Cytokine regulatory effects on alpha-1 proteinase inhibitor expression in NOD mouse islet endothelial cells

Novel insights into the relationship between α-1 anti-trypsin with the pathological development of cardio-metabolic disorders

According to the previous studies, chronic low-grade systemic inflammatory response has been shown to be significantly associated with the pathological development of cardio-metabolic disorder diseases, including atherosclerosis, type 2 diabetes mellitus, and non-alcoholic fatty liver disease (NAFLD). On the other hand, auto-immunity process could also facilitate the pathogenesis of type 1 diabetes mellitus importantly. Concerning on this notion, the anti-inflammatory therapeutic strategy is demonstrated to embrace an essential function in those cardio-metabolic disorders in clinical practice. The α-1 anti-trypsin, also named Serpin-A1 and as an acute phase endogenous protein, has been verified to have several modulatory effects such as anti-inflammatory response, anti-apoptosis, and immunomodulatory functions. In addition, it is also used for therapeutic strategy of a rare genetic disease caused by the deficiency of α-1 anti-trypsin. Recent emerging evidence has indicated that the serum concentrations of α-1 anti-trypsin levels and its biological activity are significantly changed in those inflammatory and immune related cardio-metabolic disorder diseases. Nevertheless, the underlying mechanism is still not elucidated. In the current review, the basic experiments and clinical trials which provided the evidence revealing the potential therapeutic function of the α-1 anti-trypsin in cardio-metabolic disorder diseases were well-summarized. Furthermore, the results which indicated that the α-1 anti-trypsin presented the possibility as a novel serum biomarker in humans to predict those cardio-metabolic disorder diseases were also elucidated.

Alpha-1 antitrypsin: A novel biomarker and potential therapeutic approach for metabolic diseases

It is well recognized that chronic low-grade systemic inflammation and autoimmunity contribute to the pathogenesis of metabolic syndrome, its associated diseases (e.g. type 2 diabetes, non-alcoholic fatty liver disease) and type 1 diabetes, respectively. Consequently, anti-inflammatory agents might play a role in managing these immune associated metabolic diseases. Alpha-1 antitrypsin (AAT), an endogenous acute phase protein being used for treatment of AAT deficiency (a rare genetic disease), has multiple functions including anti-inflammatory, immunomodulatory, anti-apoptosis and cytoprotective effects. In this review, we summarized basic and clinical studies that reported potential therapeutic role of AAT in metabolic syndrome associated diseases and type 1 diabetes. Studies that demonstrated AAT had the possibility to be used as a novel biomarker to predict these immune associated metabolic diseases were also included.

Intra-islet endothelial cell and β-cell crosstalk: Implication for islet cell transplantation

The intra-islet microvasculature is a critical interface between the blood and islet endocrine cells governing a number of cellular and pathophysiological processes associated with the pancreatic tissue. A growing body of evidence indicates a strong functional and physical interdependency of β-cells with endothelial cells (ECs), the building blocks of islet microvasculature. Intra-islet ECs, actively regulate vascular permeability and appear to play a role in fine-tuning blood glucose sensing and regulation. These cells also tend to behave as “guardians”, controlling the expression and movement of a number of important immune mediators, thereby strongly contributing to the physiology of islets. This review will focus on the molecular signalling and crosstalk between the intra-islet ECs and β-cells and how their relationship can be a potential target for intervention strategies in islet pathology and islet transplantation.

