Insulin modulates the inflammatory granulocyte response to streptococci via phosphatidylinositol 3-kinase

The Potentials of Melatonin in the Prevention and Treatment of Bacterial Meningitis Disease

Bacterial meningitis (BM) is an acute infectious central nervous system (CNS) disease worldwide, occurring with 50% of the survivors left with a long-term serious sequela. Acute bacterial meningitis is more prevalent in resource-poor than resource-rich areas. The pathogenesis of BM involves complex mechanisms that are related to bacterial survival and multiplication in the bloodstream, increased permeability of blood-brain barrier (BBB), oxidative stress, and excessive inflammatory response in CNS. Considering drug-resistant bacteria increases the difficulty of meningitis treatment and the vaccine also has been limited to several serotypes, and the morbidity rate of BM still is very high. With recent development in neurology, there is promising progress for drug supplements of effectively preventing and treating BM. Several in vivo and in vitro studies have elaborated on understanding the significant mechanism of melatonin on BM. Melatonin is mainly secreted in the pineal gland and can cross the BBB. Melatonin and its metabolite have been reported as effective antioxidants and anti-inflammation, which are potentially useful as prevention and treatment therapy of BM. In bacterial meningitis, melatonin can play multiple protection effects in BM through various mechanisms, including immune response, antibacterial ability, the protection of BBB integrity, free radical scavenging, anti-inflammation, signaling pathways, and gut microbiome. This manuscript summarizes the major neuroprotective mechanisms of melatonin and explores the potential prevention and treatment approaches aimed at reducing morbidity and alleviating nerve injury of BM.

Vitamin D deficiency enhances insulin resistance by promoting inflammation in type 2 diabetes

OBJECTIVE

This study was aimed to analyze the level of serum 25(OH)D in patients with type 2 diabetes (T2DM), and explore the relationship between serum 25(OH)D and insulin resistance.

METHODS

60 health people and 106 patients with T2DM were measured the level of serum 25(OH)D, fasting blood glucose, insulin, TNF-α, IL-6, IL-8, and IL-1β, etc. We established a rat model of T2DM and vitamin D (VD) deficiency, and studied the effects of VD deficiency on homeostasis model assessment insulin resistance (HOMA-IR) and pancreatic inflammation.

RESULTS

The level of serum 25(OH)D in patients with T2DM was significantly lower than that in health people, and HOMA-IR decreased with the increasing of the serum 25(OH)D level. Pearson correlation analysis showed that the serum 25(OH)D level in patients with T2DM had a negative correlation with HOMA-IR (r=-0.750, P<0.001), TNF-α (r=-0.705, P<0.001), IL-1β (r=-0.661, P<0.001), IL-8 (r=-0.645, P<0.001), and IL-6 (r=-0.609, P<0.001). In animal experiment, Vitamin D deficiency enhanced HOMA-IR in rats with T2DM and reversed it by supplementing VD. Vitamin D deficiency could increase the inflammatory response by up-regulating p-p65/RelB in the pancreas tissue.

CONCLUSION

Serum 25(OH)D was elevated and Vitamin D deficiency enhanced insulin resistance by promoting inflammation via NF-kB pathway in patients with T2DM.

Eosinophilia and reduced STAT3 signaling affect neutrophil cell death in autosomal-dominant Hyper-IgE syndrome

