Airway Glucose Homeostasis

Comparative risk of infection of medications used for type 2 diabetes

INTRODUCTION

Glucose-lowering drugs pose a potential infection risk among individuals with type 2 diabetes. The U.S. Food and Drug Administration has issued safety warnings regarding increased risks of urinary tract infections (UTIs) and genital infections with sodium-glucose cotransporter 2 (SGLT2) inhibitors. However, the infection risk associated with other glucose-lowering drugs remains unclear. We conducted a PubMed database search to review the infection risk of glucose-lowering drugs, focusing on meta-analysis of randomized controlled trials.

AREAS COVERED

We described the infection risks associated with SGLT2 inhibitors, dipeptidyl peptidase-4 (DPP-4) inhibitors, glucose-like peptide-1 receptor agonists, metformin, and thiazolidinediones, covering infections of the genitourinary, respiratory, and gastrointestinal systems, including skin and soft tissue infections (SSTIs).

EXPERT OPINION

SGLT2 inhibitors are associated with a higher genital infection risk, while their UTI risk remains inconclusive. DPP-4 inhibitors could be a treatment option for those intolerant to SGLT2 inhibitors, given their lower genital infection risk compared to placebo. Uncertainty persists regarding the risks of respiratory infections, gastroenteritis, and SSTIs with SGLT2 inhibitors. Limited evidence is available regarding the impact of DPP-4 inhibitors on respiratory infections. Additional research is needed to determine the comparative infection risk of other glucose-lowering drugs.

Predicting the risk of pulmonary infection in patients with chronic kidney failure: A-C2GH2S risk score-a retrospective study

PURPOSE

The objective of this study is to investigate the associated risk factors of pulmonary infection in individuals diagnosed with chronic kidney disease (CKD). The primary goal is to develop a predictive model that can anticipate the likelihood of pulmonary infection during hospitalization among CKD patients.

METHODS

This retrospective cohort study was conducted at two prominent tertiary teaching hospitals. Three distinct models were formulated employing three different approaches: (1) the statistics-driven model, (2) the clinical knowledge-driven model, and (3) the decision tree model. The simplest and most efficient model was obtained by comparing their predictive power, stability, and practicability.

RESULTS

This study involved a total of 971 patients, with 388 individuals comprising the modeling group and 583 individuals comprising the validation group. Three different models, namely Models A, B, and C, were utilized, resulting in the identification of seven, four, and eleven predictors, respectively. Ultimately, a statistical knowledge-driven model was selected, which exhibited a C-statistic of 0.891 (0.855-0.927) and a Brier score of 0.012. Furthermore, the Hosmer-Lemeshow test indicated that the model demonstrated good calibration. Additionally, Model A displayed a satisfactory C-statistic of 0.883 (0.856-0.911) during external validation. The statistical-driven model, known as the A-C2GH2S risk score (which incorporates factors such as albumin, C2 [previous COPD history, blood calcium], random venous blood glucose, H2 [hemoglobin, high-density lipoprotein], and smoking), was utilized to determine the risk score for the incidence rate of lung infection in patients with CKD. The findings revealed a gradual increase in the occurrence of pulmonary infections, ranging from 1.84% for individuals with an A-C2GH2S Risk Score ≤ 6, to 93.96% for those with an A-C2GH2S Risk Score ≥ 18.5.

CONCLUSION

A predictive model comprising seven predictors was developed to forecast pulmonary infection in patients with CKD. This model is characterized by its simplicity, practicality, and it also has good specificity and sensitivity after verification.

The guardians of pulmonary harmony: alveolar macrophages orchestrating the symphony of lung inflammation and tissue homeostasis

Recent breakthroughs in single-cell sequencing, advancements in cellular and tissue imaging techniques, innovations in cell lineage tracing, and insights into the epigenome collectively illuminate the enigmatic landscape of alveolar macrophages in the lung under homeostasis and disease conditions. Our current knowledge reveals the cellular and functional diversity of alveolar macrophages within the respiratory system, emphasising their remarkable adaptability. By synthesising insights from classical cell and developmental biology studies, we provide a comprehensive perspective on alveolar macrophage functional plasticity. This includes an examination of their ontology-related features, their role in maintaining tissue homeostasis under steady-state conditions and the distinct contribution of bone marrow-derived macrophages (BMDMs) in promoting tissue regeneration and restoring respiratory system homeostasis in response to injuries. Elucidating the signalling pathways within inflammatory conditions, the impact of various triggers on tissue-resident alveolar macrophages (TR-AMs), as well as the recruitment and polarisation of macrophages originating from the bone marrow, presents an opportunity to propose innovative therapeutic approaches aimed at modulating the equilibrium between phenotypes to induce programmes associated with a pro-regenerative or homeostasis phenotype of BMDMs or TR-AMs. This, in turn, can lead to the amelioration of disease outcomes and the attenuation of detrimental inflammation. This review comprehensively addresses the pivotal role of macrophages in the orchestration of inflammation and resolution phases after lung injury, as well as ageing-related shifts and the influence of clonal haematopoiesis of indeterminate potential mutations on alveolar macrophages, exploring altered signalling pathways and transcriptional profiles, with implications for respiratory homeostasis.

Ezrin Contributes to the Damage of Airway Epithelial Barrier Related to Diabetes Mellitus

Background

Diabetes mellitus predisposes individuals to respiratory infections. The airway epithelial barrier provides defense against inhaled antigens and pathogens. Ezrin, is a component of the membrane-cytoskeleton that maintains the cellular morphology, intercellular adhesion, and barrier function of epithelial cells. This study aimed to explore the role of ezrin in airway epithelial barrier damage and correlate its expression and activation with diabetes mellitus.

Methods

This study was performed in a murine model of diabetes mellitus and with human bronchial epithelial BEAS-2B cells using real-time PCR, Western blotting, immunohistochemical and immunofluorescence staining. Ezrin was knocked down in BEAS-2B cells using siRNA. Ezrin phosphorylation levels were measured to determine activation status. The integrity of the airway epithelial barrier was assessed in vivo by characterizing morphological structure, and in vitro in BEAS-2B cells by measuring tight junction protein expression, transepithelial electrical resistance (TER) and permeability.

Results

We demonstrated that ezrin expression levels were lower in the lung tissue and airway epithelium of diabetic mice than those in control mice. The morphological structure of the airway epithelium was altered in diabetic mice. High glucose levels downregulated the expression and distribution of ezrin and connexin 43, reduced the expression of tight junction proteins, and altered the epithelial barrier characteristics of BEAS-2B cells. Ezrin knockdown had effects similar to those of high glucose levels. Moreover, a specific inhibitor of ezrin Thr567 phosphorylation (NSC305787) inhibited epithelial barrier formation.

Conclusion

These results demonstrate that ezrin expression and activation are associated with airway epithelial damage in diabetes mellitus. These findings provide new insights into the molecular pathogenesis of pulmonary infections in diabetes mellitus and may lead to novel therapeutic interventions for airway epithelial barrier damage.

Epidemiology of 369 diseases and injuries attributable to 84 risk factors: 1990-2019 with 2040 projection

The global burden of diseases and injuries poses complex and pressing challenges. This study analyzed 369 diseases and injuries attributed to 84 risk factors globally from 1990 to 2019, projecting trends to 2040. In 2019, global risks caused 35 million deaths. Non-communicable diseases were responsible for 8.2 million deaths, primarily from air pollution (5.5 million). Cardiovascular disease from air pollution had a high age-standardized disability-adjusted life year rate (1,073.40). Communicable, maternal, neonatal, and nutritional diseases caused 1.4 million deaths, mainly due to unsafe water and sanitation. Occupational risks resulted in 184,269 transport-related deaths. Behavioral risks caused 21.6 million deaths, with dietary factors causing 6.9 million cardiovascular deaths. Diabetes linked to sugar-sweetened beverages showed significant growth (1990-2019). Metabolic risks led to 18.6 million deaths. Projections to 2040 indicated persistent challenges, emphasizing the urgent need for targeted interventions and policies to alleviate the global burden of diseases and injuries.

