Leucocyte response and anti-inflammatory cytokines in community acquired pneumonia

A Review on Risk Factors, Traditional Diagnostic Techniques, and Biomarkers for Pneumonia Prognostication and Management in Diabetic Patients

People of all ages can contract pneumonia, and it can cause mild to severe disease and even death. In addition to being a major cause of death for elderly people and those with prior medical conditions such as diabetes, it isthe world's biggest infectious cause of death for children. Diabetes mellitus is a metabolic condition with a high glucose level and is a leading cause of lower limb amputation, heart attacks, strokes, blindness, and renal failure. Hyperglycemia is known to impair neutrophil activity, damage antioxidant status, and weaken the humoral immune system. Therefore, diabetic patients are more susceptible to pneumonia than people without diabetes and linked fatalities. The absence of quick, precise, simple, and affordable ways to identify the etiologic agents of community-acquired pneumonia has made diagnostic studies' usefulness contentious. Improvements in biological markers and molecular testing techniques have significantly increased the ability to diagnose pneumonia and other related respiratory infections. Identifying the risk factors for developing severe pneumonia and early testing in diabetic patients might lead to a significant decrease in the mortality of diabetic patients with pneumonia. In this regard, various risk factors, traditional testing techniques, and pathomechanisms are discussed in this review. Further, biomarkers and next-generation sequencing are briefly summarized. Finding biomarkers with the ability to distinguish between bacterial and viral pneumonia could be crucial because identifying the precise pathogen would stop the unnecessary use of antibiotics and effectively save the patient's life.

The Potential Use of Saliva as a Biofluid for Systemic Inflammatory Response Monitoring in Children with Pneumonia

OBJECTIVE

To investigate the levels of C-reactive protein, procalcitonin, calprotectin, interleukin 1 beta (IL-1β), IL-6, and tumor necrosis factor-alpha (TNF-α) in both saliva and serum in children with community-acquired pneumonia and to compare the saliva response with the systemic response.

METHODS

Forty hospitalized children with community-acquired pneumonia aged between 1 mo and 15 y; and 40 healthy controls were included. Both serum and saliva samples were collected on admission and at the time of discharge.

RESULTS

Calculated differences between values for each serum and salivary parameter on admission and before discharge named delta (Δ) values were used for correlation analysis. Salivary Δ values of each parameter were moderately/strongly correlated with their corresponding serum Δ levels [IL-1β ÷ (r = 0.554, p < 0.001); IL-6 ÷ (r = 0.484, p = 0.002); PCT ÷ (r = 0.737, p < 0.001); TNF-α ÷ (r = 0.587, p < 0.001); CRP ÷ (r = 0.703, p < 0.001); and calprotectin ÷ (r = 0.774, p < 0.001)].

CONCLUSIONS

This study will evaluate the reflection of systemic changes in saliva and the efficacy of saliva in pediatric patients with pneumonia. Results will highlight saliva potential use as a biofluid for systemic monitoring in this patient group.

Inflammatory and healing environment in synovial fluid after anterior cruciate ligament reconstruction: Granulocytes and endogenous opioids as new targets of postoperative pain

Background

Biological processes after anterior cruciate ligament reconstruction (ACLR) is crucial for recovery. However, alterations in the of synovial fluid cell population during the acute phase following ACLR and the relationship between these cells and postoperative pain is unclear. The goal of this study was to reveal alterations in synovial fluid cell population during the acute phase following ACLR and relationship between postoperative pain and proportion of synovial fluid cells.

Methods

Synovial fluids were obtained from all patients (n = 50) before surgery and from patients who showed hydrarthrosis at days 4 (n = 25), and 21 (n = 42) post-surgery. The cell population was analyzed by flow cytometry. IL1β, IL8, and met-enkephalin in synovial fluid were quantitated by enzyme-linked immunosorbent assay. Patients answered numerical rating scale (NRS) questionnaire at 4 days and approximately 4 weeks postoperatively.

Results

The granulocyte population was significantly higher at 4 days after surgery than at any other time points. The population of macrophages was 3.2 times and 7.7 times as high as at surgery on days 4 and 21, respectively. T cell population was significantly higher 21 days after surgery compared to 4 days after surgery. All NRS 4 weeks after surgery showed a significant negative correlation with the granulocyte population in synovial fluid 4 days after surgery. Granulocyte population in synovial fluid significantly correlated with the levels of IL1β and IL8. Postoperative pain at rest tended to decrease with an increase in met-enkephalin concentration 4 days after ACLR.

Conclusions

Synovial fluid after ACLR had an inflammatory environment at early time points and a healing environment in the subsequent phase about concerning to the cellular composition. A proportion of synovial fluid cells and endogenous opioids affected postoperative pain.

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Granulocyte population was higher at 4 days after ACLR than at other time points.

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Postoperative pain negatively correlated with the granulocyte in synovial fluid.

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Granulocyte population in synovial fluid correlate with IL1β and IL8 concentration.

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Postoperative pain tended to decrease with an increase in met-enkephalin.

