Evaluation of pulmonary alveolo-capillary permeability in Type 2 diabetes mellitus: using technetium 99mTc-DTPA aerosol scintigraphy and carbon monoxide diffusion capacity

Non-apoptotic programmed cell deaths in diabetic pulmonary dysfunction: the new side of advanced glycation end products

Diabetes mellitus (DM) is a chronic metabolic disorder that affects multiple organs and systems, including the pulmonary system. Pulmonary dysfunction in DM patients has been observed and studied for years, but the underlying mechanisms have not been fully understood. In addition to traditional mechanisms such as the production and accumulation of advanced glycation end products (AGEs), angiopathy, tissue glycation, oxidative stress, and systemic inflammation, recent studies have focused on programmed cell deaths (PCDs), especially the non-apoptotic ones, in diabetic pulmonary dysfunction. Non-apoptotic PCDs (NAPCDs) including autophagic cell death, necroptosis, pyroptosis, ferroptosis, and copper-induced cell death have been found to have certain correlations with diabetes and relevant complications. The AGE-AGE receptor (RAGE) axis not only plays an important role in the traditional pathogenesis of diabetes lung disease but also plays an important role in non-apoptotic cell death. In this review, we summarize novel studies about the roles of non-apoptotic PCDs in diabetic pulmonary dysfunction and focus on their interactions with the AGE-RAGE axis.

A Step Toward the Exploration of Better Spirometric Parameters for Early Diagnosis of Pulmonary Dysfunction in Persons With Type 2 Diabetes Mellitus

Objectives: This study aims to determine the forced vital capacity (FVC) and slow vital capacity (SVC) along with other pulmonary functions in Indian diabetic patients for early diagnosis of pulmonary function reduction and to compare the ratios of forced expiratory volume in one second (FEV1) with FVC and SVC (FEV1/FVC and FEV1/SVC) in diabetic patients.

Materials and methods: A prospective observational study was carried out in the physiology department for two years after the approval of the institutional ethics committee. The study included 90 type 2 diabetes mellitus patients previously diagnosed by the physician and 90 age and sex-matched controls for spirometric tests. Medspiror having Helios 401 software (Recorders & Medicare Systems Pvt. Ltd., Panchkula, India) was used to assess the pulmonary function in all subjects. A comparison of dynamic pulmonary function parameters among non-diabetic and diabetic groups and non-obese vs. overweight/obese individuals of the diabetic group has been done. FEV1/FVC ratio vs. FEV1/SVC ratio comparison was conducted between the non-obese vs. the overweight/obese group in diabetic patients.

Results: A significant variation in FEV1 and FVC was observed in the type 2 diabetic group as compared to the non-diabetic group. However, in the case of type 2 diabetic subjects, FEV1/FVC ratio was almost constant in both BMI groups, whereas the FEV1/SVC ratio increased in the overweight/obese group.

Conclusion: Type 2 diabetes mellitus accounts for a predictive factor for worsening pulmonary function. SVC, particularly the FEV1/SVC ratio, can be an earlier diagnostic marker for pulmonary dysfunction in diabetic subjects as this ratio changes even with a constant FEV1/FVC ratio.

Pulmonary perfusion imaging and delayed imaging to measure pulmonary capillary permeability in pulmonary contusion

PURPOSE

Explore the application value of pulmonary perfusion imaging and delayed imaging for evaluating pulmonary capillary permeability.

MATERIALS AND METHODS

After establishing a rat model of pulmonary contusion, changes in the metabolic index of technetium-99m macroaggregated albumin (99mTC-MAA) in the lungs of model rats were evaluated for two consecutive days. 99mTC-MAA metabolic indices of rat lungs with pulmonary contusion of varying severity (mild, moderate, and severe) were correlated with lung wet/dry weight ratio (W/D) and Evans blue extravasation. Finally, the method was validated in patients with pulmonary contusion and one healthy volunteer.

