Comparison of drug efficacy in two animal models of type 2 diabetes: A systematic review and meta-analysis

Proteomics Analysis Provides Insights into the Role of Lipid Metabolism in T2DM-Related Sarcopenia

Sarcopenia has been recognized as an emerging complication of type 2 diabetes mellitus (T2DM). Currently, the pathogenesis of T2DM-related sarcopenia remains unclear. The aim of this study was to investigate the molecular mechanisms and potential therapeutic targets for T2DM-related sarcopenia. In this study, a T2DM-related sarcopenia mouse model was established using db/db mice. Proteins extracted from the gastrocnemius muscles of db/db mice and littermate control db/m mice were analyzed by a 4D label-free quantitative proteomics approach. A total of 131 upregulated and 68 downregulated proteins were identified as differentially expressed proteins (DEPs). Bioinformatics analysis revealed that DEPs were significantly enriched in lipid metabolism. Protein-protein interaction network analysis revealed that six hub proteins, including ACOX1, CPT2, ECI2, ACADVL, ACADL, and ECH1, were involved in the fatty acid oxidation. The hub protein-transcription factor-miRNA network was also constructed using the NetworkAnalyst tool. Finally, the hub proteins were validated by Western blotting and immunohistochemistry and further confirmed to be significantly negatively correlated with muscle mass and grip strength. Our study suggested that lipid metabolism, especially excessive fatty acid oxidation, may be a crucial contributor to the progression of T2DM-related sarcopenia and a common cause of the inter-relationship between T2DM and sarcopenia. Targeting lipid metabolism may be a promising therapeutic strategy for T2DM-related sarcopenia.

Sodium Butyrate Ameliorates Type 2 Diabetes-Related Sarcopenia Through IL-33-Independent ILC2s/IL-13/STAT3 Signaling Pathway

Purpose

Sarcopenia has been described as a new complication of type 2 diabetes mellitus (T2DM). T2DM and sarcopenia impact each other, resulting in a variety of adverse outcomes such as frailty, disability, poor quality of life and increased mortality. Sodium butyrate (NaB) is reported to play a protective role against T2DM. The present study aimed to investigate whether NaB could ameliorate T2DM-related sarcopenia and the underlying mechanisms.

Materials and Methods

The male db/db mice at 7-weeks were used as T2DM-related sarcopenia animal model with C57BL/6J mice as control. Mice were grouped according to whether they received NaB orally as follows: C57BL/6J+water group, C57BL/6J+NaB group, db/db+water group, and db/db+NaB group. Then, db/db mice receiving NaB orally were administered with inhibitors of group 2 innate lymphocytes (ILC2s), anti-CD90.2 by intraperitoneal injection divided into db/db+NaB+PBS group and db/db+NaB+anti-CD90.2 group. NaB dissolved in water at 150 mM. The skeletal muscle mass was measured by dural X-ray (DXA) test. ILC2s in spleen and skeletal muscle were evaluated by flow cytometry. The expressions of IL-33, IL-13, STAT3, P-STAT3, GATA-3 and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) were assessed by ELISA or WB. The morphology of skeletal muscle fibers was assessed by immunofluorescence staining.

Results

The proportion of ILC2s and the expressions of ILC2s markers IL-13 and GATA-3 were all significantly decreased in db/db mice, and these changes were improved by NaB. NaB increased the proportion of slow-twitch fibers in gastrocnemius, thus partially reversing the reduced exercise capacity of db/db mice. The expression of slow-twitch fibers marker PGC-1α induced by NaB was increased via activation of ILC2s/IL-13/STAT3 pathway. On the other way, IL-33 was not necessary for the activation of ILC2s/IL-13/STAT3 pathway. After depletion of ILC2s by anti-CD90.2, the ameliorating effect of NaB on T2DM-related sarcopenia was partially antagonized.

Conclusion

These results indicated that NaB could ameliorate type 2 diabetes-related sarcopenia by activating IL-33-independent ILC2s/IL-13/STAT3 signaling pathway.

Murine models of radiation cardiotoxicity: A systematic review and recommendations for future studies

BACKGROUND AND PURPOSE

The effects of radiation on the heart are dependent on dose, fractionation, overall treatment time, and pre-existing cardiovascular pathology. Murine models have played a central role in improving our understanding of the radiation response of the heart yet a wide range of exposure parameters have been used. We evaluated the study design of published murine cardiac irradiation experiments to assess gaps in the literature and to suggest guidance for the harmonisation of future study reporting.

METHODS AND MATERIALS

A systematic review of mouse/rat studies published 1981-2021 that examined the effect of radiation on the heart was performed. The protocol was published on PROSPERO (CRD42021238921) and the findings were reported in accordance with the PRISMA guidance. Risk of bias was assessed using the SYRCLE checklist.

RESULTS

159 relevant full-text original articles were reviewed. The heart only was the target volume in 67% of the studies and simulation details were unavailable for 44% studies. Dosimetry methods were reported in 31% studies. The pulmonary effects of whole and partial heart irradiation were reported in 13% studies. Seventy-eight unique dose-fractionation schedules were evaluated. Large heterogeneity was observed in the endpoints measured, and the reporting standards were highly variable.

