLRP3 inflammasome-mediated macrophage pyroptosis and increase serum interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α levels and, thus, exacerbate SAP-associated LI (SAP-ALI). Downstream molecules of STING, IRF7, and IRF3 connect the mtDNA-cGAS-STING axis and the NLRP3-pyroptosis axis.

CONCLUSIONS

Negative regulation of any molecule in the mtDNA-cGAS-STING-IRF7/IRF3 pathway can affect the activation of NLRP3 inflammasomes, thereby reducing macrophage pyroptosis and improving SAP-ALI in mouse model.

Intestinal Mucosal Immune Barrier: A Powerful Firewall Against Severe Acute Pancreatitis-Associated Acute Lung Injury via the Gut-Lung Axis

The pathogenesis of severe acute pancreatitis-associated acute lung injury (SAP-ALI), which is the leading cause of mortality among hospitalized patients in the intensive care unit, remains incompletely elucidated. The intestinal mucosal immune barrier is a crucial component of the intestinal epithelial barrier, and its aberrant activation contributes to the induction of sustained pro-inflammatory immune responses, paradoxical intercellular communication, and bacterial translocation. In this review, we firstly provide a comprehensive overview of the composition of the intestinal mucosal immune barrier and its pivotal roles in the pathogenesis of SAP-ALI. Secondly, the mechanisms of its crosstalk with gut microbiota, which is called gut-lung axis, and its effect on SAP-ALI were summarized. Finally, a number of drugs that could enhance the intestinal mucosal immune barrier and exhibit potential anti-SAP-ALI activities were presented, including probiotics, glutamine, enteral nutrition, and traditional Chinese medicine (TCM). The aim is to offer a theoretical framework based on the perspective of the intestinal mucosal immune barrier to protect against SAP-ALI.

Systemic Neutrophil Gelatinase-Associated Lipocalin Alterations in Chronic Pancreatitis: A Multicenter, Cross-Sectional Study

INTRODUCTION

Chronic pancreatitis (CP) is a progressive fibroinflammatory disorder lacking therapies and biomarkers. Neutrophil gelatinase-associated lipocalin (NGAL) is a proinflammatory cytokine elevated during inflammation that binds fatty acids (FAs) such as linoleic acid. We hypothesized that systemic NGAL could serve as a biomarker for CP and, with FAs, provide insights into inflammatory and metabolic alterations.

METHODS

NGAL was measured by immunoassay, and FA composition was measured by gas chromatography in plasma (n = 171) from a multicenter study, including controls (n = 50), acute and recurrent acute pancreatitis (AP/RAP) (n = 71), and CP (n = 50). Peripheral blood mononuclear cells (PBMCs) from controls (n = 16), AP/RAP (n = 17), and CP (n = 15) were measured by cytometry by time-of-flight.

RESULTS

Plasma NGAL was elevated in subjects with CP compared with controls (area under the curve [AUC] = 0.777) or AP/RAP (AUC = 0.754) in univariate and multivariate analyses with sex, age, body mass index, and smoking (control AUC = 0.874; AP/RAP AUC = 0.819). NGAL was elevated in CP and diabetes compared with CP without diabetes ( P < 0.001). NGAL + PBMC populations distinguished CP from controls (AUC = 0.950) or AP/RAP (AUC = 0.941). Linoleic acid was lower, whereas dihomo-γ-linolenic and adrenic acids were elevated in CP ( P < 0.05). Linoleic acid was elevated in CP with diabetes compared with CP subjects without diabetes ( P = 0.0471).

DISCUSSION

Elevated plasma NGAL and differences in NGAL + PBMCs indicate an immune response shift that may serve as biomarkers of CP. The potential interaction of FAs and NGAL levels provide insights into the metabolic pathophysiology and improve diagnostic classification of CP.

