Role of insulin on PGE2 generation during LPS-induced lung inflammation in rats

Outpatient insulin use in type 2 diabetes mellitus and acute respiratory distress syndrome outcomes: A retrospective cohort study

BACKGROUND

The impact of type 2 diabetes mellitus (T2DM) on acute respiratory distress syndrome (ARDS) is debatable. T2DM was suspected to reduce the risk and complications of ARDS. However, during coronavirus disease 2019 (COVID-19), T2DM predisposed patients to ARDS, especially those who were on insulin at home.

AIM

To evaluate the impact of outpatient insulin use in T2DM patients on non-COVID-19 ARDS outcomes.

METHODS

We conducted a retrospective cohort analysis using the Nationwide Inpatient Sample database. Adult patients diagnosed with ARDS were stratified into insulin-dependent diabetes mellitus (DM) (IDDM) and non-insulin-dependent DM (NIDDM) groups. After applying exclusion criteria and matching over 20 variables, we compared cohorts for mortality, duration of mechanical ventilation, incidence of acute kidney injury (AKI), length of stay (LOS), hospitalization costs, and other clinical outcomes.

RESULTS

Following 1:1 propensity score matching, the analysis included 274 patients in each group. Notably, no statistically significant differences emerged between the IDDM and NIDDM groups in terms of mortality rates (32.8% vs 31.0%, P = 0.520), median hospital LOS (10 d, P = 0.537), requirement for mechanical ventilation, incidence rates of sepsis, pneumonia or AKI, median total hospitalization costs, or patient disposition upon discharge.

CONCLUSION

Compared to alternative anti-diabetic medications, outpatient insulin treatment does not appear to exert an independent influence on in-hospital morbidity or mortality in diabetic patients with non-COVID-19 ARDS.

Effects of aerobic exercise on lipopolysaccharide-induced experimental acute lung injury in the animal model of type 1 diabetes mellitus

NEW FINDINGS

What is the central question of this study? We evaluated the effects of diabetes and exercise on lipopolysaccharide-induced acute lung injury. By providing a comprehensive analysis of redox status, blood gases and histological parameters, we aimed to contribute to the ongoing debate in the literature. What are the main findings and its importance? We demonstrated the preventive effect of exercise, but diabetes did not alter the severity of acute lung injury.

ABSTRACT

Acute lung injury (ALI) is a life-threatening respiratory condition. Diabetes (DM) is a metabolic disease characterized by hyperglycaemia. There is an ongoing debate concerning whether there is a protective effect of diabetes in ALI. Exercise is a special type of physical activity that has numerous beneficial effects. The aim of our study was to investigate the effects of diabetes and exercise on the prognosis of ALI. Male Wistar albino rats were divided into two groups (sedentary and exercise). Both groups were divided into four subgroups: Control, ALI, DM, DM+ALI (n = 6 each). Diabetes was induced by injection of streptozotocin (50 mg/kg i.p.). The maximal exercise capacity was determined with the incremental load test. Animals were exercised on a treadmill for 45 min at 70% of maximal exercise capacity, 5 days a week for 12 weeks. Acute lung injury was induced by intratracheal injection of lipopolysaccharide (100 μg/100 g body weight) 24 h before the end of the experiment. We performed arterial blood gas analysis. Redox status was measured in both plasma and lung tissue. Malondialdehyde and 8-hydroxy-2'-deoxyguanosine levels were measured in lung tissue. Lung tissue was evaluated histologically. Acute lung injury caused significant damage in the lung tissue, which was verified histologically, with an increase in oxidative stress parameters. Exercise prevented the lung damage induced by ALI and reduced oxidative stress in the lung tissue. Diabetes did not alter the magnitude of damage done by ALI. Exercise showed a protective effect against DM and ALI in rats. The effect of DM was insignificant for the prognosis of ALI.

Intrauterine growth restriction leads to a high-corticosterone producing offspring: An implication for pulmonary infection susceptibility

AIMS

Although intrauterine growth restriction (IUGR) impairs immune system homeostasis and lung development, its relationship with the susceptibility to pulmonary infections remains unclear. Thus, this study aimed to investigate the impact of IUGR on acute lung inflammatory response induced by bacterial stimulus.

