Association between HLA-DR Expression and Multidrug-resistant Infection in Patients with Severe Acute Pancreatitis

Monocytic HLA-DR Expression in Immune Responses of Acute Pancreatitis and COVID-19

Acute pancreatitis is a common gastrointestinal disease with increasing incidence worldwide. COVID-19 is a potentially life-threatening contagious disease spread throughout the world, caused by severe acute respiratory syndrome coronavirus 2. More severe forms of both diseases exhibit commonalities with dysregulated immune responses resulting in amplified inflammation and susceptibility to infection. Human leucocyte antigen (HLA)-DR, expressed on antigen-presenting cells, acts as an indicator of immune function. Research advances have highlighted the predictive values of monocytic HLA-DR (mHLA-DR) expression for disease severity and infectious complications in both acute pancreatitis and COVID-19 patients. While the regulatory mechanism of altered mHLA-DR expression remains unclear, HLA-DR^-/low monocytic myeloid-derived suppressor cells are potent drivers of immunosuppression and poor outcomes in these diseases. Future studies with mHLA-DR-guided enrollment or targeted immunotherapy are warranted in more severe cases of patients with acute pancreatitis and COVID-19.

Circulating monocytes in acute pancreatitis

Acute pancreatitis is a common gastrointestinal disease characterized by inflammation of the exocrine pancreas and manifesting itself through acute onset of abdominal pain. It is frequently associated with organ failure, pancreatic necrosis, and death. Mounting evidence describes monocytes - phagocytic, antigen presenting, and regulatory cells of the innate immune system - as key contributors and regulators of the inflammatory response and subsequent organ failure in acute pancreatitis. This review highlights the recent advances of dynamic change of numbers, phenotypes, and functions of circulating monocytes as well as their underling regulatory mechanisms with a special focus on the role of lipid modulation during acute pancreatitis.

Intra-abdominal infection in acute pancreatitis in eastern China: microbiological features and a prediction model

Background

This study aimed to investigate the microbiol distribution of intra-abdominal infection in patients with acute pancreatitis, and to develop a reliable prediction model to guide the use of antibiotics.

Methods

Inpatient with acute pancreatitis between January 2015 and June 2020 were enrolled in the study. Participants were divided into the intra-abdominal infection group and non-infection group. Isolated pathogens and antibiotic susceptibility were documented. Characteristics parameters, laboratory results, and outcomes were also compared. Least absolute shrinkage and selection operator (LASSO) regression model was used to select the risk factors associated with intra-abdominal infection in patients with acute pancreatitis. Logistic regression analysis, random forest model, and artificial neural network were also used to validate the performance of the selected predictors in intra-abdominal infection prediction. A novel nomogram based on selected predictors was established to provide individualized risk of developing intra-abdominal infection in patients with acute pancreatitis.

Results

A total amount of 711 participants were enrolled in the study, and of these, 182 (25.6%) had intra-abdominal infection. Of the 247 isolated pathogens, 45 (18.2%) were multidrug-resistant bacteria, and antibiotic susceptibility was lower than that of China Antimicrobial Surveillance Network 2020. The LASSO method identified 5 independent predictors [intra-abdominal pressure (IAP), acute physiology and chronic health evaluation II (APACHE II), computed tomography severity index (CTSI), the severity of pancreatitis, and intensive care unit (ICU) admission] of intra-abdominal infection, which were validated by three different models. The area under the curve was >0.95 for all 5 predictors. A clinically useful nomogram based on these predictors was successfully established.

Conclusions

Multidrug-resistant bacteria were quite common in intra-abdominal infection. IAP, APACHE II, CTSI, the severity of pancreatitis, and ICU admission were identified as risk factors and the new nomogram based on these could help clinicians estimate the risk of intra-abdominal infection and optimize antimicrobial prescription for acute pancreatitis patients.

Infectious Complications of Acute Pancreatitis Is Associated with Peripheral Blood Phagocyte Functional Exhaustion

BACKGROUND

Infected pancreatic necrosis is one of the most severe complications of acute pancreatitis (AP). The development of secondary infection doubles the risk of death during the late stage of necrotizing pancreatitis. Phagocytes play a major role in AP pathogenesis, as well as in local and systemic complications of the disease.

AIMS

We aimed to investigate the relationship between quantitative and functional indices of circulating phagocyte at the time of admission and onset of infectious complications in patients with AP afterward.

METHODS

A post hoc analysis of 97 patients with AP was conducted. The metabolic state of peripheral blood neutrophils and monocytes was analyzed based on their phagocytic activity and generation of reactive oxygen species (ROS), which were determined by flow cytometry on admission. The clinical end point was marked by onset of infectious complications of AP.

RESULTS

On admission, baseline values and reactivity reserve of monocyte and neutrophil phagocytic activity in AP patients, who developed septic complications, were substantially decreased, whereas monocyte ROS generation was dramatically increased as compared to the group without infectious processes. ROC curve was obtained both for neutrophil and monocyte phagocytosis reactivity reserve expressed as modulation coefficient values and categorized as the risk factor of infectious complications, showing an area under curve of 0.95 (P < 0.0001) and 0.84 (P < 0.0001), respectively.

CONCLUSIONS

Early (at the time of admission) detection of quantitative and functional indices of circulating phagocytes can be useful for the prediction of septic complications in SAP patients.

The relationship between Chlamydia pneumoniae infection and CD4/CD8 ratio, lymphocyte subsets in middle-aged and elderly individuals

Chlamydia pneumoniae (C. pneumoniae) is a common respiratory pathogen associated with many inflammatory diseases. There are few data concerning the lymphocyte subsets in middle-aged and elderly individuals with C. pneumoniae infection. A total of 191 patients were included in this study. The study population was categorized into the middle-aged group (40-64 years old) and the elderly group (65-89 years old). Lymphocyte subsets in peripheral blood were examined with multi-colored flow cytometry. Immunological monitoring included lymphocyte subsets, C. pneumoniae IgG and IgM serology. In the middle-aged group, 69.83% individuals presented IgG positivity, which was associated with the inverted CD4/CD8 ratio. Individuals with C. pneumoniae IgG positivity also presented an increased percentage of CD8⁺CD28^- cells and a decreased CD4/CD8 ratio when compared to weakly-positive individuals. In the elderly group, C. pneumoniae IgG positivity was associated with a significant increase in the percentage of CD3⁺CD56⁺CD45⁺ (NKT) cells. In conclusion, altered lymphocyte homeostasis was shown in middle-aged individuals with C. pneumoniae IgG positivity. The senescent phenotypes of T cells might be associated with C. pneumoniae infection in middle-aged individuals.