RESULTS

The 99mTC-MAA metabolic index was 23.56% ± 2.44% in healthy control (HC) rat lung, 8.56% ± 3.42% immediately after lung contusion (d0), 8.35% ± 3.20% after 1 day (d1), and 17.45% ± 6.44% after 2 days (d2); indices at d0 and d1 were significantly higher than those at HC (P < 0.05). The metabolic index of 99mTC-MAA in lung had significant negative correlations with W/D (r = -0.8025; P = 0.0092) and Evans blue extravasation (r = -0.9356; P = 0.0002). Metabolic and oxygenation indices of 99mTC-MAA exhibited a significant positive linear correlation in patients with pulmonary contusion (r = 0.8925; P = 0.0416).

CONCLUSION

Pulmonary perfusion and delayed imaging of 99mTC-MAA have potential value for evaluating pulmonary capillary permeability.

Pulmonary function tests in type 2 diabetes: a meta-analysis

OBJECTIVES

The aim of this study was to determine the association between type 2 diabetes (T2D) and pulmonary function tests.

METHODS

After conducting an exhaustive literature search, we performed a meta-analysis. We employed the inverse variance method with a random-effects model to calculate the effect estimate as the mean difference (MD) and 95% confidence interval (CI). We calculated the heterogeneity with the I2 statistic and performed a meta-regression analysis by sex, body mass index (BMI), smoking and geographical region. We also conducted a sensitivity analysis according to the studies' publication date, size of the T2D group and the study quality, excluding the study with the greatest weight in the effect.

RESULTS

The meta-analysis included 66 studies (one longitudinal, two case-control and 63 cross-sectional), with 11 134 patients with T2D and 48 377 control participants. The pooled MD (95% CI) for the predicted percentage of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), forced expiratory flow at 25-75% of FVC, peak expiratory flow, and diffusing capacity of the lung for carbon monoxide were -7.15 (95% CI -8.27, -6.03; p<0.001), -9.21 (95% CI -11.15, -7.26; p<0.001), -9.89 (95% CI -14.42, -5.36; p<0.001), -9.79 (95% CI -13.42, -6.15; p<0.001) and -7.13 (95% CI -10.62, -3.64; p<0.001), respectively. There was no difference in the ratio of FEV1/FVC (95% CI -0.27; -1.63, 1.08; p=0.69). In all cases, there was considerable heterogeneity. The meta-regression analysis showed that between studies heterogeneity was not explained by patient sex, BMI, smoking or geographical region. The findings were consistent in the sensitivity analysis.

CONCLUSIONS

T2D is associated with impaired pulmonary function, independently of sex, smoking, BMI and geographical region. Longitudinal studies are needed to investigate outcomes for patients with T2D and impaired pulmonary function.

Interstitial lung disease and diabetes

Diabetes mellitus (DM) is a chronic metabolic disease and its prevalence has been steadily increasing all over the world. DM and its associated micro and macrovascular complications result in significant morbidity and mortality. The microvascular complications are usually manifested as retinopathy, neuropathy, nephropathy and macrovascular complications generally affect the cardiovascular system. In addition to these complications, DM also affects the lungs because of its rich vascularity and abundance in connective tissue (collagen and elastin). DM has been found to cause microvascular complications and proliferation of extracellular connective tissue in the lungs, leading to decline in lung function in a restrictive pattern. Interstitial lung disease (ILD) includes a diverse group of disease conditions characterized by different degrees of inflammation and fibrosis in the pulmonary parenchyma. Idiopathic pulmonary fibrosis (IPF) is one of the common type of idiopathic interstitial pneumonia with a high mortality rate. IPF is characterized by chronic progressive fibrosis leading to progressive respiratory failure. In this review we focus on lung as the target organ in DM and the association of DM and ILD with special emphasis on IPF.

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.

