Diet modification and metformin have a beneficial effect in a fly model of obesity and mucormycosis

Metabolic homeostasis in fungal infections from the perspective of pathogens, immune cells, and whole-body systems

SUMMARYThe ability to overcome metabolic stress is a major determinant of outcomes during infections. Pathogens face nutrient and oxygen deprivation in host niches and during their encounter with immune cells. Immune cells require metabolic adaptations for producing antimicrobial compounds and mounting antifungal inflammation. Infection also triggers systemic changes in organ metabolism and energy expenditure that range from an enhanced metabolism to produce energy for a robust immune response to reduced metabolism as infection progresses, which coincides with immune and organ dysfunction. Competition for energy and nutrients between hosts and pathogens means that successful survival and recovery from an infection require a balance between elimination of the pathogen by the immune systems (resistance), and doing so with minimal damage to host tissues and organs (tolerance). Here, we discuss our current knowledge of pathogen, immune cell and systemic metabolism in fungal infections, and the impact of metabolic disorders, such as obesity and diabetes. We put forward the idea that, while our knowledge of the use of metabolic regulation for fungal proliferation and antifungal immune responses (i.e., resistance) has been growing over the years, we also need to study the metabolic mechanisms that control tolerance of fungal pathogens. A comprehensive understanding of how to balance resistance and tolerance by metabolic interventions may provide insights into therapeutic strategies that could be used adjunctly with antifungal drugs to improve patient outcomes.

Atractylodes macrocephala Koidz. and Cuscuta chinensis Lam. extract relieves insulin resistance via PI3K/Akt signalling in diabetic Drosophila

Background and aim

Type-2 diabetes mellitus (T2DM) is mainly characterized by insulin resistance (IR) induced by hyperglycaemia and insufficient insulin secretion. We employed a diabetic fly model to examine the effect and molecular mechanism of Atractylodes macrocephala Koidz. and Cuscuta chinensis Lam. (AMK-CCL) extract as traditional Chinese medicine in treating IR and T2DM.

Experimental procedure

The contents of the active ingredients (rhamnose, xylose, mannose, and hyperoside) in AMK-CCL extract were determined by high-performance liquid chromatography. Wild-type (Cg-GAL4/+) or diabetic (Cg > InRK1409A) Drosophila flies were divided into the control group or metformin group and AMK-CCL (0.0125, 0.025, 0.05, 0.1 g/ml) groups. Food intake, haemolymph glucose and trehalose, protein, weight, triglycerides (TAG), and glycogen were measured to assess glycolipid metabolism. Phosphatidylinositol-3-kinase (PI3K)/Akt signalling was detected using fluorescent reporters [tGPH, Drosophila forkhead box O (dFoxO)-green fluorescent protein (GFP), Glut1-GFP, 2-NBDG] in vivo. Glut1/3 mRNA levels and Akt phosphorylation levels were detected by quantitative polymerase chain reaction and western blotting, respectively, in vitro.

Results

AMK-CCL extract contained 0.038 % rhamnose, 0.017 % xylose, 0.69 % mannose, and 0.039 % hyperoside. AMK-CCL at 0.0125 g/mL significantly suppressed the increase in circulating glucose, and the decrease in body weight, TAG, and glycogen contents of diabetic flies. AMK-CCL improved PI3K activity, Akt phosphorylation, Glut1/3 expression, and glucose uptake in diabetic flies, and also rescued diabetes-induced dFoxO nuclear localisation.

Conclusions

These findings indicate that AMK-CCL extract ameliorates IR-induced diabetes via the PI3K/Akt signalling pathway, providing an experimental basis for clinical treatment.

The Impact of Dimitrios P. Kontoyiannis on Mucormycosis Research

Dimitrios P [...].

