Monocyte anergy is present in patients with severe acute pancreatitis and is significantly alleviated by granulocyte-macrophage colony-stimulating factor and interferon-gamma in vitro

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.

Fire in the belly: A scoping review of the immunopathological mechanisms of acute pancreatitis

Introduction

Acute pancreatitis (AP) is characterised by an inflammatory response that in its most severe form can cause a systemic dysregulated immune response and progression to acute multi-organ dysfunction. The pathobiology of the disease is unclear and as a result no targeted, disease-modifying therapies exist. We performed a scoping review of data pertaining to the human immunology of AP to summarise the current field and to identify future research opportunities.

Methods

A scoping review of all clinical studies of AP immunology was performed across multiple databases. Studies were included if they were human studies of AP with an immunological outcome or intervention.

Results

205 studies met the inclusion criteria for the review. Severe AP is characterised by significant immune dysregulation compared to the milder form of the disease. Broadly, this immune dysfunction was categorised into: innate immune responses (including profound release of damage-associated molecular patterns and heightened activity of pattern recognition receptors), cytokine profile dysregulation (particularly IL-1, 6, 10 and TNF-α), lymphocyte abnormalities, paradoxical immunosuppression (including HLA-DR suppression and increased co-inhibitory molecule expression), and failure of the intestinal barrier function. Studies including interventions were also included. Several limitations in the existing literature have been identified; consolidation and consistency across studies is required if progress is to be made in our understanding of this disease.

Conclusions

AP, particularly the more severe spectrum of the disease, is characterised by a multifaceted immune response that drives tissue injury and contributes to the associated morbidity and mortality. Significant work is required to develop our understanding of the immunopathology of this disease if disease-modifying therapies are to be established.

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.

ADAM17-Mediated Reduction in CD14++CD16+ Monocytes ex vivo and Reduction in Intermediate Monocytes With Immune Paresis in Acute Pancreatitis and Acute Alcoholic Hepatitis

Impaired immune responses and increased susceptibility to infection characterize acute inflammatory conditions such as pancreatitis and alcoholic hepatitis and are major causes of morbidity and mortality. However, the mechanisms that drive this apparent immune paresis remain poorly understood. Monocytes mediate host responses to damage and pathogens in health and disease, and three subsets of monocytes have been defined based on CD14 and CD16 expression. We sought to determine the changes in monocyte subsets in acute pancreatitis (AP) and acute alcoholic hepatitis (AAH), together with functional consequences and mechanisms that underlie this change. Peripheral blood mononuclear cells (PBMCs) from patients with AP or AAH were compared with healthy controls. Monocyte subsets were defined by HLA-DR, CD14, and CD16 expression. Changes in surface and intracellular protein expression and phosphorylation were determined by flow cytometry. Phenotype and function were assessed following stimulation with lipopolysaccharide (LPS) or other agonists in the presence of specific inhibitors of TNFα and a disintegrin and metalloproteinase 17 (ADAM17). Patients with AP and AAH had reduced CD14⁺⁺CD16⁺ intermediate monocytes compared to controls. Reduction of intermediate monocytes was recapitulated ex vivo by stimulating healthy control PBMCs with Toll-like receptor (TLR) agonists LPS, flagellin or polyinosilic:polycytidylic acid (poly I:C). Stimulation caused shedding of CD14 and CD16, which could be reversed using the ADAM17 inhibitor, TMI005 but not direct inhibitors of TNFα, a known ADAM17-target. Culturing PBMCs from healthy controls resulted in expansion of intermediate monocytes, which did not occur when LPS was in the culture medium. Cultured intermediate monocytes showed reduced expression of CX₃CR1, CCR2, TLR4, and TLR5. We found reduced migratory responses, intracellular signaling and pro-inflammatory cytokine production, and increased expression of IL-10. Stimulation with TLR agonists results in ADAM17-mediated shedding of phenotypic markers from CD16⁺ monocytes, leading to apparent “loss” of intermediate monocytes. Reduction in CD14⁺⁺CD16⁻ monocytes and increased CD14⁺⁺CD16⁺ is associated with altered responses in functional assays ex vivo. Patients with AP and AAH had reduced proportions of CD14⁺⁺CD16⁺ monocytes and reduced phosphorylation of NFκB and IL-6 production in response to bacterial LPS. Together, these processes may contribute to the susceptibility to infection observed in AP and AAH.