Comparison of Pulmonary and Systemic NO- and PGI2-Dependent Endothelial Function in Diabetic Mice

Diabetes increases the risk of pulmonary hypertension and is associated with alterations in pulmonary vascular function. Still, it is not clear whether alterations in the phenotype of pulmonary endothelium induced by diabetes are distinct, as compared to peripheral endothelium. In the present work, we characterized differences between diabetic complications in the lung and aorta in db/db mice with advanced diabetes. Male, 20-week-old db/db mice displayed increased HbA1c and glucose concentration compatible with advanced diabetes. Diabetic lungs had signs of mild fibrosis, and pulmonary endothelium displayed significantly ultrastructural changes. In the isolated, perfused lung from db/db mice, filtration coefficient (K_f,c) and contractile response to TXA₂ analogue were enhanced, while endothelial NO-dependent modulation of pulmonary response to hypoxic ventilation and cumulative production of NO₂⁻ were impaired, with no changes in immunostaining for eNOS expression. In turn, 6-keto-PGF_1α release from the isolated lung from db/db mice was increased, as well as immunostaining of thrombomodulin (CD141). In contrast to the lung, NO-dependent, acetylcholine-induced vasodilation, ionophore-stimulated NO₂⁻ generation, and production of 6-keto-PGF_1α were all impaired in aortic rings from db/db mice. Although eNOS immunostaining was not changed, that of CD141 was clearly lowered. Interestingly, diabetes-induced nitration of proteins in aorta was higher than that in the lungs. In summary, diabetes induced marked ultrastructural changes in pulmonary endothelium that were associated with the increased permeability of pulmonary microcirculation, impaired NO-dependent vascular function, with compensatory increase in PGI₂ production, and increased CD141 expression. In contrast, endothelial dysfunction in the aorta was featured by impaired NO-, PGI₂-dependent function and diminished CD141 expression.

Hyperoxia increases arterial oxygen pressure during exercise in type 2 diabetes patients: a feasibility study

Objective

The study investigated the feasibility and potential outcome measures during acute hyperoxia in type 2 diabetes patients (DM2).

Methods

Eleven DM2 patients (7 men and 4 women) were included in the study. The patients cycled (30 min at 20 % W_max) whilst breathing three different supplemental oxygen flows (SOF, 5, 10, 15 L min⁻¹). During hyperoxic exercise, arterial blood gases and intra-arterial blood pressure measurements were obtained.

Results

Arterial pO₂ levels increased significantly (ANOVA, p < 0.05) with SOF: 13.9 ± 1.2 (0 L min⁻¹); 18.5 ± 1.5 (5 L min⁻¹); 21.7 ± 1.7 (10 L min⁻¹); 24.0 ± 2.3 (15 L min⁻¹). Heart rate (HR) and pH increased significantly after terminating administration of hyperoxic air.

Conclusions

An SOF of 15 L min⁻¹ appears to be more effective than 5 or 10 L min⁻¹. Moreover, HR, blood pressure, blood lactate and pH are not recommended as primary outcome measures.

Hypoxia-induced increases in glucose uptake do not cause oxidative injury or advanced glycation end-product (AGE) formation in vascular endothelial cells

An increase in glucose uptake by endothelial cells exposed to hyperglycemia is the presumed initiating event that causes systemic vascular disease in individuals with diabetes. Diabetics do not develop clinically significant pulmonary vascular disease, however, despite the pulmonary circulation’s exposure to the same level of glucose. We hypothesized that pulmonary artery endothelial cells are protected from the detrimental effects of hyperglycemia because they take up less glucose than endothelial cells in the systemic circulation, either because of intrinsic differences between the two cell types or because the lower oxygen tension in the pulmonary arterial blood depresses glucose uptake. To test this hypothesis, we exposed normoglycemic and hyperglycemic bovine pulmonary artery (PAECs) and aortic endothelial cells (AECs) from the same animal to progressively lower oxygen tensions and determined glucose uptake. In contrast with our initial hypothesis, we detected no significant difference in glucose uptake between the two cell types. Furthermore, glucose uptake in both PAECs and AECs increased, not decreased, as the oxygen tension dropped; this oxygen-dependent increase in glucose uptake in endothelial cells predominated over the hyperglycemia-mediated decrease in glucose uptake that has been reported by others. Despite the increase in glucose uptake at lower oxygen tensions, we detected no corresponding increase in protein carbonylation or advanced glycation endproducts. These results demonstrate that small physiologically relevant changes in oxygen tension can have an important impact on glucose uptake in endothelial cells. These results also demonstrate that an increase in glucose uptake, by itself, is not sufficient to generate ROS-mediated protein carbonylation or increase intracellular advanced glycation endproducts in vascular endothelial cells.