MATERIALS AND METHODS

Pregnant female Wistar rats were subjected to 50% caloric-protein food restriction during gestation. To mimic bacterial lung infection, adult male offspring (12 weeks old) were challenged with a single lipopolysaccharide (LPS) intranasal instillation, and 6 h later, we assessed the acute inflammatory response. Normal birth weight (NBW) animals represent the control group.

KEY FINDINGS

LPS instillation increased the protein levels in the airways of both the NBW and low birth weight (LBW) groups, indicating vascular leakage. LBW animals exhibited a lower number of neutrophils, reduced production of interleukin-6 and macrophage-inflammatory protein-2 and decreased upregulation of intercellular adhesion molecule-1 gene expression in lung tissues. Further analysis revealed that the LBW group produced lower levels of prostaglandin-E₂ and failed to secrete leukotriene-B₄ upon LPS stimulation, which correlated with impaired cyclooxygenase-2 and 5-lipoxygenase expression. These results were probably associated with their inability to upregulate the expression of Toll-like receptor-4 and downstream signaling proteins, such as nuclear factor kappa-B, in the lungs. The LBW group also exhibited abnormal airway thickening and high corticosterone levels under basal conditions.

SIGNIFICANCE

This study suggests that IUGR-induced foetal programming in LBW offspring threatens HPA axis physiology and corticosterone biodisponibility, and impairs the innate response to bacterial antigens, increasing future susceptibility to pulmonary infection.

Diabetes Mellitus Is Associated with a Lower Risk of Gout: A Meta-Analysis of Observational Studies

AIMS

Although several epidemiological studies have investigated the relationship between diabetes mellitus (DM) and the risk of gout, the results are inconsistent. Therefore, we systematically retrospected available observational studies to clarify the impact of DM on the risk of gout.

METHODS

Embase, PubMed, Cochrane Library, Scopus, Web of Science, and China National Knowledge Infrastructure were searched for relevant articles from inception to 2 March 2020. The quality of the included studies was assessed using the Newcastle-Ottawa Quality Assessment Scale. The multivariate adjusted relative risks (aRR) and corresponding 95% confidence intervals (CI) were pooled based on a random-effect model. Cochran's Q test and I ² were used to evaluate heterogeneity.

RESULTS

Five studies involving 863,755 participants were included in our meta-analysis. DM was associated with a lower risk of gout (aRR: 0.66; 95% CI: 0.59 to 0.73) but had a high heterogeneity (I ² = 89.2%). Metaregression analysis revealed that the types of DM were the source of heterogeneity. Subgroup analysis by types of DM showed that the risk of gout was significantly lower in type 1 DM (T1DM) (aRR: 0.42; 95% CI: 0.28 to 0.63) than in type 2 DM (T2DM) (aRR: 0.72; 95% CI: 0.70 to 0.74). Furthermore, when stratified according to gender in DM, sex-specific association was found. The inverse association was observed in males only (aRR: 0.57; 95% CI: 0.43 to 0.77) and not in females (aRR: 0.96; 95% CI: 0.87 to 1.05). Further stratified based on glycated hemoglobin (HbA1c) levels in DM, raised A1C levels were associated with a reduced risk of gout in patients with DM.

CONCLUSIONS

This meta-analysis indicated that DM was related to a lower risk of gout, and the protective effect of DM on the risk of gout was stronger in males, T1DM, or DM with high HbA1c levels. However, more prospective cohort studies are required to confirm these results.

Diabetic lung disease: fact or fiction?

Diabetes mellitus is a chronic, progressive, incompletely understood metabolic disorder whose prevalence has been increasing steadily worldwide. Even though little attention has been paid to lung disorders in the context of diabetes, its prevalence has recently been challenged by newer studies of disease development. In this review, we summarize and discuss the role of diabetes mellitus involved in the progression of pulmonary diseases, with the main focus on pulmonary fibrosis, which represents a chronic and progressive disease with high mortality and limited therapeutic options.

