Procalcitonin in sepsis and systemic inflammation: a harmful biomarker and a therapeutic target

Kinetics of procalcitonin and C-reactive protein and the relationship to postoperative infection in young infants undergoing cardiovascular surgery

BACKGROUND

The utility of procalcitonin (PCT) and C-reactive protein (CRP) as infectious biomarkers following infant cardiothoracic surgery is not well defined.

METHODS

We designed a prospective cohort study to evaluate PCT and CRP after infant cardiothoracic surgery. PCT and CRP were drawn preoperatively and 24/72 h postoperation or daily in delayed sternal closure patients. Presence of infection within 10 d of surgery, vasoactive-inotropic scores at 24 and 72 h, and length of intubation, intensive care unit stay, and hospital stay were documented.

RESULTS

PCT and CRP were elevated at 24 h. PCT then decreased while CRP increased in patients undergoing delayed sternal closure or cardiopulmonary bypass. In the delayed sternal closure group, PCT was significantly higher on postoperative days 2-5 in patients who ultimately developed infection. Higher PCT was independently associated with increased vasoactive-inotropic score at 72 h. CRP did not correlate with infection or postoperative support.

CONCLUSION

PCT rises after cardiothoracic surgery in infants but decreases by 72 h while CRP remains elevated. Sternal closure may affect CRP but not PCT. PCT is independently associated with circulatory support requirements at 72 h postoperation and with development of infection. PCT may have greater utility as a biomarker in this population.

Elevated procalcitonin is associated with increased mortality in patients with scrub typhus infection needing intensive care admission

Context:

Procalcitonin is a biomarker of bacterial sepsis. It is unclear if scrub typhus, a rickettsial illness, is associated with elevated procalcitonin levels.

Aim:

To assess if scrub typhus infection is associated with high procalcitonin levels and whether high levels portend a poorer prognosis.

Setting and Design:

Retrospective study of patients with severe scrub typhus infection, admitted to the medical intensive care unit of a tertiary care university affiliated teaching hospital.

Materials and Methods:

Eighty-four patients with severe scrub typhus infection that also had procalcitonin levels were assessed.

Statistical Analysis:

Relationship between procalcitonin and mortality explored using univariate and multivariate analyses.

Results:

The mean (±standard deviation) age was 40.0 ± 15.5 years. Patients were symptomatic for 8.3 ± 4.3 days prior to presentation. The median admission procalcitonin level was 4.0 (interquartile range 1.8 to 8.5) ng/ml; 59 (70.2%) patients had levels >2 ng/ml. Invasive mechanical ventilation was required in 65 patients; 20 patients died. On univariate analysis, admission procalcitonin was associated with increased odds of death [odds ratio (OR) 1.09, 95% confidence interval (CI) 1.03 to 1.18]. On multivariate logistic regression analysis including procalcitonin and APACHE-II score, the APACHE-II score was significantly associated with mortality (OR 1.16, 95% CI 1.06 to 1.30, P = 0.004) while a trend was observed with procalcitonin (OR 1.05, 95%CI 1.01 to 1.13, P = 0.09). The area under the receiver operating characteristic (ROC) curve, AUC, for mortality was 0.77 for procalcitonin and 0.78 for APACHE-II.

Conclusions:

Procalcitonin is elevated in severe scrub typhus infection and may be associated with higher mortality.

Procalcitonin beyond the acute phase: novel biomediator properties?

Since inflammation has been linked to carcinogenic events, discovery of relevant biomarkers may have important preventative implications. Procalcitonin (ProCT) has been shown to be an important prognostic biomarker in severe inflammatory conditions, but there is no data regarding its biomarker role, if any, beyond the acute phase. In a recent study published in BMC Medicine, Cotoi et al. analyzed whether serum ProCT levels in healthy individuals are associated with mortality outcomes. The results are affirmative in that baseline ProCT was shown to be strongly and independently associated with all-cause and cancer mortality and with the incidence of colon cancer in men. By contrast, the study indicated that high sensitivity C-reactive protein was independently associated with cardiovascular mortality but not with cancer mortality in men. Thus, baseline levels of ProCT appear to have prognostic biomarker implications potentially related to its emerging biomediator action(s).

Plasma procalcitonin is associated with all-cause and cancer mortality in apparently healthy men: a prospective population-based study

BACKGROUND

The inflammatory mediator procalcitonin (PCT) has previously been associated with prognosis in myocardial infarction, cancer and sepsis patients. The importance of PCT in the general population is currently unknown. Our aim was to assess the relationship between plasma PCT and the risk of all-cause and cause-specific mortality in apparently healthy individuals with no previous history of cardiovascular disease or cancer.

