The clinical significance of somatostatin in pancreatic diseases

Acute Interstitial Nephritis and Oxalate Nephropathy After Rapid Pasireotide Response in Treatment-resistant Acromegaly

We report a case of interstitial nephritis, likely secondary to oxalate nephropathy, due to the development of pancreatic exocrine dysfunction after commencement of pasireotide for acromegaly. Pasireotide is known to impair insulin secretion but can also impair pancreatic exocrine function, hypothezised to result from high-affinity binding of somatostatin receptors 1, 2, 3, and 5. This has been an advantage in postoperative tissue anastomoses after pancreatic surgery, but exocrine insufficiency has not been reported when used for the treatment of acromegaly. A 73-year-old woman, diagnosed with acromegaly, was unable to achieve biochemical control despite 2 surgical resections of an invasive mammosomatotroph pituitary tumor and treatment with cabergoline and maximal-dose lanreotide. The tumor expressed somatostatin receptor type 5 but not somatostatin receptor type 2, predicting good response from pasireotide, which was commenced at 40 mg every 4 weeks. IGF-1 rapidly normalized, but the patient presented with nausea, anorexia, and acute kidney injury. Renal biopsy revealed acute-on-chronic interstitial nephritis, with numerous oxalate crystals. Increased fecal fat globules were noted on fat stain (3+), supporting malabsorption as an etiology of secondary enteric hyperoxaluria. Renal function recovered to near baseline over months following pasireotide withdrawal and high-dose glucocorticoids.

A Macrophage Membrane-Polymer Hybrid Biomimetic Nanoplatform for Therapeutic Delivery of Somatostatin Peptide to Chronic Pancreatitis

The clinical translation of therapeutic peptides is generally challenged by multiple issues involving absorption, distribution, metabolism and excretion. In this study, a macrophage membrane-coated poly(lactic-co-glycolic acid) (PLGA) nanodelivery system was developed to enhance the bioavailability of the somatostatin (SST) peptide, which faces the hurdles of short half-life and potential side effects in the treatment of chronic pancreatitis. Using a facile nanoprecipitation strategy, SST was loaded in the nanoparticles with an encapsulation efficiency (EE) and a loading efficiency (LE) of 73.68 ± 3.56% and 1.47 ± 0.07%, respectively. The final formulation of SST-loaded nanoparticles with the camouflage of macrophage membrane (MP-SST) showed a mean diameter of 151 ± 4 nm and an average zeta potential of −29.6 ± 0.3 mV, which were stable long term during storage. With an above 90% cell viability, a hemolysis level of about 2% (<5%) and a preference for being ingested by activated endothelial cells compared to macrophages, the membrane−polymer hybrid nanoparticle showed biocompatibility and targeting capability in vitro. After being intravenously administered to mice with chronic pancreatitis, the MP-SST increased the content of SST in the serum (123.6 ± 13.6 pg/mL) and pancreas (1144.9 ± 206.2 pg/g) compared to the treatment of (Dulbecco’s phosphate-buffered saline) DPBS (61.7 ± 6.0 pg/mL in serum and 740.2 ± 172.4 pg/g in the pancreas). The recovery of SST by MP-SST downregulated the expressions of chronic pancreatitis-related factors and alleviated the histologic severity of the pancreas to the greatest extent compared to other treatment groups. This augmentation of SST therapeutic effects demonstrated the superiority of integrating the synthetic polymer with biological membranes in the design of nanoplatforms for advanced and smart peptide delivery. Other peptides like SST can also be delivered via the membrane−polymer hybrid nanosystem for the treatment of diseases, broadening and promoting the potential clinical applications of peptides as therapeutics.

Pancreatic Blood Flow with Special Emphasis on Blood Perfusion of the Islets of Langerhans

The pancreatic islets are more richly vascularized than the exocrine pancreas, and possess a 5- to 10-fold higher basal and stimulated blood flow, which is separately regulated. This is reflected in the vascular anatomy of the pancreas where islets have separate arterioles. There is also an insulo-acinar portal system, where numerous venules connect each islet to the acinar capillaries. Both islets and acini possess strong metabolic regulation of their blood perfusion. Of particular importance, especially in the islets, is adenosine and ATP/ADP. Basal and stimulated blood flow is modified by local endothelial mediators, the nervous system as well as gastrointestinal hormones. Normally the responses to the nervous system, especially the parasympathetic and sympathetic nerves, are fairly similar in endocrine and exocrine parts. The islets seem to be more sensitive to the effects of endothelial mediators, especially nitric oxide, which is a permissive factor to maintain the high basal islet blood flow. The gastrointestinal hormones with pancreatic effects mainly influence the exocrine pancreatic blood flow, whereas islets are less affected. A notable exception is incretin hormones and adipokines, which preferentially affect islet vasculature. Islet hormones can influence both exocrine and endocrine blood vessels, and these complex effects are discussed. Secondary changes in pancreatic and islet blood flow occur during several conditions. To what extent changes in blood perfusion may affect the pathogenesis of pancreatic diseases is discussed. Both type 2 diabetes mellitus and acute pancreatitis are conditions where we think there is evidence that blood flow may contribute to disease manifestations. © 2019 American Physiological Society. Compr Physiol 9:799-837, 2019.