CONCLUSIONS

Current murine models of radiation cardiotoxicity cover a wide range of irradiation configurations and latency periods. There is a lack of evidence describing clinically relevant dose-fractionations, circulating biomarkers and radioprotectants. Recommendations for the consistent reporting of methods and results of in vivo cardiac irradiation studies are made to increase their suitability for informing the design of clinical studies.

Safety and Efficacy of SGLT2 Inhibitors: A Multiple-Treatment Meta-Analysis of Clinical Decision Indicators

To jointly assess the safety and effectiveness of sodium-glucose cotransporter 2 inhibitors (SGLT2i) on cardiorenal outcomes and all-cause mortality in type 2 diabetes mellitus (T2DM) with or at high risk of cardiovascular disease (CVD). We performed a systematic review and network meta-analysis, systematically searching the MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and Web of Science databases up to September 2020. Primary outcomes were composite major adverse cardiovascular events (MACEs), hospitalization for heart failure, all-cause mortality and a composite renal outcome. We performed a random effects network meta-analysis estimating the pooled hazard ratio (HR), risk ratio and number needed to treat (NNT). Six trials evaluating empagliflozin, canagliflozin, dapagliflozin and ertugliflozin met the inclusion/exclusion criteria, which comprised 46,969 patients, mostly with established CVD. Pooled estimates (95% CI) of benefits of SGLT2i in terms of HR and NNT were as follows: for all-cause mortality, 0.85 (0.75, 0.97) and 58 (28, 368); for MACE, 0.91 (0.85, 0.97) and 81 (44, 271); for hospitalization for heart failure, 0.70 (0.62, 0.78) and 32 (20, 55); and for composite renal outcome, 0.61 (0.50, 0.74) and 20 (11, 44). Pooled estimates for serious adverse events were 0.92 (95% CI 0.89, 0.95). In patients with T2DM at cardiovascular risk, ertugliflozin is a less potent drug than empagliflozin, canagliflozin or dapagliflozin to prevent cardiorenal events and all-cause mortality. In addition, our data endorse that empagliflozin is the best treatment option among SGLT2i for this type of patient, but the evidence is not consistent enough.

Bee Bread Can Alleviate Lipid Abnormalities and Impaired Bone Morphology in Obese Zucker Diabetic Rats

This study examined for the first time whether bee bread (BB, consisting of monofloral rape bee pollen) could alleviate lipid derangements and reduced bone quality in Zucker diabetic fatty (ZDF) rats, which are considered an appropriate animal model for type 2 diabetes mellitus (T2DM) investigation. Adult ZDF rats were segregated into four groups: lean non-diabetic rats (L group), obese diabetic rats untreated (C group), and those treated with the BB at two doses (500 and 700 mg/kg body weight, respectively, B1 and B2 groups) for 10 weeks. Significantly reduced levels of total cholesterol and triglyceride were recorded in the B2 group versus the C group. In both BB-treated groups, significantly increased relative volume of trabecular bone and trabecular thickness, enhanced density of secondary osteons, accelerated periosteal bone apposition, and improved blood flow were observed. A positive effect of higher dose of BB on femoral weight and cortical bone thickness was also demonstrated. Our results suggest a promising potential of BB to ameliorate T2DM-related complications associated with lipid and bone damages.

Levelling the Translational Gap for Animal to Human Efficacy Data

Reports of a reproducibility crisis combined with a high attrition rate in the pharmaceutical industry have put animal research increasingly under scrutiny in the past decade. Many researchers and the general public now question whether there is still a justification for conducting animal studies. While criticism of the current modus operandi in preclinical research is certainly warranted, the data on which these discussions are based are often unreliable. Several initiatives to address the internal validity and reporting quality of animal studies (e.g., Animals in Research: Reporting In Vivo Experiments (ARRIVE) and Planning Research and Experimental Procedures on Animals: Recommendations for Excellence (PREPARE) guidelines) have been introduced but seldom implemented. As for external validity, progress has been virtually absent. Nonetheless, the selection of optimal animal models of disease may prevent the conducting of clinical trials, based on unreliable preclinical data. Here, we discuss three contributions to tackle the evaluation of the predictive value of animal models of disease themselves. First, we developed the Framework to Identify Models of Disease (FIMD), the first step to standardise the assessment, validation and comparison of disease models. FIMD allows the identification of which aspects of the human disease are replicated in the animals, facilitating the selection of disease models more likely to predict human response. Second, we show an example of how systematic reviews and meta-analyses can provide another strategy to discriminate between disease models quantitatively. Third, we explore whether external validity is a factor in animal model selection in the Investigator's Brochure (IB), and we use the IB-derisk tool to integrate preclinical pharmacokinetic and pharmacodynamic data in early clinical development. Through these contributions, we show how we can address external validity to evaluate the translatability and scientific value of animal models in drug development. However, while these methods have potential, it is the extent of their adoption by the scientific community that will define their impact. By promoting and adopting high quality study design and reporting, as well as a thorough assessment of the translatability of drug efficacy of animal models of disease, we will have robust data to challenge and improve the current animal research paradigm.