The autosomal-dominant hyper-IgE syndrome (HIES), caused by mutations in STAT3, is a rare primary immunodeficiency that predisposes to mucocutaneous candidiasis and staphylococcal skin and lung infections. This infection phenotype is suggestive of defects in neutrophils, but data on neutrophil functions in HIES are inconsistent. This study was undertaken to functionally characterize neutrophils in STAT3-deficient HIES patients and to analyze whether the patients` eosinophilia affects the neutrophil phenotype in S. aureus infection. Neutrophil functions and cell death kinetics were studied in eight STAT3-deficient patients. Moreover, the response of STAT3-deficient neutrophils to S. aureus and the impact of autologous eosinophils on pathogen-induced cell death were analyzed. No specific aberrations in neutrophil functions were detected within this cohort. However, the half-life of STAT3-deficient neutrophils ex vivo was reduced, which was partially attributable to the presence of eosinophils. Increased S. aureus-induced cell lysis, dependent on the staphylococcal virulence controlling accessory gene regulator (agr)-locus, was observed in STAT3-deficient neutrophils and upon addition of eosinophils. Accelerated neutrophil cell death kinetics may underlie the reported variability in neutrophil function testing in HIES. Increased S. aureus-induced lysis of STAT3-deficient neutrophils might affect pathogen control and contribute to tissue destruction during staphylococcal infections in HIES.

Immune Modulation by Human Secreted RNases at the Extracellular Space

The ribonuclease A superfamily is a vertebrate-specific family of proteins that encompasses eight functional members in humans. The proteins are secreted by diverse innate immune cells, from blood cells to epithelial cells and their levels in our body fluids correlate with infection and inflammation processes. Recent studies ascribe a prominent role to secretory RNases in the extracellular space. Extracellular RNases endowed with immuno-modulatory and antimicrobial properties can participate in a wide variety of host defense tasks, from performing cellular housekeeping to maintaining body fluid sterility. Their expression and secretion are induced in response to a variety of injury stimuli. The secreted proteins can target damaged cells and facilitate their removal from the focus of infection or inflammation. Following tissue damage, RNases can participate in clearing RNA from cellular debris or work as signaling molecules to regulate the host response and contribute to tissue remodeling and repair. We provide here an overall perspective on the current knowledge of human RNases’ biological properties and their role in health and disease. The review also includes a brief description of other vertebrate family members and unrelated extracellular RNases that share common mechanisms of action. A better knowledge of RNase mechanism of actions and an understanding of their physiological roles should facilitate the development of novel therapeutics.

Basal insulin therapy is associated with beneficial effects on postoperative infective complications, independently from circulating glucose levels in patients admitted for cardiac surgery

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The effect of insulin per se on infective complications during cardiac surgery was evaluated.

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Eight hundred twelve patients were included.

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Insulin therapy decreased infections independently from glycemic levels.

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Basal + premeal insulin therapy is well tolerated without severe hypoglycemia cases.

Background

Although hyperglycemia is a strong predictor of postoperative infective complications (PIC), little is known about the effect of basal insulin therapy (BIT) per se on PIC.

Aim

To evaluate if there is an association between BIT, independent of glucose levels, and a possible improvement of PIC during the perioperative cardiosurgery period (PCP).

Methods

In 812 patients admitted for cardiac intervention and treated with a continuous intravenous insulin infusion (CIII) for hyperglycemic levels (>130 mg/dl), a retrospective analysis was performed during the PCP (January 2009–December 2011). Upon transfer to the cardiac surgery division, if fasting glucose was ≥130 mg/dl, a basal + premeal insulin therapy was initiated (121 patients, group 1); for <130 mg/dl, a premeal insulin alone was initiated (691 patients, group 2).

Findings

Compared with group 2, group 1 showed reductions in PIC (2.48% vs 7.96%, p < 0.049; odds ratio: 0.294; 95% CI: 0.110–0.780), C-Reactive Protein (p < 0.05) and white blood cell (p < 0.05) levels despite glucose levels and CIII that were higher during the first two days after surgery (179.8 ± 25.3 vs 169.5 ± 10.6 mg/dl, p < 0.01; 0.046 ± 0.008 vs 0.037 ± 0.015 U/kg/h, p < 0.05, respectively). Normal glucose levels were achieved in both groups from day 3 before the discharge. The mean length of hospital duration was 18% lower in group 1 than in group 2 (7.21 ± 05.08 vs 8.76 ± 9.08 days, p < 0.007), providing a significant impact on public health costs.