Six-minute walk test in non-insulin-dependent diabetes mellitus patients living in Northwest Africa

INTRODUCTION

International recommendations of the exploration of non-insulin-dependent diabetes mellitus (NIDDM) are focused on deficiency and not incapacity.

AIMS

(1) To estimate the incapacity of NIDDM patients through the 6-minute walk test (6MWT) data. (2) To determine their 6-minute walk distance (6MWD) influencing factors (3) To compare data of NIDDM patient group (PG; n = 100) with those of two control groups (CG): CG1 (n = 174, healthy nonobese and nonsmoker); CG2 (n = 55, obese nondiabetic free from comorbidities).

POPULATION AND METHODS

The anthropometric, socioeconomic, clinical, metabolic, and 6MWT data of 100 NIDDM patients (45 females) were collected.

RESULTS

Total sample means ± standard deviation of age, weight, and height were 54 ± 8 years, 81 ± 14 kg, and 1.64 ± 0.09 m. (1) Measured 6MWD (566 ± 81 m) was significantly lower than the theoretical 6MWD (90% ± 12%). The profile of the PG carrying the 6MWT, was as follows: 23% had an abnormal 6MWD; at the end of the 6MWT, 21% and 12% had, respectively, a low heart rate and a high dyspnea (>5/10), and 4% had desaturation during the walk. The estimated "cardiorespiratory and muscular chain" age (68 ± 16 years) was significantly higher than the chronological age. (2) The factors that significantly influenced the 6MWD (r(2) = 0.58) are included in the following equation: 6MWD (m) = -73.94 × gender (0, male; 1, female) - 3.25 × age (years) + 7.33 × leisure activity score - 35.57 × obesity (0, no; 1, yes) + 32.86 × socioeconomic level (0, low; 1, high) - 27.67 × cigarette use (0, no; 1, yes) + 8.89 × resting oxyhemoglobin saturation - 105.48. (3) Compared to the CGs, the PG had a significantly (P < 0.05) lower 6MWD (100%+9% and 100%+8%, respectively, for the CG1 and CG2).

CONCLUSION

NIDDM seems to accelerate the decline of the submaximal aerobic capacity evaluated through the 6MWD.

The diabetic lung--a new target organ?

Several abnormalities of the respiratory function have been reported in patients with type 1 and type 2 diabetes. These abnormalities concern lung volume, pulmonary diffusing capacity, control of ventilation, bronchomotor tone, and neuroadrenergic bronchial innervation. Many hypotheses have emerged, and characteristic histological changes have been described in the "diabetic lung", which could explain this abnormal respiratory function. Given the specific abnormalities in diabetic patients, the lung could thus be considered as a target organ in diabetes. Although the practical implications of these functional changes are mild, the presence of an associated acute or chronic pulmonary and/or cardiac disease could determine severe respiratory derangements in diabetic patients. Another clinical consequence of the pulmonary involvement in diabetes is the accelerated decline in respiratory function. The rate of decline in respiratory function in diabetics has been found to be two-to-three times faster than in normal non-smoking subjects, as reported in longitudinal studies. This finding, together with the presence of anatomical and biological changes similar to those described in the aging lung, indicates that the "diabetic lung" could even be considered a model of accelerated aging. This review describes and analyses the current insight into the relationship of diabetes and lung disease, and suggests intensifying research into the lung as a possible target organ in diabetes.