METHODS

We performed a prospective, population-based study on 3,322 individuals recruited from the Malmö Diet and Cancer cohort, with a median follow-up time of 16.2 years. Plasma PCT, high-sensitivity C-reactive protein (hsCRP), low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides and cystatin C were measured at baseline and a thorough risk factor assessment was performed for all subjects. The primary end-points of the study were all-cause mortality, cancer mortality and cardiovascular mortality.

RESULTS

Men had higher PCT levels compared to women. In Cox proportional hazard models adjusted for age, sex, hypertension, diabetes, plasma lipids, renal function, body mass index and smoking, baseline PCT was associated with all-cause mortality and cancer mortality in men. The hazard ratio (HR) for men with PCT levels within the highest compared with the lowest quartile was 1.52 (95% confidence interval (CI) 1.07 to 2.16; P = 0.024) for all-cause mortality and 2.37 (95% CI 1.36 to 4.14; P = 0.006) for cancer mortality. Additionally, men with increased plasma PCT were found to be at a higher risk to develop colon cancer (HR per 1 SD increase = 1.49 (95% CI 1.13 to 1.95); P = 0.005). In multivariate Cox regression analyses with mutual adjustments for PCT and hsCRP, PCT was independently associated with cancer death (HR per 1 SD increase = 1.28 (95% CI 1.10 to 1.49); P = 0.001) and hsCRP with cardiovascular death (HR per 1 SD increase = 1.42 (95% CI 1.11 to 1.83); P = 0.006) in men. We found no significant correlations between baseline PCT or hsCRP and incident cancer or cardiovascular death in women.

CONCLUSIONS

We disclose for the first time important independent associations between PCT and the risk for all-cause and cancer mortality in apparently healthy men. Our findings warrant further investigation into the mechanisms underlying the relationship between PCT and cancer.

Bacterial complications of respiratory tract viral illness: a comprehensive evaluation

Background. Respiratory tract infection is one of the most common reasons for hospitalization among adults, and recent evidence suggests that many of these illnesses are associated with viruses. Although bacterial infection is known to complicate viral infections, the frequency and impact of mixed viral-bacterial infections has not been well studied.

Methods. Adults hospitalized with respiratory illness during 3 winters underwent comprehensive viral and bacterial testing. This assessment was augmented by measuring the serum level of procalcitonin (PCT) as a marker of bacterial infection. Mixed viral-bacterial infection was defined as a positive viral test result plus a positive bacterial assay result or a serum PCT level of ≥ 0.25 ng/mL on admission or day 2 of hospitalization.

Results. Of 842 hospitalizations (771 patients) evaluated, 348 (41%) had evidence of viral infection. A total of 212 hospitalizations (61%) involved patients with viral infection alone. Of the remaining 136 hospitalizations (39%) involving viral infection, results of bacterial tests were positive in 64 (18%), and PCT analysis identified bacterial infection in an additional 72 (21%). Subjects hospitalized with mixed viral-bacterial infections were older and more commonly received a diagnosis of pneumonia. Over 90% of hospitalizations in both groups involved subjects who received antibiotics. Notably, 4 of 10 deaths among subjects hospitalized with viral infection alone were secondary to complications of Clostridium difficile colitis.

Conclusions. Bacterial coinfection is associated with approximately 40% of viral respiratory tract infections requiring hospitalization. Patients with positive results of viral tests should be carefully evaluated for concomitant bacterial infection. Early empirical antibiotic therapy for patients with an unstable condition is appropriate but is not without risk.

Argininosuccinate synthase as a novel biomarker for inflammatory conditions

Argininosuccinate synthase (ASS) plays an important role in regulating metabolic functions in mammals. We previously reported that hepatic ASS is released into circulation at very high concentrations in response to endotoxin and acute liver injury. We propose that ASS may serve as a novel biomarker for various inflammatory conditions. Our data showed that ASS accumulated in serum and urine of septic, obese or tumor mice in a condition-dependent fashion. Moreover, ASS significantly increased in urine within the first week after tumor cell implantation in mice which subsequently develop tumors. These results suggest that ASS is a novel biomarker increased upon diverse inflammatory conditions.