GLUT3-mediated cigarette smoke-induced epithelial-mesenchymal transition in chronic obstructive pulmonary disease through the NF-kB/ZEB1 pathway

BACKGROUND

Airway remodelling plays an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). Epithelial-mesenchymal transition (EMT) is a significant process during the occurrence of airway remodelling. Increasing evidence suggests that glucose transporter 3 (GLUT3) is involved in the epithelial mesenchymal transition (EMT) process of various diseases. However, the role of GLUT3 in EMT in the airway epithelial cells of COPD patients remains unclear.

METHODS

We detected the levels of GLUT3 in the peripheral lung tissue of COPD patients and cigarette smoke (CS)-exposed mice. Two Gene Expression Omnibus GEO datasets were utilised to analyse GLUT3 gene expression profiles in COPD. Western blot and immunofluorescence were used to detect GLUT3 expression. In addition, we used the AAV9-GLUT3 inhibitor to reduce GLUT3 expression in the mice model. Masson's staining and lung function measurement were used detect the collagen deposition and penh in the mice. A cell study was performed to confirm the regulatory effect of GLUT3. Inhibition of GLUT3 expression with siRNA, Western blot, and immunofluorescence were used to detect the expression of E-cadherin, N-cadherin, vimentin, p65, and ZEB1.

RESULTS

Based on the GEO data set analysis, GLUT3 expression in COPD patients was higher than in non-smokers. Moreover, GLUT3 was highly expressed in COPD patients, CS exposed mice, and BEAS-2B cells treated with CS extract (CSE). Further research revealed that down-regulation of GLUT3 significantly alleviated airway remodelling in vivo and in vitro. Lung function measurement showed that GLUT3 reduction reduced airway resistance in experimental COPD mice. Mechanistically, our study showed that reduction of GLUT3 inhibited CSE-induced EMT by down-regulating the NF-κB/ZEB1 pathway.

CONCLUSION

We demonstrate that CS enhances the expression of GLUT3 in COPD and further confirm that GLUT3 may regulate airway remodelling in COPD through the NF-κB/ZEB1 pathway; these findings have potential value in the diagnosis and treatment of COPD. The down-regulation of GLUT3 significantly alleviated airway remodelling and reduced airway resistance in vivo. Our observations uncover a key role of GLUT3 in modulating airway remodelling and shed light on the development of GLUT3-targeted therapeutics for COPD.

How Does Airway Surface Liquid Composition Vary in Different Pulmonary Diseases, and How Can We Use This Knowledge to Model Microbial Infections?

Growth environment greatly alters many facets of pathogen physiology, including pathogenesis and antimicrobial tolerance. The importance of host-mimicking environments for attaining an accurate picture of pathogen behaviour is widely recognised. Whilst this recognition has translated into the extensive development of artificial cystic fibrosis (CF) sputum medium, attempts to mimic the growth environment in other respiratory disease states have been completely neglected. The composition of the airway surface liquid (ASL) in different pulmonary diseases is far less well characterised than CF sputum, making it very difficult for researchers to model these infection environments. In this review, we discuss the components of human ASL, how different lung pathologies affect ASL composition, and how different pathogens interact with these components. This will provide researchers interested in mimicking different respiratory environments with the information necessary to design a host-mimicking medium, allowing for better understanding of how to treat pathogens causing infection in these environments.

In hospital outcomes of autologous and implant-based breast reconstruction in patients with diabetes mellitus: A population-based study of 2015-2020 national inpatient sample

BACKGROUND

Breast reconstruction encompasses autologous (ABR) and implant-based breast reconstruction (IBR) each with its own sets of potential complications. Diabetes mellitus (DM) is associated with breast reconstruction complications, although most of the studies did not differentiate between the reconstruction procedures. This study conducted a population-based study examining impact of DM on inhospital outcomes in ABR and IBR.

METHODS

Patients underwent ABR or IBR were identified in National Inpatient Sample from Q4 2015 to 2020. A 1:2 propensity score matching was used to address differences in demographics, hospital characteristics, primary payer status, comorbidities, and reconstruction staging between DM and non-DM patients. In hospital outcomes were assessed separately in ABR and IBR.

RESULTS

There were 997 (7.68%) DM and 11,987 (92.32%) non-DM patients in ABR. Meanwhile, 1325 (7.38%) DM and 16,638 (92.62%) non-DM patients underwent IBR. DM cohorts in ABR and IBR were matched to 1930 and 2558 non-DM patients, respectively. After matching, DM patients in both ABR and IBR had higher risks of renal complications (ABR, 3.73% vs. 1.76%, p < 0.01; IBR, 1.83% vs. 0.78%, p = 0.01) and longer length of stay (ABR, p = 0.01; IBR, p = 0.04). In ABR, DM patients had higher respiratory complications (2.82% vs. 1.19%, p < 0.01), excessive scarring (2.72% vs. 1.55%, p = 0.03), and infection (2.42% vs. 1.14%, p = 0.01), while in IBR, DM patients had higher hemorrhage/hematoma (5.40% vs. 3.40%, p < 0.01) and transfer out (1.52% vs. 0.78%, p = 0.04).

CONCLUSION

DM was associated with distinct sets of inhospital complications in ABR and IBR, which can be valuable for preoperative risk stratification and informing clinical decision-making for DM patients.

Unraveling the Link between Ιnsulin Resistance and Bronchial Asthma

Evidence from large epidemiological studies has shown that obesity may predispose to increased Th2 inflammation and increase the odds of developing asthma. On the other hand, there is growing evidence suggesting that metabolic dysregulation that occurs with obesity, and more specifically hyperglycemia and insulin resistance, may modify immune cell function and in some degree systemic inflammation. Insulin resistance seldom occurs on its own, and in most cases constitutes a clinical component of metabolic syndrome, along with central obesity and dyslipidemia. Despite that, in some cases, hyperinsulinemia associated with insulin resistance has proven to be a stronger risk factor than body mass in developing asthma. This finding has been supported by recent experimental studies showing that insulin resistance may contribute to airway remodeling, promotion of airway smooth muscle (ASM) contractility and proliferation, increase of airway hyper-responsiveness and release of pro-inflammatory mediators from adipose tissue. All these effects indicate the potential impact of hyperinsulinemia on airway structure and function, suggesting the presence of a specific asthma phenotype with insulin resistance. Epidemiologic studies have found that individuals with severe and uncontrolled asthma have a higher prevalence of glycemic dysfunction, whereas longitudinal studies have linked glycemic dysfunction to an increased risk of asthma exacerbations. Since the components of metabolic syndrome interact with one another so much, it is challenging to identify each one's specific role in asthma. This is why, over the last decade, additional studies have been conducted to determine whether treatment of type 2 diabetes mellitus affects comorbid asthma as shown by the incidence of asthma, asthma control and asthma-related exacerbations. The purpose of this review is to present the mechanism of action, and existing preclinical and clinical data, regarding the effect of insulin resistance in asthma.

Itaconate as a key regulator of respiratory disease

Macrophage activation results in the accumulation of endogenous metabolites capable of adopting immunomodulatory roles; one such bioactive metabolite is itaconate. After macrophage stimulation, the TCA-cycle intermediate cis-aconitate is converted to itaconate (by aconitate decarboxylase-1, ACOD1) in the mitochondrial matrix. Recent studies have highlighted the potential of targeting itaconate as a therapeutic strategy for lung diseases such as asthma, idiopathic pulmonary fibrosis (IPF), and respiratory infections. This review aims to bring together evidence which highlights a role for itaconate in chronic lung diseases (such as asthma and pulmonary fibrosis) and respiratory infections (such as SARS-CoV-2, influenza and Mycobacterium tuberculosis infection). A better understanding of the role of itaconate in lung disease could pave the way for novel therapeutic interventions and improve patient outcomes in respiratory disorders.

Prediction of viral pneumonia based on machine learning models analyzing pulmonary inflammation index scores

OBJECT

To obtain Pulmonary Inflammation Index scores from imaging chest CT and combine it with clinical correlates of viral pneumonia to predict the risk and severity of viral pneumonia using a computer learning model.

METHODS

All patients with suspected viral pneumonia on CT examination admitted to The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University from December 2022 to March 2023 were retrospectively selected. The respiratory viruses were monitored by RT-PCR and categorized into patients with viral pneumonia and those with non-viral pneumonia. The extent of lung inflammation was quantified according to the Pulmonary Inflammation Index score (PII). Information on patient demographics, comorbidities, laboratory tests, pathogenetic testing, and radiological data were collected. Five machine learning models containing Random Forest(RF), Radial Basis Function Neural Network (RBFNN), Support Vector Machine (SVM), K Nearest Neighbour Algorithm (KNN), and Kernel Ridge Regression (KRR) were used to predict the risk of onset and severity of viral pneumonia based on the clinically relevant factors or PII.