The CD14+HLA-DRlo/neg Monocyte: An Immunosuppressive Phenotype That Restrains Responses to Cancer Immunotherapy

Recent successes in cancer immunotherapy have been tempered by sub-optimal clinical responses in the majority of patients. The impaired anti-tumor immune responses observed in these patients are likely a consequence of immune system dysfunction contributed to by a variety of factors that include, but are not limited to, diminished antigen presentation/detection, leukopenia, a coordinated network of immunosuppressive cell surface proteins, cytokines and cellular mediators. Monocytes that have diminished or no HLA-DR expression, called CD14⁺HLA-DR^lo/neg monocytes, have emerged as important mediators of tumor-induced immunosuppression. These cells have been grouped into a larger class of suppressive cells called myeloid derived suppressor cells (MDSCs) and are commonly referred to as monocytic myeloid derived suppressor cells. CD14⁺HLA-DR^lo/neg monocytes were first characterized in patients with sepsis and were shown to regulate the transition from the inflammatory state to immune suppression, ultimately leading to immune paralysis. These immunosuppressive monocytes have also recently been shown to negatively affect responses to PD-1 and CTLA-4 checkpoint inhibition, CAR-T cell therapy, cancer vaccines, and hematopoietic stem cell transplantation. Ultimately, the goal is to understand the role of these cells in the context of immunosuppression not only to facilitate the development of targeted therapies to circumvent their effects, but also to potentially use them as a biomarker for understanding disparate responses to immunotherapeutic regimens. Practical aspects to be explored for development of CD14⁺HLA-DR^lo/neg monocyte detection in patients are the standardization of flow cytometric gating methods to assess HLA-DR expression, an appropriate quantitation method, test sample type, and processing guidances. Once detection methods are established that yield consistently reproducible results, then further progress can be made toward understanding the role of CD14⁺HLA-DR^lo/neg monocytes in the immunosuppressive state.

Improvement of Immune Dysfunction in Patients with Severe Acute Pancreatitis by High-Volume Hemofiltration: A Preliminary Report

Objective

The aim of this study was to investigate the effect of high-volume hemofiltration (HVHF) on ameliorating immune dysfunction in patients with severe acute pancreatitis (SAP).

Methods

Twelve patients diagnosed with SAP admitted to the intensive care unit of general surgery, Jinling Hospital, from January 2004 to December 2006 were included in this study. They were assigned to the standard medical therapy group (SMT group, n=4) or HVHF group (n=8) immediately after enrollment, in a 1:2 ratio. The SMT group were given standard treatment for SAP, while the HVHF group were given standard as well as 72-hour HVHF treatment initiated within 2 hours after enrollment. Patients in the 2 groups were comparable for the baseline clinical parameters. All patients were monitored over a 72-hour observation period for continuous clinical status, blood cell counts including monocytes, CD4+ and CD8+ T cells, and HLA-DR expression on monocytes. Blood samples were collected from those patients at 0, 6, 12, 24, 48, and 72 hour after enrollment for measurement of plasma Th1-type cytokines (interleukin-1 [IL-1], IL-2, interferon-γ [IFN-γ], and tumor necrosis factor-α [TNF-α]) and Th2-type cytokines (IL-4, IL-5, IL-6, IL-10, and IL-13) using ELISA.

Results

Within 72 hours, all measured cytokines except IL-4 were maintained at high levels, accompanied with a low level of peripheral monocytes, CD4+ and CD8+ T cell counts, and HLA-DR expression. Seventy-two hours later, plasma cytokines IFN-γ, IL-1, IL-2, IL-5, IL-10, and IL-13 (p<0.05), but not TNF-α and IL-6, in patients in the HVHF group were significantly reduced, while there was no change for these parameters in the SMT group. Plasma levels of IFN-γ, TNF-α, IL-1, IL-2, IL-5, and IL-13 in the HVHF group were significantly lower than those in the SMT group. Peripheral CD4+ and CD8+ T cells, monocyte count, and HLA-DR expression were increased significantly (p<0.05) only in the HVHF group, not in the SMT group. HLA-DR expression in the HVHF group was significant higher than that in the SMT group (p<0.05).

Conclusions

HVHF significantly reduced plasma inflammatory cytokine concentrations including those of IFN-γ, TNF-α, IL-1, IL-2, IL-5, and IL-13, while it increased monocyte HLA-DR expression in patients with SAP. The association of plasma cytokine reduction and cellular immune function recovery and clinical outcome needs further investigation.

Improvement of Monocyte Secretion Function in a Porcine Pancreatitis Model by Continuous Dose-Dependent Veno-Venous Hemofiltration

Objective

Monocyte and its secreted cytokines play a crucial role in the process of severe acute pancreatitis (SAP). It has been known that continuous veno-venous hemofiltration (CVVH) can partially attenuate the inflammatory process by removal of cytokines, but the effect of CVVH on monocyte secretion function remains unknown. This study investigated the effect of different doses of CVVH on monocyte secretion function as well as the plasma cytokine profile in a SAP porcine model.

Methods

After successful induction of SAP by pressure-controlled (100 mmHg), intraductal injection of sodium taurocholate (4%, 1 ml/kg) and trypsin (2 U/kg), 24 swine were randomly assigned to 3 groups. Swine in group I (n=8) serving as SAP controls received only standard medical therapy (SMT). Besides SMT, swine in two other groups received zero-balanced CVVH, one hour after the induction of SAP, with low volume fluid exchange (group II, n=8, ultrafiltration rate (UFR) 20 ml/kg/h, LV-CVVH) or high volume (group III, n=8, UFR 100 ml/kg/h, HV-CVVH). Using heparin as anticoagulant, the filter (AN69, Hospal, Lyon, France) was changed every 24 hours. Monocytes were isolated from porcine blood at various timepoints for detection of cytokine secretion (interleukin-6, IL-6; interleukin-10, IL-10; tumor necrosis-α, TNF-α) after LPS stimulus; plasma cytokines were measured simultaneously.