Investigation of type I interferon responses in ANCA-associated vasculitis

Type I interferon (IFN) dysregulation is a major contributory factor in the development of several autoimmune diseases, termed type I interferonopathies, and is thought to be the pathogenic link with chronic inflammation in these conditions. Anti-neutrophil cytoplasmic antibody (ANCA)-Associated Vasculitis (AAV) is an autoimmune disease characterised by necrotising inflammation of small blood vessels. The underlying biology of AAV is not well understood, however several studies have noted abnormalities in type I IFN responses. We hypothesised that type I IFN responses are systemically dysregulated in AAV, consistent with features of a type I interferonopathy. To investigate this, we measured the expression of seven interferon regulated genes (IRGs) (ISG15, SIGLEC1, STAT1, RSAD2, IFI27, IFI44L and IFIT1) in peripheral blood samples, as well as three type I IFN regulated proteins (CXCL10, MCP-1 and CCL19) in serum samples from AAV patients, healthy controls and disease controls. We found no difference in type I IFN regulated gene or protein expression between AAV patients and healthy controls. Furthermore, IRG and IFN regulated protein expression did not correlate with clinical measurements of disease activity in AAV patients. Thus, we conclude that systemic type I IFN responses are not key drivers of AAV pathogenesis and AAV should not be considered a type I interferonopathy.

Disease burden and prognostic factors for clinical failure in elderly community acquired pneumonia patients

BACKGROUND

The study was to evaluate initial antimicrobial regimen and clinical outcomes and to explore risk factors for clinical failure (CF) in elderly patients with community-acquired pneumonia (CAP).

METHODS

3011 hospitalized elderly patients were enrolled from 13 national teaching hospitals between January 1, 2014 and December 31, 2014 initiated by the CAP-China network. Risk factors for CF were screened by multivariable logistic regression analysis.

RESULTS

The incidence of CF in elderly CAP patients was 13.1%. CF patients were older, longer hospital stays and higher treatment costs than clinical success (CS) patients. The CF patients were more prone to present hyperglycemia, hyponatremia, hypoproteinemia, pleural effusion, respiratory failure and cardiovascular events. Inappropriate initial antimicrobial regimens in CF group were significantly higher than CS group. Undertreatment, CURB-65, PH < 7.3, PaO2/FiO2 < 200 mmHg, sodium < 130 mmol/L, healthcare-associated pneumonia, white blood cells > 10,000/mm3, pleural effusion and congestive heart failure were independent risk factors for CF in multivariable logistic regression analysis. Male and bronchiectasis were protective factors.

CONCLUSIONS

Discordant therapy was a cause of CF. Early accurate detection and management of prevention to potential causes is likely to improve clinical outcomes in elderly patients CAP.

TRIAL REGISTRATION

A Retrospective Study on Hospitalized Patients With Community-acquired Pneumonia in China (CAP-China) (RSCAP-China), NCT02489578. Registered 16 March 2015, https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S0005E5S&selectaction=Edit&uid=U0000GWC&ts=2&cx=1bnotb.

Comparison of clinical characteristics and inflammatory cytokines between hypoxemic and non-hypoxemic human adenovirus 55 pneumonia

Background

Human adenovirus (HAdV) can cause severe community-acquired pneumonia, but there are few studies on the associated cytokine patterns. The purpose of this study was to analyze the relationship between inflammatory cytokine and severity of adenovirus pneumonia.

Methods

This was a prospective observational study. We evaluated pneumonia patients admitted to the Armed Forces Capital Hospital in Korea. On admission, blood samples were acquired from patients who showed signs of pneumonia. HAdV infection was diagnosed using Real-Q RV detection Kit, and types of HAdV were confirmed by nucleotide blast analysis. We used enzyme-linked immunosorbent assays (ELISAs) to quantify the serum levels of cytokines [interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α, γ-interferon (IFN-γ), and IL-10]. We evaluated clinical characteristics and cytokine patterns.

Results

Of 74 pneumonia patients, respiratory specimens from 43 tested positive for HAdV-55, and the other 31 tested negatives. The length of hospital stay was significantly longer in the HAdV group. The serum concentrations of IL-6, IL-8, IL-10, and IFN-γ were all significantly higher in the HAdV group. Of the 43 HAdV pneumonia patients, 6 evidenced PaO₂/FiO₂ (PF) ratio <300, and 37 did not. Compared to the non-hypoxemic group, the hypoxemic group showed significantly lower lymphocyte and monocyte counts, and increased IL-6 and IFN-γ concentrations. Logistic regression analysis showed that the IL-6, IL-10, and IFN-γ were significantly associated with hypoxemia in the HAdV group. The IL-6, and IFN-γ levels correlated significantly with the PF ratio.

Conclusions

We found that the levels IL-6, IL-10, and IFN-γ were significantly associated with hypoxemia in patients with HAdV-55 pneumonia.

Expression Levels of Interferon Regulatory Factor 5 (IRF5) and Related Inflammatory Cytokines Associated with Severity, Prognosis, and Causative Pathogen in Patients with Community-Acquired Pneumonia

Background

Community-acquired pneumonia (CAP) is a common disease with significant morbidity and mortality. Interferon regulatory factor 5 (IRF5), which induces type I interferons (IFNs) and cytokines such as interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-10, and interferon gamma-induced protein (IP)10, is a key transcription factor involved in controlling the expression of proinflammatory cytokines and responses to infection. Here, we carefully investigated the role of IRF5 in regulating immune responses to CAP.

Material/Methods

QRT-PCR was used to detect the mRNA levels of IRF5, IL-6, IL-10, IP10, TNF-α, and IFN-α in the peripheral blood of 71 CAP patients and 31 healthy controls, as well as in the bronchoalveolar lavage cells of 20 patients with CAP and 23 patients with lung cancer (using samples from the unaffected lung). Flow cytometry was performed to detect the protein level of IRF5, and a CBA flex set was used to detect the levels of these cytokines in the volunteers.

