Intercellular adhesion molecule-1 blockade attenuates inflammatory response and improves microvascular perfusion in rat pancreas grafts

Praliciguat Promotes Ischemic Leg Reperfusion in Leptin Receptor-Deficient Mice

BACKGROUND

Lower-limb peripheral artery disease is one of the major complications of diabetes. Peripheral artery disease is associated with poor limb and cardiovascular prognoses, along with a dramatic decrease in life expectancy. Despite major medical advances in the treatment of diabetes, a substantial therapeutic gap remains in the peripheral artery disease population. Praliciguat is an orally available sGC (soluble guanylate cyclase) stimulator that has been reported both preclinically and in early stage clinical trials to have favorable effects in metabolic and hemodynamic outcomes, suggesting that it may have a potential beneficial effect in peripheral artery disease.

METHODS

We evaluated the effect of praliciguat on hind limb ischemia recovery in a mouse model of type 2 diabetes. Hind limb ischemia was induced in leptin receptor-deficient (Lepr^db/db) mice by ligation and excision of the left femoral artery. Praliciguat (10 mg/kg/day) was administered in the diet starting 3 days before surgery.

RESULTS

Twenty-eight days after surgery, ischemic foot perfusion and function parameters were better in praliciguat-treated mice than in vehicle controls. Improved ischemic foot perfusion was not associated with either improved traditional cardiovascular risk factors (ie, weight, glycemia) or increased angiogenesis. However, treatment with praliciguat significantly increased arteriole diameter, decreased ICAM1 (intercellular adhesion molecule 1) expression, and prevented the accumulation of oxidative proangiogenic and proinflammatory muscle fibers. While investigating the mechanism underlying the beneficial effects of praliciguat therapy, we found that praliciguat significantly downregulated Myh2 and Cxcl12 mRNA expression in cultured myoblasts and that conditioned medium form praliciguat-treated myoblast decreased ICAM1 mRNA expression in endothelial cells. These results suggest that praliciguat therapy may decrease ICAM1 expression in endothelial cells by downregulating Cxcl12 in myocytes.

CONCLUSIONS

Our results demonstrated that praliciguat promotes blood flow recovery in the ischemic muscle of mice with type 2 diabetes, at least in part by increasing arteriole diameter and by downregulating ICAM1 expression.

Donor insulin therapy in intensive care predicts early outcomes after pancreas transplantation

AIMS/HYPOTHESIS

Approximately 50% of organ donors develop hyperglycaemia in intensive care, which is managed with insulin therapy. We aimed to determine the relationships between donor insulin use (DIU) and graft failure in pancreas transplantation.

METHODS

UK Transplant Registry organ donor data were linked with national data from the UK solid pancreas transplant programme. All pancreas transplants performed between 2004 and 2016 with complete follow-up data were included. Logistic regression models determined associations between DIU and causes of graft failure within 3 months. Area under the receiver operating characteristic curve (aROC) and net reclassification improvement (NRI) assessed the added value of DIU as a predictor of graft failure.

RESULTS

In 2168 pancreas transplant recipients, 1112 (51%) donors were insulin-treated. DIU was associated with a higher risk of graft loss from isolated islet failure: OR (95% CI), 1.79 (1.05, 3.07), p = 0.03, and this relationship was duration/dose dependent. DIU was also associated with a higher risk of graft loss from anastomotic leak (2.72 [1.07, 6.92], p = 0.04) and a lower risk of graft loss from thrombosis (0.62 [0.39, 0.96], p = 0.03), although duration/dose-dependent relationships were only identified in pancreas transplant alone/pancreas after kidney transplant recipients with grafts failing due to thrombosis (0.86 [0.74, 0.99], p = 0.03). The relationships between donor insulin characteristics and isolated islet failure remained significant after adjusting for potential confounders: DIU 1.75 (1.02, 2.99), p = 0.04; duration 1.08 (1.01, 1.16), p = 0.03. In multivariable analyses, donor insulin characteristics remained significant predictors of lower risk of graft thrombosis in pancreas transplant alone/pancreas after kidney transplant recipients: DIU, 0.34 (0.13, 0.90), p = 0.03; insulin duration/dose, 0.02 (0.001, 0.85), p = 0.04. When data on insulin were added to models predicting isolated islet failure, a significant improvement in discrimination and risk reclassification was observed in all models: no DIU aROC 0.56; DIU aROC 0.57, p = 0.86; NRI 0.28, p < 0.00001; insulin duration aROC 0.60, p = 0.47; NRI 0.35, p < 0.00001.

CONCLUSIONS/INTERPRETATION

DIU predicts graft survival in pancreas transplant recipients. This assessment could help improve donor selection and thereby improve patient and graft outcomes.

Everolimus Improves Microcirculatory Derangements in Experimental Postischemic Pancreatitis Modulating the Expression of Vascular Endothelial Growth Factor, Interleukin 6, and Toll-Like Receptor 4

OBJECTIVES

Ischemia/reperfusion injury (IRI) of the pancreas is a serious complication following pancreatic transplantation and hemorrhagic shock. The present study was designed to investigate the influence of the potent mammalian target of rapamycin inhibitor everolimus interfering via microvascular permeability changing key proteins hypoxia-inducible factor (HIF) and vascular endothelial growth factor on pancreatic IRI-induced microvascular disturbances.