Obesity and Type 2 Diabetes mellitus induce lipopolysaccharide tolerance in rat neutrophils

Obesity and diabetes implicate in various health complications and increased mortality caused by infection. Innate immune system is broadly affected by these diseases, leading the patients to an immunosuppressive state. A mechanism that leads innate immune cells to a less capacity of killing microorganism is the impaired TLR4 activation. TLR4 recognizes a component of the outer membrane of Gram-negative bacteria, lipopolysaccharide (LPS), and when activated increases the production of inflammatory substances. Neutrophils are components of the innate immune system and are the first responders to an invading agent. The correct activation of TLR4 in these cells is required for the initiation of the inflammatory process and elimination of the microorganisms. The aim of this study was to evaluate the influence of type 2 diabetes and obesity in the TLR4 pathway in rat neutrophils. Two experimental models were used: Goto-Kakizaki rats and high-fat-diet induced obese Wistar rats. To evaluate neutrophil response to LPS, intratracheal LPS instillation was used. Neutrophils from obese and diabetic animals exhibited tolerance to LPS, mainly by the impaired production of cytokines and chemokines and the low content of phospho-NFκB and phospho-IKBα. Neutrophils from both experimental models had increased cell death, impaired in vivo migration and myeloperoxidase activity.

Immunomodulatory properties of captopril, an ACE inhibitor, on LPS-induced lung inflammation and fibrosis as well as oxidative stress

BACKGROUND

The role of angiotensin converting enzyme inhibitors on the inflammation process has been demonstrated previously. In the present study, the effects of captopril on lung injury induced by lipopolysaccharide (LPS) were investigated.

METHODS

Control, LPS, 12.5, 25 and 50 mg/kg captopril-treated before LPS administration and captopril 50 mg/kg before saline administration groups of rats were studied. Total and percentage of differential WBC, the levels of MDA, total thiol groups, the activities of SOD and CAT, the levels of IFN-γ, PGE2, TGF-β1 and IL-4 in the BALF were evaluated.

RESULTS

MDA concentration in LPS groups treated with all captopril concentrations, total WBC in LPS + Cap50, percent of neutrophils in LPS + Cap25 and LPS + Cap50, levels of IFN-γ, PGE2, TGF-β1 in LPS + Cap50 and IFN-γ/IL-4 ratio in LPS + Cap25 and LPS + Cap50 were significantly decreased but total thiol groups and activity of SOD in LPS + Cap25 and LPS + Cap50, percent of lymphocyte, CAT activity and concentration of IL-4 only in LPS + Cap50 group were increased in comparison to the LPS group (p < 0.05 to p < 0.001).

CONCLUSION

Captopril dose dependently improved oxidant-antioxidant biomarkers, the imbalance between pro-inflammatory and anti-inflammatory cytokines and showed specific immunomodulatory effect on Th1/Th2 balance in the BALF of lung injury induced by LPS.

Autophagy Is Impaired in Neutrophils from Streptozotocin-Induced Diabetic Rats

We tested the hypothesis that changes reported on functions of neutrophils from streptozotocin-induced diabetic rats involve autophagy impairment. Wistar rats were rendered diabetic by streptozotocin injection (65 mg/kg, i.v.), and the measurements were carried out 2 weeks afterward. Neutrophils were collected through intraperitoneal cavity lavage after 4 h of i.p. oyster glycogen type 2 injection. Neutrophils cultured with PMA (20 nM) for 1 h were used for analysis of plasma membrane integrity, DNA fragmentation, and mitochondrial depolarization by flow cytometry; expression of Atg5, Atg14, Beclin1, LC3BII, and Rab9 by RT-PCR; the contents of caspase 3, LC3BII/LC3BI, and pS6 by western blotting; ATP content by fluorescence essay; reactive oxygen species production by chemiluminescence (Luminol), and autophagy by immunofluorescence tracking LC3B cleavage. Herein, neutrophils from diabetic rats had high DNA fragmentation, depolarization of mitochondrial membrane, low content of ATP, and high content of cleaved caspase 3 after PMA stimulation. Neutrophils from diabetic rats also had low expression of LC3B, failed to increase the expression of Rab9 and Atg14 induced by PMA stimulation. Neutrophils from diabetic animals also had low cleavage of LC3BI to LC3BII and do not present punctate structures that label autophagosomal membranes after stimulus. The changes of neutrophil function reported in diabetic rats do involve impaired autophagy. The suppression of autophagy in neutrophils from diabetic rats may be associated with the activation of the mTOR signaling as indicated by the high content of pS6.

