Utility of neutrophil CD64 in distinguishing bacterial infection from inflammation in severe alcoholic hepatitis fulfilling SIRS criteria

Biomarker for infection in children with decompensated chronic liver disease: Neutrophilic CD64 or procalcitonin?

OBJECTIVE

Biomarkers with high accuracy for identification of infection in decompensated chronic liver disease (DCLD) are urgently needed. We compared the accuracy of neutrophilic cluster of differentiation 64 (nCD64) with procalcitonin for diagnosis of bacterial infection in children with DCLD.

METHODS

Consecutive children admitted with DCLD were enrolled prospectively. nCD64 was assessed by flow cytometry and expressed in percentage. nCD64, procalcitonin and hemogram were measured at admission and 7-14 days after treatment in those with infection. Complete work-up for infection was done. Presence, site and severity of infection was classified as per guidelines.

RESULTS

107 children [64 boys, age 97(18-168) months] were enrolled. 78(72.9%) had infection, 26(24%) had severe sepsis and 60(56%) had systemic inflammatory response syndrome. The commonest site of infection was ascitic fluid (n=37), followed by pneumonia (n=24), urinary tract (n=15), bacteraemia (n=10), cholangitis (n=8) and cellulitis (n=3). nCD64 (cut-off-51%, AUC-0.82) had a higher sensitivity (79.5%) and specificity (82.8%) than procalcitonin (cut-off ≥0.58ng/mL, AUC-0.74, sensitivity-76.9% and specificity-62.1%) for diagnosis of infection. nCD64 and procalcitonin correlated with infection severity, being highest in children with severe sepsis [88(71-97) %and 1.98(0.83-10.36) ng/mL], than in infection alone [72(45-84) % and 1.09(0.45-2.07) ng/mL], and no-infection [36(20.2-48) % and 0.42(0.19-1.08) ng/mL]. There was no difference in diagnostic utility of procalcitonin or nCD64 with different sites of infection. Elevation of all 3 parameters (nCD64, PCT and total leukocyte count) was uncommon but highly specific for presence of infection.

CONCLUSION

nCD64 identifies infection better than procalcitonin and correlates well with infection severity in children with DCLD.

Monitoring Circulating Myeloid Cells in Peritonitis with an In Vivo Imaging Flow Cytometer

Peritonitis is a common and life-threatening inflammatory disease. Myeloid cells are elevated in the peripheral blood and contribute to peritonitis, but their circulating dynamics are not clear. In vivo flow cytometry (IVFC) is a noninvasive technique for monitoring the dynamics of circulating cells in live animals. It has been extensively used to detect circulating tumor cells, but rarely for monitoring immune cells. Here, we describe a method adapting an intravital microscope for IVFC so that we can monitor LysM-EGFP-labeled circulating myeloid cells in a tumor necrosis factor (TNF) α-induced peritonitis mouse model. Using this IVFC method, we quantified the blood flow velocity and cell concentration in circulation. We observed a significant increase in LysM-EGFP+ cells in circulation after TNFα intraperitoneal (i.p.) injection, which reached a plateau in ~20 min. Conventional cytometry analysis showed that most LysM-EGFP+ cells were neutrophils. Increasing blood neutrophils were accompanied by neutrophil recruitment to the peritoneal cavity and neutrophil emigration from the bone marrow. We then monitored neutrophil CD64 expression in vivo and found a significant increase in TNFα-induced peritonitis. We also found that CD18 blockade doubled the circulating neutrophil number in TNFα-induced peritonitis, suggesting that CD18 is critical for neutrophil recruitment in peritonitis. Overall, we demonstrate that IVFC techniques are useful for studying the circulating dynamics of immune cells during inflammatory diseases.

Platelets in Alcohol-Associated Liver Disease: Interaction With Neutrophils

Alcohol-associated liver disease (ALD) is a major contributor to liver-related mortality globally. An increasing body of evidence underscores the pivotal role of platelets throughout the spectrum of liver injury and recovery, offering unique insights into liver homeostasis and pathobiology. Alcoholic-associated steatohepatitis is characterized by the infiltration of hepatic neutrophils. Recent studies have highlighted the extensive distance neutrophils travel through sinusoids to reach the liver injury site, relying on a platelet-paved endothelium for efficient crawling. The adherence of platelets to neutrophils is crucial for accurate migration from circulation to the inflammatory site. A gradual decline in platelet levels leads to diminished neutrophil recruitment. Platelets exhibit the ability to activate neutrophils. Platelet activation is heightened upon the release of platelet granule contents, which synergistically activate neutrophils through their respective receptors. The sequence culminates in the formation of platelet-neutrophil complexes and the release of neutrophil extracellular traps intensifies liver damage, fosters inflammatory immune responses, and triggers hepatotoxic processes. Neutrophil infiltration is a hallmark of alcohol-associated steatohepatitis, and the roles of neutrophils in ALD pathogenesis have been studied extensively, however, the involvement of platelets in ALD has received little attention. The current review consolidates recent findings on the intricate and diverse roles of platelets and neutrophils in liver pathophysiology and in ALD. Potential therapeutic strategies are highlighted, focusing on targeting platelet-neutrophil interactions and activation in ALD. The anticipation is that innovative methods for manipulating platelet and neutrophil functions will open promising avenues for future ALD therapy.