A New Isolated Fungus and Its Pathogenicity for Apis mellifera Brood in China

In this article, we report the pathogenicity of a new strain of fungus, Rhizopus oryzae to honeybee larvae, isolated from the chalkbrood-diseased mummies of honeybee larvae and pupae collected from apiaries in China. Based on morphological observation and internal transcribed spacer (ITS) region analyses, the isolated pathogenic fungus was identified as R. oryzae. Koch's postulates were performed to determine the cause-and-effect pathogenicity of this isolate fungus. The in vitro pathogenicity of this virulent fungus in honeybees was tested by artificially inoculating worker larvae in the lab. The pathogenicity of this new fungus for honeybee larvae was both conidial-concentration and exposure-time dependent; its highly infectious and virulent effect against the larvae was observed at 1 × 105 conidia/larva in vitro after 96 h of challenge. Using probit regression analysis, the LT50 value against the larvae was 26.8 h at a conidial concentration of 1 × 105 conidia/larva, and the LC50 was 6.2 × 103 conidia/larva. These results indicate that the new isolate of R. oryzae has considerable pathogenicity in honeybee larvae. Additionally, this report suggests that pathogenic phytofungi may harm their associated pollinators. We recommend further research to quantify the levels, mechanisms, and pathways of the pathogenicity of this novel isolated pathogen for honeybee larvae at the colony level.

Experimental Models to Study the Pathogenesis and Treatment of Mucormycosis

Mucormycosis presents a formidable challenge to clinicians and researchers. Animal models are an essential part of the effort to decipher the pathogenesis of mucormycosis and to develop novel pharmacotherapeutics against it. Diverse model systems have been established, using a range of animal hosts, immune and metabolic perturbations, and infection routes. An understanding of the characteristics, strengths, and drawbacks of these models is needed to optimize their use for specific research aims.

Mucormycosis in 2023: an update on pathogenesis and management

Mucormycosis (MCR) is an emerging and frequently lethal fungal infection caused by the Mucorales family, with Rhizopus, Mucor, and Lichtheimia, accounting for > 90% of all cases. MCR is seen in patients with severe immunosuppression such as those with hematologic malignancy or transplantation, Diabetes Mellitus (DM) and diabetic ketoacidosis (DKA) and immunocompetent patients with severe wounds. The recent SARS COV2 epidemy in India has resulted in a tremendous increase in MCR cases, typically seen in the setting of uncontrolled DM and corticosteroid use. In addition to the diversity of affected hosts, MCR has pleiotropic clinical presentations, with rhino-orbital/rhino-cerebral, sino-pulmonary and necrotizing cutaneous forms being the predominant manifestations. Major insights in MCR pathogenesis have brought into focus the host receptors (GRP78) and signaling pathways (EGFR activation cascade) as well as the adhesins used by Mucorales for invasion. Furthermore, studies have expanded on the importance of iron availability and the complex regulation of iron homeostasis, as well as the pivotal role of mycotoxins as key factors for tissue invasion. The molecular toolbox to study Mucorales pathogenesis remains underdeveloped, but promise is brought by RNAi and CRISPR/Cas9 approaches. Important recent advancements have been made in early, culture-independent molecular diagnosis of MCR. However, development of new potent antifungals against Mucorales remains an unmet need. Therapy of MCR is multidisciplinary and requires a high index of suspicion for initiation of early Mucorales-active antifungals. Reversal of underlying immunosuppression, if feasible, rapid DKA correction and in selected patients, surgical debulking are crucial for improved outcomes.

Diet supplementation with egg yolk powder fattens the beetle Tribolium castaneum

Insects have become essential models in studying human metabolic diseases, mainly due to their low maintenance cost and available tools. Both mutations and modified diets induce metabolic states similar to human obesity and diabetes. Here, we explore the effect of a high-calorie, high-fat diet on the metabolism of the beetle Tribolium castaneum. Supplementation of the wheat flour diet with powdered egg yolk for 3 weeks increased the total triacylglycerol and accelerated larval development. In addition, this diet increased the triacylglycerol levels of adult beetles. However, this egg yolk supplementation did not alter the larvae's total glucose levels or lipogenic capacity and ATP citrate lyase activity. The diet also did not change the expression profile of several lipid and carbohydrate metabolism genes and insulin-like peptides. Thus, we conclude that the diet supplemented with egg yolk induces increased fat without causing diabetes phenotypes, as seen in other hypercaloric diets in insects.

