Peri- and post-operative course of cytokines and the metabolic activity of neutrophils in human liver transplantation

The role of gut barrier dysfunction in postoperative complications in liver transplantation: pathophysiological and therapeutic considerations

PURPOSE

Gut barrier dysfunction is a pivotal pathophysiological alteration in cirrhosis and end-stage liver disease, which is further aggravated during and after the operational procedures for liver transplantation (LT). In this review, we analyze the multifactorial disruption of all major levels of defense of the gut barrier (biological, mechanical, and immunological) and correlate with clinical implications.

METHODS

A narrative review of the literature was performed using PubMed, PubMed Central and Google from inception until November 29th, 2023.

RESULTS

Systemic translocation of indigenous bacteria through this dysfunctional barrier contributes to the early post-LT infectious complications, while endotoxin translocation, through activation of the systemic inflammatory response, is implicated in non-infectious complications including renal dysfunction and graft rejection. Bacterial infections are the main cause of early in-hospital mortality of LT patients and unraveling the pathophysiology of gut barrier failure is of outmost importance.

CONCLUSION

A pathophysiology-based approach to prophylactic or therapeutic interventions may lead to enhancement of gut barrier function eliminating its detrimental consequences and leading to better outcomes for LT patients.

Cytokine response to ischemia/reperfusion injury in an ex vivo perfused porcine liver model

BACKGROUND

We evaluated the degree of inflammatory response after ischemia/reperfusion injury by an extracorporeal normothermic autologous hemoperfusion of porcine livers.

MATERIALS AND METHODS

Livers explanted from 7 pigs were perfused extracorporeally at 39 degrees C with autologous blood. Serum samples were obtained hourly until 6 hours from the beginning of reperfusion and assayed for 9 different cytokines.

RESULTS

Significant elevations in interleukin 6 (IL-6) and IL-8 were noted following reperfusion (P < .001), with both demonstrating an increase which followed a sigmoid curve; other cytokines that were assessed showed no significant change.

CONCLUSIONS

The ex vivo model excludes the liver from the influence of external systemic factors such as hormones, the autonomic nervous system, and other regulatory molecules produced elsewhere in the body, allowing the response to the ischemia/reperfusion injury to be studied in isolation and in considerable detail. Although this study examined a relatively short period, the increases in only IL-6 and IL-8 suggested that these are important molecules in the early phase after reperfusion.

Release of cytokines and hemodynamic instability during the reperfusion of a liver graft

The objectives of this prospective, observational study were (1) to determine whether a transplanted liver graft releases proinflammatory cytokines into the systemic circulation upon reperfusion and (2) to determine whether they contribute to any subsequent hemodynamic instability observed after graft reperfusion (if this release occurs). Blood samples from 17 consecutive patients undergoing liver transplantation were analyzed for cytokines, including tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), IL-2, IL-6, and IL-8. Blood samples were obtained from the radial artery, portal vein, and flush blood (a sample taken from a catheter placed above the infrahepatic inferior vena cava clamp). The amount of catecholamines necessary to maintain a mean arterial pressure between 65 and 75 mm Hg during graft reperfusion was compared with the level of cytokines. A statistical analysis was performed with the least squares method, Kendall's tau-b test, and regression analysis. We demonstrated that flush blood from the liver grafts contained a significant amount and variety of cytokines. Most of these were removed by graft irrigation. The concentration of TNF-α in samples obtained from flush blood at the end of liver irrigation was significantly higher than the concentration in samples obtained from the radial artery (P = 0.0067) or portal vein (P = 0.0003) before reperfusion. This correlated directly with the amount of catecholamines used to treat hemodynamic instability. Although there were increased levels of IL-1β, IL-2, and IL-8 in the flush blood, there was no statistically significant correlation between the levels of these cytokines and the amount of catecholamines used.

Reduced post-operative neutrophil activation in liver transplant recipients suffering from post-hepatitic cirrhosis

BACKGROUND

It has been supposed that liver transplant recipients with hepatitis C virus infection have a higher incidence of infectious complications after transplantation. This study was designed to investigate whether neutrophil function is immediately affected by liver transplantation.