Value of inflammatory response and oxidative damage in the diagnosis of infections in severe alcoholic hepatitis

Severe alcoholic hepatitis is the most lethal complication in alcohol dependent patients. The concurrence of infections in these patients is very frequent. Both produce a systemic inflammatory response syndrome (SIRS), secondary to intense release of inflammatory cytokines, which can complicate the diagnosis. In our study, Interleukin (IL)-6 and IL-10 levels are higher in patients with SIRS (p<0.001 and p = 0.033, respectively). IL-4, IL-6, Interferon-gamma (IFNγ), Tumor necrosis factor alpha (TNFα) and IL-17 levels correlate with liver function, as estimated by MELD-Na (p = 0.018, p = 0.008, p = 0.009, p = 0.016 and p = 0.006, respectively). Malondialdehyde (MDA), a product of lipid peroxidation and marker of cell damage, also correlates with liver function (p = 0.002), but not with SIRS or infections. Only elevated IL-6 correlates independently with the presence of infections (RR=1.023 IC 95% 1.000-1.047), so it may be useful for the correct diagnosis in these patients. Values greater than 30 pg/mL have a sensitivity: 86.7% and specificity: 94.7% for the diagnosis of infections.

Molecular Markers of Blood Cell Populations Can Help Estimate Aging of the Immune System

Aging of the immune system involves functional changes in individual cell populations, in hematopoietic tissues and at the systemic level. They are mediated by factors produced by circulating cells, niche cells, and at the systemic level. Age-related alterations in the microenvironment of the bone marrow and thymus cause a decrease in the production of naive immune cells and functional immunodeficiencies. Another result of aging and reduced tissue immune surveillance is the accumulation of senescent cells. Some viral infections deplete adaptive immune cells, increasing the risk of autoimmune and immunodeficiency conditions, leading to a general degradation in the specificity and effectiveness of the immune system in old age. During the COVID-19 pandemic, the state-of-the-art application of mass spectrometry, multichannel flow cytometry, and single-cell genetic analysis have provided vast data on the mechanisms of aging of the immune system. These data require systematic analysis and functional verification. In addition, the prediction of age-related complications is a priority task of modern medicine in the context of the increase in the aged population and the risk of premature death during epidemics. In this review, based on the latest data, we discuss the mechanisms of immune aging and highlight some cellular markers as indicators of age-related immune disbalance that increase the risk of senile diseases and infectious complications.

Standardization of neutrophil CD64 and monocyte HLA-DR measurement and its application in immune monitoring in kidney transplantation

Background

Infections cause high mortality in kidney transplant recipients (KTRs). The expressions of neutrophil CD64 (nCD64) and monocyte HLA-DR (mHLA-DR) provide direct evidence of immune status and can be used to evaluate the severity of infection. However, the intensities of nCD64 and mHLA-DR detected by flow cytometry (FCM) are commonly measured by mean fluorescence intensities (MFIs), which are relative values, thus limiting their application. We aimed to standardize nCD64 and mHLA-DR expression using molecules of equivalent soluble fluorochrome (MESF) and to explore their role in immune monitoring for KTRs with infection.

Methods

The study included 50 KTRs diagnosed with infection, 65 immunologically stable KTRs and 26 healthy controls. The blood samples were collected and measured simultaneously by four FCM protocols at different flow cytometers. The MFIs of nCD64 and mHLA-DR were converted into MESF by Phycoerythrin (PE) Fluorescence Quantitation Kit. The intraclass correlation coefficients (ICCs) and the Bland-Altman plots were used to evaluate the reliability between the four FCM protocols. MESFs of nCD64 and mHLA-DR, nCD64 index and sepsis index (SI) with the TBNK panel were used to evaluate the immune status. Comparisons among multiple groups were performed with ANOVA one-way analysis. Receiver operating characteristics (ROC) curve analysis was performed to diagnose infection or sepsis. Univariate and multivariate logistic analysis examined associations of the immune status with infection.