Results

The expression levels of IRF5 and its related cytokines were significantly increased in CAP patients compared with the controls. Additionally, IRF5, IL-6, IL-10, and IP10 levels were found to be related with the severity of CAP. Furthermore, the levels of IRF5 and IFN-α increased significantly in the early phase of pneumonia caused by influenza virus infection.

Conclusions

IRF5 and its related inflammatory cytokines are associated with the severity, prognosis, and causative pathogen of CAP patients. This finding may provide new drug targets for the prevention and treatment of severe pneumonia caused by influenza virus.

Cytokine kinetic profiles in children with acute lower respiratory tract infection: a post hoc descriptive analysis from a randomized control trial

OBJECTIVES

Standard inflammatory markers and chest radiography lack the ability to discriminate bacterial from non-bacterial lower respiratory tract infection (LRTI). Cytokine profiles may serve as biomarkers for LRTI, but their applicability to identify aetiology, severity of disease and need for antibiotic prescription in children remains poorly defined. Objectives were to determine the cytokine kinetic profiles over 5 days in paediatric patients with LRTI, to investigate the relationship between cytokine patterns, and clinical and laboratory variables.

METHODS

We included patients aged 1 month to 18 years, with febrile LRTI and three consecutive cytokines measurements on days 1, 3 and 5 of a randomized controlled trial (ProPAED study). We evaluated differences in cytokine concentrations between days and associations with clinical and laboratory variables.

RESULTS

A total of 181 patients (median age 4.1 years) were included; 72/181 (40%) received antibiotics. Serum concentrations of interferon (IFN)-γ, interleukin (IL)-1ra, IL-6, IL-10, IFN-γ-inducible protein (IP)-10 and tumor necrosis factor-α were elevated on day 1 and decreased subsequently, with the greatest decline between day 1 and 3 (by -8 to >-94%). Procalcitonin (PCT) and C-reactive protein (CRP) values showed a protracted decrease with the most prominent reduction in concentrations between days 3 and 5. Significantly elevated IL-6 concentrations were associated with hospital admission, antibiotic treatment, and prolonged antibiotic treatment. Bacteraemic LRTI patients had higher concentrations of IL-1ra (p <0.0055) and IL-6 (p <0.0055) on day 1.

CONCLUSIONS

We observed an earlier decrease of elevated cytokines compared to PCT or CRP. Both pro- and anti-inflammatory cytokines may serve as markers for severity of LRTI.

Cytokine responses, microbial aetiology and short-term outcome in community-acquired pneumonia

BACKGROUND

The inflammatory response to community-acquired pneumonia (CAP) is orchestrated through activation of cytokine networks and the complement system. We examined the association of multiple cytokines and the terminal complement complex (TCC) with microbial aetiology, disease severity and short-term outcome.

MATERIALS AND METHODS

Plasma levels of 27 cytokines and TCC were analysed in blood samples obtained at hospital admission, clinical stabilization and 6-week follow-up from 247 hospitalized adults with CAP. Fourteen mediators were included in final analyses. Adverse short-term outcome was defined as intensive care unit (ICU) admission and 30-day mortality.

RESULTS

Cytokine and TCC levels were dynamic in the clinical course of CAP, with highest levels seen at admission for most mediators. Admission levels of cytokines and TCC did not differ between groups of microbial aetiology. High admission levels of IL-6 (odds ratio [OR] 1.47, 95% confidence interval [CI] 1.18-1.84, P = .001), IL-8 (OR 1.79, 95% CI 1.26-2.55, P = .001) and MIP-1β (OR 2.28, 95% CI 1.36-3.81, P = .002) were associated with a CURB-65 severity score of ≥3, while IL-6 (OR 1.37, 95% CI 1.07-1.74, P = .011) and MIP-1β (OR 1.86, 95% CI 1.03-3.36, P = .040) were associated with a high risk of an adverse short-term outcome.

CONCLUSIONS

In this CAP cohort, admission levels of IL-6, IL-8 and MIP-1β were associated with disease severity and/or adverse short-term outcome. Still, for most mediators, only nonsignificant variations in inflammatory responses were observed for groups of microbial aetiology, disease severity and short-term outcome.

Utility of Assessing Cytokine Levels for the Differential Diagnosis of Pneumonia in a Pediatric Population

OBJECTIVES

Although pneumonia is easily diagnosed, determining the causative agent is difficult due to low pathogen detection rates. We performed a prospective observational study to evaluate the utility of measuring inflammatory cytokine levels to discriminate between pneumonia caused by typical bacteria, respiratory syncytial virus, or Mycoplasma pneumoniae in a pediatric population.

DESIGN

Serum inflammatory cytokine levels at early stages of the disease were evaluated for pneumonia caused by the three different pathogenic microorganisms.

SETTING

The Children's Hospital of Zhejiang University School of Medicine, China.

PATIENTS

One hundred sixty-six patients with bacterial pneumonia, 182 with M. pneumonia, and 167 with respiratory syncytial virus pneumonia.

