Bilirubin rinse of the graft ameliorates ischemia reperfusion injury in heart transplantation

Association of elevated baseline bilirubin caused by preadmission statin use with cardiovascular prognosis in patients undergoing elective percutaneous coronary intervention

Bilirubin is widely recognized to possess antioxidant and anti-inflammatory characteristics. However, the relationship between bilirubin and coronary artery disease (CAD) remains controversial, particularly in individuals receiving Percutaneous Coronary Intervention (PCI). Given that statins may enhance the production of heme oxygenase-1 (HO-1) and bilirubin, we investigated the long-term cardiovascular prognostic role of bilirubin levels elevated by statin use in patients undergoing PCI. Data of 6945 subjects undergoing PCI were enrolled in this study. We divided the patients into two groups based on serum total bilirubin (TB) levels detected prior to PCI. The high TB group consisted of patients with serum TB values > 8.4 μmmol/L, while the low TB group consisted of patients with serum TB values ≤ 8.4 μmmol/L. The median follow-up time was 836 days. Cox proportional hazards models were performed to evaluate the hazard ratios (HRs) and 95% confidence interval (CI) for the incidence of major adverse cardiovascular event (MACE) associated with bilirubin levels. The association between TB levels and risk of MACE was significant [adjusted HR = 0.557, 95% CI (0.59-0.96), p = 0.020). Linear analysis was performed to determine the association between preadmission usage of statin and bilirubin level. The preadmission usage of statin independently linearly increases TB [adjusted-β = 0.371, 95% CI (0.134-0.608), p = 0.002] and direct bilirubin (DB) [adjusted-β = 0.411, 95% CI (0.300-0.522), p < 0.001). Mediation analysis demonstrated a direct protective role of preadmission statins treatment (β = - 0.024, p < 0.01), TB (β = - 0.003, p < 0.05) and DB (β = - 0.009, p < 0.05). Furthermore, it was found that TB (4.0%) and DB (12.0%) mediated the relationship between preadmission statins therapy and MACE. Bilirubin has a protective effect against MACE. In patients with normal bilirubin level undergoing elective PCI, preadmission statin use elevated bilirubin levels, which were independently associated with a lower incidence of MACE over the long-term follow-up period.

Role of Natural Compounds Modulating Heme Catabolic Pathway in Gut, Liver, Cardiovascular, and Brain Diseases

The crucial physiological process of heme breakdown yields biliverdin (BV) and bilirubin (BR) as byproducts. BV, BR, and the enzymes involved in their production (the "yellow players-YP") are increasingly documented as endogenous modulators of human health. Mildly elevated serum bilirubin concentration has been correlated with a reduced risk of multiple chronic pro-oxidant and pro-inflammatory diseases, especially in the elderly. BR and BV per se have been demonstrated to protect against neurodegenerative diseases, in which heme oxygenase (HMOX), the main enzyme in the production of pigments, is almost always altered. HMOX upregulation has been interpreted as a tentative defense against the ongoing pathologic mechanisms. With the demonstration that multiple cells possess YP, their propensity to be modulated, and their broad spectrum of activity on multiple signaling pathways, the YP have assumed the role of an adjustable system that can promote health in adults. Based on that, there is an ongoing effort to induce their activity as a therapeutic option, and natural compounds are an attractive alternative to the goal, possibly requiring only minimal changes in the life style. We review the most recent evidence of the potential of natural compounds in targeting the YP in the context of the most common pathologic condition of adult and elderly life.

Effects of bilirubin on perioperative myocardial infarction and its long-term prognosis in patients undergoing percutaneous coronary intervention

BACKGROUND

Although bilirubin is known to be an antioxidant, any relationship with coronary heart disease remains controversial. To the best of our knowledge, no previous study has investigated the association between bilirubin and perioperative myocardial infarction (PMI), including its long-term prognosis.

AIM

To investigate the impact of bilirubin levels on PMI in patients undergoing percutaneous coronary intervention (PCI), and long-term prognosis in post-PMI patients.

METHODS

Between January 2014 and September 2018, 10236 patients undergoing elective PCI were enrolled in the present study. Total bilirubin (TB) and cardiac troponin I (cTnI) levels were measured prior to PCI and cTnI at further time-points, 8, 16 and 24 h after PCI. Participants were stratified by pre-PCI TB levels and divided into three groups: < 10.2; 10.2-14.4 and > 14.4 μmol/L. PMI was defined as producing a post-procedural cTnI level of > 5 × upper limit of normal (ULN) with normal baseline cTnI. Major adverse cardiovascular events (MACEs) included cardiac death, MI, stroke and revascularization during a maximum 5-year follow-up.