Obesity and nutrition in acute respiratory distress syndrome

This article discusses obesity, its contribution to clinical outcomes, and the current literature on nutrition. More than one third of Americans are obese. Literature suggests that, among critically ill patients, the relationship between obesity and outcomes is complex. Obese patients may be at greater risk of developing acute respiratory distress syndrome (ARDS) than normal weight patients. Although obesity may confer greater morbidity in intensive care, it seems to decrease mortality. ARDS is a catabolic state; patients demonstrate a profound inflammatory response, multiple organ dysfunction, and hypermetabolism, often with malnutrition. The concept of pharmaconutrition has emerged.

β(2)-Adrenoreceptor blockade improves early posttrauma hyperglycemia and pulmonary injury in obese rats

Early hyperglycemia after trauma increases morbidity and mortality. Insulin is widely used to control posttrauma glucose, but this treatment increases the risk of hypoglycemia. We tested a novel method for early posttrauma hyperglycemia control by suppressing hepatic glycogenolysis via β2-adrenoreceptor blockade [ICI-118551 (ICI)]. We have shown that, after severe trauma, obese Zucker (OZ) rats, similar to obese patients, exhibit increased acute lung injury compared with lean Zucker (LZ) rats. We hypothesized that OZ rats exhibit a greater increase in early posttrauma glucose compared with LZ rats, with the increased posttrauma hyperglycemia suppressed by ICI treatment. Orthopedic trauma was applied to both hindlimbs in LZ and OZ rats. Fasting plasma glucose was then monitored for 6 h with or without ICI (0.2 mg·kg(-1)·h(-1) iv.) treatment. One day after trauma, plasma IL-6 levels, lung neutrophil numbers, myeloperoxidase (MPO) activity, and wet-to-dry weight ratios were measured. Trauma induced rapid hepatic glycogenolysis, as evidenced by decreased liver glycogen levels, and this was inhibited by ICI treatment. Compared with LZ rats, OZ rats exhibited higher posttrauma glucose, IL-6, lung neutrophil infiltration, and MPO activity. Lung wet-to-dry weight ratios were increased in OZ rats but not in LZ rats. ICI treatment reduced the early hyperglycemia, lung neutrophil retention, MPO activity, and wet-to-dry weight ratio in OZ rats to levels comparable with those seen in LZ rats, with no effect on blood pressure or heart rate. These results demonstrate that β2-adrenoreceptor blockade effectively reduces the early posttrauma hyperglycemia, which is associated with decreased lung injury in OZ rats.

Effect of equal daily doses achieved by different power densities of low-level laser therapy at 635 nm on open skin wound healing in normal and diabetic rats

BACKGROUND AND OBJECTIVE

Despite the fact that the molecular mechanism of low-level laser therapy (LLLT) is not yet known, the exploitation of phototherapy in clinical medicine and surgery is of great interest. The present study investigates the effects of LLLT on open skin wound healing in normal and diabetic rats.

MATERIALS AND METHODS

Four round full-thickness skin wounds on dorsum were performed in male adult nondiabetic (n = 24) and diabetic (n = 24) Sprague-Dawley rats. AlGaInP (635 nm, wavelength; 5 J/cm(2), daily dose) was used to deliver power densities of 1, 5, and 15 mW/cm(2) three times daily until euthanasia.

RESULTS

PMNL infiltration was lower in the irradiated groups (15 mW/cm(2)). The synthesis and organisation of collagen fibres were consecutively enhanced in the 5 mW/cm(2) and 15 mW/cm(2) groups compared to the others in nondiabetic rats. In the diabetic group the only significant difference was recorded in the ratio PMNL/Ma at 15 mW/cm(2). A significant difference in the number of newly formed capillaries in the irradiated group (5, 15 mW/cm(2)) was recorded on day six after injury compared to the control group.

