Systematic review and meta-analysis of mouse models of diabetes-associated ulcers

Mouse models are frequently used to study diabetes-associated ulcers, however, whether these models accurately simulate impaired wound healing has not been thoroughly investigated. This systematic review aimed to determine whether wound healing is impaired in mouse models of diabetes and assess the quality of the past research. A systematic literature search was performed of publicly available databases to identify original articles examining wound healing in mouse models of diabetes. A meta-analysis was performed to examine the effect of diabetes on wound healing rate using random effect models. A meta-regression was performed to examine the effect of diabetes duration on wound healing impairment. The quality of the included studies was also assessed using two newly developed tools. 77 studies using eight different models of diabetes within 678 non-diabetic and 720 diabetic mice were included. Meta-analysis showed that wound healing was impaired in all eight models. Meta-regression suggested that longer duration of diabetes prior to wound induction was correlated with greater degree of wound healing impairment. Pairwise comparisons suggested that non-obese diabetic mice exhibited more severe wound healing impairment compared with db/db mice, streptozotocin-induced diabetic mice or high-fat fed mice at an intermediate stage of wound healing (p<0.01). Quality assessment suggested that the prior research frequently lacked incorporation of key clinically relevant characteristics. This systematic review suggested that impaired wound healing can be simulated in many different mouse models of diabetes but these require further refinement to become more clinically relevant

Network meta‐analysis comparing the outcomes of treatments for intermittent claudication tested in randomized controlled trials

Background: No network meta‐analysis has considered the relative efficacy of cilostazol, home exercise therapy, supervised exercise therapy (SET), endovascular revascularization (ER), and ER plus SET (ER+SET) in improving maximum walking distance (MWD) over short‐ (<1 year), moderate‐ (1 to <2 years), and long‐term (≥2 years) follow‐up in people with intermittent claudication. Methods and Results: A systematic literature search was performed to identify randomized controlled trials testing 1 or more of these 5 treatments according to Preferred Reporting Items for Systematic Review and Meta‐Analysis guidelines. The primary outcome was improvement in MWD assessed by a standardized treadmill test. Secondary outcomes were adverse events and health‐related quality of life. Network meta‐analysis was performed using the gemtc R statistical package. The Cochrane collaborative tool was used to assess risk of bias. Forty‐six trials involving 4256 patients were included. At short‐term follow‐up, home exercise therapy (mean difference [MD], 89.4 m; 95% credible interval [CrI], 20.9–157.7), SET (MD, 186.8 m; 95% CrI, 136.4–237.6), and ER+SET (MD, 326.3 m; 95% CrI, 222.6–430.6), but not ER (MD, 82.5 m; 95% CrI, −2.4 to 168.2) and cilostazol (MD, 71.1 m; 95% CrI, −24.6 to 167.9), significantly improved MWD (in meters) compared with controls. At moderate‐term follow‐up, SET (MD, 201.1; 95% CrI, 89.8–318.3) and ER+SET (MD, 368.5; 95% CrI, 195.3–546.9), but not home exercise therapy (MD, 99.4; 95% CrI, −174.0 to 374.9) or ER (MD, 84.2; 95% CrI, −35.3 to 206.4), significantly improved MWD (in meters) compared to controls. At long‐term follow‐up, none of the tested treatments significantly improved MWD compared to controls. Adverse events and quality of life were reported inconsistently and could not be meta‐analyzed. Risk of bias was low, moderate, and high in 4, 24, and 18 trials respectively. Conclusions: This network meta‐analysis suggested that SET and ER+SET are effective at improving MWD over the moderate term (<2 year) but not beyond this. Durable treatments for intermittent claudication are needed