Many parasitoids lack adult fat accumulation, despite fatty acid synthesis: A discussion of concepts and considerations for future research

Fat reserves, specifically the accumulation of triacylglycerols, are a major energy source and play a key role for life histories. Fat accumulation is a conserved metabolic pattern across most insects, yet in most parasitoid species adults do not gain fat mass, even when nutrients are readily available and provided ad libitum. This extraordinary physiological phenotype has evolved repeatedly in phylogenetically dispersed parasitoid species. This poses a conundrum because it could lead to significant constraints on energy allocation toward key adult functions such as survival and reproduction. Recent work on the underlying genetic and biochemical mechanisms has spurred a debate on fat accumulation versus fat production, because of incongruent interpretation of results obtained using different methodologies. This debate is in part due to semantics, highlighting the need for a synthetic perspective on fat accumulation that reconciles previous debates and provides new insights and terminology. In this paper, we propose updated, unambiguous terminology for future research in the field, including "fatty acid synthesis" and "lack of adult fat accumulation", and describe the distinct metabolic pathways involved in the complex process of lipogenesis. We then discuss the benefits and drawbacks of the main methods available to measure fatty acid synthesis and adult fat accumulation. Most importantly, gravimetric/colorimetric and isotope tracking methods give complementary information, provided that they are applied with appropriate controls and interpreted correctly. We also compiled a comprehensive list of fat accumulation studies performed during the last 25 years. We present avenues for future research that combine chemistry, ecology, and evolution into an integrative approach, which we think is needed to understand the dynamics of fat accumulation in parasitoids.

Sanghuang Tongxie Formula Ameliorates Insulin Resistance in Drosophila Through Regulating PI3K/Akt Signaling

Insulin resistance (IR) is a pivotal pathological characteristic that affects the occurrence and development of type 2 diabetes mellitus (T2DM). Thus, the effective control of IR is of great significance for diabetes prevention and treatment. Traditional Chinese medicine (TCM) represents a valuable tool handed down to the world by the Chinese nation and has a long history of use for diabetes clinical therapy. In this study, we focused on a self-drafted TCM-patented formula, Sanghuang Tongxie Formula (SHTXF), which exhibits clinical efficacy in the treatment of diabetes. To explore the effect and molecular mechanism of SHTXF on IR in vivo, Drosophila melanogaster was used and a (Collagen) Cg > InR^K1409A diabetic IR fly model was established. SHTXF water extract was found to contribute toward carbohydrate clearance from the circulating system by converting it into triglycerides (TAG), not glycogen, for nutrient storage. In addition, SHTXF activated phosphatidylinositol-3-kinase (PI3K) activity and improved protein kinase B (PKB, also termed Akt) phosphorylation. Finally, SHTXF promoted Drosophila Forkhead Box O (dFoxO) cytoplasmic localization and inhibited its transcriptional activity. Taken together, these findings not only highlight the positive role of SHTXF in ameliorating IR via the PI3K/Akt pathway but also provide potential drug targets and key insights for use in T2DM clinical treatment strategies.

Drosophila melanogaster as a Rapid and Reliable In Vivo Infection Model to Study the Emerging Yeast Pathogen Candida auris

While mammalian models remain the gold standard to study invasive mycoses, mini-host invertebrate models have provided complementary platforms for explorative investigations of fungal pathogenesis, host-pathogen interplay, and antifungal therapy. Specifically, our group has established Toll-deficient Drosophila melanogaster flies as a facile and cost-effective model organism to study candidiasis, and we have recently expanded these studies to the emerging and frequently multidrug-resistant yeast pathogen Candida auris. Our proof-of-concept data suggest that fruit flies could hold a great promise for large-scale applications in antifungal drug discovery and the screening of C. auris (mutant) libraries with disparate pathogenic capacity. This chapter discusses the advantages and limitations of D. melanogaster to study C. auris candidiasis and provides a step-by-step guide for establishing and troubleshooting C. auris infection and antifungal treatment of Toll-deficient flies along with essential downstream readouts.