METHODS

Biochemical values, plasma levels of myeloperoxidase (MPO), hydrogen peroxide production of neutrophils and neutrophil-platelet complexes were analyzed in 32 patients who underwent liver transplantation and 20 healthy volunteers.

RESULTS

MPO levels were significantly increased 24 h after reperfusion. In post-hepatitic patients levels were significantly lower three d up to one wk post-transplant than in patients due to other liver diseases. One wk post-operatively the respiratory burst activity following N-formyl-methionyl-leucylphenylalanine (fMLP) or (tumor necrosis factor-alpha) TNF-alpha/fMLP stimulation was depressed in post-hepatitic recipients. Respiratory burst stimulated with phorbol 12-myristate 13-acetate in these patients was increased one wk after transplantation. One d after transplantation the neutrophil-platelet complexes decreased significantly throughout the post-operative period.

CONCLUSIONS

The results of this study suggest a reduced post-operative neutrophil activation in liver transplant recipients suffering from post-hepatitic cirrhosis compared to cirrhosis due to other causes. We hypothesized that neutrophil dysfunction in those patients depends on the underlying disease with an increased susceptibility to bacterial or fungal infections.

Vasoplegic syndrome during liver transplantation

A 56-yr-old woman with chronic hepatitis B and decompensated hepatic cirrhosis was treated with liver transplantation. At the beginning of the neohepatic phase, her arterial blood pressure remained at 60/40 mm Hg for approximately 40 min and did not respond to vasoconstrictive drugs. Her other clinical and laboratory values remained normal, apart from a high cardiac output and low systemic vascular resistance. This patient was diagnosed with vasoplegic syndrome and was treated with i.v. infusion of methylene blue (0.5 mg/kg) and norepinephrine. This report has potential significance to treatment in patients who undergo orthotopic liver transplantation.

Ultrafiltered pig leukocyte extract (IMUNOR®) decreases nitric oxide formation and hematopoiesis-stimulating cytokine production in lipopolysaccharide-stimulated RAW 264.7 macrophages

A low-molecular-weight (<12 kDa) ultrafiltered pig leukocyte extract, IMUNOR, was tested in experiments in vitro on non-stimulated and lipopolysaccharide (LPS)-stimulated murine RAW 264.7 macrophages in order to assess modulation of nitric oxide (NO) production (measured indirectly as the concentration of nitrites), hematopoiesis-stimulating activity of the supernatant of the macrophage cells (ascertained by counting cell colonies growing from progenitor cells for granulocytes and macrophages (GM-CFC) in vitro), and the release of hematopoiesis-stimulating cytokines. No hematopoiesis-stimulating activity and cytokine or NO production were found in the supernatant of non-stimulated macrophages. It was found that IMUNOR does not influence this status. Supernatant of LPS-stimulated macrophages was characterized by hematopoiesis-stimulating activity, as well as by the presence of nitrites, interleukin-6 (IL-6), and granulocyte colony-stimulating factor (G-CSF). A key role in the hematopoiesis-stimulating activity of the supernatant of LPS-stimulated macrophages could be ascribed to G-CSF since the formation of the colonies could be abrogated nearly completely by monoclonal antibodies against G-CSF. IMUNOR was found to suppress all the mentioned manifestations of the LPS-activated macrophages. When considering these results together with those from our previous in vivo study revealing stimulatory effects of IMUNOR on radiation-suppressed hematopoiesis, a hypothesis may be formulated which postulates a homeostatic role of IMUNOR, consisting in stimulation of impaired immune and hematopoietic systems but also in cutting back the production of proinflammatory mediators in cases of overstimulation which threats with undesirable consequences.

Apolipoprotein AI and apolipoprotein E mRNA expression in peripheral white blood cells from patients with orthotopic liver transplantation

BACKGROUND

Apolipoprotein AI/apolipoprotein E (apo-AI/apo-E) ratio change and its induction in non-hepatic tissues have been reported during liver development, regeneration, and several pathophysiologic states. The clinical implication of such changes is unclear, but these could reflect recovery and/or severity of liver damage.

