Increased bactericidal/permeability increasing protein in patients with cirrhosis

Epithelial barrier hypothesis in the context of nutrition, microbial dysbiosis, and immune dysregulation in metabolic dysfunction-associated steatotic liver

In recent years, the prevalence of chronic liver diseases, particularly Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD), has increased significantly. This upward trend is largely associated with lifestyle-related factors such as unhealthy dietary habits, physical inactivity, and various environmental influences. Among the key elements contributing to the pathogenesis of MASLD, the integrity of the intestinal epithelial barrier emerges as a critical determinant, given its central role in maintaining immune homeostasis along the gut-liver axis. Disruption of this barrier, often driven by excessive consumption of saturated fats and refined carbohydrates in combination with low dietary fiber intake, can lead to microbial dysbiosis. This imbalance in the gut microbiota triggers immune dysregulation and promotes systemic inflammation, thereby exacerbating hepatic injury. This review discusses the contribution of epithelial barrier dysfunction to the development and progression of MASLD, with a particular focus on how increased intestinal permeability may initiate and sustain chronic liver inflammation. Additionally, the influence of dietary and environmental factors on epithelial integrity, immune responses, and the inflammatory cascade is addressed. A better understanding of the complex interplay between gut barrier impairment, immune modulation, and liver pathology may offer valuable insights into MASLD pathophysiology and contribute to the development of more targeted therapeutic strategies.

Pharmacological therapy targeting the immune response in atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory disease characterized by the formation of atherosclerotic plaques that consist of numerous cells including smooth muscle cells, endothelial cells, immune cells, and foam cells. The most abundant innate and adaptive immune cells, including neutrophils, monocytes, macrophages, B cells, and T cells, play a pivotal role in the inflammatory response, lipoprotein metabolism, and foam cell formation to accelerate atherosclerotic plaque formation. In this review, we have discussed the underlying mechanisms of activated immune cells in promoting AS and reviewed published clinical trials for the treatment of AS by suppressing immune cell activation. We have also presented some crucial shortcomings of current clinical trials. Lastly, we have discussed the therapeutic potential of novel compounds, including herbal medicine and dietary food, in alleviating AS in animals. Despite these limitations, further clinical trials and experimental studies will enhance our understanding of the mechanisms modulated by immune cells and promote widespread drug use to treat AS by suppressing immune system-induced inflammation.

Serum proteomic profiling of patients with compensated advanced chronic liver disease with and without clinically significant portal hypertension

INTRODUCTION

Portal hypertension (PH) drives the progression of liver cirrhosis to decompensation and death. Hepatic venous pressure gradient (HVPG) measurement is the standard of PH quantification, and HVPG≥10 mmHg defines clinically significant PH (CSPH). We performed proteomics-based serum profiling to search for a proteomic signature of CSPH in patients with compensated advanced chronic liver disease (cACLD).

MATERIALS AND METHODS

Consecutive patients with histologically confirmed cACLD and results of HVPG measurements were prospectively included. Serum samples were pooled according to the presence/absence of CSPH and analysed by liquid chromatography-mass spectrometry. Gene set enrichment analysis was performed, followed by comprehensive literature review for proteins identified with the most striking difference between the groups.

RESULTS

We included 48 patients (30 with, and 18 without CSPH). Protein CD44, involved in the inflammatory response, vascular endothelial growth factor C (VEGF-C) and lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1), both involved in lymphangiogenesis were found solely in the CSPH group. Although identified in both groups, proteins involved in neutrophil extracellular traps (NET) formation, as well as tenascin C, autotaxin and nephronectin which mediate vascular contractility and lymphangiogenesis were more abundant in CSPH.

DISCUSSION AND CONCLUSION

We propose that altered inflammatory response, including NET formation, vascular contractility and formation of new lymph vessels are key steps in PH development. Proteins such as CD44, VEGF-C, LYVE-1, tenascin C, Plasminogen activator inhibitor 1, Nephronectin, Bactericidal permeability-increasing protein, Autotaxin, Myeloperoxidase and a disintegrin and metalloproteinase with thrombospondin motifs-like protein 4 might be considered for further validation as potential therapeutic targets and candidate biomarkers of CSPH in cACLD.

Salivary bactericidal/permeability-increasing protein: A novel inflammatory marker associated with periodontitis

OBJECTIVES

The present case-control study aims to investigate the salivary levels of bactericidal/permeability-increasing protein (BPI) and interleukin-1beta (IL-1ß) in systemically healthy individuals with periodontitis and periodontally healthy for the evaluation of BPI's relation with periodontal inflammation and clinical diagnosis of periodontitis.