Comparative host transcriptome in response to pathogenic fungi identifies common and species-specific transcriptional antifungal host response pathways

Candidiasis, aspergillosis, and mucormycosis cause the majority of nosocomial fungal infections in immunocompromised patients. Using an unbiased transcriptional profiling in PBMCs exposed to the fungal species causing these infections, we found a core host response in healthy individuals that may govern effective fungal clearance: it consists of 156 transcripts, involving canonical and non-canonical immune pathways. Systematic investigation of key steps in antifungal host defense revealed fungal-specific signatures. As previously demonstrated, Candida albicans induced type I and Type II interferon-related pathways. In contrast, central pattern recognition receptor, reactive oxygen species production, and host glycolytic pathways were down-regulated in response to Rhizopus oryzae, which was associated with an ER-stress response. TLR5 was identified to be uniquely regulated by Aspergillus fumigatus and to control cytokine release in response to this fungus. In conclusion, our data reveals the transcriptional profiles induced by C. albicans, A. fumigatus, and R. oryzae, and describes both the common and specific antifungal host responses that could be exploited for novel therapeutic strategies.

Functional Characterization of Gomisin N in High-Fat-Induced Drosophila Obesity Models

Gomisin N (GN) is lignin derived from Schisandra chinensis that has been reported to exhibit hepato-protective, anti-cancer, and anti-inflammatory effects. However, its role in whole-body energetic homeostasis remains unclear. In this study, we employed Drosophila melanogaster as a diet-induced obese model to elucidate the effects of GN on lipid and glucose metabolism by measuring climbing activity, triglyceride levels, and lifespan under a rearing condition of a high-fat diet (HFD) containing 20% coconut oil, with or without GN. Constant exposure of flies to an HFD resulted in increased body weight and decreased climbing activity, along with a shortened life span. Importantly, the administration of GN to HFD groups lowered their body weight and induced a specific upregulation of lipid storage droplet (Lsd)-2 and hormone-sensitive lipase (Hsl), in addition to improved lifespan. Importantly, GN in HFD groups appeared to downregulate heat shock protein Hsp90 family member (dGRP94), a key regulator of the endoplasmic reticulum stress response, which may also contribute to improved life span in the presence of GN. Taken together, these in vivo findings suggest that GN could serve as a useful agent for the prevention and treatment of obesity.

Animal Models to Study Mucormycosis

Mucormycosis is a rare but often fatal or debilitating infection caused by a diverse group of fungi. Animal models have been crucial in advancing our knowledge of mechanisms influencing the pathogenesis of mucormycoses, and to evaluate therapeutic strategies. This review describes the animal models established for mucormycosis, summarizes how they have been applied to study mucormycoses, and discusses the advantages and limitations of the different model systems.

Experimental Models for Aging and their Potential for Novel Drug Discovery

Background:

An interesting area of scientific research is the development of potential antiaging drugs. In order to pursue this goal, it is necessary to gather the specific knowledge about the adequate preclinical models that are available to evaluate the beneficial effects of new potential drugs. This review is focused on invertebrate and vertebrate preclinical models used to evaluate the efficacy of antiaging compounds, with the objective to extend life span and health span.

Methods:

Research and online content related to aging, antiaging drugs, experimental aging models is reviewed. Moreover, in this review, the main experimental preclinical models of organisms that have contributed to the research in the pharmacol-ogy of lifespan extension and the understanding of the aging process are discussed.

