Neutrophil proteinase 3 induces diabetes in a mouse model of glucose tolerance

Alpha-1 Antitrypsin Inhibits Tumorigenesis and Progression of Colitis-Associated Colon Cancer through Suppression of Inflammatory Neutrophil-Activated Serine Proteases and IGFBP-3 Proteolysis

Colitis-associated colon cancer (CAC) accompanies the massive infiltration of neutrophils during tumorigenesis and progression of CAC. Depletion of neutrophils in circulation results in significant inhibition of tumor incidence in CAC. However, the underlying mechanisms are largely unclear. In this study, we provide evidence for the crucial involvement of inflammatory neutrophil-activated serine proteases (NSPs) on the dysregulation of the anti-inflammatory and antitumor IGFBP-3/IGFBP-3R signaling axis in CAC using a chronic AOM/DSS mouse model. We also provide preclinical evidence for α1-antitrypsin (AAT) as a preventive and as a therapeutic for CAC. AAT administration not only prevented colitis-associated tumorigenesis but also inhibited established CAC. AOM/DSS treatment results in the significant activation of NSPs, leading to CAC through increased pro-inflammatory cytokines and decreased anti-inflammatory and antitumor IGFBP-3. Collectively, these data suggest that the NSPs proteolyze IGFBP-3, whereas AAT inhibits chronic colonic inflammation-induced NSP activity and subsequently suppresses IGFBP-3 proteolysis. Therefore, the anti-inflammatory and antitumor functions of the IGFBP-3/IGFBP-3R axis are restored. AAT mimicking small peptides also showed their inhibitory effects on NSP-induced IGFBP-3 proteolysis. These results suggest that targeting the NSP-IGFBP-3/IGFBP-3R axis using NSP inhibitors such as AAT and the AAT mimics and IGFBP-3R agonists could lead to novel approaches for the prevention and treatment of CAC.

Latent Autoimmune Diabetes in Adults (LADA): From Immunopathogenesis to Immunotherapy

Latent autoimmune diabetes in adults (LADA) is a type of diabetes characterized by slow autoimmune damage of pancreatic β cells without insulin treatment in the early clinical stage. There are differences between LADA and classical type 1 diabetes (T1D) and type 2 diabetes (T2D) in genetic background, autoimmune response, rate of islet function decline, clinical metabolic characteristics, and so on. The disease progression and drug response of patients with LADA are closely related to the level of islet autoimmunity, thus exploring the pathogenesis of LADA is of great significance for its prevention and treatment. Previous studies reported that adaptive immunity and innate immunity play a critical role in the etiology of LADA. Recent studies have shown that the intestinal microbiota which impacts host immunity hugely, participates in the pathogenesis of LADA. In addition, the progression of autoimmune pancreatic β cell destruction in LADA is slower than in classical T1D, providing a wider window of opportunities for intervention. Therefore, therapies including antidiabetic drugs with immune-regulation effects and immunomodulators could contribute to promising interventions for LADA. We also shed light on potential interventions targeting the gut microbiota and gut-associated immunity, which may be envisaged to halt or delay the process of autoimmunity in LADA.

Neutrophils and their role in the aetiopathogenesis of type 1 and type 2 diabetes

Multiple and complex aetiological processes underlie diabetes mellitus, which invariably result in the development of hyperglycaemia. Although there are two prevalent distinct forms of the disease, that is, type 1 and type 2 diabetes, accumulating evidence indicates that these syndromes share more aetiopathological mechanisms than originally thought. This compels a rethinking of the approaches to prevent and treat the different manifestations of what eventually becomes a hyperglycaemic state. This review aims to address the involvement of neutrophils, the most abundant type of granulocytes involved in the initiation of the acute phase of inflammation, in the aetiopathogenesis of diabetes mellitus, with a focus on type 1 and type 2 diabetes. We review the evidence that neutrophils are the first leucocytes to react to and accumulate inside target tissues of diabetes, such as the pancreas and insulin-sensitive tissues. We then review available data on the role of neutrophils and their functional alteration, with a focus on NETosis, in the progression towards clinical disease. Finally, we review potential approaches as secondary and adjunctive treatments to limit neutrophil-mediated damage in the prevention of the progression of subclinical disease to clinical hyperglycaemia.