Results

CVVH showed a dose-dependent beneficial effect on the animals’ survival time. In control animals, plasma pro-inflammatory cytokine levels exhibited a double-phase fluctuation after SAP induction: IL-6 and TNF-α rapidly increased to a peak level within 6–12 hours, then dropped to very low level in the late stage. Unlike pro-inflammatory cytokines, the plasma level of anti-inflammatory cytokine IL-10 reached a plateau within 6–12 hours but dropped little. In CVVH-treated animals, the peak-nadir patterns of 3 cytokines were all flattened, most prominently in the HV-CVVH group. Similarly to plasma cytokine patterns, the monocyte ex vivo response to LPS stimulus showed an over-production of cytokines within 6–12 hours, but low production in the late stage. Although unable to totally prevent the abnormality of the monocyte secretion function, CVVH showed a dose-dependent ameliorative effect on it.

Conclusions

Monocytes are over-reactive to stimulus in the early stage of SAP, accompanied by a high level of plasma cytokines, and hypo-reactive to stimulus in the late stage of SAP, accompanied with a low level of plasma cytokines. CVVH treatment has a dose-dependent improvement effect on monocyte responsiveness.

Circulating nucleosomes as predictive markers of severe acute pancreatitis

Background

The components of nucleosomes, which contain DNA and histones, are released into the circulation from damaged cells and can promote inflammation. We studied whether the on-admission levels of circulating nucleosomes predict the development of severe acute pancreatitis (AP), in particular among the patients who present without clinical signs of organ dysfunction.

Methods

This is a prospective study of 74 AP patients admitted to Helsinki University Hospital from 2003 to 2007. Twenty-three patients had mild, 27 moderately severe, and 24 severe AP as defined by the revised Atlanta criteria. 14/24 severe AP patients had no sign of organ dysfunction on admission (modified marshall score <2). Blood samples were obtained on admission and the plasma levels of nucleosomes were measured using enzyme-linked immunosorbent assay.

Results

The on-admission levels of nucleosomes were significantly higher in severe AP than in mild or moderately severe AP (p < 0.001 for all), higher in non-survivors (n = 8) than in survivors (p = 0.019), and correlated with the on-admission levels of C-reactive protein (p < 0.001) and creatinine (p < 0.001). Among the AP patients who presented without organ dysfunction, the on-admission nucleosome level was an independent predictor of severe AP (p = 0.038, gender-adjusted forward-stepping logistic regression).

Conclusions

Circulating nucleosome levels may be helpful in identifying, on admission to hospital, the AP patients who present without clinical signs of organ dysfunction, and, yet, are bound to develop organ dysfunction during hospitalization.

A Glucuronoxylomannan-Associated Immune Signature, Characterized by Monocyte Deactivation and an Increased Interleukin 10 Level, Is a Predictor of Death in Cryptococcal Meningitis

Background. Cryptococcal meningitis remains a significant cause of death among human immunodeficiency virus type 1 (HIV)–infected persons in Africa. We aimed to better understand the pathogenesis and identify immune correlates of mortality, particularly the role of monocyte activation.

Methods. A prospective cohort study was conducted in Cape Town, South Africa. Patients with a first episode of cryptococcal meningitis were enrolled, and their immune responses were assessed in unstimulated and stimulated blood specimens, using flow cytometry and cytokine analysis.

Results. Sixty participants were enrolled (median CD4⁺ T-cell count, 34 cells/µL). Mortality was 23% (14 of 60 participants) at 14 days and 39% (22 of 57) at 12 weeks. Nonsurvivors were more likely to have an altered consciousness and higher cerebrospinal fluid fungal burden at presentation. Principal component analysis identified an immune signature associated with early mortality, characterized by monocyte deactivation (reduced HLA-DR expression and tumor necrosis factor α response to lipopolysaccharide); increased serum interleukin 6, CXCL10, and interleukin 10 levels; increased neutrophil counts; and decreased T-helper cell type 1 responses. This immune signature remained an independent predictor of early mortality after adjustment for consciousness level and fungal burden and was associated with higher serum titers of cryptococcal glucuronoxylomannan.

Conclusions. Cryptococcal-related mortality is associated with monocyte deactivation and an antiinflammatory blood immune signature, possibly due to Cryptococcus modulation of the host immune response. Validation in other cohorts is required.

Elevated Membrane and Soluble CD64: A Novel Marker Reflecting Altered FcγR Function and Disease in Early Rheumatoid Arthritis That Can Be Regulated by Anti-Rheumatic Treatment

OBJECTIVES

Fc receptors (FcR) interacting with immune complexes (ICs) is a central event in the immune pathogenesis of rheumatoid arthritis (RA). Here we asked if a specific FcR is linked to RA pathogenesis and if FcR activities relate to disease and treatment outcome in early RA.

