Granulocyte-Colony Stimulating Factor (G-CSF) as an adjunct to antibiotics in the treatment of pneumonia in adults

G-CSF - A double edge sword in neutrophil mediated immunity

Neutrophils are vital for the innate immune system's control of pathogens and neutrophil deficiency can render the host susceptible to life-threatening infections. Neutrophil responses must also be tightly regulated because excessive production, recruitment or activation of neutrophils can cause tissue damage in both acute and chronic inflammatory diseases. Granulocyte colony stimulating factor (G-CSF) is a key regulator of neutrophil biology, from production, differentiation, and release of neutrophil precursors in the bone marrow (BM) to modulating the function of mature neutrophils outside of the BM, particularly at sites of inflammation. G-CSF acts by binding to its cognate cell surface receptor on target cells, causing the activation of intracellular signalling pathways mediating the proliferation, differentiation, function, and survival of cells in the neutrophil lineage. Studies in humans and mice demonstrate that G-CSF contributes to protecting the host against infection, but conversely, it can play a deleterious role in inflammatory diseases. As such, neutrophils and the G-CSF pathway may provide novel therapeutic targets. This review will focus on understanding the role G-CSF plays in the balance between effective neutrophil mediated host defence versus neutrophil-mediated inflammation and tissue damage in various inflammatory and infectious diseases.

A review on how to do hematology consults during COVID-19 pandemic

The ongoing COVID-19 pandemic is the most trending and talked topic across the World. From its point of origin in Wuhan, China to clinical laboratory at NIH, a mere six-month-old SARS-CoV-2 virus is keeping the clinicians, and scientists busy at various fronts. However, COVID-19 is an emerging and evolving disease and each day brings in more data, new figures, and findings from the field of clinical practice. The role of hematologists has been increasingly recognized during the current pandemic because of several reasons. Most important of them are the characteristic hematological findings of COVID-19 patients that also have prognostic implications and that were not seen in other viral infections. The treatment of hematological complications in COVID-19 patients is very challenging given the critical care setting. There are interim and limited guidelines thus far due to the novelty of the disease. As this remains to be a quite fluid situation, all the appropriate medical societies including the major hematology bodies are proposing initial and interim guidelines (e.g. ASH guideline). This puts a hematologist on consult service in a dubious position where, he/she must tailor the recommendations on case to case basis. The purpose of this review is to provide the background context about the impact of COVID-19 on the blood system and to summarize the current interim guidelines to manage the associated hematological issues in COVID-19 infection.

Dynamics of cytokines, immune cell counts and disease severity in patients with community-acquired pneumonia - Unravelling potential causal relationships

BACKGROUND

Community acquired pneumonia (CAP) is a severe and often rapidly deteriorating disease. To better understand its dynamics and potential causal relationships, we analyzed time series data of cytokines, blood and clinical parameters in hospitalized CAP patients.

METHODS

Time series data of 10 circulating cytokines, blood counts and clinical parameters were related to baseline characteristics of 403 CAP patients using univariate mixed models. Bivariate mixed models were applied to analyze correlations between the time series. To identify potential causal relationships, we inferred cross-lagged relationships between pairs of parameters using latent curve models with structured residuals.

RESULTS

IL-6 levels decreased faster over time in younger patients (P_adj = 0.06). IL-8, VCAM-1, and IL-6 correlated strongly with disease severity as assessed by the sequential organ failure assessment (SOFA) score (r = 0.49, 0.48, 0.46, respectively; all P_adj < 0.001). IL-6 and bilirubin correlated with respect to their mean levels and slopes over time (r = 0.36 and r = 0.46, respectively; P_adj < 0.001). A number of potential causal relationships were identified, e.g., a negative effect of ICAM-1 on MCP-1, or a positive effect of the level of creatinine on the subsequent VCAM-1 concentration (P < 0.001).

CONCLUSIONS

These results suggest that IL-6 trajectories of CAP patients are associated with age and run parallel to bilirubin levels. The time series analysis also unraveled directed, potentially causal relationships between cytokines, blood parameters and clinical outcomes. This will facilitate the development of mechanistic models of CAP, and with it, improvements in treatment or surveillance strategies for this disease.

TRIAL REGISTRATION

clinicaltrials.gov NCT02782013, May 25, 2016, retrospectively registered.