CONCLUSION

LLLT confers a protective effect against excessive inflammatory tissue response; it stimulates neovascularization and the early formation of collagen fibres.

Effects of vitamin E on pathological changes induced by diabetes in rat lungs

Twenty-fourmale rats were divided into three groups: Control (C), non-treated diabetic (NTD), and vitamin E-treated diabetic (VETD) groups. After 6 weeks, we evaluated the changes in the alveolar epithelium, alveolar septum thickness, Hcy, and cathepsin G levels in the lung tissue and plasma serine protease inhibitor levels.The results revealed a significant increase in alveolar septum thickness, a high number of type II pneumocytes, high number of glycogen granules, increased vascular elastic membrane thickness, and increased Hcy and cathepsin G levels in the diabetic rats. Plasma level of serine protease inhibitors showed a significant decrease in the NTD animals. The vitamin E-treated rats showed significant amelioration of lung tissue changes, as well as restoration of high cathepsin G, Hcy levels, and serine protease inhibitors when compared to the control rats. These results suggest that diabetes induces lung tissue changes that may be stimulated by Hcy and cathepsin G mediated oxidative stress by, and protective effect could be achieved by using vitamin E.

Insulin modulates inflammatory and repair responses to elastase-induced emphysema in diabetic rats

As pulmonary emphysema and diabetes mellitus are common diseases, concomitance of both is correspondingly expected to occur frequently. To examine whether insulin influences the development of inflammation in the alveolar septa, diabetic male Wistar rats (alloxan, 42 mg/kg, i.v., n = 37) and matching controls (n = 31) were used. Ten days after alloxan injection, diabetic and control rats were instilled with physiologic saline solution containing porcine pancreatic elastase (PPE, 0.25 IU/0.2 ml, right lung) or saline only (left lung). The following analyses were performed: (i) number of leucocytes in the bronchoalveolar lavage (BAL) fluid of the animals, 6 h after PPE/saline instillation (early time point); and (ii) mean alveolar diameter (μm) and quantification of elastic and collagen fibres (%) 50 days after PPE/saline instillation (late time point). Relative to controls, alloxan-induced diabetic rats showed a 42% reduction in the number of neutrophils in BAL fluid, a 20% increase in the mean alveolar diameter and a 33% decrease in elastic fibre density in the alveolar septa. Treatment of diabetic rats with 4 IU neutral protamine Hagedorn (NPH) insulin, 2 h before elastase instillation, restored the number of neutrophils in the BAL fluid. The mean alveolar diameter and elastic fibre content in alveolar septa matched the values observed in control rats if diabetic rats were treated with 4 IU NPH insulin 2 h before instillation followed by 2 IU/day for the next 50 days. Density of collagen fibres did not differ between the various groups. Thus, the data presented suggest that insulin modulates the inflammatory and repair responses in elastase-induced emphysema, and assures normal repair and tissue remodelling.

Inhaled aerosolized insulin: a "topical" anti-inflammatory treatment for acute lung injury and respiratory distress syndrome?

Acute lung injury (ALI) and the more severe acute respiratory distress syndrome (ARDS) are forms of pulmonary edema that result from robust local and systemic inflammatory states, such as sepsis. The morbidity and mortality associated with ALI and ARDS are significant and the treatment of these conditions presents a formidable challenge. Controlling hyperglycemia with insulin is a core component of patient management in the critically ill. Insulin treatment also exerts beneficial metabolic effects beyond glucose control, as well as non-metabolic effects, in insulin-resistant states. For instance, insulin inhibits NF-kappaB--dependent synthesis of pro-inflammatory factors and attenuates production of ROS. Indeed, intravenous administration of insulin ameliorates pulmonary injury and dysfunction in the LPS model of ALI. Most recently, an inhalable insulin formulation was shown to effectively reduce glucose concentrations with minimal impact on long-term pulmonary function. We propose that administering inhalable insulin to hyperglycemic ALI/ARDS patients could directly reduce alveolar inflammation while reducing circulating glucose levels.