KAN0438757, a novel PFKFB3 inhibitor, prevent the progression of severe acute pancreatitis via the Nrf2/HO-1 pathway in infiltrated macrophage

Acute pancreatitis (AP) is a non-infectious pancreatic enzyme-induced disorder, a life-threatening inflammatory condition that can cause multi-organ dysfunction, characterized by high morbidity and mortality. Several therapies have been employed to target this disorder; however, few happen to be effectively employable even in the early phase. PFKFB3(6-phosphofructo-2-kinase/fructose-2,6-biphosphatase-3) is a critical regulator of glycolysis and is upregulated under inflammatory, mitogenic, and hypoxia conditions. Essential information on the targeting of the inflammatory pathway will present the termination of the disorder and recovery. Herein we investigated the protective function of KAN0438757, a potent inhibitor of PFKFB3, and its mechanism of impeding AP induced in mice. KAN0438757 was confirmed to activate the Nrf2/HO-1 inflammatory signaling pathways in response to caerulein induced acute pancreatitis (CAE-AP) and fatty acid ethyl ester induced severe acute pancreatitis (FAEE-SAP). Additionally, KAN0438757 alleviated the inflammatory process in infiltrated macrophage via the Nrf2/HO-1 inflammatory signaling pathway and demonstrated a significant effect on the growth of mice with induced AP. And more importantly, KAN0438757 displayed negligible toxicity in vivo. Taken together our data suggest KAN0438757 directly suppresses the inflammatory role of PFKFB3 and induces a protective role via the Nrf2/HO-1 pathway, which could prove as an excellent therapeutic platform for SAP amelioration.

Microenvironment of pancreatic inflammation: calling for nanotechnology for diagnosis and treatment

Acute pancreatitis (AP) is a common and life-threatening digestive disorder. However, its diagnosis and treatment are still impeded by our limited understanding of its etiology, pathogenesis, and clinical manifestations, as well as by the available detection methods. Fortunately, the progress of microenvironment-targeted nanoplatforms has shown their remarkable potential to change the status quo. The pancreatic inflammatory microenvironment is typically characterized by low pH, abundant reactive oxygen species (ROS) and enzymes, overproduction of inflammatory cells, and hypoxia, which exacerbate the pathological development of AP but also provide potential targeting sites for nanoagents to achieve early diagnosis and treatment. This review elaborates the various potential targets of the inflammatory microenvironment of AP and summarizes in detail the prospects for the development and application of functional nanomaterials for specific targets. Additionally, it presents the challenges and future trends to develop multifunctional targeted nanomaterials for the early diagnosis and effective treatment of AP, providing a valuable reference for future research.

Long non-coding RNA MM2P suppresses M1-polarized macrophages-mediated excessive inflammation to prevent sodium taurocholate-induced acute pancreatitis by blocking SHP2-mediated STAT3 dephosphorylation

M1 macrophage-mediated excessive inflammatory response plays a key role in the onset and progression of acute pancreatitis (AP), and this study aimed to investigate the role and underlying mechanisms by which the macrophage polarization-related long noncoding RNA (lncRNA) MM2P participated in the regulation of AP progression. By performing quantitative reverse-transcription PCR (qRT-PCR) assay, lncRNA MM2P was found to be downregulated in both sodium taurocholate-induced AP model mice tissues and lipopolysaccharide (LPS)-stimulated RAW264.7 cells, and gain-of-function experiments confirmed that overexpression of lncRNA MM2P counteracted inflammatory responses, reduced macrophage infiltration and facilitated M1-to-M2 transformation of macrophages to ameliorate AP development in vitro and in vivo. Further mechanical experiments revealed that lncRNA MM2P inhibited Src homology 2 containing protein tyrosine phosphatase 2 (SHP2)-mediated signal transducer and activator of transcription 3 (STAT3) dephosphorylation to activate the STAT3 signaling, and silencing of SHP2 suppressed M1 type skewing in LPS-induced RAW264.7 cells. Interestingly, our rescuing experiments verified that lncRNA MM2P-induced suppressing effects on M1-polarization of LPS-treated RAW264.7 cells were abrogated by co-treating cells with STAT3 inhibitor stattic. Collectively, our data for the first time revealed that lncRNA MM2P suppressed M1-polarized macrophages to attenuate the progression of sodium taurocholate-induced AP, and lncRNA MM2P might be an ideal biomarker for AP diagnosis and treatment.