MEASUREMENTS AND MAIN RESULTS

The levels of interleukin-6 for pneumonia were significantly higher with typical bacteria than with either Mycoplasma pneumoniae or respiratory syncytial virus (p < 0.001). The area under the curve for serum concentrations of interleukin-6 was 0.997. A serum interleukin-6 level of greater than or equal to 93.0 pg/mL had 100.0% sensitivity and 99.14% specificity in discriminating bacterial pneumonia from respiratory syncytial virus pneumonia and Mycoplasma pneumoniae pneumonia. The interleukin-6 levels were higher in patients with Mycoplasma pneumoniae pneumonia than in those with respiratory syncytial virus pneumonia (p < 0.001). They also simultaneously had lower interleukin-10 levels than patients with respiratory syncytial virus pneumonia who had interleukin-10 levels comparable to those of patients with bacterial pneumonia, indicating a significant difference in the interleukin-6/interleukin-10 ratio between patients with Mycoplasma pneumoniae pneumonia and respiratory syncytial virus pneumonia (median interleukin-6/interleukin-10 ratio, 2.5 vs 0.5; p < 0.001). At an optimal cut-off value of 0.8, the interleukin-6/interleukin-10 ratio showed 90.3% sensitivity and 88.0% specificity.

CONCLUSIONS

These results suggest that interleukin-6 is a good biomarker for identifying bacterial pneumonia and that the interleukin-6/interleukin-10 ratio is an effective biomarker for discriminating Mycoplasma pneumoniae pneumonia from respiratory syncytial virus pneumonia.

Plasma cytokines eotaxin, MIP-1α, MCP-4, and vascular endothelial growth factor in acute lower respiratory tract infection

Major overlaps of clinical characteristics and the limitations of conventional diagnostic tests render the initial diagnosis and clinical management of pulmonary disorders difficult. In this pilot study, we analyzed the predictive value of eotaxin, macrophage inflammatory protein 1 alpha (MIP-1α), monocyte chemoattractant protein 4 (MCP-4), and vascular endothelial growth factor (VEGF) in 40 patients hospitalized with acute lower respiratory tract infections (LRTI). The cytokines contribute to the pathogenesis of several inflammatory respiratory diseases, indicating a potential as markers for LRTI. Patients were stratified according to etiology and severity of LRTI, based on baseline C-reactive protein and CURB-65 scores. Using a multiplex immunoassay of plasma, levels of eotaxin and MCP-4 were shown to increase from baseline until day 6 after admission to hospital. The four cytokines were unable to predict the etiology and severity. Eotaxin and MCP-4 were significantly lower in patients with C-reactive protein ≥100, and MIP-1α was significantly higher in the patients with CURB-65 > 3, but the predictive power was low. In conclusion, further evaluation, including more patients, is required to assess the full potential of eotaxin, MCP-4, MIP-1α, and VEGF as biomarkers for LRTI because of their low predictive power and a high interindividual variation of cytokine levels.

Angiotensin-(1-7)/Mas Signaling Inhibits Lipopolysaccharide-Induced ADAM17 Shedding Activity and Apoptosis in Alveolar Epithelial Cells

A disintegrin and metalloproteinase (ADAM) 17, constitutively expressed in alveolar epithelium, is the pivotal shedding enzyme mediating acute lung inflammation. On the other hand, angiotensin (Ang)-(1-7)/Mas signaling has been shown to improve acute respiratory distress syndrome and protect alveolar epithelial cells from apoptosis. In this study, we explored the effect of Ang-(1-7)/Mas signaling on the expression and activity of ADAM17 and assessed its impact on apoptosis in lipopolysaccharide (LPS)-treated human alveolar epithelial cells. LPS markedly induced the shedding activity of ADAM17 in alveolar epithelial cells, which was blocked by selective c-Jun N-terminal kinase (JNK) inhibitor SP600125. Ang-(1-7) concentration-dependently inhibited LPS-induced ADAM17 shedding activity, which was abolished by selective Mas blocker A779 and Mas shRNA. LPS and Ang-(1-7) showed no significant effect on the expression of ADAM17. Overexpression of ADAM17 synergized with LPS on increasing the shedding activity of ADAM17 and apoptosis in alveolar epithelial cells, counteracting the inhibitory effects of Ang-(1-7). In addition, LPS significantly increased the JNK activity in alveolar epithelial cells; Ang-(1-7) concentration-dependently inhibited LPS-induced JNK activity, which was abolished by A779 and Mas shRNA. In conclusion, this study suggests that Ang-(1-7)/Mas signaling inhibits LPS-induced alveolar epithelial cell apoptosis by inhibiting LPS-induced shedding activity of ADAM17, likely by a JNK-dependent mechanism.

Contrasting inflammatory responses in severe and non-severe community-acquired pneumonia

The objective of this study was to compare systemic and local cytokine profiles and neutrophil responses in patients with severe versus non-severe community-acquired pneumonia (CAP). Hospitalized patients with CAP were grouped according to the pneumonia severity index (PSI), as non-severe (PSI < 91 points) or severe (PSI ≥ 91 points). Blood and sputum samples were collected upon admission. Compared to non-severe CAP patients, the severe CAP group showed higher plasma levels of pro- and anti-inflammatory cytokines but in contrast, lower sputum concentrations of pro-inflammatory cytokines. Blood neutrophil functional responses were elevated in CAP patients compared to healthy controls. However, neutrophils from severe CAP patients showed reduced respiratory burst activity compared to the non-severe group. Results indicate that patients with severe CAP fail to mount a robust local pro-inflammatory response but exhibit instead a more substantial systemic inflammatory response, suggesting that a key driver of CAP severity may be the ability of the patient to generate an optimal local inflammatory response.