METHODS AND RESULTS

Using RT-PCR we analysed the mRNA expression of apo-AI and apo-E in peripheral white blood cells (PWBC) of patients with different liver diseases who underwent orthotopic liver transplantation (OLT) and compared its expression with the lipid profile and liver function tests. We found that patients showed higher levels of apo-AI mRNA without detection of apo-E mRNA on PWBC at the preoperative day, compared with healthy volunteers (HV). We found an apo-AI/apo-E mRNA ratio of 2.7 during the anhepatic stage, followed by a decrease to 1.3, 0.95, and 0.55 at days 30, 60, and 90, respectively. At the last time point, the apo-AI/apo-E ratio was similar to HV. At day 3 post-OLT, the lowest levels of high-density lipoprotein (HDL)-cholesterol (17 mg/dl; P<0.05) and the highest levels of aspartate aminotransferase, total bilirubin and alkaline phosphatase (77.5 IU/l, 37.9 g/dl, 177.8 IU/l, respectively; P<0.05) were detected.

CONCLUSION

These results indicate that changes of HDL-cholesterol and apo-AI/apo-E mRNA ratio could be a good indicator of liver damage and/or hepatic functional recovery post-OLT.

Sex differences in inflammatory cytokine production in hepatic ischemia-reperfusion

BACKGROUND

The inflammatory response to hepatic ischemia-reperfusion (I/R) is associated with an increase in cytokine production. Studies have documented that sex hormones modulate both the innate and adaptive immune responses, and that females are more robust than males. The aim of this study was to determine whether a sex difference in cytokine response to hepatic I/R exists under normal pathophysiologic condition without hormone intervention.

METHODS

Adult C57BL/6 mice underwent 90 min of hepatic ischemia followed by various reperfusion periods (0, 1.5, 3, 6 hr). Plasma cytokine TNF-alpha, IL-6, MIP-2, and KC were measured. Liver injury was assessed by plasma alanine transaminase (ALT) levels and liver histopathology.

RESULTS

A reperfusion time-dependent increase in hepatocellular injury was observed in both males and females, as indicated by increasing levels of plasma ALT and liver histopathology. The plasma cytokines were significantly increased in both female and male I/R groups compared to their respective sham counterparts. However, there was a significant difference in cytokine kinetics between the female and male I/R groups. Female mice initially had a higher level of IL-6, KC, and MIP-2 in response to I/R, which began to decline after 3 hr of reperfusion and were significantly lower than the male I/R counterparts by 6 hr of reperfusion. In contrast, the hepatocellular injury and TNF production were only moderately lower in female IR than male IR.

CONCLUSION

The study underscores role of the gender in differential inflammatory cytokine expression in response to hepatic I/R, which may reflect the host response outcome.

Kinetics of phytohemaglutinin-induced IFN-γ and TNF-α expression in peripheral blood mononuclear cells from patients with chronic hepatitis B after liver transplantation

AIM: To study the association between host immunity and hepatitis B virus (HBV) recurrence after liver transplantation.

METHODS: Peripheral blood mononuclear cells (PBMC) were isolated from 40 patients with hepatitis B and underwent orthotopic liver transplantation (OLT) before and 2, 4, 8 wk after surgery. After being cultured in vitro for 72 h, the levels of INF-γ and TNF-α in culture supernatants were detected with ELISA. At the same time, the quantities of HBV DNA in serum and PBMCs were measured by real time PCR.

