Exendin-4 attenuates brain death-induced liver damage in the rat

Does liraglutide alleviate inflammation in brain-dead donors? A randomized clinical trial

Brain death triggers an inflammatory cascade that damages organs before procurement, adversely affecting the quality of grafts. This randomized clinical trial aimed to compare the efficacy of liraglutide compared to placebo in attenuating brain death-induced inflammation, endoplasmic reticulum stress, and oxidative stress. We conducted a double-blinded, placebo-controlled, randomized clinical trial with brain-dead donors. Fifty brain-dead donors were randomized to receive subcutaneous liraglutide or placebo. The primary outcome was the reduction in IL-6 plasma levels. Secondary outcomes were changes in other plasma pro-inflammatory (IL-1β, interferon-γ, TNF) and anti-inflammatory cytokines (IL-10), expression of antiapoptotic ( BCL2 ), endoplasmic reticulum stress markers ( DDIT3/CHOP , HSPA5/BIP ), and antioxidant ( superoxide dismutase 2 , uncoupling protein 2 ) genes, and expression TNF, DDIT3, and superoxide dismutase 2 proteins in liver biopsies. The liraglutide group showed lower cytokine levels compared to the placebo group during follow-up: Δ IL-6 (-28 [-182, 135] vs. 32 [-10.6, 70.7] pg/mL; p = 0.041) and Δ IL-10 (-0.01 [-2.2, 1.5] vs. 1.9 [-0.2, 6.1] pg/mL; p = 0.042), respectively. The administration of liraglutide did not significantly alter the expression of inflammatory, antiapoptotic, endoplasmic reticulum stress, or antioxidant genes in the liver tissue. Similar to gene expression, expressions of proteins in the liver were not affected by the administration of liraglutide. Treatment with liraglutide did not increase the organ recovery rate [OR = 1.2 (95% CI: 0.2-8.6), p = 0.82]. Liraglutide administration reduced IL-6 and prevented the increase of IL-10 plasma levels in brain-dead donors without affecting the expression of genes and proteins related to inflammation, apoptosis, endoplasmic reticulum stress, or oxidative stress.

Microarray Analysis For Expression Profiles of lncRNAs and circRNAs in Rat Liver after Brain-Dead Donor Liver Transplantation

The mechanisms underlying severe liver injury after brain-dead (BD) donor liver transplantation (BDDLT) remain unclear. In this study, we aimed to explore the roles of lncRNAs and circRNAs in liver injury after BDDLT. Rat liver injury was detected in the sham, BD, control, and BDDLT groups. We examined the expression profiles of lncRNAs and circRNAs in the livers of the BDDLT and control group using microarray analysis. The main functions of the differentially expressed genes were analyzed by gene ontology (GO) and KEGG pathway enrichment analysis. In addition, we used bioinformatic analyses to construct related expression networks. Liver injury was aggravated in the BD and BDDLT groups. We found various mRNAs, lncRNAs, and circRNAs that were differentially expressed in the BDDLT group compared with those in the control group. Coding-noncoding gene co-expression (CNC) network analysis showed that expression of the lncRNA LOC102553657 was associated with that of the apoptosis-related genes including HMOX1 and ATF3. Furthermore, competing endogenous RNAs (ceRNAs) network analysis revealed that the lncRNA LOC103692832 and rno_circRNA_007609 were ceRNAs of rno-miR-135a-5p targeting Atf3, Per2, and Mras. These results suggest that lncRNAs and circRNAs play important roles in the pathogenesis and development of liver injury during BDDLT.

Exenatide Reduces Graft Injury in a Rat Transplantation Model Using Kidneys Donated after Cardiac Death

Besides being used in the therapy of type 2 diabetes, exenatide reduces cerebral ischemia-reperfusion (I/R) injury. We evaluated the potential effects of exenatide on inhibition of apoptosis in kidney grafts donated after cardiac death and on reduction of I/R injury after kidney transplantation (KTx) in a rat model. We used a rat syngeneic KTx model with kidney grafts obtained after cardiac death, and apoptosis was detected in the graft before KTx. Graft function, rat survival, morphologic examination, and activation of inflammatory molecules were analyzed after KTx. By the end of the cold storage, exenatide pretreatment donors had significantly reduced caspase pathway activation, terminal deoxynucleotidyl transferase dUTP nick-end labeling--positive cells, release of mitochondrial porin proteins into the cytosol, and expression of cleaved caspase-3 and poly (ADP-ribose) polymerase in kidney grafts. Exenatide pretreatment improved renal function survival rate with lower scores of acute tubular necrosis, infiltrating macrophages, and interstitial fibrosis as well as reduced messenger RNA expression of inflammatory mediators (tumor necrosis factor α, interleukin-6, interleukin-1β, and intercellular adhesion molecule-1) after KTx. Our study showed that exenatide reduced I/R injury in kidneys donated after cardiac death in a rat transplantation model and improved recipient survival and graft function.