Inadequate glucose control in type 2 diabetes is associated with impaired lung function and systemic inflammation: a cross-sectional study

Background

Inadequate glucose control may be simultaneously associated with inflammation and decreased lung function in type 2 diabetes. We evaluated if lung function is worse in patients with inadequate glucose control, and if inflammatory markers are simultaneously increased in these subjects.

Methods

Subjects were selected at the Colombian Diabetes Association Center in Bogotá. Pulmonary function tests were performed and mean residual values were obtained for forced expiratory volume (FEV₁₎, forced vital capacity (FVC) and FEV₁/FVC, with predicted values based on those derived by Hankinson et al. for Mexican-Americans. Multiple least-squares regression was used to adjust for differences in known determinants of lung function. We measured blood levels of glycosylated hemoglobin (HBA_1c), interleukin 6 (IL-6), tumor necrosis factor (TNF-α), fibrinogen, ferritin, and C-reactive protein (C-RP).

Results

495 diabetic patients were studied, out of which 352 had inadequate control (HBA_1c > 7%). After adjusting for known determinants of lung function, those with inadequate control had lower FEV₁ (-75.4 mL, IC95%: -92, -59; P < 0.0001) and FVC (-121 mL, IC95%: -134, -108; P < 0,0001) mean residuals, and higher FEV₁/FVC (0.013%, IC95%: 0.009, 0.018, P < 0.0001) residuals than those with adequate control, as well as increased levels of all inflammatory markers (P < 0.05), with the exception of IL-6.

Conclusions

Subjects with type 2 diabetes and inadequate control had lower FVC and FEV₁ than predicted and than those of subjects with adequate control. It is postulated that poorer pulmonary function may be associated with increased levels of inflammatory mediators.

Effect of Agaricus blazei Murill on the pulmonary tissue of animals with streptozotocin-induced diabetes

The present study was designed to evaluate the oxidative stress as well as the therapeutic effect of Agaricus blazei Muril (A. Blazei) in rats with streptozotocin-induced diabetes. We used 25 Wistar rats, and DM was induced by injecting streptozotocin (70 mg/Kg i.p.). Agaricus blazei Muril was administered daily starting 40 days after disease onset. A. Blazei was tested as an aqueous extract for its phytochemical composition, and its antioxidant activity in vitro was also evaluated. Lipoperoxidation (LPO), and superoxide dismutase (SOD), catalase, and glutathione peroxidase activities were measured in the pulmonary tissue, as well as the presence of inducible nitric oxide synthase (iNOS), through immunohistochemistry. An anatomopathologic study was also performed. Phytochemical screening of A. Blazei detected the presence of alkaloids and saponins. The extract exhibited a significant antioxidant activity in the DPPH-scavenging and the hipoxanthine/xanthine oxidase assays. Pulmonary LPO increased in diabetic animals (0.43 ± 0.09; P < .001) as compared to the control group (0.18 ± 0.02), followed by a reduction in the A. Blazei-treated group (0.33 ± 0.04; P < .05). iNOS was found increased in the lung in diabetic rats and reduced in the A. Blazei-treated group. The pulmonary tissue in diabetic rats showed oxidative alterations related to the streptozotocin treatment. The A. Blazei treatment effectively reduced the oxidative stress and contributed to tissue recovery.

Fatty diabetic lung: altered alveolar structure and surfactant protein expression

