An unexpectedly high prevalence of undiagnosed diabetes in patients awaiting lung transplantation

Diaphragm and Lung Transplantation

Mutual interactions between the diaphragm and lung transplantation (LTx) are known to exist. Before LTx, many factors can exert notable impact on the diaphragmatic function, such as the underlying respiratory disease, the comorbidities, and the chronic treatments of the patient. In the post-LTx setting, even the surgical procedure itself can cause a stressful trauma to the diaphragm, potentially leading to morphological and functional alterations. Conversely, the diaphragm can significantly influence various aspects of the LTx process, ranging from graft-to-chest cavity size matching to the long-term postoperative respiratory performance of the recipient. Despite this, there are still no standard criteria for evaluating, defining, and managing diaphragmatic dysfunction in the context of LTx to date. This deficiency hampers the accurate assessment of those factors which affect the diaphragm and its reciprocal influence on LTx outcomes. The objective of this narrative review is to delve into the complex role the diaphragm plays in the different stages of LTx and into the modifications of this muscle following surgery.

Adiponectin ameliorates lung ischemia-reperfusion injury through SIRT1-PINK1 signaling-mediated mitophagy in type 2 diabetic rats

BACKGROUND

Diabetes mellitus (DM) is a key contributing factor to poor survival in lung transplantation recipients. Mitochondrial dysfunction is recognized as a critical mediator in the pathogenesis of diabetic lung ischemia-reperfusion (IR) injury. The protective effects of adiponectin have been demonstrated in our previous study, but the underlying mechanism remains unclear. Here we demonstrated an important role of mitophagy in the protective effect of adiponectin during diabetic lung IR injury.

METHODS

High-fat diet-fed streptozotocin-induced type 2 diabetic rats were exposed to adiponectin with or without administration of the SIRT1 inhibitor EX527 following lung transplantation. To determine the mechanisms underlying the action of adiponectin, rat pulmonary microvascular endothelial cells were transfected with SIRT1 small-interfering RNA or PINK1 small-interfering RNA and then subjected to in vitro diabetic lung IR injury.

RESULTS

Mitophagy was impaired in diabetic lungs subjected to IR injury, which was accompanied by increased oxidative stress, inflammation, apoptosis, and mitochondrial dysfunction. Adiponectin induced mitophagy and attenuated subsequent diabetic lung IR injury by improving lung functional recovery, suppressing oxidative damage, diminishing inflammation, decreasing cell apoptosis, and preserving mitochondrial function. However, either administration of 3-methyladenine (3-MA), an autophagy antagonist or knockdown of PINK1 reduced the protective action of adiponectin. Furthermore, we demonstrated that APN affected PINK1 stabilization via the SIRT1 signaling pathway, and knockdown of SIRT1 suppressed PINK1 expression and compromised the protective effect of adiponectin.

CONCLUSION

These data demonstrated that adiponectin attenuated reperfusion-induced oxidative stress, inflammation, apoptosis and mitochondrial dysfunction via activation of SIRT1- PINK1 signaling-mediated mitophagy in diabetic lung IR injury.

Hydrogen sulfide attenuates lung ischemia-reperfusion injury through SIRT3-dependent regulation of mitochondrial function in type 2 diabetic rats

BACKGROUND

Lung ischemia-reperfusion injury is a complex pathophysiologic process associated with high morbidity and mortality. We have demonstrated elsewhere that diabetes mellitus aggravated ischemia-induced lung injury. Oxidative stress and mitochondrial dysfunction are drivers of diabetic lung ischemia-reperfusion injury; however, the pathways that mediate these events are unexplored. In this study using a high-fat diet-fed model of streptozotocin-induced type 2 diabetes in rats, we determined the effect of hydrogen sulfide on lung ischemia-reperfusion injury with a focus on Sirtuin3 signaling.

METHODS

Rats with type 2 diabetes were exposed to GYY4137, a slow release donor of hydrogen sulfide with or without administration of the Sirtuin3 short hairpin ribonucleic acid plasmid, and then subjected to a surgical model of ischemia-reperfusion injury of the lung (n = 8). Lung function, oxidative stress, inflammation, cell apoptosis, and mitochondrial function were measured.