Neutrophil-specific ORAI1 Calcium Channel Inhibition Reduces Pancreatitis-associated Acute Lung Injury

Acute pancreatitis is initiated within pancreatic exocrine cells and sustained by dysregulated systemic inflammatory responses mediated by neutrophils. Store-operated Ca2+ entry (SOCE) through ORAI1 channels in pancreatic acinar cells triggers acute pancreatitis, and ORAI1 inhibitors ameliorate experimental acute pancreatitis, but the role of ORAI1 in pancreatitis-associated acute lung injury has not been determined. Here, we showed mice with pancreas-specific deletion of Orai1 (Orai1ΔPdx1, ∼70% reduction in the expression of Orai1) are protected against pancreatic tissue damage and immune cell infiltration, but not pancreatitis-associated acute lung injury, suggesting the involvement of unknown cells that may cause such injury through SOCE via ORAI1. Genetic (Orai1ΔMRP8) or pharmacological inhibition of ORAI1 in murine and human neutrophils decreased Ca2+ influx and impaired chemotaxis, reactive oxygen species production, and neutrophil extracellular trap formation. Unlike pancreas-specific Orai1 deletion, mice with neutrophil-specific deletion of Orai1 (Orai1ΔMRP8) were protected against pancreatitis- and sepsis-associated lung cytokine release and injury, but not pancreatic injury in experimental acute pancreatitis. These results define critical differences between contributions from different cell types to either pancreatic or systemic organ injury in acute pancreatitis. Our findings suggest that any therapy for acute pancreatitis that targets multiple rather than single cell types is more likely to be effective.

Spatially restricted tumour-associated and host-associated immune drivers correlate with the recurrence sites of pancreatic cancer

OBJECTIVE

Most patients with pancreatic ductal adenocarcinoma (PDAC) will experience recurrence after resection. Here, we investigate spatially organised immune determinants of PDAC recurrence.

DESIGN

PDACs (n=284; discovery cohort) were classified according to recurrence site as liver (n=93/33%), lung (n=49/17%), local (n=31/11%), peritoneal (n=38/13%) and no-recurrence (n=73/26%). Spatial compartments were identified by fluorescent imaging as: pancytokeratin (PanCK)+CD45- (tumour cells); CD45+PanCK- (leucocytes) and PanCK-CD45- (stromal cells), followed by transcriptomic (72 genes) and proteomic analysis (51 proteins) for immune pathway targets. Results from next-generation sequencing (n=194) were integrated. Finally, 10 tumours from each group underwent immunophenotypic analysis by multiplex immunofluorescence. A validation cohort (n=109) was examined in parallel.

RESULTS

No-recurrent PDACs show high immunogenicity, adaptive immune responses and are rich in pro-inflammatory chemokines, granzyme B and alpha-smooth muscle actin+ fibroblasts. PDACs with liver and/or peritoneal recurrences display low immunogenicity, stemness phenotype and innate immune responses, whereas those with peritoneal metastases are additionally rich in FAP+ fibroblasts. PDACs with local and/or lung recurrences display interferon-gamma signalling and mixed adaptive and innate immune responses, but with different leading immune cell population. Tumours with local recurrences overexpress dendritic cell markers whereas those with lung recurrences neutrophilic markers. Except the exclusive presence of RNF43 mutations in the no-recurrence group, no genetic differences were seen. The no-recurrence group exhibited the best, whereas liver and peritoneal recurrences the poorest prognosis.

CONCLUSIONS

Our findings demonstrate distinct inflammatory/stromal responses in each recurrence group, which might affect dissemination patterns and patient outcomes. These findings may help to inform personalised adjuvant/neoadjuvant and surveillance strategies in PDAC, including immunotherapeutic modalities.

Selective Blood Cell Hitchhiking in Whole Blood with Ionic Liquid-Coated PLGA Nanoparticles to Redirect Biodistribution After Intravenous Injection