MATERIAL AND METHODS

Twenty autoantibody-positive RA patients and 33 HC were included. The patients were evaluated before and after treatment with methotrexate and prednisolone. At follow-up, the EULAR response criteria were applied to determine the individual treatment outcomes. Serum immunoglobulin levels were measured and the expression of FcR for IgG (FcγR) and IgA (FcαR) on peripheral blood monocytes were determined by flow cytometry. The monocytic FcγR function was evaluated by human IgG1 and IgG3 IC-binding and TNFα stimulated release. Plasma levels of soluble FcRs (sFcRs) were determined with ELISA.

RESULTS

The IgG1 and IgG3 levels were elevated in the RA sera. The RA monocytes expressed more CD64 and cell surface-bound IgG than HC monocytes, and showed an impaired FcγR function as reflected by changes in IC-binding and decreased IC-stimulated TNFα secretion. These findings correlated significantly with different disease activity markers. Furthermore, sFcRs were elevated in the patient plasma, and sCD64 was specific for RA (compared with a reference group of patients with active psoriatic arthritis). Following treatment, immunoglobulins and sFcR levels were reduced, whereas membrane CD64 was only decreased in patients with good response to treatment.

CONCLUSIONS

Early RA patients display increased membrane and soluble CD64 and an impaired FcγR function correlating with joint disease activity. Beneficial responses of anti-rheumatic treatment in patients reduce CD64. These data suggest sCD64 as an important objective biomarker in RA.

The clinical course of acute pancreatitis and the inflammatory mediators that drive it

Acute pancreatitis (AP) is a common emergency condition. In the majority of cases, it presents in a mild and self-limited form. However, about 20% of patients develop severe disease with local pancreatic complications (including necrosis, abscess, or pseudocysts), systemic organ dysfunction, or both. A modern classification of AP severity has recently been proposed based on the factors that are causally associated with severity of AP. These factors are both local (peripancreatic necrosis) and systemic (organ failure). In AP, inflammation is initiated by intracellular activation of pancreatic proenzymes and/or nuclear factor-κB. Activated leukocytes infiltrate into and around the pancreas and play a central role in determining AP severity. Inflammatory reaction is first local, but may amplify leading to systemic overwhelming production of inflammatory mediators and early organ failure. Concomitantly, anti-inflammatory cytokines and specific cytokine inhibitors are produced. This anti-inflammatory reaction may overcompensate and inhibit the immune response, rendering the host at risk for systemic infection. Currently, there is no specific treatment for AP. However, there are several early supportive treatments and interventions which are beneficial. Also, increasing the understanding of the pathogenesis of systemic inflammation and the development of organ dysfunction may provide us with future treatment modalities.

Clinical observation of immunity for severe acute pancreatitis

The aim of our study was to observe the dynamic changes of immunity for patients with severe acute pancreatitis (SAP) and intervention by traditional Chinese medicine. Twenty-three patients who met the inclusion criteria were randomized to combined treatment of traditional Chinese medicine and Western medicine (TCM) or conventional western medicine treatment (WM) groups. The clinical data for all patients were collected. Peripheral venous blood samples were obtained from patients on days 1, 7, 14, and 28 after admission. Biochemical data including the percentage of CD4+/CD8+/natural killer (NK) cells/B lymphocytes/HLA-DR and CD4+/CD8+ ratio in serum were determined by flow cytometer. Patients' characteristics and immunity at admission were similar between the two groups. The secondary infection was different. The levels of T-lymphocyte subsets in the TCM group were quite different from the WM group, with much more the percentage of CD4+ and the CD4+/CD8+ ratio on days 7, 14, and 28 and much less the percentage of CD8+ on days 4 and 28. On days 14 and 28, the levels of NK cells and B lymphocytes were significantly higher in the TCM group compared with the controls. Compared with the TCM group, the levels of HLA-DR were significantly decreased in the WM group on days 7, 14, and 28. The immune dysregulation exists in the development and progression of SAP. The combined treatment of traditional Chinese medicine and western medicine can upregulate the patient's immune and maintain the immune balance.

mRNA-based approach to monitor recombinant gamma-interferon restoration of LPS-induced endotoxin tolerance

Introduction

It is now well accepted that sepsis is associated with the development of a pronounced immunosuppressive state, characterized by severe immune alterations (e.g. reduced proliferative capacity, endotoxin tolerance, apoptosis) participating in increased mortality and susceptibility to nosocomial infections. Efforts are currently aimed at restoring a functional immune response in septic patients. Successful therapy depends on the identification of appropriate immunostimulatory drugs and on the development of suitable biomarkers that could be used to stratify patients and to follow response to treatment.

Methods

In this study, we evaluated the ex vivo effect of recombinant interferon gamma (rIFN-γ) in restoring monocyte functionality (endotoxin-induced Tumor Necrosis Factor-α production) in a two-hit model of endotoxin tolerance (ET) with peripheral blood mononuclear cells from healthy volunteers and in whole blood of septic shock patients. Importantly, we used quantitative-reverse transcription polymerase-chain reaction to monitor the effect of rIFN-γ on the expression of seven genes known to participate in ET (TNF-α, IL-10, HLA-DRA, CIITA, IRAK-M, ABIN-3 and LY64).

