Effect of liver transplantation on tuftsin activity and phagocytic activity of neutrophil granulocytes in patients with liver cirrhosis

Frequent detection of functional hyposplenism via assessment of pitted erythrocytes in patients with advanced liver cirrhosis

Background

Asplenia or functional hyposplenism are risk factors for severe infections, and vaccinations against encapsulated bacteria are advised. There are only limited data regarding the spleen function of cirrhotic patients.

Methods

We evaluated spleen function in patients with liver cirrhosis, who were prospectively enrolled in this study. Spleen function was evaluated by the measurement of pitted erythrocytes. Functional hyposplenism was defined as a percentage of PE of >15%.

Results

117 patients, mean age 58.4 years and 61.5% (n = 72) male with liver cirrhosis were included. Functional hyposplenism was diagnosed in 28/117 patients (23.9%). Pitted erythrocytes correlated with albumin (p = 0.024), bilirubin (p<0.001), international normalized ratio (INR; p = 0.004), model of end-stage liver disease (MELD) score (p<0.001) and liver stiffness (p = 0.011). Patients with functional hyposplenism had higher MELD scores (median 13 vs. 10; p = 0.021), liver stiffness (46.4 kPa vs. 26.3 kPa; p = 0.011), INR (1.3 vs. 1.2; p = 0.008) and a higher Child-Pugh stage (Child C in 32.1% vs. 11.2%; p = 0.019) as compared to patients without functional hyposplenism. Functional hyposplenism was not associated with the etiology of cirrhosis. Importantly, 9/19 patients with Child C cirrhosis had functional hyposplenism.

Conclusion

A quarter of patients with liver cirrhosis and almost 50% of patients with Child C cirrhosis have functional hyposplenism. Functional hyposplenism is associated with poor liver function and the degree of portal hypertension, which is characterized by higher liver stiffness measurements in transient elastography.

Plasmodium falciparum malaria and invasive bacterial co-infection in young African children: the dysfunctional spleen hypothesis

Children with recent or acute malaria episodes are at increased risk of invasive bacterial infections (IBI). However, the exact nature of the malaria-IBI association is still unclear. Young children have an age-related spleen immunologic immaturity, mainly due to the still ongoing development of the marginal zone (MZ) B cell subset. By mounting a rapid antibody response against encapsulated bacteria, these cells are critical for the defence against highly pathogenic microorganisms that do not elicit classical T cell-dependent responses. There is increasing evidence that the anatomy of the spleen becomes disorganized during malaria infection, with complete dissolution of the MZ and apoptosis of MZ B cells. Correspondingly, a reduction in the frequency of the peripheral equivalent of the MZ B cells has been found in malaria endemic areas. A remarkable similarity exists in IBI susceptibility between African children with malaria and hyposplenic or splenectomized patients. However, studies specifically assessing the immune function of the spleen in controlling bacterial infections in young children with malaria are scarce.

Here, it is hypothesized that Plasmodium falciparum malaria infection constitutes a detrimental factor in the still immature spleen function of young children, resulting in a factually hyposplenic state during malaria episodes, putting children with malaria at a high risk to develop life-threatening bacterial infections. Studies to confirm or reject this hypothesis are greatly needed, as well as the development of affordable and feasible tools to assess the immune spleen function against encapsulated bacteria in children with malaria.

Spontaneous bacterial peritonitis: from pathophysiology to prevention

Patients with cirrhosis present an increased susceptibility to bacterial infections, which are the cause of hospital admission in about 10% of patients and are present in about 40% of those admitted for ongoing complications. Lastly, about a third of patients develop nosocomial infections. Spontaneous bacterial peritonitis (SBP) is the most frequent infection in advanced cirrhosis; it is mostly caused by Gram-negative bacteria of intestinal origin, but Gram-positive cocci can be involved in nosocomial-acquired SBP. Its occurrence is associated with complications, such as renal and circulatory failure, cardiac dysfunction, coagulopathy, encephalopathy, and relative adrenal insufficiency, ultimately leading to multi-organ failure and death within a few days or weeks in about 30% of cases. The main mechanism underlying the development of SBP, as well as other bacterial infections in cirrhosis, is represented by bacterial translocation from the intestinal lumen to mesenteric lymph nodes or other extraintestinal organs and sites. This process is facilitated by several factors, including changes in intestinal flora, portal hypertension, and, mainly, impairment in local/systemic immune defense mechanisms. Bacterial infections in advanced cirrhosis evoke an enhanced systemic inflammatory response, which explains the ominous fate of PBS. Indeed, an exaggerated production of cytokines ensues, which ultimately activates vasodilating systems and generates reactive oxygen species. Primary antibiotic prophylaxis of PBS is warranted in those conditions implying an increased incidence of bacterial infections, such as gastro-intestinal bleeding and low protein content in ascites associated with severe liver and/or renal dysfunction. Fluoroquinolones are commonly employed, but the frequent occurrence of resistant bacterial strains make third generation cephalosporins preferable in specific settings. The high PBS recurrence indicates secondary antibiotic prophylaxis.

Innate immune dysfunction in acute and chronic liver disease

Liver cirrhosis is a common disease causing great public-health concern because of the frequent complications requiring hospital care. Acute liver failure is also prone to several complications but is rare. One of the main complications for both acute and chronic liver diseases is infection, which regularly causes decompensation of cirrhosis, possibly leading to organ failure and death. This review focuses on innate immune function in cirrhosis, acute-on-chronic liver failure and acute liver failure. The known defects of Kupffer cells, neutrophils and monocytes are discussed, together with the pathophysiological importance of gut permeability, portal hypertension and intrinsic cellular defects, and the role of endotoxin, albumin, lipoproteins and toll-like receptors. Based on these different pathomechanisms, the available information on therapeutic strategies is presented. Antibiotic and probiotic treatment, nutritional support, artificial liver support, and experimental strategies such as inhibition of toll-like receptors and use of albumin and colony-stimulating factors are highlighted.