Inhibition of Notch activity suppresses hyperglycemia-augmented polarization of macrophages to the M1 phenotype and alleviates acute pancreatitis

The Pivotal Role of Macrophages in the Pathogenesis of Pancreatic Diseases

The pancreas is an organ with both exocrine and endocrine functions, comprising a highly organized and complex tissue microenvironment composed of diverse cellular and non-cellular components. The impairment of microenvironmental homeostasis, mediated by the dysregulation of cell-to-cell crosstalk, can lead to pancreatic diseases such as pancreatitis, diabetes, and pancreatic cancer. Macrophages, key immune effector cells, can dynamically modulate their polarization status between pro-inflammatory (M1) and anti-inflammatory (M2) modes, critically influencing the homeostasis of the pancreatic microenvironment and thus playing a pivotal role in the pathogenesis of the pancreatic disease. This review aims to summarize current findings and provide detailed mechanistic insights into how alterations mediated by macrophage polarization contribute to the pathogenesis of pancreatic disorders. By analyzing current research comprehensively, this article endeavors to deepen our mechanistic understanding of regulatory molecules that affect macrophage polarity and the intricate crosstalk that regulates pancreatic function within the microenvironment, thereby facilitating the development of innovative therapeutic strategies that target perturbations in the pancreatic microenvironment.

Eliminating COVID-19 as the immediate culprit for igniting pancreatitis

The impact of severe acute respiratory syndrome coronavirus 2 infection on the potential development of pancreatitis is a subject of ongoing debate within academic discourse. Establishing a causal link between COVID-19 and pancreatitis may not be fully supported by relying only on retrospective studies or case reports. This study examined the relationship between COVID-19 phenotypes and pancreatitis by Mendelian randomization (MR) method. The identification of instrumental variables (single nucleotide polymorphisms) that exhibit a robust association with the COVID-19 phenotypes was accomplished through a meticulous process of rigorous screening procedures. We included acute pancreatitis and chronic pancreatitis (CP) as the outcomes in the MR analysis, even though no definitive studies exist between COVID-19 and CP. A direct causal relationship between genetically predicted COVID-19 phenotypes and pancreatitis risk cannot be established. There is an ongoing debate over the designation of COVID-19 as a definitive cause of pancreatitis.

Notch4 participates in mesenchymal stem cell-induced differentiation in 3D-printed matrix and is implicated in eccrine sweat gland morphogenesis

Background

Eccrine sweat gland (SG) plays a crucial role in thermoregulation but exhibits very limited regenerative potential. Although SG lineage-restricted niches dominate SG morphogenesis and benefit SG regeneration, rebuilding niches in vivo is challenging for stem cell therapeutic applications. Hence, we attempted to screen and tune the critical niche-responding genes that dually respond to both biochemical and structural cues, which might be a promising strategy for SG regeneration.

Methods

An artificial SG lineage-restricted niche consisting of mouse plantar dermis homogenates (i.e. biochemical cues) and 3D architecture (i.e. structural cues) was built in vitro by using an extrusion-based 3D bioprinting approach. Mouse bone marrow-derived mesenchymal stem cells (MSCs) were then differentiated into the induced SG cells in the artificial SG lineage-restricted niche. To decouple biochemical cues from structural cues, the transcriptional changes aroused by pure biochemical cues, pure structural cues and synergistic effects of both cues were analyzed pairwise, respectively. Notably, only niche-dual-responding genes that are differentially expressed in response to both biochemical and structural cues and participate in switching MSC fates towards SG lineage were screened out. Validations in vitro and in vivo were respectively conducted by inhibiting or activating the candidate niche-dual-responding gene(s) to explore the consequent effects on SG differentiation.

Results

Notch4 is one of the niche-dual-responding genes that enhanced MSC stemness and promoted SG differentiation in 3D-printed matrix in vitro. Furthermore, inhibiting Notch4 specifically reduced keratin 19-positive epidermal stem cells and keratin 14-positive SG progenitor cells, thus further delaying embryonic SG morphogenesis in vivo.

Conclusions

Notch4 not only participates in mouse MSC-induced SG differentiation in vitro but is also implicated in mouse eccrine SG morphogenesis in vivo.

Incidence and risk factors of fasting hyperglycaemia following first-attack acute pancreatitis before discharge: a retrospective study

BACKGROUND

Pancreatic endocrine insufficiency is more likely to occur after acute pancreatitis (AP), but the risk factors affecting pancreatic endocrine function remain controversial. Therefore, exploring the incidence and risk factors of fasting hyperglycaemia following first-attack AP is important.