Less than 5% of intravenously-injected nanoparticles (NPs) reach destined sites in the body due to opsonization and immune-based clearance in vascular circulation. By hitchhiking in situ onto specific blood components post-injection, NPs can selectively target tissue sites for unprecedentedly high drug delivery rates. Choline carboxylate ionic liquids (ILs) are biocompatible liquid salts <100X composed of bulky asymmetric cations and anions. This class of ILs has been previously shown to significantly extend circulation time and redirect biodistribution in BALB/c mice post-IV injection via hitchhiking on red blood cell (RBC) membranes. Herein, we synthesized & screened 60 choline carboxylic acid-based ILs to coat PLGA NPs and present the impact of structurally engineering the coordinated anion identity to selectively interface and hitchhike lymphocytes, monocytes, granulocytes, platelets, and RBCs in whole mouse blood for in situ targeted drug delivery. Furthermore, we find this nanoparticle platform to be biocompatible (non-cytotoxic), translate to human whole blood by resisting serum uptake and maintaining modest hitchhiking, and also significantly extend circulation retention over 24 hours in BALB/c healthy adult mice after IV injection. Because of their altered circulation profiles, we additionally observe dramatically different organ accumulation profiles compared to bare PLGA NPs. This study establishes an initial breakthrough platform for a modular and transformative targeting technology to hitchhike onto blood components with high efficacy and safety in the bloodstream post-IV administration.

Distinct Serum Immune Profiles Define the Spectrum of Acute and Chronic Pancreatitis From the Multicenter Prospective Evaluation of Chronic Pancreatitis for Epidemiologic and Translational Studies (PROCEED) Study

BACKGROUND & AIMS

Pancreatitis is a disease continuum, starting with acute pancreatitis (AP) and progressing in some cases to recurrent acute pancreatitis (RAP) and chronic pancreatitis (CP). Currently, there are no approved therapies or early diagnostic or prognostic biomarkers for pancreatitis. The current study examined whether patient serum immune profiling could identify noninvasive biomarkers and provide mechanistic insight into the disease continuum of pancreatitis.

METHODS

Using Olink immunoassay, we assessed the protein levels of 92 immune markers in serum samples from participants enrolled in the Prospective Evaluation of Chronic Pancreatitis for Epidemiologic and Translational Studies (PROCEED) study of the Chronic Pancreatitis, Diabetes, and Pancreatic Cancer (CPDPC) consortium. Samples (N = 231) were obtained from individuals without pancreatic disease (n = 56) and from those with chronic abdominal pain (CAP) (n = 24), AP (n = 38), RAP (n = 56), and CP (n = 57).

RESULTS

A total of 33 immune markers differentiated the combined pancreatitis groups from controls. Immune markers related to interleukin (IL) 17 signaling distinguished CP from AP and RAP. Similarly, the serum level of IL17A and C-C motif chemokine ligand 20 differentiated CP from CAP, suggesting the involvement of T helper 17 cells in CP pathogenesis. The receiver operator characteristic curve with 2 immune markers (IL17A and sulfotransferase 1A1) could differentiate CP from CAP (optimistic area under the curve = 0.78). The macrophage classical activation pathway elevated along the continuum of pancreatitis, suggesting an accumulation of proinflammatory signals over disease progression. Several immune markers were associated with smoking, alcohol, and diabetes status.

CONCLUSIONS

Immune profiling of serum samples from a large pancreatitis cohort led to identifying distinct immune markers that could serve as potential biomarkers to differentiate the varying pancreatitis disease states. In addition, the finding of IL17 signaling in CP could provide insight into the immune mechanisms underlying disease progression.

Acinar cells and the development of pancreatic fibrosis

Pancreatic fibrosis is caused by excessive deposition of extracellular matrixes of collagen and fibronectin in the pancreatic tissue as a result of repeated injury often seen in patients with chronic pancreatic diseases. The most common causative conditions include inborn errors of metabolism, chemical toxicity and autoimmune disorders. Its pathophysiology is highly complex, including acinar cell injury, acinar stress response, duct dysfunction, pancreatic stellate cell activation, and persistent inflammatory response. However, the specific mechanism remains to be fully clarified. Although the current therapeutic strategies targeting pancreatic stellate cells show good efficacy in cell culture and animal models, they are not satisfactory in the clinic. Without effective intervention, pancreatic fibrosis can promote the transformation from pancreatitis to pancreatic cancer, one of the most lethal malignancies. In the normal pancreas, the acinar component accounts for 82% of the exocrine tissue. Abnormal acinar cells may activate pancreatic stellate cells directly as cellular source of fibrosis or indirectly via releasing various substances and initiate pancreatic fibrosis. A comprehensive understanding of the role of acinar cells in pancreatic fibrosis is critical for designing effective intervention strategies. In this review, we focus on the role of and mechanisms underlying pancreatic acinar injury in pancreatic fibrosis and their potential clinical significance.