Results

Expression analysis of those genes confirmed the presence of an immunosuppression state and the ex vivo restoration of immune functions by rIFN-γ. We show for the first time that rIFN-γ is able to bypass, at the mRNA level, the effect of negative regulators of the LPS signalling pathway such as IRAK-M, ABIN-3 and LY64.

Conclusions

Overall, mRNA expressions of a panel of genes could represent promising candidates for the ex vivo evaluation of rIFN-γ effect on monocyte functionality. This ex vivo translational research study demonstrates the potential of a mRNA-based approach to successfully monitor drug efficacy.

Immunomodulation in sepsis: state of the art and future perspective

Despite advances in supportive care of critically ill patients, sepsis remains an important cause of death worldwide. More than 750,000 individuals develop severe sepsis in North America annually, with a mortality rate varying between 35 and 50%. Over recent years, numerous efforts have been committed to understanding the pathophysiology of septic syndrome, as well as attempts to intervene in the inflammatory cascade with the aim of altering the outcome of the syndrome and to improve survival. Not all of these attempts have been successful. Issued guidelines by the International Sepsis Forum have incorporated only the use of corticosteroids, tight glycemic control and the use of recombinant activated protein C as recommendations for the management of the septic patient along with the initial resuscitation and infection-site control measures. These strategies along, with novel attempts of immunomodulation, are thoroughly reviewed in this article.

Patients with acute pancreatitis complicated by organ failure show highly aberrant monocyte signaling profiles assessed by phospho-specific flow cytometry

OBJECTIVES

To outline signaling profiles and transmigration capacity of monocytes of patients with severe acute pancreatitis.

DESIGN

Prospective study.

SETTING

University hospital intensive care unit.

PATIENTS

Thirteen patients with severe acute pancreatitis. All patients had organ dysfunction (acute respiratory distress syndrome in 12, renal dysfunction in eight). Healthy volunteers served as reference subjects.

INTERVENTIONS

Blood samples were collected after admission to the intensive care unit.

MEASUREMENTS AND MAIN RESULTS

Phosphorylation of nuclear factor-kappaB and p38, signal transducers and activators of transcription (STATs) 1, 3, 5, and extracellular signal-regulated kinases 1/2 in appropriately stimulated and nonstimulated samples were studied using phospho-specific whole-blood flow cytometry. Monocyte chemotactic protein-1-induced transmigration of monocytes among mononuclear cells obtained by density gradient centrifugation was studied using Transwell cell culture inserts covered with confluent layer of endothelial EA-HY cells. Phosphorylation levels of nuclear factor-kappaB induced by tumor necrosis factor, bacterial lipopolysaccharide, muramyl dipeptide, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis were significantly lower in patients' monocytes than monocytes of healthy reference subjects, whereas mitogen-activated protein kinase p38 phosphorylation levels were normal. Phosphorylation levels induced by interleukin-6 in STAT1 and STAT3 and by combination of phorbol 12-myristate 13-acetate and calcium ionophore A23187 in extracellular signal-regulated kinases 1/2, members of a mitogen-activated protein kinase family, were depressed in patients' monocytes, whereas phosphorylation levels induced by granulocyte-macrophage colony-stimulating factor in STAT5 was normal. In nonstimulated samples, phosphorylation levels were normal. The transmigration percentage of patients' monocytes was significantly lower than that of reference monocytes.

CONCLUSIONS

In severe acute pancreatitis, monocytes show impaired nuclear factor kappaB and STAT1 activation, which may increase susceptibility to secondary infections. p38 activation is normal and STAT3 activation is depressed, which may contribute to maintenance of systemic inflammation. Extracellular signal-regulated kinases 1/2 activation is impaired, which may depress monocytes' transmigration and may consequently increase risk of infection. Monitoring of monocyte signaling profiles may aid in finding new therapeutic approaches and predictors of outcome of severe acute pancreatitis.

Inflammation and immunosuppression in severe acute pancreatitis

Acute pancreatitis (AP) is a common disease, which usually exists in its mild form. However, in a fifth of cases, the disease is severe, with local pancreatic complications or systemic organ dysfunction or both. Because the development of organ failure is the major cause of death in AP, early identification of patients likely to develop organ failure is important. AP is initiated by intracellular activation of pancreatic proenzymes and autodigestion of the pancreas. Destruction of the pancreatic parenchyma first induces an inflammatory reaction locally, but may lead to overwhelming systemic production of inflammatory mediators and early organ failure. Concomitantly, anti-inflammatory cytokines and specific cytokine inhibitors are produced. This anti-inflammatory reaction may overcompensate and inhibit the immune response, rendering the host at risk of systemic infection. At present, there is no specific treatment for AP. Increased understanding of the pathogenesis of systemic inflammation and development of organ dysfunction may provide us with drugs to ameliorate physiological disturbances.