RESULTS

Compared with nondiabetic rats, animals with type 2 diabetes at baseline exhibited significantly decreased Sirtuin3 signaling in lung tissue and increased oxidative stress, apoptosis, inflammation, and mitochondrial dysfunction (P < .05 each). In addition, further impairment in Sirtuin3 signaling was found in diabetic rats subjected to this model of lung ischemia-reperfusion. Simultaneously, the indexes showed further aggravation. Treatment with hydrogen sulfide restored Sirtuin3 expression and decreased lung ischemia-reperfusion injury in animals with type 2 diabetes mellitus by improving lung functional recovery, decreasing oxidative damage, suppressing inflammation, ameliorating cell apoptosis, and preserving mitochondrial function (P < .05). Conversely, these protective effects were largely reversed in Sirtuin3 knockdown rats.

CONCLUSION

Impaired lung Sirtuin3 signaling associated with type 2 diabetic conditions was further attenuated by an ischemia-reperfusion insult. Hydrogen sulfide ameliorated reperfusion-induced oxidative stress and mitochondrial dysfunction via activation of Sirtuin3 signaling, thereby decreasing lung ischemia-reperfusion damage in rats with a model of type II diabetes.

Association of Elevated Pre-operative Hemoglobin A1c and Post-operative Complications in Non-diabetic Patients: A Systematic Review

IMPORTANCE

Pre-operative hyperglycemia is associated with post-operative adverse outcomes in diabetic and non-diabetic patients. Current pre-operative screening includes random plasma glucose, yet plasma glycated hemoglobin (HbA1c) is a better measure of long-term glycemic control. It is not clear whether pre-operative HbA1c can identify non-diabetic patients at risk of post-operative complications.

OBJECTIVE

The systematic review summarizes the evidence pertaining to the association of suboptimal pre-operative HbA1c on post-operative outcomes in adult surgical patients with no history of diabetes mellitus.

EVIDENCE REVIEW

A detailed search strategy was developed by a librarian to identify all the relevant studies to date from the major online databases.

FINDINGS

Six observational studies met all the eligibility criteria and were included in the review. Four studies reported a significant association between pre-operative HbA1c levels and post-operative complications in non-diabetic patients. Two studies reported increased post-operative infection rates, and two reported no difference. Of four studies assessing the length of stay, three did not observe any association with HbA1c level and only one study observed a significant impact. Only one study found higher mortality rates in patients with suboptimal HbA1c.

CONCLUSIONS AND RELEVANCE

Based on the limited available evidence, suboptimal pre-operative HbA1c levels in patients with no prior history of diabetes predict post-operative complications and represent a potentially modifiable risk factor.

Adiponectin protects against lung ischemia-reperfusion injury in rats with type 2 diabetes mellitus

Adiponectin (APN) has been associated with the pathogenesis of acute brain, liver and heart injury. However, the role of APN in lung ischemia-reperfusion injury (LIRI) in diabetes mellitus remains unclear. To investigate this, the present study evaluated the effects of APN on lung dysfunction and pathological alterations in rats with type 2 diabetes mellitus via lung ischemia/reperfusion (I/R). The lung‑protective effects of APN globular domain (gAPN) in rats with type 2 diabetes mellitus were also investigated by measuring the oxygenation index, inflammatory cytokines, lung edema, histopathology, oxidative stress, apoptosis and the protein expression levels of phosphorylated 5'adenosine monophosphate‑activated protein kinase (p‑AMPK), endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS). The results of the present study demonstrated that the diabetes mellitus rats + I/R (DIR) group exhibited greater concentrations of tumor necrosis factor‑α and interleukin‑6, and increases in the wet‑weight to dry‑weight ratio, lung injury score, oxidative stress and cellular apoptosis. These effects were accompanied by lower pulmonary oxygenation compared with the normal rat + I/R (NIR) group (P<0.05). Additionally, all of these alterations were attenuated in the NIR + gAPN and DIR + gAPN groups compared with in the NIR and DIR groups, respectively. In the DIR group, the expression levels of p‑AMPK/AMPK and eNOS were significantly downregulated, and the levels of iNOS were upregulated, compared with those of the NIR group. Treatment with APN activated AMPK, increased eNOS expression and attenuated iNOS expression. The results of the present study demonstrated that APN exerted protective effects against LIRI via its anti‑inflammatory, antioxidative stress and anti‑apoptotic activities. These protective effects of APN were eliminated in rats with type 2 diabetes mellitus, in which LIRI was exacerbated. The present study indicated that APN may be a potential therapeutic agent for LIRI in type 2 diabetes mellitus.

Effects of p38 mitogen-activated protein kinase on lung ischemia-reperfusion injury in diabetic rats

BACKGROUND

Lung ischemia-reperfusion injury (LIRI) is a pathologic process that is observed in several clinical conditions, and p38 mitogen-activated protein kinase (MAPK) is involved. Diabetes mellitus (DM) results in an increased incidence of ischemia-induced organ damage. The aims of this study were to examine the effects of DM on LIRI in a rat model of DM and to explore the possible mechanisms in relation to the p38 MAPK pathway.