Results:

Dietary restriction (DR) constitutes a common experimental process to extend life span in all organisms. Besides, classical antiaging drugs such as resveratrol, rapamycin and metformin denominated as DR mimetics are also discussed. Likewise, the main therapeutic targets of these drugs include sirtuins, IGF-1, and mTOR, all of them being modulated by DR.

Conclusion:

Advances in molecular biology have uncovered the potential molecular pathways involved in the aging process. Due to their characteristics, invertebrate models are mainly used for drug screening. The National Institute on Aging (NIA) developed the Interventions Testing Program (ITP). At the pre-clinical level, the ITP uses Heterogeneous mouse model (HET) which is probably the most suitable rodent model to study potential drugs against aging prevention. The accelerated-senescence mouse P8 is also a mammalian rodent model for aging research. However, when evaluating the effect of drugs on a preclinical level, the evaluation must be done in non-human primates since it is the mammalian specie closest to humans. Research is needed to investigate the impact of new potential drugs for the increase of human quality of

Interplay between diet-induced obesity and oxidative stress: Comparison between Drosophila and mammals

Obesity caused by excessive fat accumulation in adipocytes is a growing global problem and is a major contributing risk factor for many chronic metabolic diseases. There is increasing evidence that oxidative stress plays a crucial role in both obesity progression and obesity-related complications. In recent years, Drosophila models of diet-induced obesity and associated pathologies have been successfully developed through manipulation of carbohydrate or fat concentrations in the food. Obese flies accumulate triacylglycerols in the fat body, an organ homologous to mammalian adipose tissue and exhibit metabolic and physiological complications including hyperglycemia, redox imbalance and shortened longevity; these are all similar to those observed in obese humans. In this review, we summarize current data on the mechanisms of oxidative stress induction in obesity, with emphasis on metabolic switches and the involvement of redox-responsive signaling pathways such as NF-κB and Nfr2. The recent achievements with D. melanogaster model suggest a complicated relationship between obesity, oxidative stress, and longevity but the Drosophila model offers probably the best opportunities to delve further into unraveling these interactions, particularly the roles of antioxidants and of Nrf2-regulated responses, in order to increase our understanding of the obese metabolic phenotype and test and develop anti-obesity pharmaceuticals.

Recent Advances in the Pathogenesis of Mucormycoses

PURPOSE

The purposes of this review are to describe the pathogenesis of mucormycosis and to address recent research advances in understanding the mechanisms of fungal invasion and dissemination.

METHODS

Studies and reviews published in the PubMed and ClinicalTrials.gov databases until December 2017 that explored or reported recent advances in the understanding of the pathogenesis of mucormycosis were reviewed.

FINDINGS

To cause disease, fungal spores need to evade the innate immune system and germinate, leading to angioinvasion and tissue destruction. Recent studies have found that Mucorales are able to downregulate several host defense mechanisms and have identified the specific receptors through which Mucorales attach to the endothelium, facilitating their endocytosis and subsequent angioinvasion. In addition, certain conditions found to act through various mechanisms and pathways in experimental and animal studies, such as hyperglycemia, elevated iron concentrations, and acidosis (particularly diabetic ketoacidosis), increase the virulence of the fungi and enhance their attachment to the endothelium, rendering patients with uncontrolled diabetes and patients with iron overload susceptible to mucormycosis. The role and various antifungal functions of platelets and natural killer cells are highlighted, and the potential contribution of alternative therapies, such as manipulating the innate immune host defenses with granulocyte transfusions or administration of growth factors and using the antifungal effects of calcineurin inhibitors, are presented. Finally, directions and possible implications for future research are provided.

IMPLICATIONS

This article provides a comprehensive overview of research advances in the pathogenesis of infections caused by Mucorales and helps future studies develop effective treatment strategies and improve patient outcomes.