Advances in researches on the immune dysregulation and therapy of severe acute pancreatitis

During the development and progression of severe acute pancreatitis (SAP), conspicuous immune dysregulation develops, which is mainly manifested as excessive immune response in the early stage and immunosuppression in the late stage. This process involves complex changes in a variety of immune molecules and cells, such as cytokines, complements, lymphocytes, and leukocytes. With the gradual deepening of studies on the development and progression of SAP, the role of immune dysregulation in the pathogenesis of SAP has attracted more and more attention. In this article, we review the advances in research on the immune dysregulation in SAP and the immunotherapy of this disease through exploring the formation of excessive immune response and immune suppression as well as their mutual transformation.

CpG oligonucleotides activate the immune response in burned mice

BACKGROUND

Immunosuppression after burn injury increases the risk of sepsis and multiple organ failure. We examined changes of immune function in mice after burn injury and investigated the immunostimulatory effect of oligodeoxynucleotides containing CpG motifs.

MATERIALS AND METHODS

Male BALB/c mice (8-10 wk old) received a full-thickness burn to 20% of their body surface area, after which the immunological parameters of splenic macrophages were evaluated. To assess the immunostimulatory effect of oligodeoxynucleotide treatment, splenic macrophages harvested from burned mice were incubated with oligodeoxynucleotides. Then cytokine production and major histocompatibility complex class II antigen expression were measured. To assess the in vivo effect of oligodeoxynucleotides, intraperitoneal administration was done on day 4 after burn injury, and class II antigen expression by splenic macrophages was measured 10 d later.

RESULTS

Class II antigen expression and the synthesis of cytokines (interleukin-12, tumor necrosis factor-alpha, interleukin-6, and interleukin-1) by splenic macrophages were significantly reduced after burn injury, while incubation of splenic macrophages from burned mice with oligodeoxynucleotides partially enhanced the production of interleukin-12, tumor necrosis factor-alpha, interleukin-6, and interleukin-1. In addition, intraperitoneal administration of oligodeoxynucleotides enhanced class II antigen expression by splenic macrophages.

CONCLUSIONS

The reduction of class II antigen expression and synthesis of cytokines (interleukin-12, tumor necrosis factor-alpha, interleukin-6, and interleukin-1) by splenic macrophages after burn injury was partially reversed by oligodeoxynucleotide treatment. Therefore, immunostimulatory oligodeoxynucleotides may be a potential treatment for post-burn immunosuppression.

Differential preservation of lipopolysaccharide-induced chemokine/cytokine expression during experimental pancreatitis-associated organ failure in rats shows a regulatory expressed phenotype

BACKGROUND

Altered lipopolysaccharide (LPS)-responsiveness is a key feature of acute pancreatitis (AP)-associated multiple organ failure (AP-MOF) in rats and humans.

AIM

To determine the differential expression of 16 cytokines and chemokines in response to delayed LPS administration in established experimental AP-MOF in rats.

METHODS

In a cubic factorial group design (12 groups, n = 6 rats/group), 0, 6 and 30 microg/kg Escherichia coli 0111:B4 LPS was administered intra-arterially, 18 h into experimental AP-MOF or sham laparotomy. AP was induced by intraductal glycodeoxycholic acid and intravenous caerulein. Central venous serum concentrations of 16 cytokines and chemokines were measured by Searchlight multiplex ELISA.

RESULTS

Four patterns were observed: (1) TNF-alpha, IL-1alpha, IL-1beta, IL-6, IFN-gamma, MCP-1, MIP-2alpha, MIP-3alpha, fractalkine and RANTES showed a diminished LPS response in AP versus sham (p < 0.001, ANOVA); (2) IL-2, IL-4 and GM-CSF levels were undetectable; (3) CINC-2alpha and GRO/KC showed little or no difference between AP and controls, and (4) IL-10 concentrations after 0 and 6 microg/kg, but not 30 microg/kg LPS injection were significantly higher in AP than controls (p < 0.001, ANOVA).

CONCLUSION

Experimental AP-MOF in rats results in differential preservation of the cytokine and chemokine response to LPS challenge, with a predominantly regulatory expressed phenotype.

Diversity of interferon gamma and granulocyte-macrophage colony-stimulating factor in restoring immune dysfunction of dendritic cells and macrophages during polymicrobial sepsis

The development of immunosuppression during polymicrobial sepsis is associated with the failure of dendritic cells (DC) to promote the polarization of T helper (Th) cells toward a protective Th1 type. The aim of the study was to test potential immunomodulatory approaches to restore the capacity of splenic DC to secrete interleukin (IL) 12 that represents the key cytokine in Th1 cell polarization. Murine polymicrobial sepsis was induced by cecal ligation and puncture (CLP). Splenic DC were isolated at different time points after CLP or sham operation, and stimulated with bacterial components in the presence or absence of neutralizing anti-IL-10 antibodies, murine interferon (IFN) gamma, and/or granulocyte macrophage colony-stimulating factor (GM-CSF). DC from septic mice showed an impaired capacity to release the pro-inflammatory and Th1-promoting cytokines tumor necrosis factor alpha, IFN-gamma, and IL-12 in response to bacterial stimuli, but secreted IL-10. Endogenous IL-10 was not responsible for the impaired IL-12 secretion. Up to 6 h after CLP, the combined treatment of DC from septic mice with IFN-gamma and GM-CSF increased the secretion of IL-12. Later, DC from septic mice responded to IFN-gamma and GM-CSF with increased expression of the co-stimulatory molecule CD86, while IL-12 secretion was no more enhanced. In contrast, splenic macrophages from septic mice during late sepsis responded to GM-CSF with increased cytokine release. Thus, therapy of sepsis with IFN-gamma/GM-CSF might be sufficient to restore the activity of macrophages, but fails to restore DC function adequate for the development of a protective Th1-like immune response.