The relationship of neutrophil elastase and proteinase 3 with risk factors, and chronic complications in type 2 diabetes: A Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) sub-study

INTRODUCTION

Neutrophil elastase (NE) and proteinase 3 (PR3) are novel inflammation biomarkers. We investigated their associations with chronic complications, determinants of biomarker levels and effects of fenofibrate in patients with type 2 diabetes mellitus (T2DM) from Fenofibrate Intervention and Event Lowering in Diabetes study.

METHODS

Plasma NE and PR3 levels were quantified at baseline (n = 2000), and relationships with complications over 5-years assessed. Effects of fenofibrate on biomarker levels (n = 200) were determined at four follow-up visits.

RESULTS

Higher waist-to-hip ratio, homocysteine and C-reactive protein and lower apoA-II were determinants of higher NE and PR3 levels. Higher NE levels were associated with on-trial stroke and cardiovascular mortality, and higher PR3 levels with on-trial stroke, but associations were not significant after adjustment for confounding factors. Although higher NE and PR3 levels were associated with baseline total microvascular disease, only NE levels were associated with on-trial neuropathy or amputation. These associations were not significant after adjusting for multiple comparisons. NE and PR3 levels did not change with fenofibrate.

CONCLUSIONS

In T2DM plasma NE and PR3 levels are associated with vascular risk factors, and total microvascular disease at baseline, but on rigorous analyses were not associated with on-trial complications. Levels were not changed by fenofibrate.

PR3 levels are impaired in plasma and PBMCs from Arabs with cardiovascular diseases

Cardiovascular disease (CVD) risks persist in patients despite treatment. CVD susceptibility also varies with sex and ethnicity and is not entirely explained by conventional CVD risk factors. The aim of the present study was to identify novel CVD candidate markers in circulating Peripheral blood mononuclear cells (PBMCs) and plasma from Arab obese subjects with and without CVD using proteomic approaches. Human adults with confirmed CVD (n = 208) and matched non-CVD controls (n = 152) living in Kuwait were examined in the present cross-sectional study. Anthropometric and classical biochemical parameters were determined. We employed a shotgun proteomic profiling approach on PBMCs isolated from a subset of the groups (n = 4, each), and differentially expressed proteins selected between the two groups were validated at the mRNA level using RT-PCR (n = 6, each). Plasma levels of selected proteins from the proteomics profiling: Proteinase-3 (PR3), Annexin-A3 (ANX3), Defensin (DEFA1), and Matrix Metalloproteinase-9 (MMP9), were measured in the entire cohort using human enzyme-linked immunosorbent assay kits and were subsequently correlated with various clinical parameters. Out of the 1407 we identified and quantified from the proteomics profiling, 47 proteins were dysregulated with at least twofold change between the two subject groups. Among the differentially expressed proteins, 11 were confirmed at the mRNA levels. CVD influenced the levels of the shortlisted proteins (MMP9, PR3, ANX3, and DEFA1) in the PBMCs and plasma differentially. Despite the decreased levels of both protein and mRNA in PBMCs, PR3 circulating levels increased significantly in patients with CVD and were influenced by neither diabetes nor statin treatment. No significant changes were; however, observed in the DEFA1, MMP9, and ANX3 levels in plasma. Multivariate logistic regression analysis revealed that only PR3 was independently associated with CVD. Our results suggest that the dysregulation of PR3 levels in plasma and PBMCs reflects underlying residual CVD risks even in the treated population. More prospective and larger studies are required to establish the role of PR3 in CVD progression.

Abnormal Peripheral Neutrophil Transcriptome in Newly Diagnosed Type 2 Diabetes Patients

AIM

There are increasing evidence demonstrating that neutrophil-mediated inflammation plays a role in the etiology of type 2 diabetes. However, the molecular mechanisms by which neutrophils contribute to type 2 diabetes remain largely unknown. The aim of the present work was to identify possible changes in circulating neutrophils to better elucidate neutrophil involvement in human type 2 diabetes.

METHODS

Patients newly diagnosed with type 2 diabetes (n = 5) and age- and sex-matched healthy controls (n = 5) were recruited. Neutrophils were purified from type 2 diabetes patients and controls, and RNA sequencing (RNA-seq) was used for comprehensive transcriptome analysis. Differentially expressed genes (DEGs) were screened, and Gene Ontology (GO) and KEGG pathway enrichment analyses were performed. Real-time polymerase chain reaction (qPCR) was used for validation in external samples of type 2 diabetes patients (n = 8) and healthy controls (n = 8).