Metformin Use and Severe Dengue in Diabetic Adults

Diabetes mellitus is a risk factor for severe dengue in adults, but few studies have examined the association between metformin use and disease severity in dengue. In addition to its effect on glucose control, metformin has been associated with pleiotropic properties in preclinical studies. Using a cohort of laboratory-confirmed adult (≥21 years) dengue patients with diabetes mellitus admitted to Tan Tock Seng Hospital, we conducted a retrospective cohort study involving 131 (58.7%) metformin users and 92 (41.3%) non-users. Dengue severity was categorized as dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS) in World Health Organization (WHO) 1997 criteria and severe dengue (SD) in WHO 2009 criteria. Multivariable Poisson regression with robust error variance was used to estimate risk ratio (RR). Compared with non-use, metformin use was associated with a decreased risk of developing severe dengue (adjusted risk ratio [aRR] = 0.60, 95% confidence interval [CI]: 0.37–0.98, P = 0.04). Additionally, there was an inverse dose-response relationship (aRR = 0.69, 95% CI: 0.49–0.98, P = 0.04) with dengue severity as classified by WHO 2009 criteria. Use of metformin, however, was not associated with dengue severity based on WHO 1997 criteria; and no dose-response relationship was noted. Our results suggest metformin use could attenuate disease severity in dengue-infected diabetes mellitus individuals.

Higher In vitro Proliferation Rate of Rhizopus oryzae in Blood of Diabetic Individuals in Chronic Glycaemic Control Compared with Non-diabetic Individuals

Metabolic control improves outcomes associated with mucormycosis. The aim of this study was to compare the in vitro proliferation of Rhizopus oryzae in blood of individuals with and without diabetes at different glycaemic levels. Ninety-five individuals were included. Blood samples from each participant were incubated with sporangiospores of R. oryzae. The germination, filamentation and growth of R. oryzae were compared at different time points. Four groups were defined, one without (group A, n = 30) and three with diabetes: group B (HbA1c ≤7%, N = 24), group C (HbA1c 7.1-9%, N = 20) and group D (HbA1c > 9%, N = 21). The percentage of germinated sporangiospores was higher in the group A after 6 h (group A 56% ± 3, group B 35% ± 4, group C 48% ± 4, group D 46% ± 1.4, p = 0.01), 12 h (group A 54% ± 1.4, group B 19% ± 4, group C 16% ± 1, group D 9.5% ± 5, p < 0.001) and 24 h (group A 29% ± 1, group B 12% ± 4, group C 13.5% ± 3.5, group D 12% ± 1, p < 0.01). The filamentation was higher in groups with diabetes. Group B showed higher filamentation grade than group A at 6 h (0.4 ± 0.04 vs 1 ± 0.09, p < 0.001) and 24 h (1.6 ± 0.05 vs 2.1 ± 0.1, p = 0.05). In conclusion, R. oryzae proliferation was higher among diabetic individuals, including good glycaemic control, than among non-diabetic individuals.

A Class of Diacylglycerol Acyltransferase 1 Inhibitors Identified by a Combination of Phenotypic High-throughput Screening, Genomics, and Genetics

Excess lipid storage is an epidemic problem in human populations. Thus, the identification of small molecules to treat or prevent lipid storage-related metabolic complications is of great interest. Here we screened > 320.000 compounds for their ability to prevent a cellular lipid accumulation phenotype. We used fly cells because the multifarious tools available for this organism should facilitate unraveling the mechanism-of-action of active small molecules. Of the several hundred lipid storage inhibitors identified in the primary screen we concentrated on three structurally diverse and potent compound classes active in cells of multiple species (including human) and negligible cytotoxicity. Together with Drosophila in vivo epistasis experiments, RNA-Seq expression profiles suggested that the target of one of the small molecules was diacylglycerol acyltransferase 1 (DGAT1), a key enzyme in the production of triacylglycerols and prominent human drug target. We confirmed this prediction by biochemical and enzymatic activity tests.

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We identified > 600 potent small molecule inhibitors of cellular lipid storage deposition.

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RNA-Seq expression profiling discriminated the activity of three lead scaffolds and guided subsequent functional studies.