Comparison of lung accumulation of cationic liposomes in normal rats and LPS-treated rats

OBJECTIVE

Cationic liposomes have been shown to target angiogenic endothelial cells in lungs and joints with evidence of chronic inflammation. We sought to determine whether cationic liposomes accumulate in acutely inflamed lung tissue. SUBJECTS, TREATMENT AND METHODS: Acute lung injury was induced by intratracheal instillation of lipopolysaccharide (LPS) in Sprague Dawley rats. The controls received saline. Following instillation, the rats were ventilated for 5 h. Four hours after LPS-instillation each rat received rhodamine-labeled, cationic liposomes intravenously. The liposomes were allowed to circulate for 1 h. Thereafter, a bronchoalveolar lavage (BAL) was done and the lungs were perfused with saline and formalin. Accumulation of liposomes was assessed by quantitative confocal microscopy and determination of rhodamine-content in lung tissue.

RESULTS

LPS induced a significant increase in BAL white blood cell count (3,444 ± 1,420 vs. 1,314 ± 906*10(3)/μl) and cytokines (IL-1β: 145.57 vs. 51.94 pg/ml; TNF-α: 3,467.5 vs. 42.1 pg/ml) as compared to controls. Cationic liposomes exhibited an accumulation up to twofold in the inflamed lung tissue as compared to healthy lungs (fluorescent pixels 2.93 vs. 1.90(%)).

CONCLUSIONS

Our findings indicate that cationic liposomes accumulate in the acutely inflamed lung tissue. This uptake raises the possibility of using cationic liposomes to direct diagnostic/therapeutic agents selectively to the sites of acute inflammation in the lung.

Insulin modulates cytokine release and selectin expression in the early phase of allergic airway inflammation in diabetic rats

BACKGROUND

Clinical and experimental data suggest that the inflammatory response is impaired in diabetics and can be modulated by insulin. The present study was undertaken to investigate the role of insulin on the early phase of allergic airway inflammation.

METHODS

Diabetic male Wistar rats (alloxan, 42 mg/Kg, i.v., 10 days) and controls were sensitized by s.c. injection of ovalbumin (OA) in aluminium hydroxide 14 days before OA (1 mg/0.4 mL) or saline intratracheal challenge. The following analyses were performed 6 hours thereafter: a) quantification of interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha and cytokine-induced neutrophil chemoattractant (CINC)-1 in the bronchoalveolar lavage fluid (BALF) by Enzyme-Linked Immunosorbent Assay, b) expression of E- and P- selectins on lung vessels by immunohistochemistry, and c) inflammatory cell infiltration into the airways and lung parenchyma. NPH insulin (4 IU, s.c.) was given i.v. 2 hours before antigen challenge.

RESULTS

Diabetic rats exhibited significant reduction in the BALF concentrations of IL-1beta (30%) and TNF-alpha (45%), and in the lung expression of P-selectin (30%) compared to non-diabetic animals. This was accompanied by reduced number of neutrophils into the airways and around bronchi and blood vessels. There were no differences in the CINC-1 levels in BALF, and E-selectin expression. Treatment of diabetic rats with NPH insulin, 2 hours before antigen challenge, restored the reduced levels of IL-1beta, TNF-alpha and P-selectin, and neutrophil migration.

CONCLUSION

Data presented suggest that insulin modulates the production/release of TNF-alpha and IL-1beta, the expression of P- and E-selectin, and the associated neutrophil migration into the lungs during the early phase of the allergic inflammatory reaction.

Impact of diabetes against the future risk of developing gout

OBJECTIVE

Although hyperuricaemia and gout are associated with an increased future risk of diabetes, diabetes may reduce the future risk of gout through the uricosuric effect of glycosuria or the impaired inflammatory response. The present work evaluates the impact of diabetes on the future risk of developing gout.

METHODS

A case-control study nested in a UK general practice database (the health improvement network) was conducted by identifying all incident cases of gout (N=24 768) and randomly sampling 50,000 controls who were 20-89 years between 2000 and 2007. The independent effect of type 1 and type 2 diabetes on the development of incident gout was examined.