RESULTS

PMI was detected in 526 (15.3%), 431 (12.7%) and 424 (12.5%) of patients with pre-PCI TB levels of < 10.2, 10.2-14.4 and > 14.4 μmol/L (P = 0.001), respectively. Multivariate logistical analysis indicated that patients with TB 10.2-14.4 and > 14.4 μmol/L had a lower incidence of PMI [TB 10.2-14.4 μmol/L: Odds ratio (OR): 0.854; 95% confidence interval (CI): 0.739-0.987; P = 0.032; TB > 14.4 μmol/L: OR: 0.846; 95%CI: 0.735-0.975; P = 0.021] compared with patients with TB < 10.2 μmol/L. Construction of a Kaplan-Meier curve demonstrated a higher MACE-free survival time for patients with higher TB than for those with lower TB (log-rank P = 0.022). After adjustment for cardiovascular risk factors and angiographic characteristics, multivariate Cox analysis showed that a TB level > 14.4 μmol/L was associated with a reduced risk of MACEs compared with a TB level < 10.2 μmol/L (hazard ratio 0. 667; 95%CI: 0.485-0.918; P = 0.013).

CONCLUSION

Bilirubin was a protective factor in PMI prediction. For post-PMI patients, elevated bilirubin levels were independently associated with a reduced risk of MACEs during long-term follow-up.

Bilirubin as a Therapeutic Molecule: Challenges and Opportunities

There is strong evidence that serum free bilirubin concentration has significant effects on morbidity and mortality in the most significant health conditions of our times, including cardiovascular disease, diabetes, and obesity/metabolic syndrome. Supplementation of bilirubin in animal and experimental models has reproduced these protective effects, but several factors have slowed the application bilirubin as a therapeutic agent in human patients. Bilirubin is poorly soluble in water, and is a complex molecule that is difficult to synthesize. Current sources of this molecule are animal-derived, creating concerns regarding the risk of virus or prion transmission. However, recent developments in nanoparticle drug delivery, biosynthetic strategies, and drug synthesis have opened new avenues for applying bilirubin as a pharmaceutical agent. This article reviews the chemistry and physiology of bilirubin, potential clinical applications and summarizes current strategies for safe and efficient drug delivery.

Biomarkers and Mechanisms of Oxidative Stress-Last 20 Years of Research with an Emphasis on Kidney Damage and Renal Transplantation

Oxidative stress is an imbalance between pro- and antioxidants that adversely influences the organism in various mechanisms and on many levels. Oxidative damage occurring concomitantly in many cellular structures may cause a deterioration of function, including apoptosis and necrosis. The damage leaves a molecular “footprint”, which can be detected by specific methodology, using certain oxidative stress biomarkers. There is an intimate relationship between oxidative stress, inflammation, and functional impairment, resulting in various diseases affecting the entire human body. In the current narrative review, we strengthen the connection between oxidative stress mechanisms and their active compounds, emphasizing kidney damage and renal transplantation. An analysis of reactive oxygen species (ROS), antioxidants, products of peroxidation, and finally signaling pathways gives a lot of promising data that potentially will modify cell responses on many levels, including gene expression. Oxidative damage, stress, and ROS are still intensively exploited research subjects. We discuss compounds mentioned earlier as biomarkers of oxidative stress and present their role documented during the last 20 years of research. The following keywords and MeSH terms were used in the search: oxidative stress, kidney, transplantation, ischemia-reperfusion injury, IRI, biomarkers, peroxidation, and treatment.

Clinical impact of serum bilirubin levels on kidney transplant outcomes

Serum bilirubin, a potent endogenous antioxidant, has been associated with decreased risks of cardiovascular disease, diabetes, and kidney disease. However, the effects of serum bilirubin on kidney transplant outcomes remain undetermined. We analyzed 1628 patients who underwent kidney transplantations between 2003 and 2017. Patients were grouped into sex-specific quartiles according to mean serum bilirubin levels, 3–12 months post-transplantation. Median bilirubin levels were 0.66 mg/dL in males and 0.60 mg/dL in females. The intra-individual variability of serum bilirubin levels was low (9%). Serum bilirubin levels were inversely associated with graft loss, death-censored graft failure, and all-cause mortality, independent of renal function, donor status, and transplant characteristics. Multivariable analysis revealed that the lowest serum bilirubin quartile was associated with increased risk of graft loss (HR 2.64, 95% CI 1.67–4.18, P < 0.001), death-censored graft failure (HR 2.97, 95% CI 1.63–5.42, P < 0.001), and all-cause mortality (HR 2.07, 95% CI 1.01–4.22, P = 0.046). Patients with lower serum bilirubin were also at greater risk of rejection and exhibited consistently lower glomerular filtration rates than those with higher serum bilirubin. Serum bilirubin levels were significantly associated with transplantation outcomes, suggesting that bilirubin could represent a therapeutic target for improving long-term transplant outcomes.