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We discovered a class of DGAT1 inhibitors, which is active in fly and mammalian cell lines as well as whole flies.

Obesity and other lipid storage associated diseases are a growing health threat of human populations. In an undirected phenotypic screen, we identified pharmacologically active small molecules that reduce or enhance lipid storage. Our work focuses on three lead structures that prevent lipid storage in diverse cellular systems including cells from a diabetes patient. In order to elucidate the compound mechanisms-of-action and cellular targets, we used a combination of RNA-Seq transcriptional profiling and diverse functional assays. Our results strongly suggest that one of our lead structures represents a class of inhibitors targeting the key lipogenic enzyme diacylglycerol acyltransferase 1.

Finding Ponce de Leon's Pill: Challenges in Screening for Anti-Aging Molecules

Aging is characterized by the progressive accumulation of degenerative changes, culminating in impaired function and increased probability of death. It is the major risk factor for many human pathologies - including cancer, type 2 diabetes, and cardiovascular and neurodegenerative diseases - and consequently exerts an enormous social and economic toll. The major goal of aging research is to develop interventions that can delay the onset of multiple age-related diseases and prolong healthy lifespan (healthspan). The observation that enhanced longevity and health can be achieved in model organisms by dietary restriction or simple genetic manipulations has prompted the hunt for chemical compounds that can increase lifespan. Most of the pathways that modulate the rate of aging in mammals have homologs in yeast, flies, and worms, suggesting that initial screening to identify such pharmacological interventions may be possible using invertebrate models. In recent years, several compounds have been identified that can extend lifespan in invertebrates, and even in rodents. Here, we summarize the strategies employed, and the progress made, in identifying compounds capable of extending lifespan in organisms ranging from invertebrates to mice and discuss the formidable challenges in translating this work to human therapies.

Repurposing metformin: an old drug with new tricks in its binding pockets

Improvements in healthcare and nutrition have generated remarkable increases in life expectancy worldwide. This is one of the greatest achievements of the modern world yet it also presents a grave challenge: as more people survive into later life, more also experience the diseases of old age, including type 2 diabetes (T2D), cardiovascular disease (CVD) and cancer. Developing new ways to improve health in the elderly is therefore a top priority for biomedical research. Although our understanding of the molecular basis of these morbidities has advanced rapidly, effective novel treatments are still lacking. Alternative drug development strategies are now being explored, such as the repurposing of existing drugs used to treat other diseases. This can save a considerable amount of time and money since the pharmacokinetics, pharmacodynamics and safety profiles of these drugs are already established, effectively enabling preclinical studies to be bypassed. Metformin is one such drug currently being investigated for novel applications. The present review provides a thorough and detailed account of our current understanding of the molecular pharmacology and signalling mechanisms underlying biguanide-protein interactions. It also focuses on the key role of the microbiota in regulating age-associated morbidities and a potential role for metformin to modulate its function. Research in this area holds the key to solving many of the mysteries of our current understanding of drug action and concerted effects to provide sustained and long-life health.

Association between Use of Oral Anti-Diabetic Drugs and the Risk of Sepsis: A Nested Case-Control Study

Although oral antidiabetic drugs (OADs) have been associated with immunomodulation in preclinical studies, little is still known about the association between the use of OADs and the risk of sepsis. Using a cohort of patients, extracted from Taiwan's National Health Insurance Research Database, with type 2 diabetes who were newly diagnosed between 2010 and 2012 and treated with OADs, we conducted a nested case-control study involving 43,015 cases (patients who were first hospitalized for sepsis) and 43,015 matched controls. Compared with non-use, metformin use was associated with a decreased risk of developing sepsis (adjusted odds ratio [OR] 0.80, 95% confidence interval [CI] 0.77-0.83, P < 0.001), but meglitinide (adjusted OR 1.32, 95% CI 1.25-1.40, P < 0.001) use was associated with the increased risk of developing sepsis. The risk for development of sepsis was also lower among current (adjusted OR 0.87, 95% CI 0.78-0.96) and recent (adjusted OR 0.83, 95% CI 0.73-0.94) thiazolidinedione users. Current or recent sulfonylurea use and dipeptidyl peptidase-4 inhibitor use were not significantly associated with the development of sepsis. Our results highlight the need to consider the potential pleiotropic effect of OADs against sepsis in addition to the lowering of blood glucose.