RESULTS

After adjusting for age, sex, body mass index, general practitioner visits, smoking, alcohol intake, ischaemic heart disease and presence of cardiovascular risk factors, the RR for incident gout among patients with diabetes, as compared with individuals with no diabetes was 0.67 (95% CI 0.63 to 0.71). The multivariate RRs with the duration of diabetes of 0-3, 4-9 and ≥ 10 years were 0.81 (95% CI 0.74 to 0.90), 0.67 (95% CI 0.61 to 0.73) and 0.52 (95% CI 0.46 to 0.58), respectively. The inverse association was stronger with type 1 diabetes than with type 2 diabetes (multivariate RR, 0.33 vs 0.69) and stronger among men than women (p value for interaction < 0.001).

CONCLUSIONS

Individuals with diabetes are at a lower future risk of gout independent of other risk factors. These data provide support for a substantial role of the pathophysiology associated with diabetes against the risk of developing gout.

Diabetes, insulin, and development of acute lung injury

OBJECTIVES

Recently, many studies have investigated the immunomodulatory effects of insulin and glucose control in critical illness. This review examines evidence regarding the relationship between diabetes and the development of acute lung injury/acute respiratory distress syndrome (ALI/ARDS), reviews studies of lung injury related to glycemic and nonglycemic metabolic features of diabetes, and examines the effect of diabetic therapies.

DATA SOURCES AND STUDY SELECTION

A MEDLINE/PubMed search from inception to August 1, 2008, was conducted using the search terms acute lung injury, acute respiratory distress syndrome, hyperglycemia, diabetes mellitus, insulin, hydroxymethylglutaryl-CoA reductase inhibitors (statins), angiotensin-converting enzyme inhibitor, and peroxisome proliferator-activated receptors, including combinations of these terms. Bibliographies of retrieved articles were manually reviewed.

DATA EXTRACTION AND SYNTHESIS

Available studies were critically reviewed, and data were extracted with special attention to the human and animal studies that explored a) diabetes and ALI; b) hyperglycemia and ALI; c) metabolic nonhyperglycemic features of diabetes and ALI; and d) diabetic therapies and ALI.

CONCLUSIONS

Clinical and experimental data indicate that diabetes is protective against the development of ALI/ARDS. The pathways involved are complex and likely include effects of hyperglycemia on the inflammatory response, metabolic abnormalities in diabetes, and the interactions of therapeutic agents given to diabetic patients. Multidisciplinary, multifaceted studies, involving both animal models and clinical and molecular epidemiology techniques, are essential.

Insulin regulates cytokines and intercellular adhesion molecule-1 gene expression through nuclear factor-kappaB activation in LPS-induced acute lung injury in rats

Diabetic patients have increased susceptibility to infection, which may be related to impaired inflammatory response observed in experimental models of diabetes, and restored by insulin treatment. The goal of this study was to investigate whether insulin regulates transcription of cytokines and intercellular adhesion molecule 1 (ICAM-1) via nuclear factor-kappaB (NF-kappaB) signaling pathway in Escherichia coli LPS-induced lung inflammation. Diabetic male Wistar rats (alloxan, 42 mg/kg, i.v., 10 days) and controls were instilled intratracheally with saline containing LPS (750 microg/0.4 mL) or saline only. Some diabetic rats were given neutral protamine Hagedorn insulin (4 IU, s.c.) 2 h before LPS. Analyses performed 6 h after LPS included: (a) lung and mesenteric lymph node IL-1 beta, TNF-alpha, IL-10, and ICAM-1 messenger RNA (mRNA) were quantified by real-time reverse transcriptase-polymerase chain reaction; (b) number of neutrophils in the bronchoalveolar lavage (BAL) fluid, and concentrations of IL-1 beta, TNF-alpha, and IL-10 in the BAL were determined by the enzyme-linked immunosorbent assay; and (c) activation of NF-kappaB p65 subunit and phosphorylation of I-kappaB alpha were quantified by Western blot analysis. Relative to controls, diabetic rats exhibited a reduction in lung and mesenteric lymph node IL-1 beta (40%), TNF-alpha (approximately 30%), and IL-10 (approximately 40%) mRNA levels and reduced concentrations of IL-1 beta (52%), TNF-alpha (62%), IL-10 (43%), and neutrophil counts (72%) in the BAL. Activation of NF-kappaB p65 subunit and phosphorylation of I-kappaB alpha were almost suppressed in diabetic rats. Treatment of diabetic rats with insulin completely restored mRNA and protein levels of these cytokines and potentiated lung ICAM-1 mRNA levels (30%) and number of neutrophils (72%) in the BAL. Activation of NF-kappaB p65 subunit and phosphorylation of I-kappaB alpha were partially restored by insulin treatment. In conclusion, data presented suggest that insulin regulates transcription of proinflammatory (IL-1 beta, TNF-alpha) and anti-inflammatory (IL-10) cytokines, and expression of ICAM-1 via the NF-kappaB signaling pathway.