ADAM-family metalloproteinases in lung inflammation: potential therapeutic targets

Acute and chronic lung inflammation is driven and controlled by several endogenous mediators that undergo proteolytic conversion from surface-expressed proteins to soluble variants by a disintegrin and metalloproteinase (ADAM)-family members. TNF and epidermal growth factor receptor ligands are just some of the many substrates by which these proteases regulate inflammatory or regenerative processes in the lung. ADAM10 and ADAM17 are the most prominent members of this protease family. They are constitutively expressed in most lung cells and, as recent research has shown, are the pivotal shedding enzymes mediating acute lung inflammation in a cell-specific manner. ADAM17 promotes endothelial and epithelial permeability, transendothelial leukocyte migration, and inflammatory mediator production by smooth muscle and epithelial cells. ADAM10 is critical for leukocyte migration and alveolar leukocyte recruitment. ADAM10 also promotes allergic asthma by driving B cell responses. Additionally, ADAM10 acts as a receptor for Staphylococcus aureus (S. aureus) α-toxin and is crucial for bacterial virulence. ADAM8, ADAM9, ADAM15, and ADAM33 are upregulated during acute or chronic lung inflammation, and recent functional or genetic analyses have linked them to disease development. Pharmacological inhibitors that allow us to locally or systemically target and differentiate ADAM-family members in the lung suppress acute and asthmatic inflammatory responses and S. aureus virulence. These promising results encourage further research to develop therapeutic strategies based on selected ADAMs. These studies need also to address the role of the ADAMs in repair and regeneration in the lung to identify further therapeutic opportunities and possible side effects.

Inhaled corticosteroids and systemic inflammatory response in community-acquired pneumonia: a prospective clinical study

BACKGROUND AND OBJECTIVE

The previous use of inhaled corticosteroids (ICS) may reduce the inflammatory response and mortality in patients with community-acquired pneumonia (CAP).

METHODS

We measured serum levels of several inflammatory biomarkers, as well as mortality at various time-points, in 663 consecutive patients hospitalized for CAP; 128 (19%) were receiving chronic outpatient treatment with ICS. Patients on previous oral corticosteroids were excluded from the analysis.

RESULTS

On admission, patients treated with ICS were older; had been diagnosed with chronic obstructive pulmonary disease (COPD), asthma and pneumonia in the previous year more often; and had higher CAP severity risk classes and lower tumour necrosis factor (TNF)-alpha (P < 0.001) and interleukin (IL)-6 (P = 0.015) serum levels. After adjusting for potential confounders, this association persisted for TNF-alpha (P < 0.001), but not for IL-6. Mortality at 30 and 90 days tended to be lower in patients treated with ICS (P = 0.062 and 0.050, respectively), but mortality was similar after 1 year in both groups (16, 13% vs 81, 15% for patients treated and not treated with ICS, respectively). Hospital readmission rate after 1 year was higher in patients treated with ICS (49, 38% vs 109, 20%, P < 0.001). The association of ICS treatment with a previous diagnosis of pneumonia, lower levels of TNF-alpha and IL-6 on admission and higher readmission rates during follow up persisted in the subpopulation of 210 patients with COPD.

CONCLUSIONS

Previous use of ICS in patients hospitalized for CAP is associated with a reduced systemic inflammatory response without any impact on long-term mortality.

IL6-174 G/C gene polymorphism and its relation to serum IL6 in Egyptian children with community-acquired pneumonia

Cytokines are involved in the pathogenesis of community acquired pneumonia (CAP). The aim of this study is to investigate the association of IL6-174 G/C gene polymorphism with CAP in Egyptian children, to assess its effect on CAP outcome and to determine its effect on the serum IL6 levels in these children. IL6-174 G/C gene polymorphism was genotyped in 210 Egyptian children (100 patients with CAP and 110 healthy controls) using PCR-RFLP, while the serum IL6 levels were measured by ELISA method. We found a significant association between the GG genotype, G allele of IL6-174 G/C SNP and susceptibility to CAP (P=0.02, 0.01 respectively). However, GG genotype and G allele were protective against severe sepsis (p=0.004), acute respiratory failure (p<0.001) and hospital mortality (p<0.001). Serum IL6 levels were significantly increased in these children while there was no relation between GG genotype and serum IL6. In conclusion, IL6-174 G/C gene polymorphism may contribute to susceptibility to CAP in Egyptian children.

Alcohol abuse and Streptococcus pneumoniae infections: consideration of virulence factors and impaired immune responses

Alcohol is the most frequently abused substance in the world. Both acute and chronic alcohol consumption have diverse and well-documented effects on the human immune system, leading to increased susceptibility to infections like bacterial pneumonia. Streptococcus pneumoniae is the most common bacterial etiology of community-acquired pneumonia worldwide. The frequency and severity of pneumococcal infections in individuals with a history of alcohol abuse is much higher than the general population. Despite this obvious epidemiological relevance, very few experimental studies have focused on the interaction of pneumococci with the immune system of a host acutely or chronically exposed to alcohol. Understanding these host-pathogen interactions is imperative for designing effective prophylactic and therapeutic interventions for such populations. Recent advances in pneumococcal research have greatly improved our understanding of pneumococcal pathogenesis and virulence mechanisms. Additionally, a large body of data is available on the effect of alcohol on the physiology of the lungs and the innate and adaptive immune system of the host. The purpose of this review is to integrate the available knowledge in these diverse areas of for a better understanding of the how the compromised immune system derived from alcohol exposure responds to pneumococcal infections.