MATERIALS AND METHODS

A total of 100 participants were enrolled in this study and divided into periodontitis (P group) (n = 50) and periodontally healthy (H group) (n = 50) groups based on their full-mouth periodontal examination results including plaque index, probing pocket depth, gingival index, bleeding on probing, and clinical attachment level. Unstimulated whole saliva was collected. Salivary BPI and IL-1β levels were determined using an enzyme-linked immunosorbent assay. Receiver operating characteristic (ROC) curves were created to determine the diagnostic value of BPI.

RESULTS

The levels of BPI and IL-1ß in saliva were significantly higher in the P group than in the H group (p<0.001). Moreover, salivary BPI and IL-1ß levels correlated significantly with all clinical periodontal parameters (all p<0.001). Interestingly, there was a strong positive correlation between salivary levels of BPI and IL-1ß (r=0.544, p<0.001). In addition, the results of the ROC curve analysis showed that BPI had a high diagnostic potential to distinguish periodontitis from healthy controls with an area under the curve value of 0.94% (p<0.000).

CONCLUSION

The significantly higher salivary levels of BPI in periodontitis patients together with strong positive correlations between all periodontal parameters and salivary IL-1ß levels suggest that BPI may be involved in the inflammatory process of periodontal disease.

CLINICAL RELEVANCE

The present study for the first time report that salivary BPI levels may serve as a potential biomarker of inflammation in periodontal disease.

TRIAL REGISTRATION NUMBER

Thai Clinical Trials.gov (TCTR20211222008) (22 December 2021).

Low-Avidity Autoantibodies against Bactericidal/Permeability-Increasing Protein Occur in Gram-Negative and Gram-Positive Bacteremia

Antibody autoreactivity against bactericidal/permeability-increasing protein (BPI) is strongly associated with Pseudomonas aeruginosa infection in cystic fibrosis (CF), non-CF bronchiectasis (BE), and chronic obstructive pulmonary disease (COPD). We examined the pathogen-specific nature of this autoreactivity by examining antibodies to BPI in bacteremia patients. Antibodies to BPI and bacterial antigens were measured in sera by ELISA from five patient cohorts (n = 214).

Antibody autoreactivity against bactericidal/permeability-increasing protein (BPI) is strongly associated with Pseudomonas aeruginosa infection in cystic fibrosis (CF), non-CF bronchiectasis (BE), and chronic obstructive pulmonary disease (COPD). We examined the pathogen-specific nature of this autoreactivity by examining antibodies to BPI in bacteremia patients. Antibodies to BPI and bacterial antigens were measured in sera by ELISA from five patient cohorts (n = 214). Antibody avidity was investigated. Bacteremic patient sera (n = 32) exhibited IgG antibody autoreactivity against BPI in 64.7% and 46.7% of patients with positive blood cultures for P. aeruginosa and Escherichia coli, respectively. Autoantibody titers correlated with IgG responses to bacterial extracts and lipopolysaccharide (LPS). A prospective cohort of bacteremic patient sera exhibited anti-BPI IgG responses in 23/154 (14.9%) patients with autoreactivity present at the time of positive blood cultures in patients with Gram-negative and Gram-positive bacteria, including 8/60 (13.3%) patients with Staphylococcus aureus. Chronic tissue infection with S. aureus was associated with BPI antibody autoreactivity in 2/15 patients (13.3%). Previously, we demonstrated that BPI autoreactivity in CF patient sera exhibits high avidity. Here, a similar pattern was seen in BE patient sera. In contrast, sera from patients with bacteremia exhibited low avidity. These data indicate that low-avidity IgG responses to BPI can arise acutely in response to bacteremia and that this association is not limited to P. aeruginosa. This is to be contrasted with chronic respiratory infection with P. aeruginosa, suggesting that either the chronicity or the site of infection selects for the generation of high-avidity responses, with biologic consequences for airway immunity.

Bacterial translocation in patients with liver cirrhosis: physiology, clinical consequences, and practical implications

The gut liver axis is an operative unit that works to protect the human body against potentially harmful substances and microorganisms, maintaining the homeostasis of the immune system. Liver cirrhosis profoundly alters this complex system. The intestine becomes more permeable allowing the translocation of bacteria, bacterial products and fragments into the portal circulation, triggering an abnormal local and systemic inflammatory response and a condition of perpetual immunologic alarm. This immune-inflammatory disorder related to dysbiosis is involved in the development of liver damage and liver cirrhosis complications and increases intestinal permeability in a vicious circle. Areas covered: The most relevant studies on bacterial translocation, the mechanism of intestinal barrier dysfunction and its consequences in patients with liver cirrhosis have been revised through a PubMed search. Data have been discussed with particular regard to their significance in clinical practice. Expert commentary: The assessment of bacterial translocation and intestinal permeability is not currently used in clinical practice but may be useful to stratify patients' prognosis.