Colchicine Does Not Reduce Abdominal Aortic Aneurysm Growth in a Mouse Model

Background and Aims. The nacht domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) inflammasome is upregulated in human abdominal aortic aneurysm (AAA), but its pathogenic role is unclear. The aims of this study were firstly to examine whether the inflammasome was upregulated in a mouse model of AAA and secondly to test whether the inflammasome inhibitor colchicine limited AAA growth. Methods. AAA was induced in eight-week-old male C57BL6/J mice with topical application of elastase to the infrarenal aorta and oral 3-aminopropionitrile (E-BAPN). For aim one, inflammasome activation, abdominal aortic diameter, and rupture were compared between mice with AAA and sham controls. For aim two, 3 weeks after AAA induction, mice were randomly allocated to receive colchicine (n=28, 0.2 mg/kg/d) or vehicle control (n=29). The primary outcome was the rate of maximum aortic diameter increase measured by ultrasound over 13 weeks. Results. There was upregulation of NLRP3 markers interleukin- (IL-) 1 beta (median, IQR; 15.67, 7.11-22.60 pg/mg protein versus 6.87, 4.54-11.60 pg/mg protein, p=.048) and caspase-1 (109, 83-155 relative luminosity units (RLU) versus 45, 38-65 RLU, p <.001) in AAA samples compared to controls. Aortic diameter increase over 80 days (mean difference, MD, 4.3 mm, 95% CI 3.3, 5.3, p <.001) was significantly greater in mice in which aneurysms were induced compared to sham controls. Colchicine did not significantly limit aortic diameter increase over 80 days (MD -0.1 mm, 95% CI -1.1, 0.86, p=.922). Conclusions. The inflammasome was activated in this mouse model of AAA; however, daily oral administration of colchicine did not limit AAA growth

Kallistatin limits abdominal aortic aneurysm by attenuating generation of reactive oxygen species and apoptosis

Aims: Inflammation, vascular smooth muscle cell apoptosis and oxidative stress are believed to play important roles in abdominal aortic aneurysm (AAA) pathogenesis. Human kallistatin (KAL; gene SERPINA4) is a serine proteinase inhibitor previously shown to inhibit inflammation, apoptosis and oxidative stress.The aim of this study was to investigate the role of KAL in AAA through studies in experimental mouse models and patients. Methods and results: Serum KAL concentration was negatively associated with the diagnosis and growth of human AAA. Transgenic overexpression of the human KAL gene (KS-Tg) or administration of recombinant human KAL (rhKAL) inhibited AAA in the calcium phosphate (CaPO4) and subcutaneous angiotensin II (AngII) infusion mouse models, respectively. Upregulation of KAL in both models resulted in reduction in the severity of aortic elastin degradation, reduced markers of oxidative stress and less vascular smooth muscle apoptosis within the aorta. Administration of rhKAL to vascular smooth muscle cells incubated in the presence of AngII or in human AAA thrombus-conditioned media reduced apoptosis and downregulated markers of oxidative stress. These effects of KAL were associated with upregulation of Sirtuin 1 activity within the aortas of both KS-Tg mice and rodents receiving rhKAL. Conclusions: These results suggest KAL-Sirtuin 1 signalling limits aortic wall remodelling and aneurysm development through reductions in oxidative stress and vascular smooth muscle cell apoptosis. Upregulating KAL may be a novel therapeutic strategy for AAA

The Pathological Role of Cell Division Autoantigen 1 (CDA1) in renal fibrosis

Cell Division Autoantigen 1 (CDA1) has been validated as a potential target to treat diabetic patients with kidney disease. My project was to further examine the role of CDA1 in a scenario similar to the clinical setting were I experimentally targeted CDA1 after the disease has been established. Indeed, my study confirms that targeting CDA1 at early stages of diabetic kidney disease was effective in reducing kidney scarring in experimental diabetic mice

Transforming growth factor β (TGFβ) and related molecules in chronic kidney disease (CKD)