Early gene expression events in ferrets in response to SARS coronavirus infection versus direct interferon-alpha2b stimulation

Type I interferons (IFNs) are essential to the clearance of viral diseases, however, a clear distinction between genes upregulated by direct virus-cell interactions and genes upregulated by secondary IFN production has not been made. Here, we investigated differential gene regulation in ferrets upon subcutaneous administration of IFN-α2b and during SARS-CoV infection. In vivo experiments revealed that IFN-α2b causes STAT1 phosphorylation and upregulation of abundant IFN response genes (IRGs), chemokine receptors, and other genes that participate in phagocytosis and leukocyte transendothelial migration. During infection with SARS-CoV not only a variety of IRGs were upregulated, but also a significantly broader range of genes involved in cell migration and inflammation. This work allowed dissection of several molecular signatures present during SARS-CoV which are part of a robust IFN antiviral response. These signatures can be useful markers to evaluate the status of IFN responses during a viral infection and specific features of different viruses.

Of mice and men: innate immunity in pneumococcal pneumonia

Pneumococcal pneumonia is characterised by an intense inflammatory response induced mainly by cell wall components of the bacterium. Recognition of cell wall components by Toll-like receptors (TLRs) induces intracellular signalling pathways that culminate in the activation of pro-inflammatory genes through nuclear factor kappaB (NF-kappaB). Tumour necrosis factor-alpha (TNFalpha) is one of the earliest mediators produced and induces a second wave of pro- and anti-inflammatory cytokines that orchestrate the immune response. The magnitude of this response in patients with pneumococcal pneumonia is a complex network and many factors must be considered in the analysis of the cytokine production pattern. First, bacterial growth and the inflammatory response are dynamic processes, produced initially as a local phenomenon with a late systemic extension. Second, host characteristics, such as different cytokine gene polymorphisms, can cause a distinct immune response. Finally, other microorganism determinants and even the immunomodulatory effect of antimicrobials may play a role in cytokine production. Recent data on innate immunity against Streptococcus pneumoniae gathered from the murine model of pneumonia, from studies of human genetic polymorphisms associated with increased susceptibility to pneumococcal infection, and from human clinical trials are discussed. Special emphasis has been placed on the description of the chronology of the complex network of innate immunity triggered by pneumococcal infection.

Polymorphonuclear leucocytes selectively produce anti-inflammatory interleukin-1 receptor antagonist and chemokines, but fail to produce pro-inflammatory mediators

The role of neutrophils in the immune response has long been regarded as mainly phagocytic, but recent publications have indicated the production of several cytokines by polymorphonuclear leucocytes (PMN). The results of the individual reports, however, vary considerably. In this study, we established a cytokine profile of pure human neutrophils and demonstrated that minor contamination of peripheral blood mononuclear cells (PBMCs) in PMN preparations can lead to false-positive results. In our hands, peripheral blood PMN fail to produce the pro-inflammatory cytokines interleukin (IL)-1beta, IL-6 and tumour necrosis factor-alpha (TNF-alpha). Instead, they secrete large amounts of the chemokine IL-8 and the anti-inflammatory IL-1 receptor antagonist (IL-1ra). Additionally, PMN preparations of a high purity show production of the chemokines macrophage inflammatory protein (MIP)-1alpha, MIP-1beta and growth-related oncogene-alpha (GRO-alpha), as well as macrophage colony-stimulating factor (M-CSF). The neutrophil therefore represents a novelty by producing the antagonist of IL-1beta (i.e. IL-1ra) in the absence of IL-1beta itself. To support our results, we differentiated stem cells from human cord blood into PMN and monocytes, respectively. These in vitro-differentiated PMN showed the same cytokine profile as peripheral blood PMN lacking IL-1beta, while differentiated monocytes produced the expected IL-1beta in addition to IL-1ra. The clear anti-inflammatory nature of their cytokine profile enables PMN to antagonize pro-inflammatory signals in experimental conditions. It is therefore possible that PMN play a key role in immune regulation by counteracting a dysregulation of the inflammatory process. Clinical studies, in which administration of recombinant G-CSF had a favourable effect on the outcome of severe infections and even sepsis without worsening inflammation, could thus be explained by our results.

Comment évaluer, orienter et suivre un patient ayant une pneumonie aiguë communautaire ? Une exacerbation de bronchopneumopathie chronique obstructive ?

L'objectif de cette revue est de présenter une analyse bibliographique de la littérature de ces cinq dernières années concernant les pneumonies aiguës communautaires (PAC) et les exacerbations aiguës de bronchopneumopathies chroniques obstructives (EABPCO). La PAC et l'EABPCO sont des pathologies fréquentes grevées d'une mortalité et/ou morbidité encore élevée de nos jours. La connaissance des facteurs de risque d'évolution compliquée et l'identification des signes de gravité souvent liés au risque de mortalité permettent d'orienter le patient pour un traitement ambulatoire, en hospitalisation conventionnelle ou en secteur de réanimation ; des règles prédictives ont été établies dans ce sens. La littérature concernant les critères de sortie d'hospitalisation et le suivi des patients est plus pauvre.

Neutrophil apoptosis, activation and anti-inflammatory cytokine response in granulocyte colony-stimulating factor-treated patients with community-acquired pneumonia

BACKGROUND

Despite antibiotic treatment, the mortality of severe community-acquired pneumonia (CAP), especially in patients with severe comorbidity, remains high. Innate defense mechanisms including polymorphonuclear neutrophil (PMN) activation and survival, orchestrated by cytokines, are primarily responsible for the elimination of bacterial organisms from the alveolus.

OBJECTIVES

The aim of this study was to evaluate the effect of granulocyte colony-stimulating factor (G-CSF) on PMN activation, apoptosis and cytokine response in patients with CAP.