METHODS

Data were collected from 311 individuals with first-attack AP without previous diabetes mellitus (DM) or impaired fasting glucose (IFG) history treated in the Renmin Hospital of Wuhan University. Relevant statistical tests were performed. A two-sided p-value < 0.05 was considered statistically significant.

RESULTS

The incidence of fasting hyperglycaemia in individuals with first-attack AP was 45.3%. Univariate analysis showed that age (χ² = 6.27, P = 0.012), aetiology (χ² = 11.184, P = 0.004), serum total cholesterol (TC) (χ² = 14.622, P < 0.001), and serum triglyceride (TG) (χ² = 15.006, P < 0.001) were significantly different between the hyperglycaemia and non-hyperglycaemia groups (P < 0.05). The serum calcium concentration (Z=-2.480, P = 0.013) was significantly different between the two groups (P < 0.05). Multiple logistic regression analysis showed that age- ≥60 years (P < 0.001, OR = 2.631, 95%Cl = 1.529-4.527) and TG ≥ 5.65 mmol/L (P < 0.001, OR = 3.964, 95%Cl = 1.990-7.895) were independent risk factors for fasting hyperglycaemia in individuals with first-attack AP (P < 0.05).

CONCLUSIONS

Old age, serum triglycerides, serum total cholesterol, hypocalcaemia, and aetiology are associated with fasting hyperglycaemia following first-attack AP. Age ≥ 60 years and TG ≥ 5.65 mmol/L are independent risk factors for fasting hyperglycaemia following first-attack AP.

Epsin1-mediated exosomal sorting of Dll4 modulates the tubular-macrophage crosstalk in diabetic nephropathy

Tubular epithelial cells (TECs) play critical roles in the development of diabetic nephropathy (DN), and can activate macrophages through the secretion of exosomes. However, the mechanism(s) of TEC-exosomes in macrophage activation under DN remains unknown. By mass spectrometry, 1,644 differentially expressed proteins, especially Dll4, were detected in the urine exosomes of DN patients compared with controls, which was confirmed by western blot assay. Elevated Epsin1 and Dll4/N1ICD expression was observed in kidney tissues in both DN patients and db/db mice and was positively associated with tubulointerstitial damage. Exosomes from high glucose (HG)-treated tubular cells (HK-2) with Epsin1 knockdown (KD) ameliorated macrophage activation, TNF-α, and IL-6 expression, and tubulointerstitial damage in C57BL/6 mice in vivo. In an in vitro study, enriched Dll4 was confirmed in HK-2 cells stimulated with HG, which was captured by THP-1 cells and promoted M1 macrophage activation. In addition, Epsin1 modulated the content of Dll4 in TEC-exosomes stimulated with HG. TEC-exosomes with Epsin1-KD significantly inhibited N1ICD activation and iNOS expression in THP-1 cells compared with incubation with HG alone. These findings suggested that Epsin1 could modulate tubular-macrophage crosstalk in DN by mediating exosomal sorting of Dll4 and Notch1 activation.

Preexisting diabetes, serum calcium and D-dimer levels as predictable risk factors for pancreatic necrosis of patients with acute pancreatitis: a retrospective study

BACKGROUND

Some individuals with acute pancreatitis (AP) suffer from pancreatic necrosis. Diabetes affects the severity of AP, but whether diabetes influences pancreatic necrosis is unclear. This study aims to investigate the clinical characteristics of AP patients with and without diabetes as well as analyze the risk factors of pancreatic necrosis.

RESEARCH DESIGN AND METHODS

A total of 625 AP patients participated in the study. Clinical and laboratory data were retrieved. Multivariate logistic regression analysis was used to identify the risk factors for pancreatic necrosis. ROC curves assess the accuracy of indicators for predicting pancreatic necrosis in AP.

RESULTS

AP patients with diabetes had high BMI, CTSI scores, pancreatitis severity, WBC, neutrophil, CRP, triacylglycerols and glucose levels. Diabetes, serum calcium and D-dimer were independent risk factors for pancreatic necrosis. Pancreatic necrosis in diabetes patients is also associated with sex and age. D-dimer is a better predictor of pancreatic necrosis in AP patients than serum calcium.

CONCLUSIONS

Diabetic patients are more likely to suffer severe AP. Serum calcium and D-dimer are independent predictors for pancreatic necrosis. Furthermore, low serum calcium, high D-dimer levels, younger age and female sex are independent risk factors for pancreatic necrosis in AP patients with diabetes.