Results

MESFs of nCD64 and mHLA-DR measured by four protocols had excellent reliability (ICCs 0.993 and 0.957, respectively). The nCD64, CD64 index and SI in infection group were significantly higher than those of stable KTRs group. Patients with sepsis had lower mHLA-DR but higher SI than non-sepsis patients. ROC analysis indicated that nCD64 had the highest area under the curve (AUC) for infection, and that mHLA-DR had the highest AUC for sepsis. Logistic analysis indicated that nCD64 > 3089 and B cells counts were independent risk factors for infection.

Conclusion

The standardization of nCD64 and mHLA-DR made it available for widespread application. MESFs of nCD64 and mHLA-DR had good diagnostic performance on infection and sepsis, respectively, which could be promising indicators for immune status of KTRs and contributed to individualized treatment.

Clinical Value of Neutrophil CD64 Index, PCT, and CRP in Acute Pancreatitis Complicated with Abdominal Infection

Objective: To study the clinical diagnostic value of neutrophil CD64 index, PCT, and CRP in patients with acute pancreatitis with abdominal infection. Methods: A number of patients with acute pancreatitis (n = 234) participated in the study. According to the infection and health conditions, they were further divided into the non-infection group (n = 122), infection group (n = 78), and sepsis group (n = 34), and 40 healthy subjects were selected in the control group (n = 40). Expression levels of infection indexes, such as CD64 index, PCT, and CRP, were detected and compared. ROC curves were drawn to compare the efficacy of each index in the diagnosis of acute pancreatitis with abdominal infection and sepsis. The study was retrospectively registered under the China Clinical Trial Registry as a trial number ChiCTR2100054308. Results: All indexes were significantly higher in three clinical groups than the healthy control group (p < 0.05). The CD64 index, CD64 positive rate, and PCT in the infected group were significantly higher than those in the uninfected group (ALL p < 0.05). The PCT of patients infected with Gram-negative bacteria was significantly higher than that of Gram-positive bacteria-infected patients (p < 0.05). CD64 index had the best diagnostic efficiency for acute pancreatitis infection, with 82.14% sensitivity, 88.51% specificity, and 0.707 Youden indexes. The CD64 Youden index (0.780) for sepsis diagnosis was the highest, while the AUC of PCT was the highest (0.897). Conclusion: CD64 index combined with PCT has good sensitivity and specificity in diagnosing acute pancreatitis infection and sepsis.

INFLUENCE OF SYSTEMIC INFLAMMATORY RESPONSE SYNDROME ON THE DEVELOPMENT OF OXIDATIVE STRESS DURING SIMULATION OF CHRONIC ALCOHOL INTOXICATION IN RATS

The aim of our study was to analyze changes in the development of oxidative stress in the liver of rats with chronic alcohol intoxication against the background of systemic inflammatory response syndrome based on the study of catalase and superoxide dismutase activity, concentration of malonic dialdehyde, oxidatively modified proteins and sulfide anion and superoxide anion production. Methods. Experimental studies were performed on 12 male Wistar rats weighing 180‒220 g. Animals were divided into two groups: 1 ‒ control and 2 ‒ animals, on which we simulated alcoholic hepatitis and SIRS. The activity of catalase and superoxide dismutase (SOD), the concentration of malonic dialdehyde (MDA) , oxidatively modified proteins (OMP) sulfide anion and superoxide anion production were studied in the rat liver homogenate. The obtained results were subjected to statistical processing using the Mann-Whitney test. Results. Analyzing the development of oxidative stress in the liver of rats, on which we simulated the combined effects of SIRS and prolonged alcohol intoxication, we found that the activity of SOD increased by 1.72 times (P<0.05), and catalase decreased by 1.18 times (P<0.05) compared with the control group. The production of superoxide anion radical in the liver of rats increased 2.21 times (P<0.05) in the group of animals with combined exposure to bacterial LPS and alcohol intoxication compared to control. The concentration of MDA increased 2.25 times (P<0.05), and OMP by 9.5 times (P<0.05) compared with control group. The concentration of sulfide anion in the liver of rats under the conditions of modeling the combined effects of SIRS and alcohol intoxication decreased by 1.44 times (P <0.05) compared with the control. Conclusions. Modeling of alcohol intoxication against the background of systemic inflammatory response syndrome leads to oxidative damage to lipid and protein structures of the liver due to increased production of superoxide anion radical and imbalance of antiradical protection.