Reduced cytokine production by glycogen-elicited peritoneal cells from diabetic rats

IL-1beta, TNF-alpha, cytokine-induced neutrophil chemoattractant-2alpha/beta, and IL-10 measurements were performed in elicited peritoneal cells from control, diabetic, and insulin-treated diabetic rats. Production/liberation of these cytokines was decreased in elicited peritoneal cells from diabetic rats. These changes were abolished by insulin treatment of diabetic rats. The alterations observed might be involved in the impaired inflammatory response and high occurrence of apoptosis observed in neutrophils under diabetic states.

Neutrophil function and metabolism in individuals with diabetes mellitus

Neutrophils act as first-line-of-defense cells and the reduction of their functional activity contributes to the high susceptibility to and severity of infections in diabetes mellitus. Clinical investigations in diabetic patients and experimental studies in diabetic rats and mice clearly demonstrated consistent defects of neutrophil chemotactic, phagocytic and microbicidal activities. Other alterations that have been reported to occur during inflammation in diabetes mellitus include: decreased microvascular responses to inflammatory mediators such as histamine and bradykinin, reduced protein leakage and edema formation, reduced mast cell degranulation, impairment of neutrophil adhesion to the endothelium and migration to the site of inflammation, production of reactive oxygen species and reduced release of cytokines and prostaglandin by neutrophils, increased leukocyte apoptosis, and reduction in lymph node retention capacity. Since neutrophil function requires energy, metabolic changes (i.e., glycolytic and glutaminolytic pathways) may be involved in the reduction of neutrophil function observed in diabetic states. Metabolic routes by which hyperglycemia is linked to neutrophil dysfunction include the advanced protein glycosylation reaction, the polyol pathway, oxygen-free radical formation, the nitric oxide-cyclic guanosine-3'-5'monophosphate pathway, and the glycolytic and glutaminolytic pathways. Lowering of blood glucose levels by insulin treatment of diabetic patients or experimental animals has been reported to have significant correlation with improvement of neutrophil functional activity. Therefore, changes might be primarily linked to a continuing insulin deficiency or to secondary hyperglycemia occurring in the diabetic individual. Accordingly, effective control with insulin treatment is likely to be relevant during infection in diabetic patients.

Perioperative management of the diabetic patient

Diabetes mellitus is a significant global public health problem and is a major source of morbidity and mortality in the world today. Type 2 diabetes mellitus is the predominant form of diabetes worldwide and represents approximately 90% of all cases. There is an epidemic of type 2 diabetes mellitus in the world today in both developed and developing countries. Globally, it is expected that the number of people with diabetes will increase from the current 150 million to 220 million by the year 2010 and to 300 million by the year 2025. In addition, there has been an alarming increase in the incidence of type 2 diabetes in children and adolescents. It is therefore increasingly likely that diabetic patients will appear for dental and oral maxillofacial surgical treatment in both the office and ambulatory surgery clinic setting. Surgical stress often produces hyperglycemia in the perioperative period. Hyperglycemia has been shown to cause a significant increase in perioperative morbidity and mortality. It is the general consensus that strict glycemic control is beneficial and should be achieved for diabetic patients in the perioperative period. Preoperative, intraoperative, and postoperative management protocols for improved perioperative glycemic control of both type 1 and type 2 diabetics are presented.