Renal effects of exendin-4 in an animal model of brain death

Organ transplantation is the gold standard therapy for the majority of patients with terminal organ failure. However, it is still a limited treatment especially due to the low number of brain death (BD) donors in relation to the number of waiting list recipients. Strategies to increase the quantity and quality of donor organs have been studied, and the administration of exendin-4 (Ex-4) to the donor may be a promising approach. Male Wistar rats were randomized into 3 groups: (1) control, without central nervous system injury; (2) BD induced experimentally, and (3) BD induced experimentally + Ex-4 administered immediately after BD induction. After BD induction, animals were monitored for 6 h before blood collection and kidney biopsy. Kidney function was assessed by biochemical quantification of plasma kidney markers. Gene and protein expressions of inflammation- and stress-related genes were evaluated by RT-qPCR and immunoblot analysis. Animals treated with Ex-4 had lower creatinine and urea levels compared with controls. BD induced oxidative stress in kidney tissue through increased expression of Ucp2, Sod2 and Inos, and Ex-4 administration reduced the expression of these genes. Ex-4 also induced increased expression of the anti-apoptotic Bcl2 gene. Nlrp3 and Tnf expressions were up-regulated in the BD group compared with controls, but Ex-4 treatment had no effect on these genes. Our findings suggest that Ex-4 administration in BD rats reduces BD-induced kidney damage by decreasing the expression of oxidative stress genes and increasing the expression of Bcl2.

Pleiotropic Effects of GLP-1 and Analogs on Cell Signaling, Metabolism, and Function

The incretin hormone Glucagon-Like Peptide-1 (GLP-1) is best known for its "incretin effect" in restoring glucose homeostasis in diabetics, however, it is now apparent that it has a broader range of physiological effects in the body. Both in vitro and in vivo studies have demonstrated that GLP-1 mimetics alleviate endoplasmic reticulum stress, regulate autophagy, promote metabolic reprogramming, stimulate anti-inflammatory signaling, alter gene expression, and influence neuroprotective pathways. A substantial body of evidence has accumulated with respect to how GLP-1 and its analogs act to restore and maintain normal cellular functions. These findings have prompted several clinical trials which have reported GLP-1 analogs improve cardiac function, restore lung function and reduce mortality in patients with obstructive lung disease, influence blood pressure and lipid storage, and even prevent synaptic loss and neurodegeneration. Mechanistically, GLP-1 elicits its effects via acute elevation in cAMP levels, and subsequent protein kinase(s) activation, pathways well-defined in pancreatic β-cells which stimulate insulin secretion in conjunction with elevated Ca2+ and ATP. More recently, new studies have shed light on additional downstream pathways stimulated by chronic GLP-1 exposure, findings which have direct relevance to our understanding of the potential therapeutic effects of longer lasting analogs recently developed for clinical use. In this review, we provide a comprehensive description of the diverse roles for GLP-1 across multiple tissues, describe downstream pathways stimulated by acute and chronic exposure, and discuss novel pleiotropic applications of GLP-1 mimetics in the treatment of human disease.

Inflammation-Induced Adverse Pregnancy and Neonatal Outcomes Can Be Improved by the Immunomodulatory Peptide Exendin-4

Preterm birth is the leading cause of neonatal morbidity and mortality worldwide. Inflammation is causally linked to preterm birth; therefore, finding an intervention that dampens maternal and fetal inflammatory responses may provide a new strategy to prevent adverse pregnancy and neonatal outcomes. Using animal models of systemic maternal inflammation [intraperitoneal injection of lipopolysaccharide (LPS)] and fetal inflammation (intra-amniotic administration of LPS), we found that (1) systemic inflammation induced adverse pregnancy and neonatal outcomes by causing a severe maternal cytokine storm and a mild fetal cytokine response; (2) fetal inflammation induced adverse pregnancy and neonatal outcomes by causing a mild maternal cytokine response and a severe fetal cytokine storm; (3) exendin-4 (Ex4) treatment of dams with systemic inflammation or fetal inflammation improved adverse pregnancy outcomes by modestly reducing the rate of preterm birth; (4) Ex4 treatment of dams with systemic, but not local, inflammation considerably improved neonatal outcomes, and such neonates continued to thrive; (5) systemic inflammation facilitated the diffusion of Ex4 through the uterus and the maternal-fetal interface; (6) neonates born to Ex4-treated dams with systemic inflammation displayed a similar cytokine profile to healthy control neonates; and (7) treatment with Ex4 had immunomodulatory effects by inducing an M2 macrophage polarization and increasing anti-inflammatory neutrophils, as well as suppressing the expansion of CD8+ regulatory T cells, in neonates born to dams with systemic inflammation. Collectively, these results provide evidence that dampening maternal systemic inflammation through novel interventions, such as Ex4, can improve the quality of life for neonates born to women with this clinical condition.