Serum procalcitonin as a marker of post-cardiac arrest syndrome and long-term neurological recovery, but not of early-onset infections, in comatose post-anoxic patients treated with therapeutic hypothermia

OBJECTIVE

To examine the relationship of early serum procalcitonin (PCT) levels with the severity of post-cardiac arrest syndrome (PCAS), long-term neurological recovery and the risk of early-onset infections in patients with coma after cardiac arrest (CA) treated with therapeutic hypothermia (TH).

METHODS

A prospective cohort of adult comatose CA patients treated with TH (33°C, for 24h) admitted to the medical/surgical intensive care unit, Lausanne University Hospital, was studied. Serum PCT was measured early after CA, at two time-points (days 1 and 2). The SOFA score was used to quantify the severity of PCAS. Diagnosis of early-onset infections (within the first 7 days of ICU stay) was made after review of clinical, radiological and microbiological data. Neurological recovery at 3 months was assessed with Cerebral Performance Categories (CPC), and was dichotomized as favorable (CPC 1-2) vs. unfavorable (CPC 3-5).

RESULTS

From December 2009 to April 2012, 100 patients (median age 64 [interquartile range 55-73] years, median time from collapse to ROSC 20 [11-30]min) were studied. Peak PCT correlated with SOFA score at day 1 (Spearman's R=0.44, p<0.0001) and was associated with neurological recovery at 3 months (peak PCT 1.08 [0.35-4.45]ng/ml in patients with CPC 1-2 vs. 3.07 [0.89-9.99] ng/ml in those with CPC 3-5, p=0.01). Peak PCT did not differ significantly between patients with early-onset vs. no infections (2.14 [0.49-6.74] vs. 1.53 [0.46-5.38]ng/ml, p=0.49).

CONCLUSIONS

Early elevations of serum PCT levels correlate with the severity of PCAS and are associated with worse neurological recovery after CA and TH. In contrast, elevated serum PCT did not correlate with early-onset infections in this setting.

Can serum procalcitonin levels help interpret indeterminate chest radiographs in patients hospitalized with acute respiratory illness?

BACKGROUND

Clinical diagnosis of pneumonia is difficult and chest radiographs often indeterminate, leading to incorrect diagnoses and antibiotic overuse.

OBJECTIVE

To determine if serum procalcitonin (ProCT) could assist in managing patients with respiratory illness and indeterminate radiographs.

DESIGN

Subjects were prospectively enrolled during 2 consecutive winters.

SETTING

A 520-bed hospital in Rochester, NY.

PATIENTS

Five hundred twenty-eight adults admitted with acute respiratory illness were enrolled.

MEASUREMENTS

Serum ProCT, admission diagnoses, and chest radiographic findings were used to derive receiver operating characteristics curves to assess predictive accuracy of ProCT for the presence of infiltrates.

RESULTS

Subjects with pneumonia had higher ProCT (median 0.27 ng/ml) than those with exacerbations of chronic obstructive pulmonary disease (0.08 ng/ml), acute bronchitis (0.09 ng/ml), or asthma (0.06 ng/ml). ProCT had moderate accuracy for the presence of infiltrates (area under curve [AUC] 0.72), when indeterminate radiographs were independently classified as infiltrates by a pulmonologist evaluating patients.

CONCLUSIONS

ProCT may be useful in diagnosing pneumonia when chest radiographs are indeterminate.

Analysis of procalcitonin and CRP concentrations in serum of patients with chronic spontaneous urticaria

Background

Our previous findings showed the importance of analysing the peripheral markers of acute phase response (APR) activation, C-reactive protein (CRP) and IL-6 in the context of urticaria activity and severity. However, these biomarkers do not reliably differentiate between APR to infectious and the disease severity.

Aim

In order to investigate a possible association between the immune-inflammatory activation markers CRP and procalcitonin (PCT).

Methods

Serum PCT and CRP concentrations were measured in patients with CU of varying severity as well as in healthy subjects.

Results

Serum PCT and CRP concentrations were significantly increased in more severe CU patients when compared to healthy controls and mild CU, and within the CU population there was a significant correlation between concentrations of PCT and CRP. Serum PCT concentrations remained within normal ranges in most CU patients and were only slightly elevated in some severe CU cases.

Conclusions

PCT serum concentration may be only slightly elevated in some cases of severe CU. Upregulation of PCT synthesis accompanied by parallel changes in CRP concentration reflects a low-grade systemic inflammatory response in CU. PCT should be considered as a better marker than CRP to distinguish between APR to infection and an active non-specific urticarial inflammation.