RESULTS

Among the five models, the SVM model performed best in ACC (76.75 %), SN (73.99 %), and F1 (72.42 %) and achieved a better area under the receiver operating characteristic curve (ROC) (0.8409) when predicting the risk of developing viral pneumonia. RF had the best overall classification accuracy in predicting the severity of viral pneumonia, especially in predicting pneumonia with a PII classification of grade I, the RF model achieved an accuracy of 98.89%.

CONCLUSION

Machine learning models are valuable in assessing the risk of viral pneumonia. Meanwhile, machine learning models confirm the importance in predicting the severity of viral pneumonia through PII. The establishment of machine learning models for predicting the risk and severity of viral pneumonia promotes the further development of machine learning in the medical field.

Metabolic syndrome, genetic susceptibility, and risk of chronic obstructive pulmonary disease: The UK Biobank Study

AIM

To investigate the effect of metabolic syndrome (MetS), genetic predisposition, and their interactions, on the risk of developing chronic obstructive pulmonary disease (COPD).

METHODS

Cohort analyses included 287 868 participants from the UK Biobank Study. A genetic risk score for COPD was created using 277 single nucleotide polymorphisms. Cox proportional hazard models were used to evaluate the hazard ratios (HRs) with 95% confidence intervals (CIs) for COPD in relation to exposure factors.

RESULTS

During 2 658 936 person-years of follow-up, 5877 incident cases of COPD were documented. Compared with participants without MetS, those with MetS had a higher risk of COPD (HR 1.24, 95% CI 1.17-1.32). Compared to participants with low genetic predisposition, those with high genetic predisposition had a 17% increased risk of COPD. In the joint analysis, compared with participants without MetS and low genetic predisposition, the HR for COPD for those with MetS and high genetic predisposition was 1.50 (95% CI 1.36-1.65; P < 0.001). However, no significant interaction between MetS and genetic risk was found.

CONCLUSIONS

Metabolic syndrome was found to be associated with an increased risk of COPD, regardless of genetic risk. It is crucial to conduct further randomized control trials to determine whether managing MetS and its individual components can potentially reduce the likelihood of developing COPD.

Microarray analysis of hub genes, non-coding RNAs and pathways in lung after whole body irradiation in a mouse model

PURPOSE

Previous research has highlighted the impact of radiation damage, with cancer patients developing acute disorders including radiation induced pneumonitis or chronic disorders including pulmonary fibrosis months after radiation therapy ends. We sought to discover biomarkers that predict these injuries and develop treatments that mitigate this damage and improve quality of life.

MATERIALS AND METHODS

Six- to eight-week-old female C57BL/6 mice received 1, 2, 4, 8, 12 Gy or sham whole body irradiation. Animals were euthanized 48 h post exposure and lungs removed, snap frozen and underwent RNA isolation. Microarray analysis was performed to determine dysregulation of messenger RNA (mRNA), microRNA (miRNA), and long non-coding RNA (lncRNA) after radiation injury.

RESULTS

We observed sustained dysregulation of specific RNA markers including: mRNAs, lncRNAs, and miRNAs across all doses. We also identified significantly upregulated genes that can indicate high dose exposure, including Cpt1c, Pdk4, Gdf15, and Eda2r, which are markers of senescence and fibrosis. Only three miRNAs were significantly dysregulated across all radiation doses: miRNA-142-3p and miRNA-142-5p were downregulated and miRNA-34a-5p was upregulated. IPA analysis predicted inhibition of several molecular pathways with increasing doses of radiation, including: T cell development, Quantity of leukocytes, Quantity of lymphocytes, and Cell viability.

CONCLUSIONS

These RNA biomarkers might be highly relevant in the development of treatments and in predicting normal tissue injury in patients undergoing radiation treatment. We are conducting further experiments in our laboratory, which includes a human lung-on-a-chip model, to develop a decision tree model using RNA biomarkers.

Interkingdom Detection of Bacterial Quorum-Sensing Molecules by Mammalian Taste Receptors

Bitter and sweet taste G protein-coupled receptors (known as T2Rs and T1Rs, respectively) were originally identified in type II taste cells on the tongue, where they signal perception of bitter and sweet tastes, respectively. Over the past ~15 years, taste receptors have been identified in cells all over the body, demonstrating a more general chemosensory role beyond taste. Bitter and sweet taste receptors regulate gut epithelial function, pancreatic β cell secretion, thyroid hormone secretion, adipocyte function, and many other processes. Emerging data from a variety of tissues suggest that taste receptors are also used by mammalian cells to "eavesdrop" on bacterial communications. These receptors are activated by several quorum-sensing molecules, including acyl-homoserine lactones and quinolones from Gram-negative bacteria such as Pseudomonas aeruginosa, competence stimulating peptides from Streptococcus mutans, and D-amino acids from Staphylococcus aureus. Taste receptors are an arm of immune surveillance similar to Toll-like receptors and other pattern recognition receptors. Because they are activated by quorum-sensing molecules, taste receptors report information about microbial population density based on the chemical composition of the extracellular environment. This review summarizes current knowledge of bacterial activation of taste receptors and identifies important questions remaining in this field.

Shaping of the alveolar landscape by respiratory infections and long-term consequences for lung immunity

Respiratory infections and especially viral infections, along with other extrinsic environmental factors, have been shown to profoundly affect macrophage populations in the lung. In particular, alveolar macrophages (AMs) are important sentinels during respiratory infections and their disappearance opens a niche for recruited monocytes (MOs) to differentiate into resident macrophages. Although this topic is still the focus of intense debate, the phenotype and function of AMs that recolonize the niche after an inflammatory insult, such as an infection, appear to be dictated in part by their origin, but also by local and/or systemic changes that may be imprinted at the epigenetic level. Phenotypic alterations following respiratory infections have the potential to shape lung immunity for the long-term, leading to beneficial responses such as protection against allergic airway inflammation or against other infections, but also to detrimental responses when associated with the development of immunopathologies. This review reports the persistence of virus-induced functional alterations in lung macrophages, and discusses the importance of this imprinting in explaining inter-individual and lifetime immune variation.

Association of adverse respiratory events with sodium-glucose cotransporter 2 inhibitors versus dipeptidyl peptidase 4 inhibitors among patients with type 2 diabetes in South Korea: a nationwide cohort study

BACKGROUND

Impaired respiratory function remains underrecognized in patients with type 2 diabetes (T2D), despite common pulmonary impairment. Meanwhile, there is little data available on the respiratory effects of sodium glucose cotransporter 2 inhibitors (SGLT2i). Hence, we examined the association between SGLT2i use and the risk of adverse respiratory events in a real-world setting.

METHODS

We conducted a population-based, nationwide cohort study using an active-comparator new-user design and nationwide claims data of South Korea from January 2015 to December 2020. Among individuals aged 18 years or older, propensity score matching was done to match each new user of SGLT2is with dipeptidyl peptidase 4 inhibitors (DPP4is), with patients followed up according to an as-treated definition. The primary outcome was respiratory events, a composite endpoint of acute pulmonary edema, acute respiratory distress syndrome (ARDS), pneumonia, and respiratory failure. Secondary outcomes were the individual components of the primary outcome and in-hospital death. Cox models were used to estimate hazard ratios (HRs) and 95% CIs.

RESULTS

Of 205,534 patient pairs in the propensity score matched cohort, the mean age of the entire cohort was 53.8 years and 59% were men, with a median follow-up of 0.66 years; all baseline covariates achieved balance between the two groups. Incidence rates for overall respiratory events were 4.54 and 7.54 per 1000 person-years among SGLT2i and DPP4i users, respectively, corresponding to a rate difference of 3 less events per 1000 person-years (95% CI - 3.44 to - 2.55). HRs (95% CIs) were 0.60 (0.55 to 0.64) for the composite respiratory endpoint, 0.35 (0.23 to 0.55) for acute pulmonary edema, 0.44 (0.18 to 1.05) for ARDS, 0.61 (0.56 to 0.66) for pneumonia, 0.49 (0.31 to 0.76) for respiratory failure, and 0.46 (0.41 to 0.51) for in-hospital death. Similar trends were found across individual SGLT2is, subgroup analyses of age, sex, history of comorbidities, and a range of sensitivity analyses.