Conclusions

Basal + preprandial insulin therapy was associated with a lower frequency of PIC than preprandial insulin therapy alone, suggesting a beneficial effect of basal insulin therapy on post-surgery outcome.

Insulin and the phosphatidylinositol 3-kinase signaling pathway regulate Ribonuclease 7 expression in the human urinary tract

Diabetes mellitus is a systemic disease associated with a deficiency of insulin production or action. Diabetic patients have an increased susceptibility to infection with the urinary tract being the most common site. Recent studies suggest that Ribonuclease 7 (RNase 7) is a potent antimicrobial peptide that plays an important role in protecting the urinary tract from bacterial insult. Because the impact of diabetes on RNase 7 expression and function are unknown, we investigated the effects of insulin on RNase 7 using human urine specimens. The urinary RNase 7 concentrations were measured in healthy control patients and insulin-deficient type 1 diabetics before and after starting insulin therapy. Compared with controls, diabetic patients had suppressed urinary RNase 7 concentrations, which increased with insulin. Using primary human urothelial cells, the mechanisms by which insulin stimulates RNase 7 synthesis were next explored. Insulin induced RNase 7 production via the phosphatidylinositide 3-kinase signaling pathway (PI3K/AKT) to shield urothelial cells from uropathogenic E. coli. In contrast, uropathogenic E. coli suppressed PI3K/AKT activity and RNase 7 production. Thus, insulin and PI3K/AKT signaling are essential for RNase 7 expression and increased infection risks in diabetic patients may be secondary to suppressed RNase 7 production. Our data may provide unique insight into novel urinary tract infection therapeutic strategies in at-risk populations.

Retrospective evaluation of risk factors and outcome predictors in cats with diabetic ketoacidosis (1997-2007): 93 cases

OBJECTIVES

To determine risk factors and outcome predictors in cats with diabetic ketoacidosis (DKA).

DESIGN

Retrospective study. Inclusion in the DKA group required blood glucose concentration > 13.9 mmol/L (250 mg/dL), venous pH < 7.35, and urine or serum acetoacetate concentration greater than 1.5 mmol/L (15 mg/dL). Signalment and weight were recorded in all cats with uncomplicated diabetes mellitus (DM) without DKA and in all other nondiabetic cats examined during the study period. Clinicopathologic variables, concurrent disorders, and initial insulin intravenous (IV) continuous-rate infusion (CRI) concentration of 1.1 or 2.2 U/kg/240 mL bag of 0.9% NaCl, were examined for a possible association with outcome.

SETTING

University teaching hospital.

ANIMALS

Ninety-three cats with DKA, 682 cats with uncomplicated DM, and 16,926 cats without DM or DKA.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Cats with DKA were younger (median age 9.4 years; range, 1-17.9 years) than cats with uncomplicated DM (median 11.6 years; range 0.7-19.5 years, P < 0.0003). Siamese cats were overrepresented in the DKA group compared to the uncomplicated DM or nondiabetic group (P = 0.038 and P = 0.01, respectively). Poor outcome (defined as death due to disease or by euthanasia) in 36 cats with DKA (39%) was associated with increased initial creatinine, BUN, total serum magnesium, and total bilirubin concentrations (P = 0.007, P = 0.005, P = 0.03, P = 0.03, respectively). Cats treated with a higher concentration of insulin were less likely to have a poor outcome compared to cats treated with a lower concentration of insulin (odds ratio 0.14, 95% confidence interval 0.02-1.16, P = 0.02).

CONCLUSIONS

Cats with DKA are more likely to be Siamese than cats with uncomplicated DM. Poor outcome of cats with DKA is associated with increased initial creatinine, BUN, total magnesium, and total bilirubin concentrations. Good outcome was associated with a higher concentration of IV insulin CRI.