Advances in acute and chronic pancreatitis

Acute pancreatitis (AP) and chronic pancreatitis are the third leading gastrointestinal causes for admissions and readmissions to hospitals in the United States. This review of articles published between 2019-2022 (December) from international sources identified four categories of crucial new findings: The report includes (1) New genetic pathogenic mutations (TRPV6); expected genetic outcomes in a Northern European population; (2) a new serum diagnostic marker for AP-fatty acid ethyl esters-distinguishing acute pancreatitis associated with alcohol; explanations of the impact of monocytes/macrophages on the inflammatory process that defines their future in diagnosis, staging, and treatment; (3) innovations in timing of per os low-fat, solid food intake immediately on admission; resolution of concepts of aggressive parenteral fluid intake; dramatic shifts to non-operative from operative treatment of infected pancreatic necrosis. Each modification reduced interventions, complications, and lengths-of-stay; and (4) authoritarian recommendations for medical treatment of chronic pain. These advances offer opportunities to initiate newly proven treatments to enhance outcomes, alter the natural history, and envision the future of two diseases that have no known cure.

Monocytic HLA-DR Expression in Immune Responses of Acute Pancreatitis and COVID-19

Acute pancreatitis is a common gastrointestinal disease with increasing incidence worldwide. COVID-19 is a potentially life-threatening contagious disease spread throughout the world, caused by severe acute respiratory syndrome coronavirus 2. More severe forms of both diseases exhibit commonalities with dysregulated immune responses resulting in amplified inflammation and susceptibility to infection. Human leucocyte antigen (HLA)-DR, expressed on antigen-presenting cells, acts as an indicator of immune function. Research advances have highlighted the predictive values of monocytic HLA-DR (mHLA-DR) expression for disease severity and infectious complications in both acute pancreatitis and COVID-19 patients. While the regulatory mechanism of altered mHLA-DR expression remains unclear, HLA-DR-/low monocytic myeloid-derived suppressor cells are potent drivers of immunosuppression and poor outcomes in these diseases. Future studies with mHLA-DR-guided enrollment or targeted immunotherapy are warranted in more severe cases of patients with acute pancreatitis and COVID-19.

Integration of scRNA-Seq and Bulk RNA-Seq Reveals Molecular Characterization of the Immune Microenvironment in Acute Pancreatitis

Acute pancreatitis (AP) is an acute inflammatory disease of the exocrine pancreas. The pathogenesis of AP is still unclear, and there is currently no specific treatment. A variety of immune cells infiltrate in AP, which may play an important role in the progression of the disease. In this study, for the first time, scRNA-Seq and Bulk RNA-Seq data were used to show the characteristics of immune cell infiltration in AP, and to explore the specific molecular markers of different cell types. The present study also investigated cell-to-cell communication networks using the CellChat package, and AP-specific gene signatures (Clic1, Sat1, Serpina3n, Atf3, Lcn2, Osmr, Ccl9, Hspb1, Anxa2, Krt8, Cd44, Cd9, Hsp90aa1, Tmsb10, Hmox1, Fxyd5, Plin2, Pnp) were identified through integrative analysis of multiple sequencing datasets. We also defined disease-specific associated genes in different cell types, revealing dynamic changes through cell trajectory and pseudo-time analysis using the Monocle2 package. The results showed that macrophages were significantly increased in acute pancreatitis, and the number of interactions and interaction weight/strength of the macrophages in AP were significantly higher than those in the controls. The activities of various signaling pathways were abnormally regulated such as apoptosis, oxidative stress, lysosome, autophagy, ferroptosis, and inflammatory responses signaling pathways. In conclusion, this study comprehensively depicted the immune microenvironment of AP, explored the interaction network between different cell types, and defined AP-specific gene signatures, providing many new directions for basic research in AP.