CONCLUSIONS

These findings suggest a lower risk of adverse respiratory events associated with patients with T2D initiating SGLT2is versus DPP4is. This real-world evidence helps inform patients, clinicians, and guideline writers regarding the respiratory effects of SGLT2i in routine practice.

The lung, the niche, and the microbe: Exploring the lung microbiome in cancer and immunity

The lung is a complex and unique organ system whose biology is strongly influenced by environmental exposure, oxygen abundance, connection to extrapulmonary systems via a dense capillary network, and an array of immune cells that reside in the tissue at steady state. The lung also harbors a low biomass community of commensal microorganisms that are dynamic during both health and disease with the capacity to modulate regulatory immune responses during diseases such as cancer. Lung cancer is the third most common cancer worldwide with the highest mortality rate amongst cancers due to the difficulty of an early diagnosis. This review discusses the current body of work addressing the interactions between the lung microbiota and the immune system, and how these two components of the pulmonary system are linked to lung cancer development and outcomes. Bringing in lessons from broader studies examining the effects of the gut microbiota on cancer outcomes, we highlight many challenges and gaps in this nascent field.

Getting sweeter: new evidence for glucose transporters in specific cell types of the airway?

New technologies such as single-cell RNA sequencing (scRNAseq) has enabled identification of the mRNA transcripts expressed by individual cells. This review provides insight from recent scRNAseq studies on the expression of glucose transporters in the epithelial cells of the airway epithelium from trachea to alveolus. The number of studies analyzed was limited, not all reported the full range of glucose transporters and there were differences between cells freshly isolated from the airways and those grown in vitro. Furthermore, glucose transporter mRNA transcripts were expressed at lower levels than other epithelial marker genes. Nevertheless, these studies highlighted that there were differences in cellular expression of glucose transporters. GLUT1 was the most abundant of the broadly expressed transporters that included GLUT8, 10, and 13. GLUT9 transcripts were more common in basal cells and GLUT12 in ionocytes/ciliated cells. In addition to alveolar cells, SGLT1 transcripts were present in secretory cells. GLUT3 mRNA transcripts were expressed in a cell cluster that expressed monocarboxylate (MCT2) transporters. Such distributions likely underlie cell-specific metabolic requirements to support proliferation, ion transport, mucous secretion, environment sensing, and airway glucose homeostasis. These studies have also highlighted the role of glucose transporters in the movement of dehydroascorbic acid/vitamin C/myoinositol/urate, which are factors important to the innate immune properties of the airways. Discrepancies remain between detection of mRNAs, protein, and function of glucose transporters in the lungs. However, collation of the data from further scRNAseq studies may provide a better consensus and understanding, supported by qPCR, immunohistochemistry, and functional experiments.

Mechanistic Insights into the Impact of Air Pollution on Pneumococcal Pathogenesis and Transmission

Streptococcus pneumoniae (the pneumococcus) is the leading cause of pneumonia and bacterial meningitis. A number of recent studies indicate an association between the incidence of pneumococcal disease and exposure to air pollution. Although the epidemiological evidence is substantial, the underlying mechanisms by which the various components of air pollution (particulate matter and gases such as NO2 and SO2) can increase susceptibility to pneumococcal infection are less well understood. In this review, we summarize the various effects air pollution components have on pneumococcal pathogenesis and transmission; exposure to air pollution can enhance host susceptibility to pneumococcal colonization by impairing the mucociliary activity of the airway mucosa, reducing the function and production of key antimicrobial peptides, and upregulating an important pneumococcal adherence factor on respiratory epithelial cells. Air pollutant exposure can also impair the phagocytic killing ability of macrophages, permitting increased replication of S. pneumoniae. In addition, particulate matter has been shown to activate various extra- and intracellular receptors of airway epithelial cells, which may lead to increased proinflammatory cytokine production. This increases recruitment of innate immune cells, including macrophages and neutrophils. The inflammatory response that ensues may result in significant tissue damage, thereby increasing susceptibility to invasive disease, because it allows S. pneumoniae access to the underlying tissues and blood. This review provides an in-depth understanding of the interaction between air pollution and the pneumococcus, which has the potential to aid the development of novel treatments or alternative strategies to prevent disease, especially in areas with high concentrations of air pollution.

ATP citrate lyase links increases in glycolysis to diminished release of vesicular suppressor of cytokine signaling 3 by alveolar macrophages

Extracellular vesicles (EVs) are important vectors for intercellular communication. Lung-resident alveolar macrophages (AMs) tonically secrete EVs containing suppressor of cytokine signaling 3 (SOCS3), a cytosolic protein that promotes homeostasis in the distal lung via its actions in recipient neighboring epithelial cells. AMs are metabolically distinct and exhibit low levels of glycolysis at steady state. To our knowledge, whether cellular metabolism influences the packaging and release of an EV cargo molecule has never been explored in any cellular context. Here, we report that increases in glycolysis following in vitro exposure of AMs to the growth and activating factor granulocyte-macrophage colony-stimulating factor inhibit the release of vesicular SOCS3 by primary AMs. Glycolytically diminished SOCS3 secretion requires export of citrate from the mitochondria to the cytosol and its subsequent conversion to acetyl-CoA by ATP citrate lyase. Our data for the first time implicate perturbations in intracellular metabolites in the regulation of vesicular cargo packaging and secretion.

Biology of lung macrophages in health and disease

Tissue-resident alveolar and interstitial macrophages and recruited macrophages are critical players in innate immunity and maintenance of lung homeostasis. Until recently, assessing the differential functional contributions of tissue-resident versus recruited macrophages has been challenging because they share overlapping cell surface markers, making it difficult to separate them using conventional methods. This review describes how scRNA-seq and spatial transcriptomics can separate these subpopulations and help unravel the complexity of macrophage biology in homeostasis and disease. First, we provide a guide to identifying and distinguishing lung macrophages from other mononuclear phagocytes in humans and mice. Second, we outline emerging concepts related to the development and function of the various lung macrophages in the alveolar, perivascular, and interstitial niches. Finally, we describe how different tissue states profoundly alter their functions, including acute and chronic lung disease, cancer, and aging.

Association of admission blood glucose level and clinical outcomes in elderly community-acquired pneumonia patients with or without diabetes

INTRODUCTION

Community-acquired pneumonia (CAP) is the major cause of infection-related mortality worldwide. Patients with CAP frequently present with admission hyperglycemia.

OBJECTIVES

The aim of this study was to evaluate the association between admission blood glucose (ABG) level and clinical outcomes in elderly CAP patients (≥80 years of age) with or without diabetes.

METHODS

In this single center retrospective study, 290 elderly patients diagnosed with CAP were included. Demographic and clinical information were collected and compared. The associations between admission blood glucose level and the 30-day mortality as well as intensive care unit (ICU) admission and invasive mechanical ventilation (IMV) in elderly CAP patients with or without diabetes were assessed.

RESULTS

Of the 290 eligible patients with CAP, 159 (66.5%) patients were male, and 64 (22.1%) had a known history of diabetes at hospital admission. After adjusting for age and sex, the logistic regression analysis had identified several risk factors that might be associated with clinical outcomes in elderly patients with CAP. Multivariable logistic regression analysis revealed that admission glucose level > 11.1 mmol/L was significant associated with ICU admission, IMV, and 30-day mortality both in non-diabetic and diabetic patients. Furthermore, Kaplan-Meier analysis indicated that patients with higher admission glucose level were correlated statistically significantly with 30-day mortality in patients with CAP (P < 0.001).

CONCLUSION

Admission blood glucose is correlated with 30-day hospital mortality, ICU admission, and IMV of CAP in elderly patients with and without diabetes. Specially, admission glucose > 11.1 mmol/L was a significant risk factor for 30-day hospital mortality.