RESULTS: The levels of INF-γ and TNF-α in PBMC culture supernatants decreased before and 2, 4 wk after surgery in turns (INF-γ 155.52±72.32 ng/L vs 14.76±9.88 ng/L vs 13.22±10.35 ng/L, F = 6.946, P = 0.027<0.05; TNF-α 80.839±46.75 ng/L vs 18.59±17.29 ng/L vs 9.758±7.96 ng/L, F = 22.61, P = 0.0001<0.05). The levels of INF-γ and TNF-α were higher in groups with phytohemagglutinin (PHA) than in those without PHA before surgery. However, the difference disappeared following OLT. Furthermore, INF-γ and TNF-α could not be detected in most patients at wk 4 and none at wk 8 after OLT. The HBV detection rate and virus load in PBMC before and 2, 4 wk after surgery were fluctuated (HBV detected rate: 51.4%, 13.3%, 50% respectively; HBV DNA: 3.55±0.674 log(10) copies/mL vs 3.00±0.329 log(10) copies/mL vs 4.608±1.344 log(10) copies/mL, F = 7.582, P = 0.002<0.05). HBV DNA in serum was 4.48±1.463 log(10) copies/mL before surgery and <103 copies/mL after OLT except for one with 5.72±106 copies/mL 4 wk after OLT who was diagnosed as HBV recurrence. The levels of INF-γ and TNF-α were lower in patients with a high HBV load than in those with a low HBV load (HBV DNA detected/undetected in PBMCs: IFN-γ 138.08±72.44 ng/L vs 164.24±72.07 ng/L, t = 1.065, P = 0.297>0.05, TNF-α 80.75±47.30 ng/L vs 74.10±49.70 ng/L, t = 0.407, P = 0.686>0.05; HBV DNA positive/negative: IFN-γ 136.77±70.04 ng/L vs 175.27±71.50 ng/L, t = 1.702, P = 0.097>0.05; TNF-α 75.37±43.02 ng/L vs 81.53±52.46 ng/L, t = 0.402, P = 0.690>0.05).

CONCLUSION: The yielding of INF-γ and TNF-α from PBMCs is inhibited significantly by immunosuppressive agents following OLT with HBV load increased, indicating that the impaired immunity of host is associated with HBV recurrence after OLT.

Effects of ovariohysterectomy on canine blood neutrophil respiratory burst: a chemiluminescence study

OBJECTIVE

To examine blood neutrophil counts and luminol-enhanced chemiluminescence (CL) responses in dogs undergoing ovariohysterectomy (OH), premedicated with 2 different drugs.

STUDY DESIGN

Randomized clinical study.

ANIMALS

Forty-two healthy client-owned bitches.

METHODS

Dogs had OH under isoflurane anesthesia with either acepromazine or medetomidine, both in combination with butorphanol, administered as preanesthetic medication. Blood samples were collected when the dog was admitted, at the end of surgery, and the next day (approximately 20 hours after surgery). Blood neutrophils were counted automatically, and neutrophil oxidative activity was assessed by measuring blood CL responses (induced by opsonized zymosan and enhanced by luminol) at 37 degrees C for 40 minutes.

RESULTS

Number of circulating neutrophils was significantly increased the day after surgery reflected by enhanced blood CL responses. Neutrophil CL, however, was not significantly altered. No significant differences were detected for perioperative Polymorphonuclear neutrophil (PMN) characteristics between the 2 preanesthetic regimens.

CONCLUSIONS

In conclusion, despite clearly increasing the number of circulating neutrophils, OH did not significantly affect neutrophil respiratory burst, as measured by whole-blood CL responses.

CLINICAL RELEVANCE

Surgical operation of moderate intensity (e.g., OH) did not significantly alter one of the important immune functions, neutrophil oxidative activity. Further studies are warranted to confirm the significance of this finding, and to assess the value of following this variable in different animal patient populations.

Balance of pro- and anti-inflammatory cytokines in liver surgery

Inflammatory response in surgery is associated with the release of cytokines. Many cytokines are produced by macrophages; therefore surgical injuries to the liver may have great influence on the release of cytokines. Ischemia creates tissue injury and may contribute to the cytokine release. A balanced ratio of pro- and anti-inflammatory cytokines is important for appropriate immune response; excessive inflammation or hypo-responsiveness can lead to post-operative complications. To determine the magnitude of the cytokine response caused by liver surgery and to evaluate the balance of pro- and anti-inflammatory cytokines released during the operation, we measured levels of tumor necrosis factor-alpha (TNFalpha), interleukin (IL)-1beta, IL-6 and IL-10 in 19 patients undergoing liver resection. The results showed a continuous rise of IL-6 and a transient elevation of IL-10. Levels of TNFalpha remained low; IL-1beta was not detected at any sampling time. We conclude that liver surgery induces cytokine response characterized predominantly by an early appearance of IL-6 and IL-10, the elevation of IL-6 may be mainly caused by splanchnic ischemia. The IL-6/IL-10 ratio could possibly reflect the balance of pro- and anti-inflammatory cytokines in liver surgery better than the TNFalpha/IL-10 ratio, which can well represent inflammatory status in sepsis.