Circulating monocytes in acute pancreatitis

Acute pancreatitis is a common gastrointestinal disease characterized by inflammation of the exocrine pancreas and manifesting itself through acute onset of abdominal pain. It is frequently associated with organ failure, pancreatic necrosis, and death. Mounting evidence describes monocytes - phagocytic, antigen presenting, and regulatory cells of the innate immune system - as key contributors and regulators of the inflammatory response and subsequent organ failure in acute pancreatitis. This review highlights the recent advances of dynamic change of numbers, phenotypes, and functions of circulating monocytes as well as their underling regulatory mechanisms with a special focus on the role of lipid modulation during acute pancreatitis.

A Mini-Review of Diagnostic and Therapeutic Nano-Tools for Pancreatitis

Pancreatitis is an inflammatory reaction of pancreatic tissue digestion, edema, bleeding and even necrosis caused by activation of pancreatin due to various causes. In particular, patients with severe acute pancreatitis (SAP) often suffer from secondary infection, peritonitis and shock, and have a high mortality rate. Chronic pancreatitis (CP) can cause permanent damage to the pancreas. Due to the innate characteristics, structure and location of the pancreas, there is no effective treatment, only relief of symptoms. Especially, AP is an unpredictable and potentially fatal disease, and the timely diagnosis and treatment remains a major challenge. With the rapid development of nanomedicine technology, many potential tools can be used to address this problem. In this review, we have introduced the pathophysiological processes of pancreatitis to understanding its etiology and severity. Most importantly, the current progress in the diagnosis and treatment tools of pancreatitis based on nanomedicine is summarized and prospected.

USP25 Deficiency Exacerbates Acute Pancreatitis via Up-Regulating TBK1-NF-κB Signaling in Macrophages

BACKGROUND & AIMS

Severe acute pancreatitis can easily lead to systemic inflammatory response syndrome and death. Macrophages are known to be involved in the pathophysiology of acute pancreatitis (AP), and macrophage activation correlates with disease severity. In this study, we examined the role of ubiquitin-specific protease 25, a deubiquitinating enzyme and known regulator of macrophages, in the pathogenesis of AP.

METHODS

We used L-arginine, cerulein, and choline-deficient ethionine-supplemented diet-induced models of AP in Usp25^-/- mice and wild-type mice. We also generated bone marrow Usp25^-/- chimeric mice and initiated L-arginine-mediated AP. Primary acinar cells and bone marrow-derived macrophages were isolated from wild-type and Usp25^-/- mice to dissect molecular mechanisms.

RESULTS

Our results show that Usp25 deficiency exacerbates pancreatic and lung injury, neutrophil and macrophage infiltration, and systemic inflammatory responses in L-arginine, cerulein, and choline-deficient ethionine-supplemented diet-induced models of AP. Bone marrow Usp25^-/- chimeric mice challenged with L-arginine show that Usp25 deficiency in macrophages exaggerates AP by up-regulating the TANK-binding kinase 1 (TBK1)-nuclear factor-κB (NF-κB) signaling pathway. Similarly, in vitro data confirm that Usp25 deficiency enhances the TBK1-NF-κB pathway, leading to increased expression of inflammatory cytokines in bone marrow-derived macrophages.

CONCLUSIONS

Usp25 deficiency in macrophages enhances TBK1-NF-κB signaling, and the induction of inflammatory chemokines and type I interferon-related genes exacerbates pancreatic and lung injury in AP.

Evaluating the Immunopathogenesis of Diabetes After Acute Pancreatitis in the Diabetes RElated to Acute Pancreatitis and Its Mechanisms Study: From the Type 1 Diabetes in Acute Pancreatitis Consortium

ABSTRACT

The association between acute pancreatitis (AP) and diabetes mellitus (DM) has long been established, with the initial descriptions of AP patients presenting with DM after a bout of AP published in the 1940s and 50s. However, the potential mechanisms involved, particularly those components related to the immune system, have not been well defined. The Diabetes RElated to Acute pancreatitis and its Mechanisms (DREAM) study is a multicenter clinical study designed to understand the frequency and phenotype of DM developing after AP. This article describes one objective of the DREAM study: to determine the immunologic mechanisms of DM after AP, including the contribution of β-cell autoimmunity. This component of the study will assess the presence of islet autoimmunity, as well as the magnitude and kinetics of the innate and adaptive immune response at enrollment and during longitudinal follow-up after 1 or more episodes of AP. Finally, DREAM will evaluate the relationship between immune features, DM development, and pancreatitis etiology and severity.