The incidence of chronic kidney diseases (CKDs) is expected to rise, fuelled by the ever increasing epidemic of Type 2 diabetes. Despite extensive research in this area, there are currently no effective treatments available to sufficiently halt the progression of CKD towards renal failure. This is largely due to ongoing secondary pathological processes generally elicited by the onset of disease. Fibrosis, in particular, is a prominent pathological hallmark of many forms of CKD and considered to be a central contributing factor for the progression of CKD towards end-stage renal disease. Transforming growth factor β (TGFβ) has been implicated to be a major regulatory cytokine in CKD, especially in fibrosis development, and reduced TGFβ signalling activity has been previously shown to be associated with improved renal outcomes in experimental animal studies. A number of molecules related to and/or interacting with the TGFβ signalling pathway have been identified as potential therapeutic targets. However, due to its pleiotropic nature, complete inhibition of the TGFβ signalling pathway is likely to lead to deleterious side effects. Therefore, a better understanding of this pathway and the molecules modulating this pathway is necessary to develop more efficacious and therapeutic strategies to combat progression of CKD

Targeting the CDA1/CDA1BP1 axis retards renal fibrosis in experimental diabetic nephropathy

Targeting cell division autoantigen 1 (CDA1) is postulated to attenuate the profibrotic actions of transforming growth factor-β in diabetic nephropathy. This study has identified a regulatory protein for CDA1 and has then used genetic and pharmacological approaches to test in vivo whether strategies to target this pathway would lead to reduced renal injury. A novel protein, named CDA1BP1 (CDA1 binding protein 1), was identified as critical in regulating the profibrotic activity of CDA1. Genetic deletion of CDA1BP1 attenuated key parameters of renal fibrosis in diabetic mice. Furthermore, a series of short synthetic CDA1BP1 peptides competitively inhibited CDA1-CDA1BP1 binding in vitro with a hybrid peptide, CHA-050, containing a 12mer CDA1BP1 peptide and a previously known "cell-penetrating peptide," dose-dependently reducing expression of collagens I and III in HK-2 cells. In vivo, a d–amino acid retro-inverso peptide, CHA-061, significantly attenuated diabetes-associated increases in the renal expression of genes involved in fibrotic and proinflammatory pathways. In a delayed intervention study, CHA-061 treatment reversed diabetes-associated molecular and pathological changes within the kidney. Specifically, CHA-061 significantly attenuated renal extracellular matrix accumulation and glomerular injury. Taken together, targeting the CDA1/CDA1BP1 axis is a safe, efficacious, and feasible approach to retard experimental diabetic nephropathy

Diabetes reduces severity of aortic aneurysms depending on the presence of cell division autoantigen 1 (CDA1)

Diabetes is a negative risk factor for aortic aneurysm, but the underlying explanation for this phenomenon is unknown. We have previously demonstrated that Cell Division Autoantigen 1 (CDA1), which enhances TGF-β signaling, is upregulated in diabetes. We hypothesized that CDA1 plays a key role in conferring the protective effect of diabetes against aortic aneurysms. Male wildtype, CDA1 knockout, Apolipoprotein E (ApoE) knockout and CDA1/ApoE double knockout (dKO) mice were rendered diabetic. Whereas aneurysms were not observed in diabetic ApoE knockout and wildtype mice, 40% of diabetic dKO mice developed aortic aneurysms. These aneurysms were associated with attenuated aortic TGF-β signaling, reduced expression of various collagens as well as increased aortic macrophage infiltration and matrix metalloproteinase12 expression. In the well characterized model of angiotensin II (AngII) induced aneurysm formation, concomitant diabetes reduced fatal aortic rupture and attenuated suprarenal aortic expansion, changes not seen in dKO mice. Furthermore, aortic CDA1 expression was downregulated ∼70% within biopsies from human abdominal aortic aneurysms. The identification that diabetes is associated with upregulation of vascular CDA1 and that CDA1 deletion in diabetic mice promotes aneurysm formation provides evidence that CDA1 plays a role in diabetes to reduce susceptibility to aneurysm formation