Fungal-mediated lung allergic airway disease: The critical role of macrophages and dendritic cells

Fungi are abundant in the environment, causing our lungs to be constantly exposed to a diverse range of species. While the majority of these are cleared effectively in healthy individuals, constant exposure to spores (especially Aspergillus spp.) can lead to the development of allergic inflammation that underpins and worsen diseases such as asthma. Despite this, the precise mechanisms that underpin the development of fungal allergic disease are poorly understood. Innate immune cells, such as macrophages (MΦs) and dendritic cells (DCs), have been shown to be critical for mediating allergic inflammation to a range of different allergens. This review will focus on the crucial role of MΦ and DCs in mediating antifungal immunity, evaluating how these immune cells mediate allergic inflammation within the context of the lung environment. Ultimately, we aim to highlight important future research questions that will lead to novel therapeutic strategies for fungal allergic diseases.

HIF-1α induces glycolytic reprograming in tissue-resident alveolar macrophages to promote cell survival during acute lung injury

Cellular metabolism is a critical regulator of macrophage effector function. Tissue-resident alveolar macrophages (TR-AMs) inhabit a unique niche marked by high oxygen and low glucose. We have recently shown that in contrast to bone marrow-derived macrophages (BMDMs), TR-AMs do not utilize glycolysis and instead predominantly rely on mitochondrial function for their effector response. It is not known how changes in local oxygen concentration that occur during conditions such as acute respiratory distress syndrome (ARDS) might affect TR-AM metabolism and function; however, ARDS is associated with progressive loss of TR-AMs, which correlates with the severity of disease and mortality. Here, we demonstrate that hypoxia robustly stabilizes HIF-1α in TR-AMs to promote a glycolytic phenotype. Hypoxia altered TR-AM metabolite signatures, cytokine production, and decreased their sensitivity to the inhibition of mitochondrial function. By contrast, hypoxia had minimal effects on BMDM metabolism. The effects of hypoxia on TR-AMs were mimicked by FG-4592, a HIF-1α stabilizer. Treatment with FG-4592 decreased TR-AM death and attenuated acute lung injury in mice. These findings reveal the importance of microenvironment in determining macrophage metabolic phenotype and highlight the therapeutic potential in targeting cellular metabolism to improve outcomes in diseases characterized by acute inflammation.

Worsening Glycemia Increases the Odds of Intermittent but Not Persistent Staphylococcus aureus Nasal Carriage in Two Cohorts of Mexican American Adults

Numerous host and environmental factors contribute to persistent and intermittent nasal Staphylococcus aureus carriage in humans. The effects of worsening glycemia on the odds of S. aureus intermittent and persistent nasal carriage was established in two cohorts from an adult Mexican American population living in Starr County, Texas. The anterior nares were sampled at two time points and the presence of S. aureus determined by laboratory culture and spa-typing. Persistent carriers were defined by the presence of S. aureus of the same spa-type at both time points, intermittent carriers were S. aureus-positive for 1 of 2 swabs, and noncarriers were negative for S. aureus at both time points. Diabetes status was obtained through personal interview and physical examination that included a blood draw for the determination of percent glycated hemoglobin A1c (%HbA1c), fasting plasma glucose, and other blood chemistry values. Using logistic regression and general estimating equations, the odds of persistent and intermittent nasal carriage compared to noncarriers across the glycemic spectrum was determined controlling for covariates. Increasing fasting plasma glucose and %HbA1c in the primary and replication cohort, respectively, were significantly associated with increasing odds of S. aureus intermittent, but not persistent nasal carriage. These data suggest that increasing dysglycemia is a risk factor for intermittent S. aureus nasal carriage potentially placing those with poorly controlled diabetes at an increased risk of acquiring an S. aureus infection. IMPORTANCE Factors affecting nasal S. aureus colonization have been studied primarily in the context of persistent carriage. In contrast, few studies have examined factors affecting intermittent nasal carriage with this pathogen. This study demonstrates that the odds of intermittent but not persistent nasal carriage of S. aureus significantly increases with worsening measures of dysglycemia. This is important in the context of poorly controlled diabetes since the risk of becoming colonized with one of the primary organisms associated with diabetic foot infections can lead to increased morbidity and mortality.

The impact of the lung environment on macrophage development, activation and function: diversity in the face of adversity

The last decade has been somewhat of a renaissance period for the field of macrophage biology. This renewed interest, combined with the advent of new technologies and development of novel model systems to assess different facets of macrophage biology, has led to major advances in our understanding of the diverse roles macrophages play in health, inflammation, infection and repair, and the dominance of tissue environments in influencing all of these areas. Here, we discuss recent developments in our understanding of lung macrophage heterogeneity, ontogeny, metabolism and function in the context of health and disease, and highlight core conceptual advances and key unanswered questions that we believe should be focus of work in the coming years.

SAKrificing an Essential Stress-Sensing Pathway Improves Aspergillus fumigatus Germination

Fungal infections represent a major problem in human health. This is particularly the case of infections caused by the filamentous fungus Aspergillus fumigatus, affecting millions of people worldwide. While active germination of conidia is documented to be essential for the A. fumigatus pathogenicity in the context of chronic infections, the molecular mechanisms underlying this morphogenetic transition remain unclear. In a new report, Kirkland and colleagues shed light on a central role of a major stress-sensing pathway in orchestrating the germination process in A. fumigatus. This work provides insight into disruption of an essential cell signaling circuitry for an adequate and long-term adaptation of the fungus to the lung microenvironment.

Host Lung Environment Limits Aspergillus fumigatus Germination through an SskA-Dependent Signaling Response

Aspergillus fumigatus isolates display significant heterogeneity in growth, virulence, pathology, and inflammatory potential in multiple murine models of invasive aspergillosis. Previous studies have linked the initial germination of a fungal isolate in the airways to the inflammatory and pathological potential, but the mechanism(s) regulating A. fumigatus germination in the airways is unresolved. To explore the genetic basis for divergent germination phenotypes, we utilized a serial passaging strategy in which we cultured a slow germinating strain (AF293) in a murine-lung-based medium for multiple generations. Through this serial passaging approach, a strain emerged with an increased germination rate that induces more inflammation than the parental strain (herein named LH-EVOL for lung homogenate evolved). We identified a potential loss-of-function allele of Afu5g08390 (sskA) in the LH-EVOL strain. The LH-EVOL strain had a decreased ability to induce the SakA-dependent stress pathway, similar to AF293 ΔsskA and CEA10. In support of the whole-genome variant analyses, sskA, sakA, or mpkC loss-of-function strains in the AF293 parental strain increased germination both in vitro and in vivo. Since the airway surface liquid of the lungs contains low glucose levels, the relationship of low glucose concentration on germination of these mutant AF293 strains was examined; interestingly, in low glucose conditions, the sakA pathway mutants exhibited an enhanced germination rate. In conclusion, A. fumigatus germination in the airways is regulated by SskA through the SakA mitogen-activated protein kinase (MAPK) pathway and drives enhanced disease initiation and inflammation in the lungs.

IMPORTANCEAspergillus fumigatus is an important human fungal pathogen particularly in immunocompromised individuals. Initiation of growth by A. fumigatus in the lung is important for its pathogenicity in murine models. However, our understanding of what regulates fungal germination in the lung environment is lacking. Through a serial passage experiment using lung-based medium, we identified a new strain of A. fumigatus that has increased germination potential and inflammation in the lungs. Using this serially passaged strain, we found it had a decreased ability to mediate signaling through the osmotic stress response pathway. This finding was confirmed using genetic null mutants demonstrating that the osmotic stress response pathway is critical for regulating growth in the murine lungs. Our results contribute to the understanding of A. fumigatus adaptation and growth in the host lung environment.

On the footsteps of Hippocrates, Sanctorius and Harvey to better understand the influence of cold on the occurrence of COVID-19 in European countries in 2020

COVID-19 pandemic has been characterized by a pattern of consecutive declines and regrowth in European countries in 2020. After being partially regressed during the summer, the reappearance of the infection during fall 2020 in many temperate countries strongly suggests that temperature and cold may play a role in influencing the infectivity and virulence of SARS-CoV-2. While promoting medicine as an art, Hippocrates interpreted with logical reasoning the occurrence of diseases such as epidemics, as a consequence of environmental factors, in particular climatic variations. During the Renaissance, Sanctorius was one of the first to perform quantitative measurements, and Harvey discovered the circulation of blood by performing experimental procedures in animals. We think that a reasoning mixing various observations, measurements and experiments is fundamental to understand how cold increases infectivity and virulence of SARS-CoV-2. By this review, we provide evidence linking cold, angiotensin-II, vasoconstriction, hypoxia and aerobic glycolysis (the Warburg effect) to explain how cold affects the epidemiology of COVID-19. Also, a low humidity increases virus transmissibility, while a warm atmosphere, a moderate airway humidity, and the production of vasodilator angiotensin 1-7 by ACE2 are less favorable to the virus entry and/or its development. The meteorological and environmental parameters impacting COVID-19 pandemic should be reintegrated into a whole perspective by taking into account the different factors influencing transmissibility, infectivity and virulence of SARS-CoV-2. To understand the modern enigma represented by COVID-19, an interdisciplinary approach is surely essential.