Relationship between somatostatin and interleukin-6: A cross-sectional study in patients with acute pancreatitis

OBJECTIVES

The aim of the analysis is to determine dynamic changes in somatostatin (SS) and interleukin-6 (IL-6) concentrations during in acute pancreatitis (AP).

METHODS

The influence of tobacco smoking on IL-6 and SS levels in the serum of non-smoking (n = 10) and smoking (n = 27) patients with diagnosed AP and control group: non-smoking (n = 44), smoking (n = 42) and passive smoking (n = 29) healthy persons was proved. The concentration of IL-6 and SS was determined by means of ELISA. Differences between the groups analyzed were tested using the U Mann Whitney test. The Spearman rank correlation analysis was used to evaluate the correlations.

RESULTS

The concentrations of IL-6 and SS were significantly higher in smoking patients with AP and healthy persons when compared with non-smoking population on every day (1 day: p = 0.0002, p = 0.015; 3 day: p = 0.005, p = 0.001 and 7 day: p = 0.025, p = 0.038). Dynamic changes in concentrations of IL-6 and SS in the serum of patients with AP were demonstrated in the ensuing days of the disease. In case of non-smoking and smoking patients, significant positive correlations between IL-6 and SS was observed.

CONCLUSIONS

These findings suggest that some of the antiinflammatory effects of SS against acute pancreatitis may be mediated by reducing the local proinflammatory cytokine secretion in the pancreas.

The association between Helicobacter pylori seropositivity and risk of new-onset diabetes: a prospective cohort study

AIMS/HYPOTHESIS

Previous studies have suggested a possible connection between Helicobacter pylori (H. pylori) infection and diabetes risk. However, prospective studies examining direct associations between these two factors are relatively lacking. In this prospective cohort study, we aimed to evaluate the association between H. pylori infection and risk of developing diabetes.

METHODS

We performed a population-based prospective study, recruiting participants aged 45-74 years and without diabetes from the Chinese Multi-provincial Cohort Study in 2002, with a 10 year follow-up to investigate development of diabetes. H. pylori serostatus was determined by measuring serum H. pylori antibodies. H. pylori seropositivity was defined as the antibody concentration ≥ 10 U/ml. To examine the association between H. pylori seropositivity and diabetes risk, modified Poisson regression was performed.

RESULTS

Of 2085 participants without diabetes, 1208 (57.9%) were H. pylori seropositive in 2002. After multivariate adjustment of possible diabetes risk factors, H. pylori seropositivity was associated with lower risk of diabetes (RR 0.78 [95% CI 0.63, 0.97], p = 0.022). Of the 1275 participants with H. pylori antibody measurements in both 2002 and 2007, 677 (53.1%) were persistently seropositive. A lower risk of diabetes was also observed in participants with persistent H. pylori seropositivity (RR 0.61 [95% CI 0.41, 0.93], p = 0.020), compared with those persistently seronegative.

CONCLUSIONS/INTERPRETATION

H. pylori seropositivity was associated with lower risk of diabetes in this prospective cohort study. Extrapolation of these results and the mechanism underlying the observed association require further investigation.

Evaluation of HVHF for the treatment of severe acute pancreatitis accompanying MODS

Systemic inflammatory response syndrome (SIRS) prevention is key to severe acute pancreatitis (SAP) treatment and the assessment of high-volume hemofiltration (HVHF) for treating SAP accompanying multiple organ dysfunction syndromes.In this prospective controlled study, 40 SAP patients were divided into 2 groups: control (n = 22, treated with fasting, decompression, and intravenous somatostatin) and HVHF (n = 18, HVHF administration in addition to the treatment in the control group) groups; and were assessed for serum and urine amylase, WBC, C-reactive protein (CRP), and hepatic and renal functions. Vital signs and abdominal symptoms were recorded, and complications and mortality were analyzed.APACHE II scores in the HVHF group were significantly lower than in the control group at 3 and 7 days (6.3 ± 1.7 vs 9.2 ± 2.1 and 3.3 ± 0.8 vs 6.2 ± 1.7, respectively). Compared with controls, serum, and urine amylase, WBC, CRP, and organ functions significantly improved after HVHF treatment. Meanwhile, mortality (16.7% vs 31.8%) and complication (11.1% vs 40.9%) rates were significantly reduced.The other clinical parameters were significantly ameliorated by HVHF. HVHF rapidly reduces abdominal symptoms and improves prognosis, reducing mortality in SAP patients; and is likely through systemic inflammatory response syndrome attenuation in the early disease stage.