Monocyte subsets and natural killer cells in acute pancreatitis

BACKGROUND

Alteration of the immune system is one of the major mechanisms responsible for complications in severe acute pancreatitis (AP). The aim of our study was to provide a complex evaluation of peripheral blood monocyte subsets, natural killer cells (NK cells) and cytotoxic T lymphocytes in patients with different severity forms of AP.

METHODS

20 patients with mild AP and 15 with severe AP (S-AP) were included in our study. Peripheral blood mononuclear cells were studied on days 1-3, 5, 10 and 30, by means of flow cytometry.

RESULTS

In peripheral blood of patients with pancreatitis, we found a marked increase in total monocyte count. In S-AP, circulating monocytes were significantly activated, which was presumed from increased expression of HLA-DR, CD54, CD69 and CD25. Concurrent increased expression of CD95 (FasR) may indicate enhanced susceptibility of these cells to apoptosis. In patients with S-AP, a dramatic depletion of circulating NK cells (CD16/56 and CD3- CD8+) was found along with a reduction of circulating CD3+ CD8+ lymphocytes (cytotoxic T lymphocytes).

CONCLUSION

Our findings suggest profound disturbances of innate cellular immunity in patients with S-AP.

Cytokine profiles in acute liver failure treated with albumin dialysis

Cytokines are released within the liver in response to hepatic injury, and acute liver failure (ALF) triggers systemic inflammation. Pro-inflammatory (tumor necrosis factor-alpha [TNF-alpha] and interleukin-8 [IL-8]) and anti-inflammatory (interleukin-10 [IL-10] and interleukin-6 [IL-6]) cytokines and the lymphocyte activation marker (interleukin-2-soluble receptor alpha chain [IL-2sRalpha]) were monitored in 49 ALF patients considered for liver transplantation and treated with albumin dialysis (molecular adsorbent recirculating system [MARS]). Twenty-six patients were categorized by clinical outcome as "good" (native liver recovered) and 23 as "poor" (patient bridged to liver transplantation or deceased). MARS did not clearly affect cytokine profiles during treatment; only IL-10 levels decreased in the whole patient population and mostly in patients with the worst prognosis. In the good outcome group, IL-8 and IL-6 levels decreased during treatment; on the contrary, in poor outcome patients IL-6 levels even increased. Initial IL-2sRalpha levels were higher in poor outcome patients relative to the good outcome subset. Cytokine profiles seem to differ in ALF according to patient outcome. A deeper understanding of cytokine patterns during pathogenesis could reveal prognostic markers and aid the development of immunomodulating ALF therapies.

Early inflammatory response in acute pancreatitis is little affected by body mass index

OBJECTIVE

Obesity is a known risk factor for severe acute pancreatitis (AP), but the mechanism by which it affects the severity of AP is not fully understood. The main objective of this study was to investigate the relationship between obesity and inflammatory markers in AP.

MATERIAL AND METHODS

Thirty patients with AP who developed organ failure (Group I) and 87 patients with AP who survived without organ failure (Group II) were studied. Patients' height and weight were measured at admission for calculation of body mass index (BMI). Blood samples were taken at admission for measurement of plasma interleukin (IL)-1beta, IL-6, IL-10, IL-1 receptor antagonist, procalcitonin, C-reactive protein (CRP) and monocyte human leucocyte antigen (HLA)-DR expression.

RESULTS

Group I patients had higher BMI values (median 26.2 kg/m2) than Group II patients (25.2 kg/m2), p =0.033. Both CRP values and monocyte HLA-DR expression showed a significant correlation with BMI (Spearman's rank correlation r=0.32, p =0.003 and r= -0.33, p = 0.002, respectively). The correlation between BMI and monocyte HLA-DR expression was significant in Group II patients (r = -0.34, p =0.002) but not in Group I patients (r = -0.02, p >0.05). There was no correlation between BMI and IL-1beta, IL-6, IL-10, IL-1 receptor antagonist or procalcitonin.

CONCLUSIONS

BMI did not affect either proinflammatory or anti-inflammatory cytokine levels in early AP. However, in patients with mild AP, BMI correlated positively with CRP levels and inversely with monocyte HLA-DR expression, which might reflect an amplified inflammatory response in these patients. Taken together, acute inflammatory response in AP, which ultimately determines the severity of AP, was little affected by BMI.