Clinical practice guidelines for hospital-acquired pneumonia and ventilator-associated pneumonia in adults

Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are important causes of morbidity and mortality, with mortality rates approaching 62%. HAP and VAP are the second most common cause of nosocomial infection overall, but are the most common cause documented in the intensive care unit setting. In addition, HAP and VAP produce the highest mortality associated with nosocomial infection. As a result, evidence-based guidelines were prepared detailing the epidemiology, microbial etiology, risk factors and clinical manifestations of HAP and VAP. Furthermore, an approach based on the available data, expert opinion and current practice for the provision of care within the Canadian health care system was used to determine risk stratification schemas to enable appropriate diagnosis, antimicrobial management and nonantimicrobial management of HAP and VAP. Finally, prevention and risk-reduction strategies to reduce the risk of acquiring these infections were collated. Future initiatives to enhance more rapid diagnosis and to effect better treatment for resistant pathogens are necessary to reduce morbidity and improve survival.

Guidelines for the management of hospital-acquired pneumonia in the UK: report of the working party on hospital-acquired pneumonia of the British Society for Antimicrobial Chemotherapy

These evidence-based guidelines have been produced after a systematic literature review of a range of issues involving prevention, diagnosis and treatment of hospital-acquired pneumonia (HAP). Prevention is structured into sections addressing general issues, equipment, patient procedures and the environment, whereas in treatment, the structure addresses the use of antimicrobials in prevention and treatment, adjunctive therapies and the application of clinical protocols. The sections dealing with diagnosis are presented against the clinical, radiological and microbiological diagnosis of HAP. Recommendations are also made upon the role of invasive sampling and quantitative microbiology of respiratory secretions in directing antibiotic therapy in HAP/ventilator-associated pneumonia.

Granulocyte-colony stimulating factor (G-CSF) as an adjunct to antibiotics in the treatment of pneumonia in adults

BACKGROUND

Granulocyte colony stimulating factor (G-CSF) is a naturally-occurring cytokine that has been shown to increase neutrophil function and number. Exogenous administration of recombinant G-CSF (filgrastim, pegfilgrastim or lenograstim) has found extensive use in the treatment of febrile neutropenia, but its role in the treatment of infection in non-neutropenic hosts is less well defined.

OBJECTIVES

We explored the role of G-CSF as an adjunct to antibiotics in the treatment of pneumonia in non-neutropenic adults.

SEARCH STRATEGY

For this updated review we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 4, 2006); MEDLINE (1950 to January 2007); EMBASE (1988 to January 2007); and online databases of clinical trials (www.controlled-trials.com, updated 10 November, 2006).

SELECTION CRITERIA

We considered randomized controlled trials (RCTs) which included hospitalized adult patients with either community-acquired pneumonia or hospital-acquired pneumonia.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality. The primary outcome measure was 28-day mortality. Secondary outcome measures included other markers of mortality as well as markers of adverse events, including organ dysfunction. An assessment of methodological quality was made for each study.

MAIN RESULTS

Six studies with a total of 2018 people were identified. G-CSF use appeared to be safe with no increase in the incidence of total serious adverse events (pooled odds ratio (OR) 0.91; 95% confidence interval (CI): 0.73 to 1.14) or organ dysfunction. However, the use of G-CSF was not associated with improved 28-day mortality (pooled OR 0.81; 95% CI: 0.52 to 1.27).

AUTHORS' CONCLUSIONS

There is no current evidence supporting the routine use of G-CSF in the treatment of pneumonia. Studies in which G-CSF is administered prophylactically or earlier in therapy may be of interest.

What drives our choices? Evidence, guidelines or habit?

Physicians' treatment choices are influenced by a number of factors, including guidelines, evidence-based medicine, past experience and, to a certain extent, habit. Evidence-based medicine is the foundation of clinical practice guidelines. This article reviews the influence of evidence and guidelines on physicians' treatment choices. As examples, the role of evidence in guiding treatment decisions in chronic obstructive pulmonary disease is explored, and the impact of guidelines on treatment choices in community-acquired pneumonia is discussed. When choosing the most appropriate treatment for a patient, physicians need to continuously evaluate new evidence, in addition to implementing clinical practice guidelines. Additional factors that should also influence this decision are physicians' prior experience and the individual patient's circumstances.

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.