Interaction of Streptococcus agalactiae and Cellular Innate Immunity in Colonization and Disease

Streptococcus agalactiae (Group B streptococcus, GBS) is highly adapted to humans, where it is a normal constituent of the intestinal and vaginal flora. Yet, GBS has highly invasive potential and causes excessive inflammation, sepsis, and death at the beginning of life, in the elderly and in diabetic patients. Thus, GBS is a model pathobiont that thrives in the healthy host, but has not lost its potential virulence during coevolution with mankind. It remains incompletely understood how the innate immune system contains GBS in the natural niches, the intestinal and genital tracts, and which molecular events underlie breakdown of mucocutaneous resistance. Newborn infants between days 7 and 90 of life are at risk of a particularly striking sepsis manifestation (late-onset disease), where the transition from colonization to invasion and dissemination, and thus from health to severe sepsis is typically fulminant and not predictable. The great majority of late-onset sepsis cases are caused by one clone, GBS ST17, which expresses HvgA as a signature virulence factor and adhesin. In mice, HvgA promotes the crossing of both the mucosal and the blood–brain barrier. Expression levels of HvgA and other GBS virulence factors, such as pili and toxins, are regulated by the upstream two-component control system CovR/S. This in turn is modulated by acidic epithelial pH, high glucose levels, and during the passage through the mouse intestine. After invasion, GBS has the ability to subvert innate immunity by mechanisms like glycerinaldehyde-3-phosphate-dehydrogenase-dependent induction of IL-10 and β-protein binding to the inhibitory phagocyte receptors sialic acid binding immunoglobulin-like lectin 5 and 14. On the host side, sensing of GBS nucleic acids and lipopeptides by both Toll-like receptors and the inflammasome appears to be critical for host resistance against GBS. Yet, comprehensive models on the interplay between GBS and human immune cells at the colonizing site are just emerging.

Hypomorphic homozygous mutations in phosphoglucomutase 3 (PGM3) impair immunity and increase serum IgE levels

BACKGROUND

Recurrent bacterial and fungal infections, eczema, and increased serum IgE levels characterize patients with the hyper-IgE syndrome (HIES). Known genetic causes for HIES are mutations in signal transducer and activator of transcription 3 (STAT3) and dedicator of cytokinesis 8 (DOCK8), which are involved in signal transduction pathways. However, glycosylation defects have not been described in patients with HIES. One crucial enzyme in the glycosylation pathway is phosphoglucomutase 3 (PGM3), which catalyzes a key step in the synthesis of uridine diphosphate N-acetylglucosamine, which is required for the biosynthesis of N-glycans.

OBJECTIVE

We sought to elucidate the genetic cause in patients with HIES who do not carry mutations in STAT3 or DOCK8.

METHODS

After establishing a linkage interval by means of SNPchip genotyping and homozygosity mapping in 2 families with HIES from Tunisia, mutational analysis was performed with selector-based, high-throughput sequencing. Protein expression was analyzed by means of Western blotting, and glycosylation was profiled by using mass spectrometry.

RESULTS

Mutational analysis of candidate genes in an 11.9-Mb linkage region on chromosome 6 shared by 2 multiplex families identified 2 homozygous mutations in PGM3 that segregated with disease status and followed recessive inheritance. The mutations predict amino acid changes in PGM3 (p.Glu340del and p.Leu83Ser). A third homozygous mutation (p.Asp502Tyr) and the p.Leu83Ser variant were identified in 2 other affected families, respectively. These hypomorphic mutations have an effect on the biosynthetic reactions involving uridine diphosphate N-acetylglucosamine. Glycomic analysis revealed an aberrant glycosylation pattern in leukocytes demonstrated by a reduced level of tri-antennary and tetra-antennary N-glycans. T-cell proliferation and differentiation were impaired in patients. Most patients had developmental delay, and many had psychomotor retardation.

CONCLUSION

Impairment of PGM3 function leads to a novel primary (inborn) error of development and immunity because biallelic hypomorphic mutations are associated with impaired glycosylation and a hyper-IgE-like phenotype.