Continuous glucose monitoring systems for monitoring cystic fibrosis-related diabetes

BACKGROUND

Cystic fibrosis (CF) is one of the most common life-shortening autosomal-recessive genetic conditions with around 100,000 people affected globally. CF mainly affects the respiratory system, but cystic fibrosis-related diabetes (CFRD) is a common extrapulmonary co-morbidity and causes excess morbidity and mortality in this population. Continuous glucose monitoring systems (CGMS) are a relatively new technology and, as yet, the impact of these on the monitoring and subsequent management of CFRD remains undetermined.

OBJECTIVES

To establish the impact of insulin therapy guided by continuous glucose monitoring compared to insulin therapy guided by other forms of glucose data collection on the lives of people with CFRD.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. Date of latest search: 23 September 2021. We also searched the reference lists of relevant articles and reviews and online trials registries. Date of last search: 23 September 2021.

SELECTION CRITERIA

Randomised controlled studies comparing insulin regimens led by data from CGMS (including real-time or retrospective data, or both) with insulin regimens guided by abnormal blood glucose measurements collected through other means of glycaemic data collection in people with CFRD. Studies with a cross-over design, even with a washout period between intervention arms, are not eligible for inclusion due to the potential long-term impact of each of the interventions and the potential to compromise the outcomes of the second intervention.

DATA COLLECTION AND ANALYSIS

No studies were included in the review, meaning that no data were available to be collected for analysis.

MAIN RESULTS

Review authors screened 14 studies at the full-text stage against the review's inclusion criteria. Consequently, seven were excluded due to the study type being ineligible (not randomised), two studies were excluded due to their cross-over design, and two studies was excluded since the intervention used was not eligible and one was a literature review. One study in participants hospitalised for a pulmonary exacerbation is ongoing. Investigators are comparing insulin dosing via insulin pump with blood sugar monitoring by a CGMS to conventional diabetes management with daily insulin injections (or on an insulin pump if already on an insulin pump in the outpatient setting) and capillary blood glucose monitoring. The participants in the control arm will wear a blinded continuous glucose monitoring system for outcome assessment. In addition to this, one further study is still awaiting classification, and will be screened to determine whether it is eligible for inclusion, or is to be excluded, in an update of this review.

AUTHORS' CONCLUSIONS

No studies were included in the review, indicating that there is currently insufficient evidence to determine the impact of insulin therapy guided by CGMS compared to insulin therapy guided by other forms of glucose data collection on the lives of people with CFRD, nor on potential adverse effects of continuous glucose monitoring in this context. Randomised controlled studies are needed to generate evidence on the efficacy and safety of continuous glucose monitoring in people with CFRD. There is one relevant ongoing study that may be eligible for inclusion in a future update of this Cochrane Review, and whose results may help answer the review question.

Clustering of catalytic nanocompartments for enhancing an extracellular non-native cascade reaction

Compartmentalization is fundamental in nature, where the spatial segregation of biochemical reactions within and between cells ensures optimal conditions for the regulation of cascade reactions. While the distance between compartments or their interaction are essential parameters supporting the efficiency of bio-reactions, so far they have not been exploited to regulate cascade reactions between bioinspired catalytic nanocompartments. Here, we generate individual catalytic nanocompartments (CNCs) by encapsulating within polymersomes or attaching to their surface enzymes involved in a cascade reaction and then, tether the polymersomes together into clusters. By conjugating complementary DNA strands to the polymersomes' surface, DNA hybridization drove the clusterization process of enzyme-loaded polymersomes and controlled the distance between the respective catalytic nanocompartments. Owing to the close proximity of CNCs within clusters and the overall stability of the cluster architecture, the cascade reaction between spatially segregated enzymes was significantly more efficient than when the catalytic nanocompartments were not linked together by DNA duplexes. Additionally, residual DNA single strands that were not engaged in clustering, allowed for an interaction of the clusters with the cell surface as evidenced by A549 cells, where clusters decorating the surface endowed the cells with a non-native enzymatic cascade. The self-organization into clusters of catalytic nanocompartments confining different enzymes of a cascade reaction allows for a distance control of the reaction spaces which opens new avenues for highly efficient applications in domains such as catalysis or nanomedicine.

Assessment of in vitro kinetics and biological impact of nebulized trehalose on human bronchial epithelium

Trehalose is added in drug formulations to act as fillers or improve aerosolization performance. Its characteristics as a carrier molecule have been explored; however, the fate of trehalose in human airway tissues has not been thoroughly investigated. Here, we investigated the fate of nebulized trehalose using in vitro human air-liquid bronchial epithelial cultures. First, a tracing experiment was conducted using ¹³C₁₂-trehalose; we measured trehalose distribution in different culture compartments (apical surface liquid, epithelial culture, and basal side medium) at various time points following acute exposure to ¹³C₁₂-labeled trehalose. We found that ¹³C₁₂-trehalose was metabolized into ¹³C₆-glucose. The data was then used to model the kinetics of trehalose disappearance from the apical surface of bronchial cultures. Secondly, we evaluated the potential adverse effects of nebulized trehalose on the bronchial cultures after they were acutely exposed to nebulized trehalose up to a level just below its solubility limit (50 g/100 g water). We assessed the ciliary beating frequency and histological characteristics. We found that nebulized trehalose did not lead to marked alteration in ciliary beating frequency and morphology of the epithelial cultures. The in vitro testing approach used here may enable the early selection of excipients for future development of inhalation products.

A Machine-Generated View of the Role of Blood Glucose Levels in the Severity of COVID-19

SARS-CoV-2 started spreading toward the end of 2019 causing COVID-19, a disease that reached pandemic proportions among the human population within months. The reasons for the spectrum of differences in the severity of the disease across the population, and in particular why the disease affects more severely the aging population and those with specific preconditions are unclear. We developed machine learning models to mine 240,000 scientific articles openly accessible in the CORD-19 database, and constructed knowledge graphs to synthesize the extracted information and navigate the collective knowledge in an attempt to search for a potential common underlying reason for disease severity. The machine-driven framework we developed repeatedly pointed to elevated blood glucose as a key facilitator in the progression of COVID-19. Indeed, when we systematically retraced the steps of the SARS-CoV-2 infection, we found evidence linking elevated glucose to each major step of the life-cycle of the virus, progression of the disease, and presentation of symptoms. Specifically, elevations of glucose provide ideal conditions for the virus to evade and weaken the first level of the immune defense system in the lungs, gain access to deep alveolar cells, bind to the ACE2 receptor and enter the pulmonary cells, accelerate replication of the virus within cells increasing cell death and inducing an pulmonary inflammatory response, which overwhelms an already weakened innate immune system to trigger an avalanche of systemic infections, inflammation and cell damage, a cytokine storm and thrombotic events. We tested the feasibility of the hypothesis by manually reviewing the literature referenced by the machine-generated synthesis, reconstructing atomistically the virus at the surface of the pulmonary airways, and performing quantitative computational modeling of the effects of glucose levels on the infection process. We conclude that elevation in glucose levels can facilitate the progression of the disease through multiple mechanisms and can explain much of the differences in disease severity seen across the population. The study provides diagnostic considerations, new areas of research and potential treatments, and cautions on treatment strategies and critical care conditions that induce elevations in blood glucose levels.

Dietary glycemic index, glycemic load and mortality: Japan Public Health Center-based prospective study

PURPOSE

Long-term associations of dietary glycemic index (GI) and glycemic load (GL) with mortality outcomes remain unclear.

METHODS

The present analysis included 72,783 participants of the Japan Public Health Center-based Prospective Study. Participants who responded to the 5-year follow-up questionnaire in 1995-1999 were followed-up until December 2015. We estimated the risk of total and cause-specific mortality associated with GI and GL using Cox proportional hazards regression models.