Dan-Qi prescription ameliorates insulin resistance through overall corrective regulation of glucose and fat metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Danshen and Sanqi Prescription (Dan-Qi) is commonly used to treat cardiovascular diseases (CVD) in China. Since Danshen and Sanqi are reported to ameliorate lipid metabolism disorders at treatment of cardiovascular diseases. Meanwhile, it is reported that co-administration of Danshen and Sanqi exhibited significant pharmacokinetic herb-herb interactions. We reasoned that Danshen and Sanqi combination could be potentially function synergistically in treating diet induced insulin resistance.

MATERIALS AND METHODS

Using high calori food induced Drosophila and mice models, we assessed Danshen and Sanqi treatment for their anti-diabetic effects.

RESULTS

The combination of Danshen and Sanqi (Dan-Qi) effectively improved fat and glucose metabolism of the high-sugar and high-fat diet fed fruit flies. More importantly, Dan-Qi significantly ameliorated hyperlipidemia and hyperglycemia phenotype caused in high-fat diet induced obesity (DIO) mouse model. The Dan-Qi treated DIO mice showed lower fasting insulin, triglycerides, total and low-density lipoprotein cholesterol (LDL-C) levels in plasma, much better than Danshen or Sanqi treated alone. It was shown that Dan-Qi prescription reduced fat accumulation in the liver with Sanqi playing the major role. Interestingly, it was not Danshen or Sanqi alone, but the combination markedly increased glycogen deposition in mice liver. Quantitative RT-PCR showed Dan-Qi increased liver glycogen synthesis gene like Glut-1, GK, and Glut-4, reduced fat and cholesterol anabolism genes such as SREBP-1c, ACC, ATP-CL, ACS. Meanwhilpose tissues and muscle tissues, the glucose and fat metabolism genes are changed accordingly to pro-catabolism status. Notably, endogenous plasma metabolites of Dan-Qi treated mice displayed much better overral rectifying effects than the Danshen or Sanqi alone.

CONCLUSIONS

Our data demonstrated that Danshen and Sanqi combination exerted significant anti-diabetic efficacy, and Dan-Qi prescription could be potentially considered as a therapeutic application in diabetes.

Metformin inhibits age-related centrosome amplification in Drosophila midgut stem cells through AKT/TOR pathway

We delineated the mechanism regulating the inhibition of centrosome amplification by metformin in Drosophila intestinal stem cells (ISCs). Age-related changes in tissue-resident stem cells may be closely associated with tissue aging and age-related diseases, such as cancer. Centrosome amplification is a hallmark of cancers. Our recent work showed that Drosophila ISCs are an excellent model for stem cell studies evaluating age-related increase in centrosome amplification. Here, we showed that metformin, a recognized anti-cancer drug, inhibits age- and oxidative stress-induced centrosome amplification in ISCs. Furthermore, we revealed that this effect is mediated via down-regulation of AKT/target of rapamycin (TOR) activity, suggesting that metformin prevents centrosome amplification by inhibiting the TOR signaling pathway. Additionally, AKT/TOR signaling hyperactivation and metformin treatment indicated a strong correlation between DNA damage accumulation and centrosome amplification in ISCs, suggesting that DNA damage might mediate centrosome amplification. Our study reveals the beneficial and protective effects of metformin on centrosome amplification via AKT/TOR signaling modulation. We identified a new target for the inhibition of age- and oxidative stress-induced centrosome amplification. We propose that the Drosophila ISCs may be an excellent model system for in vivo studies evaluating the effects of anti-cancer drugs on tissue-resident stem cell aging.