Role of early systemic inflammatory response in simultaneous pancreas-kidney transplantation

Pancreas grafts are susceptible to surgical complications mostly related to exocrine secretions and the low microcirculatory blood flow through the gland. During simultaneous kidney-pancreas transplantation, the systemic response depends on reperfusion of two organs acute graft pancreatitis, immunotherapy, coagulopathy, bleeding, and other factors. We performed a retrospective review of 10 adult simultaneous pancreas-kidney transplant patients to evaluate progression of early postoperative inflammation in the absence of infection. All patients were treated with four-drug therapy. We performed analyses of procalcitonin (PCT), C-reactive protein, serum creatinine, amylase, and lipase levels over the first 5 postoperative days. Relatively high peak PCT levels (maximum 130 ng/mL) were reached within 24 to 48 hours postoperatively followed by a moderate decrease. Consistent with this observation, the serum creatinine, amylase, and lipase levels decreased continuously to normal concentrations within the first week. The increased PCT levels seemed depend upon the surgical procedure and intraoperative events. PCT was superior to C-reactive protein to discriminate infection from inflammation in this setting. The dynamics of PCT levels, rather than absolute values, seemed to be important. Lack of a decrease in PCT levels after the peak, suggested an infectious complication or the development of sepsis. Monitoring and assessment of PCT levels may help in early recognition of infection and institution of therapy.

Interpretation of serum calcitonin in patients with chronic autoimmune thyroiditis

Calcitonin (CT) is an important clinical marker for the diagnosis and follow-up of medullary thyroid carcinoma, although it is not absolutely specific. Some authors have reported C-cell hyperplasia in a number of thyroid specimens affected by Hashimoto's thyroiditis. The association between thyroiditis and hypercalcitoninemia is still controversial because some authors have reported low CT levels. The aim of this study is to evaluate the basal CT values in patients with and without thyroid autoimmunity. From May 2005 to February 2010, 1073 patients underwent ultrasonography-guided fine-needle aspiration cytology at the Thyroid Center of Sapienza University of Rome, with evaluation of basal serum FT4, FT3, TSH, and antithyroid peroxidase (anti-TPO) antibodies as well as CT levels. Forty-one patients presented a basal CT level above the reference upper limit. The mean serum CT was significantly lower in women than in men (4.28 ± 6.63 vs 7.50 ± 25.50  pg/ml; P<0.01). Basal serum CT was not significantly higher in patients showing anti-TPO Ab positivity (4.71 ± 6.46 vs 4.84 ± 13.11  pg/ml; P>0.05). Importantly, the rate of 'suspicious' CT values (above the 10  pg/ml cutoff) was not significantly different between patients with or without thyroid autoimmunity (3.9 vs 3.0%). Patients with hypercalcitoninemia suffering from chronic autoimmune thyroiditis should undergo the same clinical evaluation procedure as patients do without thyroid autoimmunity.

Procalcitonin neutralizes bacterial LPS and reduces LPS-induced cytokine release in human peripheral blood mononuclear cells

BACKGROUND

Procalcitonin (PCT) is a polypeptide with several cationic aminoacids in its chemical structure and it is a well known marker of sepsis. It is now emerging that PCT might exhibit some anti-inflammatory effects. The present study, based on the evaluation of the in vitro interaction between PCT and bacterial lipopolisaccharide (LPS), reports new data supporting the interesting and potentially useful anti-inflammatory activity of PCT.

RESULTS

PCT significantly decreased (p < 0.05) the limulus amoebocyte lysate (LAL) assay reactivity of LPS from both Salmonella typhimurium (rough chemotype) and Escherichia coli (smooth chemotype). Subsequently, the in vitro effects of PCT on LPS-induced cytokine release were studied in human peripheral blood mononuclear cells (PBMC). When LPS was pre-incubated for 30 minutes with different concentrations of PCT, the release of interleukin-10 (IL-10) and tumor necrosis factor alpha (TNFα) by PBMC decreased in a concentration-dependent manner after 24 hours for IL-10 and 4 hours for TNFα. The release of monocyte chemotactic protein-1 (MCP-1) exhibited a drastic reduction at 4 hours for all the PCT concentrations assessed, whereas such decrease was concentration-dependent after 24 hours.

CONCLUSIONS

This study provides the first evidence of the capability of PCT to directly neutralize bacterial LPS, thus leading to a reduction of its major inflammatory mediators.

