Interleukin-22 Connects Smoking and Pancreatic Fibrosis During Chronic Pancreatitis

Malondialdehyde-Acetaldehyde Extracellular Matrix Protein Adducts Attenuate Unfolded Protein Response During Alcohol and Smoking-Induced Pancreatitis

BACKGROUND & AIMS

Epidemiological studies have established alcohol and smoking as independent risk factors for recurrent acute pancreatitis and chronic pancreatitis. However, the molecular players responsible for the progressive loss of pancreatic parenchyma and fibroinflammatory response are poorly characterized.

METHODS

Tandem mass tag-based proteomic and bioinformatics analyses were performed on the pancreata of mice exposed to alcohol, cigarette smoke, or a combination of alcohol and cigarette smoke. Biochemical, immunohistochemistry, and transcriptome analyses were performed on the pancreatic tissues and primary acinar cells treated with cerulein in combination with ethanol (50 mmol/L) and cigarette smoke extract (40 μg/mL) for the mechanistic studies.

RESULTS

A unique alteration in the pancreatic proteome was observed in mice exposed chronically to the combination of alcohol and cigarette smoke (56.5%) compared with cigarette smoke (21%) or alcohol (17%) alone. The formation of toxic metabolites (P < .001) and attenuated unfolded protein response (P < .04) were the significantly altered pathways on combined exposure. The extracellular matrix (ECM) proteins showed stable malondialdehyde-acetaldehyde (MAA) adducts in the pancreata of the combination group and chronic pancreatitis patients with a history of smoking and alcohol consumption. Interestingly, MAA-ECM adducts significantly suppressed expression of X-box-binding protein-1, leading to acinar cell death in the presence of alcohol and smoking. The stable MAA-ECM adducts persist even after alcohol and smoking cessation, and significantly delay pancreatic regeneration by abrogating the expression of cyclin-dependent kinases (CDK7 and CDK5) and regeneration markers.

CONCLUSIONS

The combined alcohol and smoking generate stable MAA-ECM adducts that increase endoplasmic reticulum stress and acinar cell death due to attenuated unfolded protein response and suppress expression of cell cycle regulators. Targeting aldehyde adducts might provide a novel therapeutic strategy for the management of recurrent acute pancreatitis and chronic pancreatitis.

Mitochondria oxidative stress mediated nicotine-promoted activation of pancreatic stellate cells by regulating mitochondrial dynamics

Nicotine, one of the main ingredients of cigarettes, promotes activation of pancreatic stellate cells(PSCs) and exacerbates pancreatic fibrosis in previous studies. Here we focus on the inner relationship between mitochondrial oxidative stress and mitochondrial dynamics to explore the possible mechanism. Primary human PSCs were stimulated by nicotine. The effect of nicotine on oxidative stress and mitochondrial dynamics was analyzed by reactive oxygen species (ROS) assay, quantitative real-time PCR, and western blotting. Mitochondrial morphology was observed. Antioxidant and small interfering RNA transfection were applied to explore the interrelationship between oxidative stress and mitochondrial dynamics, as well as its effect on PSCs activation. Nicotine exposure significantly increased Intracellular and mitochondrial ROS of hPSCs and promoted mitochondrial fission by upregulating dynamin-related protein 1(DRP1). Knockdown Drp1 reversed mitochondrial fragmentation and hPSCs activation that promoted by nicotine, but fail to alleviate oxidative stress. A mitochondrial-targeted antioxidant could reverse all the above changes. Our finding suggests that mitochondria oxidative stress mediated nicotine-promoted activation of PSCs by inducing Drp1-mediated mitochondrial fission, provides a new perspective on the possible mechanism by which nicotine affects PSCs, and reveals a potential therapeutic strategy.

Alcohol and Smoking Mediated Modulations in Adaptive Immunity in Pancreatitis

Pancreatitis is a condition of pancreatic inflammation driven by injury to the pancreatic parenchyma. The extent of acinar insult, intensity, and type of immune response determines the severity of the disease. Smoking, alcohol and autoimmune pancreatitis are some of the predominant risk factors that increase the risk of pancreatitis by differentially influencing the adaptive immune system. The overall decrease in peripheral lymphocyte (T-, B- and (natural killer T-) NKT-cell) count and increased infiltration into the damaged pancreatic tissue highlight the contribution of adaptive immunity in the disease pathology. Smoking and alcohol modulate the responsiveness and apoptosis of T- and B-cells during pancreatic insult. Acute pancreatitis worsens with smoking and alcohol, leading to the development of systemic inflammatory response syndrome and compensatory anti-inflammatory response syndrome, suggesting the critical role of adaptive immunity in fatal outcomes such as multiple organ dysfunction. The presence of CD4⁺ and CD8⁺ T-lymphocytes and perforin-expressing cells in the fibrotic tissue in chronic pancreatitis modulate the severity of the disease. Due to their important role in altering the severity of the disease, attempts to target adaptive immune mediators will be critical for the development of novel therapeutic interventions.

T Lymphocytes: A Promising Immunotherapeutic Target for Pancreatitis and Pancreatic Cancer?

Pancreatic disorders cause a broad spectrum of clinical diseases, mainly including acute and chronic pancreatitis and pancreatic cancer, and are associated with high global rates of morbidity and mortality. Unfortunately, the pathogenesis of pancreatic disease remains obscure, and there is a lack of specific treatments. T lymphocytes (T cells) play a vital role in the adaptive immune systems of multicellular organisms. During pancreatic disease development, local imbalances in T-cell subsets in inflammatory and tumor environments and the circulation have been observed. Furthermore, agents targeting T cells have been shown to reverse the natural course of pancreatic diseases. In this review, we have discussed the clinical relevance of T-cell alterations as a potential outcome predictor and the underlying mechanisms, as well as the present status of immunotherapy targeting T cells in pancreatitis and neoplasms. The breakthrough findings summarized in this review have important implications for innovative drug development and the prospective use of immunotherapy for pancreatitis and pancreatic cancer.

Diverse effects of interleukin-22 on pancreatic diseases

Interleukin-22 (IL-22) is involved in the development of lymphocytes and serves as a rapid and early source of the effector cytokines that are released in response to pathogen-induced changes in the microenvironment. Recent research has implicated IL-22 as a potential contributing factor to the spectrum of inflammation-related pancreatic diseases, particularly pancreatitis, fibrosis, carcinoma and diabetes. In this review, we summarize the current knowledge on the roles of IL-22 in the various pancreatic pathogenesis, providing insights into the underlying cellular and signaling mechanisms that will help guide future research into promising interventional targets with therapeutic potential.