Predicting severity of acute pancreatitis

Severity stratification is a critical issue in acute pancreatitis that strongly influences diagnostic and therapeutic decision making. According to the widely used Atlanta classification, "severe" disease comprises various local and systemic complications that are associated with an increased risk of mortality. However, results from recent clinical studies indicate that these complications vary in their effect on outcome, and many are not necessarily life threatening on their own. Therefore, "severe," as defined by Atlanta, must be distinguished from "prognostic," aiming at nonsurvival. In the first week after disease onset, pancreatitis-related organ failure is the preferred variable for predicting severity and prognosis because it outweighs morphologic complications. Contrast-enhanced CT and MRI allow for accurate stratification of local severity beyond the first week after symptom onset. Among the biochemical markers, C-reactive protein is still the parameter of choice to assess attack severity, although prognostic estimation is not possible. Other markers, including pancreatic protease activation peptides, interleukins-6 and -8, and polymorphonuclear elastase are useful early indicators of severity. Procalcitonin is one of the most promising single markers for assessment of major complications and prognosis throughout the disease course.

Effect of somatostatin on immune inflammatory response in patients with severe acute pancreatitis

OBJECTIVE

Somatostatin regulates immune inflammatory response via apoptosis and adhesion of leukocytes in many diseases. This article reported a study that aimed to observe the mechanism and effect of somatostatin on the immune inflammatory response through apoptosis and adhesion of leukocytes in severe acute pancreatitis.

METHODS

Thirty-eight patients with severe acute pancreatitis, that fulfilled the guidelines for the treatment of severe acute pancreatitis of China and Balthazar computed tomography severity index (>or=5) were enrolled consecutively. Nineteen of these patients received our routine treatment and 19 received additional somatostatin. In all patients the expressions of CD4, CD8, CD95/CD95 ligand and CD18/CD62 ligand on leukocytes were determined by flow cytometry, both upon admission and on the fourth day. Thirty healthy volunteers constituted the normal healthy group.

RESULTS

In the treatment group, CD4, CD4:CD8 ratio and CD62 ligand on leukocytes increased from 11.4+/-8.2, 0.47+/-0.10 and 25.5+/-9.2 to 22.1+/-9.7, 0.68+/-0.11 and 36.2+/-11.7 (P<0.05) respectively, while CD95 ligand on both lymphocyte and polymorphonuclear cells increased from 0.65+/-0.21 and 0.76+/-0.29 to 1.18+/-0.32 and 1.58+/-0.43 after treatment with somatostatin (P<0.05). Furthermore, lactate dehydrogenase, aspartate aminotransferase, amylase, C reactive protein and acute physiology and chronic healthy evaluation (APACHE II) score in the treatment group reduced faster than those in the control group (P<0.05), though there was no difference in mortality (15.7% vs 5.3%) between the two patient groups (P>0.05).

CONCLUSION

Somatostatin can modulate the immune inflammatory response and the severity of severe acute pancreatitis through apoptosis and adhesion of leukocytes, but this modulatory effect by itself is not strong enough to improve the final.

Effects of immunosuppressive and immunostimulative treatment on pancreatic injury and mortality in severe acute experimental pancreatitis

OBJECTIVES

Acute pancreatitis is associated with substantial alterations of the immunologic host response which has been claimed to promote remote organ dysfunction, septic complications, and mortality. Treatment with immunomodulating substances has been subject of few experimental studies with still conflicting results.

METHODS

We used the taurocholate-induced model of severe acute pancreatitis (SAP) in rats which were assigned to different treatment regimen: isotonic saline (SAP-S) for nontreated controls, recombinant rat interferon-gamma for immunostimulation (SAP-IFN-gamma), and FK506 for immunosuppression (SAP-FK506). Animals were killed after 3, 6, and 24 hours as well as 3 and 7 days, and parameters of local and systemic severity were assessed.

RESULTS

Treatment with IFN-gamma and FK506 attenuated the progression of intrapancreatic necrosis within the first 24 hours after pancreatitis induction along with a substantial reduction of subsequent neutrophil tissue infiltration as shown by decreased myeloperoxidase activity. Enhanced cell death by apoptosis during the postacute course was reduced in FK506-treated animals only. Pancreatic interleukin (IL) 1beta messenger RNA up-regulation occurred early and was slightly suppressed in both treatment groups; tumor necrosis factor alpha (TNF-alpha) and IL-2 messenger RNA expression paralleled the onset of apoptosis and was markedly decreased in IFN-gamma- and FK506-treated rats. The 2 therapeutic regimens had similar effects on intrapancreatic and systemic IL-1beta and TNF-alpha protein release; however, the profiles of both cytokines were differently influenced. Whereas IFN-gamma and FK506 treatment lead to an enhanced intrapancreatic and systemic TNF-alpha protein release during the early course, IL-1beta concentrations were significantly reduced within the late intervals. Seven-day mortality was 44% in saline-, 29% in IFN-gamma-, and 25% in FK506-treated rats (P = not significant).

CONCLUSIONS

Severe acute pancreatitis is associated with early alterations of the immune response comprising overt T-cell activation and impaired monocyte/macrophage function alike. Targeting either immunologic derangement improves local pancreatic damage and systemic severity. However, because mortality was not improved, a therapeutic benefit of immunomodulating substances in clinical SAP remains to be defined.