Utility of serum procalcitonin values in patients with acute exacerbations of chronic obstructive pulmonary disease: a cautionary note

BACKGROUND

Serum procalcitonin levels have been used as a biomarker of invasive bacterial infection and recently have been advocated to guide antibiotic therapy in patients with chronic obstructive pulmonary disease (COPD). However, rigorous studies correlating procalcitonin levels with microbiologic data are lacking. Acute exacerbations of COPD (AECOPD) have been linked to viral and bacterial infection as well as noninfectious causes. Therefore, we evaluated procalcitonin as a predictor of viral versus bacterial infection in patients hospitalized with AECOPD with and without evidence of pneumonia.

METHODS

Adults hospitalized during the winter with symptoms consistent with AECOPD underwent extensive testing for viral, bacterial, and atypical pathogens. Serum procalcitonin levels were measured on day 1 (admission), day 2, and at one month. Clinical and laboratory features of subjects with viral and bacterial diagnoses were compared.

RESULTS

In total, 224 subjects with COPD were admitted for 240 respiratory illnesses. Of these, 56 had pneumonia and 184 had AECOPD alone. A microbiologic diagnosis was made in 76 (56%) of 134 illnesses with reliable bacteriology (26 viral infection, 29 bacterial infection, and 21 mixed viral bacterial infection). Mean procalcitonin levels were significantly higher in patients with pneumonia compared with AECOPD. However, discrimination between viral and bacterial infection using a 0.25 ng/mL threshold for bacterial infection in patients with AECOPD was poor.

CONCLUSION

Procalcitonin is useful in COPD patients for alerting clinicians to invasive bacterial infections such as pneumonia but it does not distinguish bacterial from viral and noninfectious causes of AECOPD.

Immune regulation of procalcitonin: a biomarker and mediator of infection

Procalcitonin (PCT) has recently emerged as a powerful biomarker for an early and accurate diagnosis of bacterial infection. Here we summarize our current understanding of the expression pathways of PCT, its potential cellular sources including immune cells, and factors inducing its secretion. Also addressed is the significance of increased blood PCT concentration, which may allow this molecule not only to act as a clinical biomarker but also as an active participant in the development and progression of infectious processes. Experimental approaches to delineate a better understanding of PCT functions, molecular pathways that modulate its expression and therapeutic opportunities to curtail its biological actions are discussed, as well.

[Prognostic value of procalcitonin, C-reactive protein and leukocytes in septic shock]

OBJECTIVES

This study evaluates the potential prognostic value of serial measurements of different biomarkers (procalcitonin [PCT], C-reactive protein and leukocytes [CRP]) in septic shock patients.

DESIGN

Prospective observational study.

SETTING

Intensive care unit of a third-level University Hospital.

PATIENTS

The study comprised a total of 88 septic shock patients defined using the 2001 Consensus Conference SCCM/ESICM/ACCP/ATS/SIS criteria. The PCT, CRP and leukocytes were recorded on admission to the ICU and again 72 hours after admission.

INTERVENTIONS

None.

RESULTS

Those patients with increasing procalcitonin levels showed higher hospital mortality than those with a decreasing levels (58.8% vs. 15.4%, P<0.01). No such effect was observed in relation to C-reactive protein or leukocytes. The best area under the curve for prognosis was for procalcitonin clearance (0.79). A procalcitonin clearance of 70% or higher offered a sensitivity and specificity of 94.7% and 53%, respectively.

CONCLUSIONS

Serial procalcitonin measurements are more predictive of the prognosis of septic shock patients than single measurements of this parameter. The prognostic reliability of the latter is also better than in the case of C-reactive protein and leukocytes. The application of serial procalcitonin measurements may allow the identification of those septic patients at increased mortality risk, and help improve their treatment.

Assessment of procalcitonin to predict outcome in hypothermia-treated patients after cardiac arrest

Objective. Determine the potential of procalcitonin (PCT) to predict neurological outcome after hypothermia treatment following cardiac arrest. Methods. Retrospective analysis of patient data over a 2-year period. Mortality and neurological outcome of survivors were determined 6 months after cardiac arrest using the Cerebral Performance Category (CPC) score. Results. Data from 53 consecutive patients were analyzed. Median age was 63 (54–71) and 79% were male. Twenty-seven patients had good outcome (CPC ≤ 2) whereas 26 had severe neurological sequelae or died (CPC 3–5). At 48 h, after regaining normothermia, PCT was significantly higher in patients with bad outcome compared to those with good outcome: 3.38 (1.10–24.48) versus 0.28 (0–0.75) ng/mL (P < 0.001). PCT values correlated with bad neurological outcome (r = 0.54, P = 0.00004) and predicted outcome with an area under the curve of 0.84 (95% CI 0.73–0.96). A cutoff point of 1 ng/mL provided a sensitivity of 85% and a specificity of 81%. Above a PCT level of 16 ng/mL, no patient regained consciousness. PCT provided an additive value over simplified acute physiology score II. Conclusions. PCT might be an ancillary marker for outcome prediction after cardiac arrest treated by induced hypothermia.