Association between vitamin D levels and inflammatory activity in brain death: A prospective study

BACKGROUND

Vitamin D insufficiency is linked to several common inflammatory disorders. Brain death (BD) causes a massive catecholamine release, leading to intense inflammatory activity. We aimed to evaluate vitamin D serum levels in brain-dead individuals in comparison to critically ill patients without BD to assess the correlation between vitamin D and cytokine levels.

METHODS

Sixteen brain-dead patients and 32 critically ill controls were prospectively enrolled. Blood samples from 25 brain-dead patients from a previous study were also used for vitamin D quantification. Plasma TNF, IL-1β, IL-6, IL-8, IL-10, IFN-γ and serum vitamin D levels were compared using Student's t-test or one-way ANOVA. Spearman's test was used to assess the correlation between vitamin D and cytokine levels.

RESULTS

Mean vitamin D levels were 16.4 ± 7.9 ng/mL, with 52 patients (71.2%) classified as vitamin D deficient (serum levels < 20 ng/mL). Vitamin D levels were similar in 41 brain-dead patients as compared to control subjects (15.6 ± 6.9 ng/mL vs 17.4 ± 9.0 ng/mL; p = 0.383). Moderate direct correlations were observed between vitamin D and IL-8, IL-10, and IFN-γ in the prospective group of 16 brain-dead patients (IL-8: r = 0.5, p = 0.049; IL-10 r = 0.67, p = 0.005; IFN-γ r = 0.6, p = 0.015). Vitamin D was inversely correlated with IL-6 (r = -0.36, p = 0.044) in critically ill controls.

CONCLUSIONS

Vitamin D serum levels were similarly low in brain-dead and critically ill patients. In brain-dead patients, vitamin D serum levels correlated with plasma IL-8, IL-10 and IFN-γ.

Insulin and IGF-1 receptor autocrine loops are not required for Exendin-4 induced changes to pancreatic β-cell bioenergetic parameters and metabolism in BRIN-BD11 cells

Pharmacological long lasting Glucagon-like peptide-1 (GLP-1) analogues, such as Exendin-4, have become widely used diabetes therapies. Chronic GLP-1R stimulation has been linked to β-cell protection and these pro-survival actions of GLP-1 are dependent on the activation of the mammalian target of rapamycin (mTOR) leading to accumulation of Hypoxia inducible factor 1 alpha (HIF-1α). Recent studies from our lab indicate that prolonged GLP-1R stimulation promotes metabolic reprograming of β-cells towards a highly glycolytic phenotype and activation of the mTOR/HIF-1α pathway was required for this action. We hypothesised that GLP-1 induced metabolic changes depend on the activation of mTOR and HIF-1α, in a cascade that occurs after triggering of a potential Insulin-like growth factor 1 receptor (IGF-1R) or the Insulin receptor (IR) autocrine loops. Loss of function of these receptors, through the use of small interfering RNA, or neutralizing antibodies directed towards their products, was undertaken in conjunction with functional assays. Neither of these strategies mitigated the effect of GLP-1 on glucose uptake, protein expression or bioenergetic flux. Our data indicates that activation of IGF-1R and/or the IR autocrine loops resulting in β-cell protection and function, involve mechanisms independent to the enhanced metabolic effects resulting from sustained GLP-1R activation.

Organ donation protocols

Organ transplantation improves survival and quality of life in patients with end-organ failure. Waiting lists continue to grow across the world despite remarkable advances in the transplantation process, from the creation of public engagement campaigns to the development of critical pathways for the timely identification, referral, approach, and treatment of the potential organ donor. The pathophysiology of dying triggers systemic changes that are intimately related to organ viability. The intensive care management of the potential organ donor optimizes organ function and improves the donation yield, representing a significant step in reducing the mismatch between organ supply and demand. Different beliefs and cultures reflect diverse legislations and donation practices amongst different countries, creating a challenge to standardized practices. Maintaining public trust is necessary for continued progress in organ donation and transplantation, hence the urge for a joint effort in creating uniform protocols that ensure transparent practices within the medical community.