The hepatic protective effects of tacrolimus as a rinse solution in liver transplantation: A meta-analysis

BACKGROUND

Tacrolimus was used as a rinse solution against ischaemia-reperfusion injury (IRI) in liver transplantation for years but its protective effects remain controversies.

METHODS

We conducted literature retrieval in electronic databases including MEDLINE, EMBASE and Cochrane Central to identify relevant randomized controlled trials (RCTs) investigating the effects of tacrolimus as a rinse solution in liver transplantation. Postoperative liver function, including alanine aminotransferase (ALT), aspartate aminotransferase (AST) and total bilirubin (TBIL), at postoperative day (POD) 1, 2 and 7 was extracted for pooled estimation. Forest plots were generated to calculate the differences between the groups. The I2 index statistic was used to assess heterogeneity. Publication bias was evaluated using funnel plots and Egger's test.

RESULTS

Three RCTs including 70 liver transplants were evaluated in this study. Pooled estimation revealed that rinse with tacrolimus in liver transplantation did not provide hepatic protection with respect to postoperative ALT (Test Z = 1.36; P = .175), AST (Test Z = 1.70; P = .090) or TBIL (Test Z = 0.69; P = .490). Sensitivity analysis by excluding extended donor criteria (EDC) livers showed similar results. Funnel plots and Egger's test demonstrated that there was no substantial bias.

CONCLUSION

We may tentatively conclude that tacrolimus is ineffective for amelioration of postoperative liver function as a rinse solution in liver transplantation. Nevertheless, there is great space for future research in this area, and the potential clinical value of tacrolimus needs to be further addressed. We are expecting more evidence to support our speculations.

Impact of Melatonin in Solid Organ Transplantation-Is It Time for Clinical Trials? A Comprehensive Review

Solid organ transplantation is the "gold standard" for patients with end-stage organ disease. However, the supply of donor organs is critical, with an increased organ shortage over the last few years resulting in a significant mortality of patients on waiting lists. New strategies to overcome the shortage of organs are urgently needed. Some experimental studies focus on melatonin to improve the donor pool and to protect the graft; however, current research has not reached the clinical level. Therefore, this review provides a comprehensive overview of the data available, indicating that clinical evaluation is warranted.

Gender differences in trauma, shock and sepsis

Despite efforts in prevention and intensive care, trauma and subsequent sepsis are still associated with a high mortality rate. Traumatic injury remains the main cause of death in people younger than 45 years and is thus a source of immense social and economic burden. In recent years, the knowledge concerning gender medicine has continuously increased. A number of studies have reported gender dimorphism in terms of response to trauma, shock and sepsis. However, the advantageous outcome following trauma-hemorrhage in females is not due only to sex. Rather, it is due to the prevailing hormonal milieu of the victim. In this respect, various experimental and clinical studies have demonstrated beneficial effects of estrogen for the central nervous system, the cardiopulmonary system, the liver, the kidneys, the immune system, and for the overall survival of the host. Nonetheless, there remains a gap between the bench and the bedside. This is most likely because clinical studies have not accounted for the estrus cycle. This review attempts to provide an overview of the current level of knowledge and highlights the most important organ systems responding to trauma, shock and sepsis. There continues to be a need for clinical studies on the prevailing hormonal milieu following trauma, shock and sepsis.

Bilirubin acts as a multipotent guardian of cardiovascular integrity: more than just a radical idea

Bilirubin, a potentially toxic catabolite of heme and indicator of hepatobiliary insufficiency, exhibits potent cardiac and vascular protective properties. Individuals with Gilbert's syndrome (GS) may experience hyperbilirubinemia in response to stressors including reduced hepatic bilirubin excretion/increased red blood cell breakdown, with individuals usually informed by their clinician that their condition is of little consequence. However, GS appears to protect from all-cause mortality, with progressively elevated total bilirubin associated with protection from ischemic heart and chronic obstructive pulmonary diseases. Bilirubin may protect against these diseases and associated mortality by reducing circulating cholesterol, oxidative lipid/protein modifications, and blood pressure. In addition, bilirubin inhibits platelet activation and protects the heart from ischemia-reperfusion injury. These effects attenuate multiple stages of the atherosclerotic process in addition to protecting the heart during resultant ischemic stress, likely underpinning the profound reduction in cardiovascular mortality in hyperbilirubinemic GS. This review outlines our current knowledge of and uses for bilirubin in clinical medicine and summarizes recent progress in revealing the physiological importance of this poorly understood molecule. We believe that this review will be of significant interest to clinicians, medical researchers, and individuals who have GS.