Expanding the clinical indications for α(1)-antitrypsin therapy

α(1)-Antitrypsin (AAT) is a 52-kDa circulating serine protease inhibitor. Production of AAT by the liver maintains 0.9-1.75 mg/mL circulating levels. During acute-phase responses, circulating AAT levels increase more than fourfold. In individuals with one of several inherited mutations in AAT, low circulating levels increase the risk for lung, liver and pancreatic destructive diseases, particularly emphysema. These individuals are treated with lifelong weekly infusions of human plasma-derived AAT. An increasing amount of evidence appears to suggest that AAT possesses not only the ability to inhibit serine proteases, such as elastase and proteinase-3 (PR-3), but also to exert antiinflammatory and tissue-protective effects independent of protease inhibition. AAT modifies dendritic cell maturation and promotes T regulatory cell differentiation, induces interleukin (IL)-1 receptor antagonist and IL-10 release, protects various cell types from cell death, inhibits caspases-1 and -3 activity and inhibits IL-1 production and activity. Importantly, unlike classic immunosuppressants, AAT allows undeterred isolated T-lymphocyte responses. On the basis of preclinical and clinical studies, AAT therapy for nondeficient individuals may interfere with disease progression in type 1 and type 2 diabetes, acute myocardial infarction, rheumatoid arthritis, inflammatory bowel disease, cystic fibrosis, transplant rejection, graft versus host disease and multiple sclerosis. AAT also appears to be antibacterial and an inhibitor of viral infections, such as influenza and human immunodeficiency virus (HIV), and is currently evaluated in clinical trials for type 1 diabetes, cystic fibrosis and graft versus host disease. Thus, AAT therapy appears to have advanced from replacement therapy, to a safe and potential treatment for a broad spectrum of inflammatory and immune-mediated diseases.

Homeostatic alterations induced by interleukin-1β microinjection into the orbitofrontal cortex in the rat

The present experiments were designed to elucidate the effect of direct orbitofrontal cortical administration of interleukin-1beta (IL-1beta) on the homeostatic regulation. Short- and long-term food intakes (FI), water intakes and body temperature (BT) were measured before and after a bilateral microinjection of IL-1beta (with or without paracetamol /P/ pretreatment) into the orbitofrontal cortex (OBF) of Wistar rats, and the effects were compared with those found in vehicle-treated and i.p. injected IL-1beta, IL-1beta+P or control animals. In addition, blood glucose levels (BGLs), along a glucose tolerance test, and plasma concentrations of insulin, leptin, cholesterol, triglycerides and urate were determined in cytokine treated and control rats. Short-term FI was suppressed after orbitofrontal cortical or peripheral application of IL-1beta. In the long-term FI, however, there was no significant difference among the groups. Cytokine microinjection into the OBF, similar to the i.p. administration, was also followed by a significant increase in BT. Pretreatment with P failed to influence the anorexigenic and hyperthermic effects of the centrally administered IL-1beta. The sugar load led to a diabetes-like prolonged elevation of BGL in the IL-1beta treated animals. Following cytokine administration, plasma levels of insulin and that of triglycerides were found decreased, whereas that of uric acid increased. The present findings confirm that the OBF is one of the neural routes through which IL-1beta exerts modulatory effect on the central homeostatic regulation.

Expression and secretion of alpha1-proteinase inhibitor are regulated by proinflammatory cytokines in human pancreatic islet cells

AIMS/HYPOTHESIS

Alpha1-proteinase inhibitor (alpha1-PI) has been considered a key player in inflammatory processes. In humans, the main production site of alpha1-PI is the liver, but other tissues, including pancreatic islets, also synthesise this molecule. The aims of this study were to assess the islet cell types that produce alpha1-PI, to determine whether alpha1-PI is actually secreted by islet cells, and to assess how its production and/or secretion are regulated.

METHODS

Expression of alpha1-PI in human islet cells was assessed by immunofluorescence, electron microscopy and western blotting. Release of alpha1-PI was analysed by reverse haemolytic plaque assay and ELISA. The effects of cytokines on alpha1-PI synthesis and secretion were tested.

RESULTS

Immunofluorescence showed that alpha and delta cells do express alpha1-PI, whereas beta cells do not. By electron microscopy, we demonstrated a colocalisation of alpha1-PI with glucagon and somatostatin within secretory granules. Immunolabelling also revealed localisation of alpha1-PI within the Golgi apparatus, related vesicles and lysosomal structures. The expression of alpha1-PI in islet cells was also demonstrated by western blotting and ELISA of protein extracts. ELISA and reverse haemolytic plaque assay showed that alpha1-PI is secreted into the culture medium. Treatment of islet cells with IL-1beta and oncostatin M for 4 days increased the production and release of alpha1-PI.

CONCLUSIONS/INTERPRETATION

Our results demonstrate that alpha1-PI is expressed by the alpha and delta cells of human islets, and that proinflammatory cytokines enhance the production and release of this inhibitor.