METHODS

Patients received a single dose of G-CSF (1 x 300 or 480 microg s.c.) prior to standard antibiotic treatment (n=8) or standard treatment only (n=8). Apoptosis rate and expression of CD11b, CD66b, CD64 and CD114 surface molecules on systemic PMN were assessed using fluorescence-activated cell sorter analysis. Levels of the interleukin-1 receptor antagonist (IL-1 RA), the soluble tumor necrosis factor receptor inhibitor (sTNF-p55) and G-CSF were measured by ELISA.

RESULTS

In the treatment group, 12 h after G-CSF application, neutrophil count increased, neutrophil activation marker CD11b was stimulated (CD11b: 48.6+/-9.7 vs. 71.2+/-17.7, p<0.01), neutrophil apoptosis decreased (apoptosis: 1.36+/-0.27 vs. 0.2+/-0.12%, p <.01) and the concentration of IL-1RA and sTNF-p55 increased (IL-1RA 136.4+/-72.2 vs. 340.1+/-194.6 ng/ml, p<0.01; sTNF-p55,382+/-4,243 vs. 632+/-4,714 ng/ml, p<0.01; control group nonsignificant). These effects were not seen in the control group.

CONCLUSIONS

The application of a single dose of G-CSF in patients with CAP caused a prolonged survival and increased activation of neutrophils combined with a sustained release of anti-inflammatory cytokines.

Complicaciones infecciosas asociadas al uso de fármacos antagonistas del factor de necrosis tumoral. Revisión de conjunto

Treatment with tumor necrosis factor antagonists (anti-TNF) is an innovative therapeutic approach that requires supervised administration by specialists in rheumatology and inflammatory diseases. Collaboration by infectious diseases consultants with expertise in these biological therapies is crucial to detect the development of one of the most frequent and fearsome associated adverse events: infections, particularly, tuberculosis. The tasks of these specialists include screening for tuberculosis prior to anti-TNF therapy, recommending prophylactic measures, detecting latent tuberculosis and avoiding its reactivation, and assessing potential risk and benefits before starting anti-TNF therapy. Moreover, close follow-up of on-treatment patients is mandatory to achieve early diagnosis and treatment of any infectious event caused by bacteria, fungi or mycobacteria.

Physical activity and modulation of systemic low-level inflammation

It has been recognized for some time that cardiovascular disease and type 2 diabetes are, to a major extent, inflammatory disorders associated with an environment characterized by a sedentary lifestyle together with abundant intakes of calories. Systemic low-level inflammation is suggested to be a cause as well as consequence of pathological processes with local tumor necrosis factor alpha production as an important biological driver. It is hypothesized that physical inactivity contributes to an enhanced proinflammatory burden independently of obesity, as regular muscle contractions mediate signals with myokines/cytokines as important messengers, which suppress proinflammatory activity at distant sites as well as within skeletal muscle. Muscle-derived interleukin (IL)-6 is considered to possess a central role in anti-inflammatory activities and health beneficial effects in relation to physical exercise. It is discussed how this fits the consistent observation that enhanced plasma levels of IL-6 represent a strong risk marker in chronic disorders associated with systemic low-level inflammation and all-cause mortality.

[Guidelines for the management of community pneumonia in adult who needs hospitalization]

Community acquired pneumonia is still an important health problem. In Spain the year incidence is 162 cases per 100,000 inhabitants with 53,000 hospital admission costing 115 millions of euros per year. In the last years there have been significant advances in the knowledge of: aetiology, diagnostic tools, treatment alternatives and antibiotic resistance. The Spanish Societies of Intensive and Critical Care (SEMICYUC), Infectious Diseases and Clinical Microbiology (SEIMC) and Pulmonology and Thoracic Surgery (SEPAR) have produced these evidence-based Guidelines for the management of community acquired pneumonia in Adults. The main objective is to help physicians to make decisions about this disease. The different points that have been developed are: aetiology, diagnosis, treatment and prevention.

Anti-inflammatory effects of macrolides—an underappreciated benefit in the treatment of community-acquired respiratory tract infections and chronic inflammatory pulmonary conditions?

BACKGROUND

It has been recognized for more than 20 years that the macrolides have immunomodulatory effects that are beneficial for those suffering from chronic pulmonary inflammatory syndromes, such as diffuse panbronchiolitis, cystic fibrosis, asthma and bronchiectasis. The macrolides have consistently been associated with decreased length of stay and mortality when used alone or in combination with beta-lactam antibiotics. This effect can be demonstrated against combinations consisting of beta-lactams and other antibiotics active against 'atypical chest pathogens' when treating community-acquired pneumonia (CAP) in hospitalized patients. As such, it appears that the macrolides' effects in CAP patients are more than just antibacterial in nature. AIMS OF THIS REVIEW: This review aims: to give the reader information on the background areas described, as well as related areas; to review the CAP benefits with macrolides and how they may be related to the immunomodulatory properties they demonstrate, albeit in a shorter period of time than previously demonstrated with chronic pulmonary disorders; to use ex vivo data to support these extrapolations.

LITERATURE SEARCH

A literature search using Medline was conducted from 1966 onwards, searching for articles with relevant key words such as macrolide, diffuse panbronchiolitis, community-acquired pneumonia, biofilm, immunomodulation, cystic fibrosis, erythromycin, clarithromycin, roxithromycin and azithromycin, bronchiectasis and asthma. When appropriate, additional references were found from the bibliographies of identified papers of interest. Any relevant scientific conference proceedings or medical texts were checked when necessary.