RESULTS

During 1,244,553 person years of follow-up, 7535 men and 4913 women died. GI was positively associated with all-cause mortality. As compared with the lowest quartile, the multivariable HR for those who had the highest quartile of GI was 1.14 (95% CI 1.08-1.20). The HRs for death comparing the highest with the lowest quartile were 1.28 (95% CI 1.14-1.42) for circulatory system diseases, 1.33 (95% CI 1.14-1.55) for heart disease, 1.32 (95% CI 1.11-1.57) for cerebrovascular disease, and 1.45 (95% CI 1.18-1.78) for respiratory diseases. GI was not associated with mortality risks of cancer and digestive diseases. GL showed a null association with all-cause mortality (highest vs lowest quartile; HR 1.04; 95% CI 0.96-1.12). However, among those who had the highest quartile of GL, the HRs for death from circulatory system diseases was 1.24 (95% CI 1.05-1.46), cerebrovascular disease was 1.34 (95% CI 1.03-1.74), and respiratory diseases was 1.35 (95% CI 1.00-1.82), as compared with the lowest quartile.

CONCLUSION

In this large prospective cohort study, dietary GI and GL were associated with mortality risks.

Fueling influenza and the immune response: Implications for metabolic reprogramming during influenza infection and immunometabolism

Recent studies support the notion that glycolysis and oxidative phosphorylation are rheostats in immune cells whose bioenergetics have functional outputs in terms of their biology. Specific intrinsic and extrinsic molecular factors function as molecular potentiometers to adjust and control glycolytic to respiratory power output. In many cases, these potentiometers are used by influenza viruses and immune cells to support pathogenesis and the host immune response, respectively. Influenza virus infects the respiratory tract, providing a specific environmental niche, while immune cells encounter variable nutrient concentrations as they migrate in response to infection. Immune cell subsets have distinct metabolic programs that adjust to meet energetic and biosynthetic requirements to support effector functions, differentiation, and longevity in their ever-changing microenvironments. This review details how influenza coopts the host cell for metabolic reprogramming and describes the overlap of these regulatory controls in immune cells whose function and fate are dictated by metabolism. These details are contextualized with emerging evidence of the consequences of influenza-induced changes in metabolic homeostasis on disease progression.

Staphylococcus aureus Arsenal To Conquer the Lower Respiratory Tract

Staphylococcus aureus is both a commensal and a pathogenic bacterium for humans. Its ability to induce severe infections is based on a wide range of virulence factors. S. aureus community-acquired pneumonia (SA-CAP) is rare and severe, and the contribution of certain virulence factors in this disease has been recognized over the past 2 decades. First, the factors involved in metabolism adaptation are crucial for S. aureus survival in the lower respiratory tract, and toxins and enzymes are required for it to cross the pulmonary epithelial barrier. S. aureus subsequently faces host defense mechanisms, including the epithelial barrier, but most importantly the immune system. Here, again, S. aureus uses myriad virulence factors to successfully escape from the host's defenses and takes advantage of them. The impact of S. aureus virulence, combined with the collateral damage caused by an overwhelming immune response, leads to severe tissue damage and adverse clinical outcomes. In this review, we summarize step by step all of the S. aureus factors implicated in CAP and described to date, and we provide an outlook for future research.

Cystic fibrosis-related diabetes and lung disease: an update

The development of cystic fibrosis-related diabetes (CFRD) often leads to poorer outcomes in patients with cystic fibrosis including increases in pulmonary exacerbations, poorer lung function and early mortality. This review highlights the many factors contributing to the clinical decline seen in patients diagnosed with CFRD, highlighting the important role of nutrition, the direct effect of hyperglycaemia on the lungs, the immunomodulatory effects of high glucose levels and the potential role of genetic modifiers in CFRD.

Influence of Hypoxia on the Epithelial-Pathogen Interactions in the Lung: Implications for Respiratory Disease

Under normal physiological conditions, the lung remains an oxygen rich environment. However, prominent regions of hypoxia are a common feature of infected and inflamed tissues and many chronic inflammatory respiratory diseases are associated with mucosal and systemic hypoxia. The airway epithelium represents a key interface with the external environment and is the first line of defense against potentially harmful agents including respiratory pathogens. The protective arsenal of the airway epithelium is provided in the form of physical barriers, and the production of an array of antimicrobial host defense molecules, proinflammatory cytokines and chemokines, in response to activation by receptors. Dysregulation of the airway epithelial innate immune response is associated with a compromised immunity and chronic inflammation of the lung. An increasing body of evidence indicates a distinct role for hypoxia in the dysfunction of the airway epithelium and in the responses of both innate immunity and of respiratory pathogens. Here we review the current evidence around the role of tissue hypoxia in modulating the host-pathogen interaction at the airway epithelium. Furthermore, we highlight the work needed to delineate the role of tissue hypoxia in the pathophysiology of chronic inflammatory lung diseases such as asthma, cystic fibrosis, and chronic obstructive pulmonary disease in addition to novel respiratory diseases such as COVID-19. Elucidating the molecular mechanisms underlying the epithelial-pathogen interactions in the setting of hypoxia will enable better understanding of persistent infections and complex disease processes in chronic inflammatory lung diseases and may aid the identification of novel therapeutic targets and strategies.

Glucose-Binding of Periplasmic Protein GltB Activates GtrS-GltR Two-Component System in Pseudomonas aeruginosa

A two-component system GtrS-GltR is required for glucose transport activity in P. aeruginosa and plays a key role during P. aeruginosa-host interactions. However, the mechanism of action of GtrS-GltR has not been definitively established. Here, we show that gltB, which encodes a periplasmic glucose binding protein, is essential for the glucose-induced activation of GtrS-GltR in P. aeruginosa. We determined that GltB is capable of binding to membrane regulatory proteins including GtrS, the sensor kinase of the GtrS-GltR TCS. We observed that alanine substitution of glucose-binding residues abolishes the ability of GltB to promote the activation of GtrS-GltR. Importantly, like the gtrS deletion mutant, gltB deletion mutant showed attenuated virulence in both Drosophila melanogaster and mouse models of infection. In addition, using CHIP-seq experiments, we showed that the promoter of gltB is the major in vivo target of GltR. Collectively, these data suggest that periplasmic binding protein GltB and GtrS-GltR TCS form a complex regulatory circuit that regulates the virulence of P. aeruginosa in response to glucose.

SGLT-2 inhibitors and the risk of hospitalization for community-acquired pneumonia: A population-based cohort study

PURPOSE

Sodium-glucose co-transporter 2 inhibitors (SGLT-2i) have been associated with an increased risk of genitourinary tract infections. Through similar biological mechanisms, they may also increase the risk of community-acquired pneumonia. Our objective was to compare the rate of hospitalization for community-acquired pneumonia (HCAP) with SGLT-2i compared to dipeptidyl peptidase-4 inhibitors (DPP-4i) among patients with type 2 diabetes.

METHODS

We used the United Kingdom's Clinical Practice Research Datalink Gold, linked to hospitalization data, to construct a cohort of patients with type 2 diabetes. Using a time-dependent Cox proportional hazards model, we estimated the adjusted hazard ratio (HR) for HCAP with current use of SGLT-2i versus DPP-4i.

RESULTS

Among 29 896 patients, 705 HCAPs occurred over a mean follow-up of 1.7 years (SD: 1.2). Incidence rates for SGLT-2i and DPP-4i users were 6.2 (95% confidence interval [CI]: 3.7, 10.2) and 17.8 (95% CI: 15.3, 20.7) per 1000 person-years, respectively. Current use of SGLT-2i was associated with a decreased risk of HCAP compared to current use of DPP-4i (adjusted HR: 0.48, 95% CI: 0.28, 0.82). However, a comparison of SGLT-2i versus glucagon-like peptide-1 receptor agonists (GLP-1 RA) found no difference in risk of HCAP (adjusted HR: 0.94, 95% CI: 0.44, 1.89).

CONCLUSIONS

SGLT-2i are associated with a decreased rate of HCAP compared to DPP-4i, but not when compared to GLP-1 RA, among patients with type 2 diabetes.