Add-on effect of crude rhubarb to somatostatin for acute pancreatitis: A meta-analysis of randomized controlled trials

ETHNOPHARMACOLOGICAL RELEVANCE

Rhubarb is one of the common herbs used in traditional Chinese complex prescriptions for the treatment of various inflammatory diseases. We sought to determine the add-on effect of crude rhubarb to somatostatin in patients with acute pancreatitis by conducting a meta-analysis.

MATERIALS AND METHODS

We searched the Pubmed, EMBASE, Cochrane Library, CNKI, Wanfang, VIP databases up to November 2015. Randomized controlled trials (RCTs) comparing crude rhubarb plus somatostatin to somatostatin alone for acute pancreatitis were included. Risk ratio (RR) or weighted mean difference (WMD) with their 95% confidence interval (CI) was calculated between with and without crude rhubarb therapy.

RESULTS

A total of 19 RCTs involving 1161 patients were identified. Compared with somatostatin alone, crude rhubarb plus somatostatin significantly reduced the total complications (RR 0.55; 95% CI 0.41-0.73) and APACHE Ⅱ scores (WMD -1.16; 95% CI -1.91 to -0.41) as well as shortened the duration of elevated serum amylase (WMD -2.01 days; 95% CI -2.57 to -1.44), duration of abdominal pain (WMD -1.33 days; 95% CI -1.61 to -1.05), the first defecation time (WMD -2.27 days; 95% CI -3.06 to -1.47), and duration of hospital stay (WMD -6.70 days; 95% CI -8.81 to -4.60). However, there were no significant differences in total mortality rates (RR 0.61; 95% CI 0.34 to 1.12) between two groups.

CONCLUSIONS

Crude rhubarb as adjuvant therapy to somatostatin appears to have additional benefits in patients with acute pancreatitis. However, interpretation of these results should be cautioned due to the methodological flaws.

Somatostatin expression in the pancreatic cells of smoking and non-smoking chronic pancreatitis patients with or without diabetes

OBJECTIVES

The aim of the analysis is to determine the location and degree of the hormone immunoreactivity in tissues of patients with chronic pancreatitis and diabetes.

METHODS

The study was performed on 11 non-smoking and 12 smoking patients with chronic pancreatitis (CP) with/without diabetes. The hormone was located in the pancreatic tissues by means of the immunohistochemical method using somatostatin antibodies. The histopathological evaluation of the hormone expression intensity in tissue sections was carried out using the semi-quantitative method and was calculated by means of a digital image analysis.

RESULTS

The hormone's strong immunohistochemical reaction and the modified D-cell location may be a result of the pancreatic tissue fibrosis process prevention in patients with CP. Changes in the intensity of SS immunoreactivity and the D-cell distribution in the pancreas of patients with CP and diabetes may possibly result from the additional hormone compensatory effect in the excessive glucagon secretion inhibition. Smoking patients with diabetes showed significantly higher hormone immunostaining in the pancreas compared to non-smoking patients without diabetes and healthy persons.

CONCLUSIONS

The severity of histopathological changes in smoking CP patients indicates that the cigarette smoke components may further exacerbate the inflammatory reactions. Patients with CP were found to have a strong immunohistochemical reaction to SS and changes in the distribution of D cells when compared to healthy patients. The strongest immunohistochemical SS reaction has been identified in the pancreatic tissue from smoking patients with diabetes.

Therapeutic uses of somatostatin and its analogues: Current view and potential applications

Somatostatin is an endogeneous cyclic tetradecapeptide hormone that exerts multiple biological activities via five ubiquitously distributed receptor subtypes. Classified as a broad inhibitory neuropeptide, somatostatin has anti-secretory, anti-proliferative and anti-angiogenic effects. The clinical use of native somatostatin is limited by a very short half-life (1 to 3min) and the broad spectrum of biological responses. Thus stable, receptor-selective agonists have been developed. The majority of these somatostatin therapeutic agonists bind strongly to two of the five receptor subtypes, although recently an agonist of wider affinity has been introduced. Somatostatin agonists are established in the treatment of acromegaly with recently approved indications in the therapy of neuroendocrine tumours. Potential therapeutic uses for somatostatin analogues include diabetic complications like retinopathy, nephropathy and obesity, due to inhibition of IGF-1, VEGF together with insulin secretion and effects upon the renin-angiotensin-aldosterone system. Wider uses in anti-neoplastic therapy may also be considered and recent studies have further revealed anti-inflammatory and anti-nociceptive effects. This review provides a comprehensive, current view of the biological functions of somatostatin and potential therapeutic uses, informed by the wide range of pharmacological advances reported since the last published review in 2004 by P. Dasgupta. The pharmacology of somatostatin receptors is explained, the current uses of somatostatin agonists are discussed, and the potential future of therapeutic applications is explored.