RESULTS

Gene expression analysis showed that, compared with neutrophils from healthy controls, there were 1990 upregulated DEGs and 1314 downregulated DEGs in neutrophils from type 2 diabetes patients. GO analysis demonstrated that the DEGs were mainly involved in myeloid leukocyte activation, T cell activation, adaptive immunity, and cytokine production. The top 20 enriched KEGG pathways included the cytokine-cytokine receptor interaction pathway, NF-κB signaling pathway, cell adhesion molecules, and chemokine signaling pathway. Furthermore, qPCR of genes related to neutrophil activation revealed that the expression of SELL, SELP, CXCR1, and S100A8 was significantly increased in neutrophils from type 2 diabetes patients compared with that in neutrophils from controls.

CONCLUSIONS

Our study reveals an abnormal activation of circulating neutrophils at the transcriptome level in type 2 diabetes patients. These findings suggest a potential involvement of neutrophil dysfunction in the pathologic process of type 2 diabetes and provide insight into potential therapeutic targets for type 2 diabetes.

Distinct neutrophil counts and functions in newly diagnosed type 1 diabetes, latent autoimmune diabetes in adults, and type 2 diabetes

BACKGROUND

Recent discoveries from animal models demonstrated that neutrophils can induce type 1 diabetes (T1D) through infiltrating into the islets. However, the evidence of their actions in T1D patients is relatively rare, and the change trend of neutrophil numbers and functions in different subtypes of diabetes has not been investigated.

METHODS

Patients with newly diagnosed T1D (n = 189), latent autoimmune diabetes in adults (LADA) (n = 86), T2D (n = 235), and healthy controls (n = 709) were enrolled. Circulating neutrophil counts were measured, and their correlations with clinical parameters were analysed. Neutrophils were isolated by density gradient centrifugation and magnetic bead cell sorting method. Neutrophil migration rate and chemokine levels in the blood were explored by trans-well and ELISA, respectively. Neutrophil phagocytosis rate, adhesion molecules and chemokine receptors expression were investigated by flow cytometry.

RESULTS

Compared with controls, neutrophil counts decreased in T1D patients but increased in T2D patients, with no change in LADA patients. The numbers showed a gradual increase trend from T1D, LADA to T2D. In autoimmune diabetes, neutrophil counts were associated with the number and titre of positive autoantibodies against β-cell antigens. No difference was found in neutrophil phagocytosis rate, but neutrophil migration in T1D patients was impaired and associated with CD62L expression, which was related closely to the titre of autoantibody.

CONCLUSIONS

Neutrophil numbers and migration abilities displayed distinct levels in different types of diabetes. In T1D, CD62L seems to play an important role in the migration of neutrophils and β-cell autoimmunity.

IL-1 Family Cytokine Pathways Underlying NAFLD: Towards New Treatment Strategies

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide. Pathways responsible for the activation of IL-1 family cytokines are key in the development of NAFLD but underlying mechanisms are not fully understood. Many studies have focused on the inflammasome-caspase-1 pathway and have shown that this pathway is an important inducer of inflammation in NAFLD. However, this pathway is not solely responsible for the activation of proinflammatory cytokines. Also, neutrophil serine proteases (NSPs) are capable of activating cytokines and recent studies reported that these proteases also contribute to NAFLD. These studies provided, for the first time, evidence that this inflammasome-independent pathway is involved in NAFLD. In our opinion, these new insights open up new approaches for therapeutic intervention.

Activation of proteinase 3 contributes to Non-alcoholic Fatty Liver Disease (NAFLD) and insulin resistance

Activation of inflammatory pathways is known to accompany development of obesity-induced non-alcoholic fatty liver disease (NAFLD), insulin resistance and type 2 diabetes. In addition to caspase-1, the neutrophil serine proteases proteinase 3, neutrophil elastase and cathepsin G are able to process the inactive pro-inflammatory mediators IL-1β and IL-18 to their bioactive forms, thereby regulating inflammatory responses. In the present study, we investigated whether proteinase 3 is involved in obesity-induced development of insulin resistance and NAFLD. We investigated the development of NAFLD and insulin resistance in mice deficient for neutrophil elastase/proteinase 3 and neutrophil elastase/cathepsin G and in wild-type mice treated with the neutrophil serine proteinase inhibitor human alpha-1 antitrypsin. Expression profiling of metabolically relevant tissues obtained from insulin resistant mice showed that expression of proteinase 3 was specifically upregulated in the liver, whereas neutrophil elastase, cathepsin G and caspase-1 were not. Neutrophil elastase/proteinase 3 deficient mice showed strongly reduced levels of lipids in the liver after fed a high fat diet. Moreover, these mice were resistant to high fat diet-induced weight gain, inflammation and insulin resistance. Injection of proteinase 3 exacerbated insulin resistance in caspase-1(-/-) mice, indicating that proteinase 3 acts independently of caspase-1. Treatment with alpha-1 antitrypsin during the last 10 days of a 16 week high fat diet reduced hepatic lipid content and decreased fasting glucose levels. We conclude that proteinase 3 is involved in NAFLD and insulin resistance and that inhibition of proteinase 3 may have therapeutic potential.