The Performance of CURB-65 and PSI for Predicting In-Hospital Mortality of Community-Acquired Pneumonia in Patients with Type 2 Diabetes Compared with the Non-Diabetic Population

OBJECTIVE

To compare the performance of CURB-65 and Pneumonia Severity Index (PSI) for predicting in-hospital mortality of community-acquired pneumonia (CAP) between patients with and without type 2 diabetes (T2DM).

METHODS

A retrospective study was conducted on 2365 CAP patients in The First Hospital of Qinhuangdao, China. The primary outcome was in-hospital mortality. The area under curves (AUCs) was used to evaluate the abilities of CRB-65, CURB-65, and PSI class for predicting in-hospital mortality in patients with CAP.

RESULTS

Among CAP patients, 127 patients (5.4%) died, 80 patients were without diabetes, and 47 patients had T2DM. In-hospital mortality increased with the risk stratification defined as CURB-65 and PSI class in both non-diabetes and T2DM patients (P<0.05). The AUCs for predicting in-hospital mortality were 0.728～0.798 in patients without T2DM (CRB-65: 0.728, CURB-65: 0.757 and PSI class: 0.798) and 0.641～0.716 in patients with T2DM (CRB-65: 0.641, CURB-65: 0.677 and PSI class: 0.716)(P<0.001). The AUC of the PSI class was lower in patients with T2DM than in patients without T2DM (P<0.05).

CONCLUSION

CURB-65 and PSI class are correlated with in-hospital mortality of CAP in patients with and without T2DM. Compared with non-diabetes patients, the predictive performance of CURB-65 and PSI class decreased in patients with T2DM. A prediction model for evaluating the CAP severity in the T2DM population should be developed by future studies.

Pathophysiology of SARS-CoV-2 in Lung of Diabetic Patients

Novel coronavirus disease (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Its impact on patients with comorbidities is clearly related to fatality cases, and diabetes has been linked to one of the most important causes of severity and mortality in SARS-CoV-2 infected patients. Substantial research progress has been made on COVID-19 therapeutics; however, effective treatments remain unsatisfactory. This unmet clinical need is robustly associated with the complexity of pathophysiological mechanisms described for COVID-19. Several key lung pathophysiological mechanisms promoted by SARS-CoV-2 have driven the response in normoglycemic and hyperglycemic subjects. There is sufficient evidence that glucose metabolism pathways in the lung are closely tied to bacterial proliferation, inflammation, oxidative stress, and pro-thrombotic responses, which lead to severe clinical outcomes. It is also likely that SARS-CoV-2 proliferation is affected by glucose metabolism of type I and type II cells. This review summarizes the current understanding of pathophysiology of SARS-CoV-2 in the lung of diabetic patients and highlights the changes in clinical outcomes of COVID-19 in normoglycemic and hyperglycemic conditions.

E-cigarette constituents propylene glycol and vegetable glycerin decrease glucose uptake and its metabolism in airway epithelial cells in vitro

Electronic nicotine delivery systems, or e-cigarettes, utilize a liquid solution that normally contains propylene glycol (PG) and vegetable glycerin (VG) to generate vapor and act as a carrier for nicotine and flavorings. Evidence indicated these "carriers" reduced growth and survival of epithelial cells including those of the airway. We hypothesized that 3% PG or PG mixed with VG (3% PG/VG, 55:45) inhibited glucose uptake in human airway epithelial cells as a first step to reducing airway cell survival. Exposure of H441 or human bronchiolar epithelial cells (HBECs) to PG and PG/VG (30-60 min) inhibited glucose uptake and mitochondrial ATP synthesis. PG/VG inhibited glycolysis. PG/VG and mannitol reduced cell volume and height of air-liquid interface cultures. Mannitol, but not PG/VG, increased phosphorylation of p38 MAPK. PG/VG reduced transepithelial electrical resistance, which was associated with increased transepithelial solute permeability. PG/VG decreased fluorescence recovery after photobleaching of green fluorescent protein-linked glucose transporters GLUT1 and GLUT10, indicating that glucose transport function was compromised. Puffing PG/VG vapor onto the apical surface of primary HBECs for 10 min to mimic the effect of e-cigarette smoking also reduced glucose transport. In conclusion, short-term exposure to PG/VG, key components of e-cigarettes, decreased glucose transport and metabolism in airway cells. We propose that this was a result of PG/VG reduced cell volume and membrane fluidity, with further consequences on epithelial barrier function. Taking these results together, we suggest these factors contribute to reduced defensive properties of the epithelium. We propose that repeated/chronic exposure to these agents are likely to contribute to airway damage in e-cigarette users.

Mutation-induced remodeling of the BfmRS two-component system in Pseudomonas aeruginosa clinical isolates

Genetic mutations are a primary driving force behind the adaptive evolution of bacterial pathogens. Multiple clinical isolates of Pseudomonas aeruginosa, an important human pathogen, have naturally evolved one or more missense mutations in bfmS, which encodes the sensor histidine kinase of the BfmRS two-component system (TCS). A mutant BfmS protein containing both the L181P and E376Q substitutions increased the phosphorylation and thus the transcriptional regulatory activity of its cognate downstream response regulator, BfmR. This reduced acute virulence and enhanced biofilm formation, both of which are phenotypic changes associated with a chronic infection state. The increased phosphorylation of BfmR was due, at least in part, to the cross-phosphorylation of BfmR by GtrS, a noncognate sensor kinase. Other spontaneous missense mutations in bfmS, such as A42E/G347D, T242R, and R393H, also caused a similar remodeling of the BfmRS TCS in P. aeruginosa This study highlights the plasticity of TCSs mediated by spontaneous mutations and suggests that mutation-induced activation of BfmRS may contribute to host adaptation by P. aeruginosa during chronic infections.

Dipeptidyl peptidase-4 inhibitor treatment could decrease Klebsiella pneumoniae pneumonia in patients with type 2 diabetes

OBJECTIVES

To investigate the effect of dipeptidyl peptidase-4 inhibitor (DPP4i) for Klebsiella pneumoniae (KP) pneumonia in patients with diabetes.

PATIENTS AND METHODS

Patients newly diagnosed with type 2 diabetes from 2009 to 2012 were recruited for this population-based and observational study. Diabetes complications severity index (DCSI) score and defined daily dose (DDD) were used for analysis. The multivariable Cox proportional hazards models were used to estimate the risk of KP pneumonia by DPP4i use, with adjustments for propensity score. The Kaplan-Meier method with the log-rank test was used to estimate the risk of KP pneumonia for DPP4i users.

RESULTS

34774 patients were included. The incidence rate of KP pneumonia in DDP4i users was 1.51 per 1000 person-years and that for the comparison was 2.25 per 1000 person-years. DDP4i users also had a significantly lower cumulative incidence of KP pneumonia (log-rank test p-value = 0.03). DDP4i users had a significantly lower risk of developing KP pneumonia compared with nonusers (adjusted HR = 0.67, 95% CI = 0.48-0.95).

CONCLUSIONS

For public health issue with type2 diabetes and infection, DPP4i use decreased KP pneumonia. Male gender, patients with co-morbidities, patients with higher DSCI score and higher DDD of DPP4i were observed to decrease KP pneumonia infection in our analysis. The possible role of DPP4i causing immunological disturbances should be considered.

Clinical Management of Diabetes Mellitus in the Era of COVID-19: Practical Issues, Peculiarities and Concerns

The management of patients with diabetes mellitus (DM) in the era of the COVID-19 pandemic can be challenging. Even if they are not infected, they are at risk of dysregulated glycemic control due to the restrictive measures which compromise and disrupt healthcare delivery. In the case of infection, people with DM have an increased risk of developing severe complications. The major principles of optimal care for mild outpatient cases include a patient-tailored therapeutic approach, regular glucose monitoring and adherence to medical recommendations regarding lifestyle measures and drug treatment. For critically ill hospitalized patients, tight monitoring of glucose, fluids, electrolytes, pH and blood ketones is of paramount importance to optimize outcomes. All patients with DM do not have an equally increased risk for severity and mortality due to COVID-19. Certain clinical and biological characteristics determine high-risk phenotypes within the DM population and such prognostic markers need to be characterized in future studies. Further research is needed to examine which subgroups of DM patients are expected to benefit the most from specific antiviral, immunomodulatory and other treatment strategies in the context of patient-tailored precision medicine, which emerges as an urgent priority in the era of COVID-19.