Bacterial translocation markers in liver cirrhosis

Bacterial translocation (BT) is an important mechanism in the development of infection in liver cirrhosis. The migration and colonization of bacteria and/or bacterial products from the bowel to mesenteric lymph nodes is a controlled process in healthy persons. Increased intestinal permeability, bacterial overgrowth and defect of gut-associated lymphatic tissue promote impaired BT in cirrhotics. We reviewed the reports on markers used for the evaluation of BT published between 1987 and 2016. We focused on the clinical consequences of BT in cirrhosis, as indicated by the values of the BT markers. Patients with cirrhosis are reported to have elevated levels of surrogate markers associated with BT compared with controls. The most widely used BT parameters are C-reactive protein, procalcitonin, bacterial DNA, endotoxin or lipopolysaccharide, lipopolysaccharide binding protein, calprotectin, and bactericidal/permeability increasing protein. High levels of these factors in serum and/or ascitic fluid in humans may be associated with advanced liver disease, hemodynamic instability, high levels of proinflammatory cytokines, susceptibility to the development of severe or recurrent infections, acute-on-chronic liver failure, hepatic encephalopathy, hepatorenal syndrome and poor prognosis during follow up. In conclusion, high levels of BT markers are associated with a high inflammatory response, increased complications of liver cirrhosis and occasionally high fatality rates.

High serum lipopolysaccharide binding protein is associated with increased mortality in patients with decompensated cirrhosis

BACKGROUND & AIMS

Lipopolysaccharide-binding-protein (LBP) is an acute-phase-protein produced by hepatocytes. Changes in LBP are associated with the dynamics of bacterial translocation and intestinal permeability in decompensated cirrhosis (DC). We assessed serum and ascitic-fluid (AF) LBP and examined their association with mortality in patients with DC.

METHODS

Eighty-eight consecutive patients (73.9% males) underwent thorough diagnostic investigations for infection. LBP (ng/mL) was assessed in serum (N=88) and AF (n=49) by enzyme-linked-immunosorbent-assay and expressed in natural logarithm (ln).

RESULTS

Serum lnLBP was higher in 18 patients with overt infection compared to those without (P<.001). Serum and AF lnLBP 13.49 and 12.11 displayed a very good-negative-predictive value of 90% and 95.1% to rule out infection and spontaneous-bacterial-peritonitis (SBP), respectively. LBP was higher in serum than in AF (P<.001). Serum and AF LBP levels showed a positive correlation with surrogate markers of inflammation. Patients without overt infection were prospectively followed up. The 90-day-mortality rate was 48% and 24.4% in patients with high (≥13.49) and low (<13.49) lnLBP, respectively, (log rank P=0.045). In univariate Cox regression analysis, neutrophils, LBP, MELD score and CRP were predictive of mortality. However, only high LBP (HR 8.1 95%CI 2.0-31.5, P=0.003) and MELD (HR 1.1 95%CI 1.0-1.2, P=0.002) were predictive of mortality in multivariate analysis.

CONCLUSIONS

Serum and AF LBP concentrations showed a high negative-predictive-value to exclude infection and SBP, respectively. High serum LBP was detected in patients without infection at presentation who died during the 90-day-follow-up period. Elevated serum LBP is a marker of short-term mortality in patients without overt bacterial infection.

Large-scale survey of gut microbiota associated with MHE Via 16S rRNA-based pyrosequencing

OBJECTIVES

Elucidating the minimal hepatic encephalopathy (MHE)-associated gut microbiome may help in predicting and lowering the high risk for MHE in patients with cirrhosis.

METHODS

Twenty-six MHE patients were recruited and screened from among those with liver cirrhosis without overt hepatic encephalopathy as defined by abnormality seen on two test modalities: number connection test part A and the digit symbol test. Using 26 MHE-matched normal relatives and 25 cirrhotic patients without MHE as controls, by means of 16S ribosomal RNA (rRNA)-based pyrosequencing, we examined and analyzed 241,622 bacterial 16S rDNA gene sequences from feces of 77 subjects.

RESULTS

Using multiple comparative analyses, our results found the continuous overrepresentation of two bacterial families, Streptococcaceae and Veillonellaceae, in cirrhotic patients with and without MHE, compared with normal individuals. In addition, we also discovered an MHE-unique interplay pattern of gut microbiota largely influenced by the members of those two families. Following these findings, we further revealed that gut urease-containing bacteria Streptococcus salivarius was absent in the normal group but was present in cirrhotic patients with and without MHE. The abundance of S. salivarius was significantly higher in cirrhotic patients with MHE than in those without (P=0.030), and the change in the amount of this bacteria was positively correlated with ammonia accumulation (R=0.58, P=0.003) in cirrhotic patients with MHE but not in those without.