CONCLUSIONS

(1) Research into macrolide immunomodulation for chronic pulmonary disorders demonstrates consistent positive effects, although of types other than seen with diffuse panbronchiolitis. These effects, together with their inhibitory activity on biofilms, have the potential to make them a useful option. (2) The benefits for CAP are consistent, and higher when a macrolide is given with another atypical agent than if the other atypical agent is given alone, suggesting a non-antibacterial benefit. (3) Recent research of the immunomodulatory properties of azithromycin imply that azithromycin may have a previously unknown short-term biphasic effect on inflammation modulation: enhancement of host defence mechanisms shortly after initial administration followed by curtailment of local infection/inflammation in the following period. (4) Additional in vivo research is needed prior to developing any firm conclusions.

Risk factors of treatment failure in community acquired pneumonia: implications for disease outcome

BACKGROUND

An inadequate response to initial empirical treatment of community acquired pneumonia (CAP) represents a challenge for clinicians and requires early identification and intervention. A study was undertaken to quantify the incidence of failure of empirical treatment in CAP, to identify risk factors for treatment failure, and to determine the implications of treatment failure on the outcome.

METHODS

A prospective multicentre cohort study was performed in 1424 hospitalised patients from 15 hospitals. Early treatment failure (<72 hours), late treatment failure, and in-hospital mortality were recorded.

RESULTS

Treatment failure occurred in 215 patients (15.1%): 134 early failure (62.3%) and 81 late failure (37.7%). The causes were infectious in 86 patients (40%), non-infectious in 34 (15.8%), and undetermined in 95. The independent risk factors associated with treatment failure in a stepwise logistic regression analysis were liver disease, pneumonia risk class, leucopenia, multilobar CAP, pleural effusion, and radiological signs of cavitation. Independent factors associated with a lower risk of treatment failure were influenza vaccination, initial treatment with fluoroquinolones, and chronic obstructive pulmonary disease (COPD). Mortality was significantly higher in patients with treatment failure (25% v 2%). Failure of empirical treatment increased the mortality of CAP 11-fold after adjustment for risk class.

CONCLUSIONS

Although these findings need to be confirmed by randomised studies, they suggest possible interventions to decrease mortality due to CAP.

Increased Proportions of Activated and Proliferating Memory CD8+ T Lymphocytes in Both Blood and Lung are Associated with Blood HIV Viral Load

One mechanism of HIV pathogenesis has been proposed to be the activation of T lymphocytes, resulting in proliferation and decreased survival of these activated cells. Others have suggested that co-infections may exacerbate this process. These hypotheses were tested by examining the relationship between HIV blood viral load with the proportion of activated and proliferating CD8+ lymphocytes in lung and blood. In the lung these responses were compared in patients with or without respiratory pathogens. Thirty-five HIV-positive patients and five controls underwent bronchoalveolar lavage (BAL). BAL and blood samples were fixed and permeabilized and the proportions of memory CD8+ lymphocytes that expressed the activation marker CD38 and the cell cycling marker Ki67 were measured by flow cytometry. CD38bright CD8+ lymphocytes from both sites increased with increasing blood viral load. In BAL there was no significant difference between the CD38 activation status in those with respiratory pathogens compared with those without. More CD38bright CD8+ lymphocytes expressed Ki67 when compared with the CD38dim lymphocytes. These findings provide evidence that HIV is the primary factor in stimulating CD8+ cell activation.

Neutrophil immunity of the elderly

Due to age-related changes of the immune system, elderly people are more susceptible to microbial infections than the young. Most research concerning immune senescence has been done on T and B cells, yet the first cells to migrate into microbe-infected tissue are neutrophils, which phagocytose and kill the pathogens. Long regarded as mere phagocytes, the neutrophils' importance for the immune response has been recognized in current publications, which acknowledge them an active participation in the cytokine network. Similarities in the symptoms of patients with genetical neutrophil deficiencies and those of the elderly indicate a leading role of neutrophils in the effects of immune senescence. While the number of circulating neutrophils remains unaltered in the elderly compared with young controls, phagocytosis and intracellular killing have been reported impaired. Oddly enough, the results for various stimuli differed: while some showed a decrease in neutrophil activation, the response to others remained unaltered. More research needs to be done on this, preferably using preparations of high purity to exclude monocytic interventions. Elucidation of immune deficiencies caused by neutrophil senescence can be an important contribution to a healthier elderly population.

Asymptomatic bacteriuria in elderly humans is associated with increased levels of circulating TNF receptors and elevated numbers of neutrophils

Low-grade inflammatory activity is strongly associated with age-associated diseases such as atherosclerosis, dementia, type-2 diabetes, sarcopenia, and osteoporosis and predicts mortality risk in elderly populations. The aim of the current study was to investigate if asymptomatic bacteriuria in elderly humans was associated with inflammation. Midstream clean-catch urine culture was collected from consecutive, elderly patients at admission to a department of internal medicine due to functional disability. Forty patients (age 70-91 years) were selected and included in the current study; 20 subjects had positive urine culture and 20 sex- and age-matched subjects had negative urine culture. Inclusion criteria were temperature below 37.8 degrees C, no clinical signs of infection and no current antibiotic treatment. Patients with asymptomatic bacteriuria had significantly increased levels of circulating tumor necrosis factor receptors (sTNFR-I) and a higher number of neutrophils in the blood compared to the group without bacteriuria. Thus, the present study provides some support for the hypothesis that asymptomatic urinary infections are associated with low-grade immune activity in frail, elderly humans.