Pulmonary dysfunction develops in type 2 diabetes mellitus (T2DM) in direct correlation with glycemia and is exacerbated by obesity; however, the associated structural derangement has not been quantified. We studied lungs from obese diabetic (fa/fa) male Zucker diabetic fatty (ZDF) rats at 4, 12, and 36 wk of age, before and after onset of T2DM, compared with lean nondiabetic (+/+) rats. Surfactant proteins A and C (SP-A and SP-C) immunoexpression in lung tissue was quantified at ages 14 and 18 wk, after the onset of T2DM. In fa/fa animals, lung volume was normal despite obesity. Numerous lipid droplets were visible within alveolar interstitium, lipofibroblasts, and macrophages, particularly in subpleural regions. Total triglyceride content was 136% higher. By 12 wk, septum volume was 21% higher, and alveolar duct volume was 36% lower. Capillary basement membrane was 29% thicker. Volume of lamellar bodies was 45% higher. By age 36 wk, volumes of interstitial collagen fibers, cells, and matrix were respectively 32, 25, and 80% higher, and capillary blood volume was 18% lower. ZDF rats exhibited a strain-specific increase in resistance of the air-blood diffusion barrier with age, which was exaggerated in fa/fa lungs compared with +/+ lungs. In fa/fa lungs, SP-A and SP-C expression were elevated at age 14-18 wk; the normal age-related increase in SP-A expression was accelerated, whereas SP-C expression declined with age. Thus lungs from obese T2DM animals develop many qualitatively similar changes as in type 1 diabetes mellitus but with extensive lipid deposition, altered alveolar type 2 cell ultrastructure, and surfactant protein expression patterns that suggest additive effects of hyperglycemia and lipotoxicity.

Pulmonary complications in diabetes mellitus

Clear decrements in lung function have been reported in patients with diabetes over the past two decades, and many reports have suggested plausible pathophysiological mechanisms. However, there are no reports of functional limitations of activities of daily living ascribable to pulmonary disease in patients with diabetes. This review attempts to summarize the available information from the present literature, to describe the nature of the lung dysfunction in diabetes and the emerging clinical implications of such dysfunction.

Long-term tolerability of inhaled human insulin (Exubera) in patients with poorly controlled type 2 diabetes

OBJECTIVE

Inhaled human insulin (Exubera; EXU) has shown encouraging tolerability in short-term trials. We evaluated the safety profile of EXU after long-term exposure.

DESIGN

In two, open-label, 2-year studies patients poorly controlled on a sulphonylurea were randomised to adjunctive EXU or metformin (study 1) and patients poorly controlled on metformin were randomised to adjunctive EXU or the sulphonylurea, glibenclamide (study 2).

PATIENTS

The studies included 446 (study 1) and 476 (study 2) patients with type 2 diabetes, no clinically significant respiratory disease and glycosylated haemoglobin (HbA(1c)) levels of 8-12%.

MEASUREMENTS

Main outcome measures were pulmonary function tests and insulin antibody assays.

RESULTS

A total of 109 patients (study 1) and 195 patients (study 2) completed 104 weeks treatment. In both studies, small treatment group differences in change from baseline forced expiratory volume in 1 s were greatest at 6 months (first time-point measured) and less at later visits, and reversed on treatment discontinuation. At 2 years, differences in mean changes were -0.10 and -0.01 l in studies 1 and 2, respectively, and -0.04 l for the pooled studies. There was no discernable effect of long-term EXU therapy on pulmonary gas exchange. Insulin antibody binding reached a plateau at 6 months and did not correlate with HbA(1c) or lung function changes. Glycaemic control was maintained over 2 years.

CONCLUSIONS

Exubera was well tolerated during long-term use. Pulmonary function changes compared with comparator groups were small, non-progressive and reversed upon treatment discontinuation. Importantly, rates of lung function change were indistinguishable between EXU and comparator after 6 months of therapy.

Current perioperative treatment of patients with type 1 and type 2 diabetes

Diabetes mellitus is rapidly increasing, diabetic patients are likely to undergo surgical procedures more than non-diabetic patients, the hospital stay of diabetic patients is longer, and diabetic patients have increased mortality and morbidity. The correct treatment of diabetic patients in the perioperative period is crucial to improve clinical outcomes. Diabetic patients must be carefully evaluated for cardiovascular risk, keeping in mind micro- and macroangiopathic diabetic complications. Metabolic control deserves great attention because hyperglycemia is related to increased complications and worse outcomes. Insulin infusion regimens to achieve near normoglycemia must be implemented in surgical and critically ill patients.