METHODS

Forty rats were randomly divided into the following five groups (n = 8 each): a control + sham group, a control + IR group (CIR), a DM + sham group, a DM + IR group (DIR), and a DM + IR + SB203580 group. The control and streptozotocin-induced diabetic rats underwent a sham operation or left hilum occlusion for 90 min followed by reperfusion for 4 h. SB203580 was used to inhibit the p38 MAPK pathway. The pulmonary oxygenation index, inflammatory cytokines in the serum, lung edema, histopathology, oxidant stress, apoptosis, and phosphorylated/total-p38 MAPK protein levels were measured.

RESULTS

The DIR group displayed greater concentrations of tumor necrosis factor-α, interleukin-6, and intercellular adhesion molecule-1 and increases in the wet weight-to-dry weight ratio, lung injury scores, malondialdehyde levels, and cellular apoptosis, and these effects were accompanied by lower pulmonary oxygenation compared with the CIR group (P < 0.05). In the DIR group, the expression levels of p38 MAPK protein were significantly upregulated compared with those of the CIR group. Additionally, all of these alterations were attenuated in the DM + IR + SB203580 group compared with the DIR group.

CONCLUSIONS

Diabetes exacerbates LIRI by activating the p38 MAPK pathway.

Prevalence and predictors of diabetes after lung transplantation: a prospective, longitudinal study

OBJECTIVE

To determine incidence and prevalence of diabetes mellitus (DM) after lung transplantation (LTx), identify risk factors for persistent DM after LTx, and determine its effect on survival.

RESEARCH DESIGN AND METHODS

This was a prospective, longitudinal study comparing DM status before and after LTx using oral glucose tolerance tests (OGTTs). DM prevalence and changes in metabolic control over time were determined. Risk factors for persistent DM and survival differences by DM status were assessed.

RESULTS

Between August 2010 and December 2012, 156 patients underwent LTx. DM prevalence after 3, 12, and 24 months was 47%, 44%, and 40%, respectively. A further 20%, 11%, and 7% had impaired glucose tolerance and/or impaired fasting glucose. Incidence of new-onset DM after transplant (NODAT) was 32%, 30%, and 24% after 3, 12, and 24 months. Nonfasting insulin levels and second phase insulin release fell 3 months after transplant (Tx) but returned to baseline by 2 years. The only risk factors for NODAT were 1- and 2-h glucose levels on pre-Tx OGTT (OR 1.73 [95% CI 1.19-2.50], P = 0.004, and 1.84 [1.22-2.77], P = 0.004, respectively). Survival was reduced in patients with DM at study end versus those without (estimated mean 979 days [95% CI 888-1,071] vs. 1,140 days [1,070-1,210], P = 0.023).

CONCLUSIONS

Most patients had dysglycemia during the first year after LTx, and 32% developed NODAT. Hyperglycemia was caused both by β-cell dysfunction and by insulin resistance. Only pre-Tx OGTT glucose levels predicted persistent NODAT. As DM was common and associated with reduced survival, early detection and management of DM in LTx recipients are warranted.

Diabetes is a major risk factor for mortality after lung transplantation

Survival following lung transplant (LTx) remains significantly lower than after other solid organ transplants. Diabetes mellitus (DM) is a mortality risk factor not comprehensively studied in LTx recipients. Notably, neither the relation of time of DM onset to survival nor the actual causes of DM-associated excess mortality have been described. We determined DM status, DM diagnosis date and all-cause mortality in 386 consecutive adults who underwent LTx at our institution from January 1, 2001 to July 31, 2010. The relationship of DM to survival both as a categorical and time-dependent variable was studied. Fifty-three percent of patients had DM. Overall median survival was 5.2 (95% CI 3.8-6.6) years. At study end, 52% of patients had died, of whom 64% had DM. Estimated median survival was 10 years in patients without DM, 5.0 (3.3-6.8) years in patients with DM pre- and post-LTx and 4.3 (3.1-5.5) years in patients with new onset DM. As a time-dependent covariate, DM was the strongest risk factor for mortality, hazard ratio 3.96 (2.85-5.51). Bronchiolitis obliterans syndrome was the main cause of death in all patients surviving >90 days, but its incidence was not increased in patients with DM. Further studies are warranted to determine whether improved glycemic control could improve outcomes in LTx recipients.