METHODS

Anesthetized male Sprague-Dawley rats were assigned to 3 groups (n = 7/group): (1) sham, (2) 60-minute ischemia/reperfusion of the pancreas (I/R), and (3) I/R and everolimus (10 mg/kg BW orally). Quantification of the effective microvascular permeability (P), functional capillary density (FCD), and leukocyte-endothelial cell interaction (LEI) was performed using digital and analog intravital epifluorescence microscopy. Serum-amylase, lipase, interleukin 6, and vascular endothelial growth factor concentration were quantified using enzyme-linked immunosorbent assay.

RESULTS

Sham compared with I/R (P: [×10 cm/s] 0.068 ± 0.079 vs 1.516 ± 0.314; FCD: [cm/cm] 357 ± 14 vs 258 ± 13; LEI: [cells/mm] 148 ± 25 vs 349 ± 75) demonstrates a significant increase in microcirculatory damage and all previously mentioned serum parameters. Except amylase, I/R + everolimus led to a statistically significant improvement of almost all increased parameters (P: 0.434 ± 0.296, FCD: 347 ± 16, LEI: 178 ± 30).

CONCLUSIONS

Everolimus attenuated experimental microvascular and inflammatory IRI of the pancreas. Therefore, these results may warrant further investigation of everolimus as a therapeutic agent following clinical states with pancreatic ischemia/reperfusion.

Intercellular adhesion molecular-1, Fas, and Fas ligand as diagnostic biomarkers for acute allograft rejection of pancreaticoduodenal transplantation in pigs

BACKGROUND

The early diagnosis of pancreas allograft dysfunction is crucial for the management and long-term survival of transplanted pancreases. We investigated whether intercellular adhesion molecular-1 (ICAM-1), Fas, and Fas ligand (FasL) can be used as novel biomarkers of acute pancreaticoduodenal allograft dysfunction in pigs.

METHODS

Forty outbred landraces were randomly divided into three groups. In the control group (8 pigs), a sham operation was performed but no drugs were administered. In groups 1 and 2 (8 pairs each), pancreaticoduodenal transplantation was performed, with the latter administered immunosuppressive drugs and the former not administered drugs. The expression of ICAM-1, Fas, and FasL mRNA in the peripheral vein blood was assessed by flow cytometry and RT-PCR, pre-transplant and on days 1, 3, 5, and 7 after transplantation. Simultaneously, the levels of glucose, insulin, and glucagon in the serum of the recipients were evaluated. The allograft pancreas tissue was obtained to assess the pathological damage and the expression of Fas and FasL by immunohistochemistry.

RESULTS

On the first 7 days after transplantation, ICAM-1, Fas, and FasL mRNA expression in the blood leukocytes of the recipient increased significantly in groups 1 and 2 compared with the control group (P < 0.01). However, the levels in group 2 were significantly lower than those in group 1 (P < 0.05). Interestingly, the FasL expression increased but the Fas expression decreased gradually in the graft pancreas tissue during the first week after transplantation in both groups 1 and 2 compared with the control group (P < 0.05). The levels of serous glucose, insulin, and glucagon in groups 1 and 2 obviously changed on day 1 after transplantation but returned to normal on day 2. The recipient's pancreas pathological sections did not exhibit any rejection changes on days 1 and 3 after transplantation but showed rejection damage on days 5 and 7.

CONCLUSION

ICAM-1, Fas, and FasL were found to be sensitive biomarkers of acute pancreas allograft dysfunction after pancreaticoduodenal transplantation in pigs, and their monitoring could be used to evaluate the effectiveness of the immunosuppression therapy.

Donor risk factors, retrieval technique, preservation and ischemia/reperfusion injury in pancreas transplantation

PURPOSE OF REVIEW

Pancreas transplantation is still hampered by a high incidence of early graft loss, and organ quality concerns result in high nonrecovery/discard rates. Demographic donor characteristics, surgical retrieval strategy, preservation fluid and ischemia time are crucial factors in the process of organ selection and are discussed in this review.

RECENT FINDINGS

The donor shortage is driving an increasing utilization of nonideal organs which would previously have been identified as unsuitable. Recent literature suggests that organs from extended criteria donors - older (>45 years), BMI >30  kg/m(2), and donation after cardiac death (DCD) - can achieve the same graft and patient survival as those from standard criteria donors, with the proviso that the accumulation of risk factors and long ischemic times should be avoided. Visual assessment of the pancreas is advisable before declining/accepting a pancreas. University of Wisconsin represents the gold standard solution; however, histidine-tryptophan-ketoglutarate and Celsior result in equal outcomes if cold ischemia time (CIT) is less than 12  h. Currently in pancreas transplantation, there is no proven effective ischemia/reperfusion injury prophylaxis than trying to keep CIT as short as possible.

SUMMARY

Demographic risk factors, inspection of the pancreas by an experienced surgeon and predicted CIT are crucial factors in deciding whether to accept a pancreas for transplantation. However, there is a need for an improved evidence base to determine where to set the 'cut-off' for unsuitable pancreatic grafts.