CONCLUSIONS

Gut microbiota dysbiosis may be associated with the presence of MHE in cirrhotic patients, in particular with ammonia-increasing phenotype in MHE. Gut ammonia-increasing bacteria S. salivarius might be expected to be a potential biomarker of ammonia-lowering therapies in cirrhotic patients with MHE.

Bactericidal/permeability increasing protein: a multifaceted protein with functions beyond LPS neutralization

Bactericidal permeability increasing protein (BPI), a 55-60 kDa protein, first reported in 1975, has gone a long way as a protein with multifunctional roles. Its classical role in neutralizing endotoxin (LPS) raised high hopes among septic shock patients. Today, BPI is not just a LPS-neutralizing protein, but a protein with diverse functions. These functions can be as varied as inhibition of endothelial cell growth and inhibition of dendritic cell maturation, or as an anti-angiogenic, chemoattractant or opsonization agent. Though the literature available is extremely limited, it is fascinating to look into how BPI is gaining major importance as a signalling molecule. In this review, we briefly summarize the recent research focused on the multiple roles of BPI and its use as a therapeutic.

The role of bactericidal/permeability-increasing protein in men with chronic obstructive pulmonary disease

BACKGROUND AND OBJECTIVE

Bactericidal/permeability-increasing protein (BPI) is a member of the pattern recognition receptors of the innate immune system. Recently, an association between genetic polymorphism in the BPI gene and a risk of airflow decline after transplantation was demonstrated, but whether these findings are reproducible in nontransplantation populations, such as those with COPD, is still unknown. The aim of this study is to explore the role of BPI in COPD.

METHODS

The genotypes of 107 patients with COPD and 110 control subjects were evaluated by polymerase chain reaction and polymorphism analysis of the BPI genes and ELISA analysis of the plasma BPI level. All subjects were men over 40 years old who smoked.

RESULTS

BPI mutation PstI (T→C) polymorphism in intron 5 was associated with an increased risk of developing COPD (OR 3.73, 95%CI: 1.62-9.10), and the frequency was significantly increased in the COPD group compared with the control group (26/107 [24.3%] vs 12/110 [10.9%], p = 0.002). In addition, COPD patients exhibited a decreased plasma level of BPI compared with the control group (10.6 ± 2.2 vs 23.4 ± 2.1 ng/ml, p < 0.0001).

CONCLUSIONS

BPI mutation (PstI in intron 5) and a decreased plasma BPI level were significant risk factors in susceptibility to COPD. These results demonstrate that BPI genetic mutation and impaired BPI production or release may result in airflow obstruction in smokers.

The augmented neutrophil respiratory burst in response to Escherichia coli is reduced in liver cirrhosis during infection

Several functional abnormalities in phagocytes from patients with liver cirrhosis contribute to an increased risk of infection. An increased resting respiratory burst has been observed in neutrophils from cirrhotic patients. We investigated whether an infection in cirrhosis affects the respiratory burst capacity of neutrophils and monocytes in response to Escherichia coli. This study included 45 hospitalized patients with liver cirrhosis and clinical signs of infection, 39 patients with liver cirrhosis in the absence of infection and 29 healthy subjects. Respiratory burst, lipopolysaccharide-binding protein (LBP), and immunoglobulin (Ig)G-autoantibodies against oxidized low-density lipoproteins (ab-oxLDL) were measured. The fraction of neutrophils spontaneously producing reactive oxygen species (ROS) was elevated in liver cirrhosis (P < 0·01). The neutrophil resting burst increased with Child-Pugh stage (P = 0·02) and correlated with augmented ROS release in response to opsonized E. coli (P < 0·05). Although LBP was increased in patients with cirrhosis (P < 0·01), higher LBP levels correlated with a lower resting burst in neutrophils (r(s)  = -0·395; P < 0·01). In the presence of infection, the resting burst was unaltered. However, neutrophil ROS release in response to E. coli was reduced markedly (P = 0·01), and it decreased as serum C-reactive protein (CRP) concentration rose (r(s)  = -0·437; P < 0·01), indicating the development of a sepsis-like immune paralysis. A positive correlation between ab-oxLDL and ROS release was observed (P < 0·01). In conclusion, the respiratory burst increases with severity of liver cirrhosis but is restrained by increasing LBP levels. Augmented ROS release in response to E. coli is accompanied by elevated markers of oxidative damage and becomes exhausted in the presence of infection.