The gut-lung axis in severe acute Pancreatitis-associated lung injury: The protection by the gut microbiota through short-chain fatty acids

The role of gut microbiota in regulating the intestinal homeostasis, as well as the pathogenesis of severe acute pancreatitis-associated lung injury (PALI) is widely recognized. The bioactive functions of metabolites with small molecule weight and the detail molecular mechanisms of PALI mediated by "gut-lung axis" have gradually raised the attentions of researchers. Several studies have proved that short-chain fatty acids (SCFAs) produced by gut microbiome play crucial roles and varied activities in the process of PALI. However, relevant reviews reporting SCFAs in the involvement of PALI is lacking. In this review, we firstly introduced the synthetic and metabolic pathways of SCFAs, as well as the transport and signal transduction routes in brief. Afterwards, we focused on the possible mechanisms and clues of SCFAs to participate in the fight against PALI which referred to the inhibition of pathogen proliferation, anti-inflammatory effects, enhancement of intestinal barrier functions, and the maintenance and regulation of immune homeostasis via pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). In addition, the latest reported pathological and physiological mechanisms of the gut-lung axis involved in PALI were reviewed. Finally, we summarized the potential therapeutic interventions of PALI by targeting SCFAs, including dietary fiber supplementation, direct supplementation of SCFAs/prebiotics/probiotics, and drugs administration, which is expected to provide new sights for clinical use in the future.

Drug D, a Diosgenin Derive, Inhibits L-Arginine-Induced Acute Pancreatitis through Meditating GSDMD in the Endoplasmic Reticulum via the TXNIP/HIF-1α Pathway

Acute pancreatitis (AP) is one of the most common causes of hospitalization for gastrointestinal diseases, with high morbidity and mortality. Endoplasmic reticulum stress (ERS) and Gasdermin D (GSDMD) mediate AP, but little is known about their mutual influence on AP. Diosgenin has excellent anti-inflammatory and antioxidant effects. This study investigated whether Diosgenin derivative D (Drug D) inhibits L-arginine-induced acute pancreatitis through meditating GSDMD in the endoplasmic reticulum (ER). Our studies were conducted in a mouse model of L-arginine-induced AP as well as in an in vitro model on mouse pancreatic acinar cells. The GSDMD accumulation in ER was found in this study, which caused ERS of acinar cells. GSDMD inhibitor Disulfiram (DSF) notably decreased the expression of GSDMD in ER and TXNIP/HIF-1α signaling. The molecular docking study indicated that there was a potential interaction between Drug D and GSDMD. Our results showed that Drug D significantly inhibited necrosis of acinar cells dose-dependently, and we also found that Drug D alleviated pancreatic necrosis and systemic inflammation by inhibiting the GSDMD accumulation in the ER of acinar cells via the TXNIP/HIF-1α pathway. Furthermore, the level of p-IRE1α (a marker of ERS) was also down-regulated by Drug D in a dose-dependent manner in AP. We also found that Drug D alleviated TXNIP up-regulation and oxidative stress in AP. Moreover, our results revealed that GSDMD^-/- mitigated AP by inhibiting TXNIP/HIF-1α. Therefore, Drug D, which is extracted from Dioscorea zingiberensis, may inhibit L-arginine-induced AP by meditating GSDMD in the ER by the TXNIP /HIF-1α pathway.

Soluble mannose receptor CD206 and von Willebrand factor are early biomarkers to identify patients at risk for severe or necrotizing acute pancreatitis

Background

In acute pancreatitis (AP), microcirculatory dysfunction and leukocyte activation contribute to organ damage, inflammation, and mortality. Given the role of macrophage activation, monocyte recruitment, and microthrombus formation in the early pathogenesis of AP, we examined the macrophage activation marker soluble mannose receptor (sCD206) and the endothelial function marker von Willebrand factor (vWF) in patients admitted for AP.