Proteases and protease inhibitors of urinary extracellular vesicles in diabetic nephropathy

Diabetic nephropathy (DN) is one of the major complications of diabetes mellitus (DM), leads to chronic kidney disease (CKD), and, ultimately, is the main cause for end-stage kidney disease (ESKD). Beyond urinary albumin, no reliable biomarkers are available for accurate early diagnostics. Urinary extracellular vesicles (UEVs) have recently emerged as an interesting source of diagnostic and prognostic disease biomarkers. Here we used a protease and respective protease inhibitor array to profile urines of type 1 diabetes patients at different stages of kidney involvement. Urine samples were divided into groups based on the level of albuminuria and UEVs isolated by hydrostatic dialysis and screened for relative changes of 34 different proteases and 32 protease inhibitors, respectively. Interestingly, myeloblastin and its natural inhibitor elafin showed an increase in the normo- and microalbuminuric groups. Similarly, a characteristic pattern was observed in the array of protease inhibitors, with a marked increase of cystatin B, natural inhibitor of cathepsins L, H, and B as well as of neutrophil gelatinase-associated Lipocalin (NGAL) in the normoalbuminuric group. This study shows for the first time the distinctive alterations in comprehensive protease profiles of UEVs in diabetic nephropathy and uncovers intriguing mechanistic, prognostic, and diagnostic features of kidney damage in diabetes.

Increased neutrophil elastase and proteinase 3 and augmented NETosis are closely associated with β-cell autoimmunity in patients with type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease resulting from the self-destruction of insulin-producing β-cells. Reduced neutrophil counts have been observed in patients with T1D. However, the pathological roles of neutrophils in the development of T1D remain unknown. Here we show that circulating protein levels and enzymatic activities of neutrophil elastase (NE) and proteinase 3 (PR3), both of which are neutrophil serine proteases stored in neutrophil primary granules, were markedly elevated in patients with T1D, especially those with disease duration of less than 1 year. Furthermore, circulating NE and PR3 levels increased progressively with the increase of the positive numbers and titers of the autoantibodies against β-cell antigens. An obvious elevation of NE and PR3 was detected even in those autoantibody-negative patients. Increased NE and PR3 in T1D patients are closely associated with elevated formation of neutrophil extracellular traps. By contrast, the circulating levels of α1-antitrypsin, an endogenous inhibitor of neutrophil serine proteases, are decreased in T1D patients. These findings support an early role of neutrophil activation and augmented neutrophil serine proteases activities in the pathogenesis of β-cell autoimmunity and also suggest that circulating NE and PR3 may serve as sensitive biomarkers for the diagnosis of T1D.

A carbon nanotube toxicity paradigm driven by mast cells and the IL-₃₃/ST₂ axis

Concern about the use of nanomaterials has increased significantly in recent years due to potentially hazardous impacts on human health. Mast cells are critical for innate and adaptive immune responses, often modulating allergic and pathogenic conditions. Mast cells are well known to act in response to danger signals through a variety of receptors and pathways including IL-33 and the IL-1-like receptor ST2. Here, the involvement of mast cells and the IL-33/ST2 axis in pulmonary and cardiovascular responses to multi-walled carbon nanotube (MWCNT) exposure are examined. Toxicological effects of MWCNTs are observed only in mice with a sufficient population of mast cells and are not observed when mast cells are absent or incapable of responding to IL-33. Our findings establish for the first time that mast cells and the IL-33/ST2 axis orchestrates adverse pulmonary and cardiovascular responses to an engineered nanomaterial, giving insight into a previously unknown mechanism of toxicity. This novel mechanism of toxicity could be used for assessing the safety of engineered nanomaterials and provides a realistic therapeutic target for potential nanoparticle induced toxicities.