Methods

In an exploratory analysis, serum sCD206 and plasma vWF were prospectively analyzed on day 1 and day 3 in 81 patients with AP admitted to the hospital. In addition, blood samples from 59 patients with early AP admitted to the intensive care unit and symptom onset < 24 h were retrospectively analyzed. Patients were dichotomized as per study protocol into two groups: (i) “non-severe edematous AP” including patients with mild AP without organ failure and patients with transient organ failure that resolves within 48 h and (ii) “severe/necrotizing AP” including patients with severe AP and persistent organ failure > 48 h and/or patients with local complications.

Results

In the prospective cohort, 17% developed severe/necrotizing pancreatitis compared with 56% in the ICU cohort. Serum concentrations of sCD206 on admission were higher in patients with severe/necrotizing AP than in patients with non-severe edematous AP (prospective: 1.57 vs. 0.66 mg/l, P = 0.005; ICU: 1.76 vs. 1.25 mg/l, P = 0.006), whereas other inflammatory markers (leukocytes, C-reactive protein, procalcitonin) and disease severity (SOFA, SAPS II, APACHE II) did not show significant differences. Patients with severe/necrotizing AP had a greater increase in sCD206 than patients with non-severe edematous AP at day 3 in the prospective cohort. In contrast to routine coagulation parameters, vWF antigen levels were elevated on admission (prospective cohort: 375 vs. 257%, P = 0.02; ICU cohort: 240 vs. 184%, P = 0.03). When used as continuous variables, sCD206 and VWF antigen remained predictors of severe/necrotizing AP after adjustment for etiology and age in both cohorts.

Conclusions

sCD206 identifies patients at risk of severe AP at earlier timepoints than routine markers of inflammation and coagulation. Prospective studies are needed to investigate whether incorporating early or repeated measurements into the existing scoring system will better identify patients at increased risk for complications of AP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40560-022-00619-2.

Exposure to binge ethanol and fatty acid ethyl esters exacerbates chronic ethanol-induced pancreatic injury in hepatic alcohol dehydrogenase-deficient deer mice

Alcoholic chronic pancreatitis (ACP) is a fibroinflammatory disease of the pancreas. However, metabolic basis of ACP is not clearly understood. In this study, we evaluated differential pancreatic injury in hepatic alcohol dehydrogenase-deficient (ADH^-) deer mice fed chronic ethanol (EtOH), chronic plus binge EtOH, and chronic plus binge EtOH and fatty acid ethyl esters (FAEEs, nonoxidative metabolites of EtOH) to understand the metabolic basis of ACP. Hepatic ADH^- and ADH normal (ADH⁺) deer mice were fed Lieber-DeCarli liquid diet containing 3% (wt/vol) EtOH for 3 mo. One week before the euthanization, chronic EtOH-fed mice were further administered with an oral gavage of binge EtOH with/without FAEEs. Blood alcohol concentration (BAC), pancreatic injury, and inflammatory markers were measured. Pancreatic morphology, ultrastructural changes, and endoplasmic reticulum (ER)/oxidative stress were examined using H&E staining, electron microscopy, immunostaining, and/or Western blot, respectively. Overall, BAC was substantially increased in chronic EtOH-fed groups of ADH^- versus ADH⁺ deer mice. A significant change in pancreatic acinar cell morphology, with mild to moderate fibrosis and ultrastructural changes evident by dilatations and disruption of ER cisternae, ER/oxidative stress along with increased levels of inflammatory markers were observed in the pancreas of chronic EtOH-fed groups of ADH^- versus ADH⁺ deer mice. Furthermore, chronic plus binge EtOH and FAEEs exposure elevated BAC, enhanced ER/oxidative stress, and exacerbated chronic EtOH-induced pancreatic injury in ADH^- deer mice suggesting a role of increased body burden of EtOH and its metabolism under reduced hepatic ADH in initiation and progression of ACP.NEW & NOTEWORTHY We established a chronic EtOH feeding model of hepatic alcohol dehydrogenase-deficient (ADH^-) deer mice, which mimics several fibroinflammatory features of human alcoholic chronic pancreatitis (ACP). The fibroinflammatory and morphological features exacerbated by chronic plus binge EtOH and FAEEs exposure provide a strong case for metabolic basis of ACP. Most importantly, several pathological and molecular targets identified in this study provide a much broader understanding of the mechanism and avenues to develop therapeutics for ACP.