Procalcitonin gene expression after LPS stimulation in the porcine animal model

Procalcitonin (PCT), recognised as a marker of sepsis, was investigated in a porcine model of endotoxic shock. The results showed that continuous IV infusion (1-4 h) of LPS (40 μg/kg) in pigs was able to induce a generalised increase of PCT expression in lung, heart, kidney and liver. The increase in PCT was significant only in kidney and was accompanied by an increase in IL-6 gene expression. In vitro results demonstrated that peripheral blood mononuclear cells (PBMCs), as well as endothelial cells, were potentially capable of contributing to in vivo extrathyroidal PCT production. These findings support previous data from pigs concerning the occurrence of widespread activation of PCT extrathyroidal gene expression during endotoxic shock in pigs. Nevertheless, the levels of PCT detected were very low, suggesting the need for additional studies to validate the pig as a reliable animal model for investigating the role of PCT in sepsis.

Established and novel biomarkers of sepsis

The increased incidence of sepsis, a systemic response to infection that occurs in some patients, has stimulated interest in identifying infected patients who are at risk and intervening early. When this condition progresses to severe sepsis (characterized by organ dysfunction), mortality is high. Hospitals that have implemented recommendations of the Surviving Sepsis Campaign have seen a reduction in mortality rate for hospital-acquired severe sepsis. They may reduce this further by focusing on new approaches to diagnosing sepsis, especially at an early stage. Sepsis is a complicated syndrome with many physiological derangements and many emerging laboratory markers of sepsis have been proposed as adjuncts to clinical evaluation. The list includes cytokines, acute phase proteins, neutrophil activation markers, markers of abnormal coagulation and, recently, markers of suppression of both the innate and adaptive immune response. The perfect biomarker would accurately identify patients at risk of developing severe sepsis and then guide targeted therapy.

Biomarker discovery and development in pediatric critical care medicine

OBJECTIVES

To frame the general process of biomarker discovery and development; and to describe a proposal for the development of a multibiomarker-based risk model for pediatric septic shock.

DATA SOURCE

Narrative literature review and author-generated data.

DATA SELECTION

Biomarkers can be grouped into four broad classes, based on the intended function: diagnostic, monitoring, surrogate, and stratification.

DATA EXTRACTION AND SYNTHESIS

Biomarker discovery and development requires a rigorous process, which is frequently not well followed in the critical care medicine literature. Very few biomarkers have successfully transitioned from the candidate stage to the true biomarker stage. There is great interest in developing diagnostic and stratification biomarkers for sepsis. Procalcitonin is currently the most promising diagnostic biomarker for sepsis. Recent evidence suggested that interleukin-8 can be used to stratify children with septic shock having a high likelihood of survival with standard care. Currently, there is a multi-institutional effort to develop a multibiomarker-based sepsis risk model intended to predict outcome and illness severity for individual children with septic shock.

CONCLUSIONS

Biomarker discovery and development are an important portion of the pediatric critical care medicine translational research agenda. This effort will require collaboration across multiple institutions and investigators. Rigorous conduct of biomarker-focused research holds the promise of transforming our ability to care for individual patients and our ability to conduct clinical trials in a more effective manner.

Immunoneutralization of the aminoprocalcitonin peptide of procalcitonin protects rats from lethal endotoxaemia: neuroendocrine and systemic studies

Severe sepsis and septic shock are an important cause of mortality and morbidity. These illnesses can be triggered by the bacterial endotoxin LPS (lipopolysaccharide) and pro-inflammatory cytokines, particularly TNF-α (tumour necrosis factor-α) and IL (interleukin)-1β. Severity and mortality of sepsis have also been associated with high concentrations of N-PCT (aminoprocalcitonin), a 57-amino-acid neuroendocrine peptide derived from ProCT (procalcitonin). Previous studies in a lethal model of porcine polymicrobial sepsis have revealed that immunoneutralization with IgG that is reactive to porcine N-PCT significantly improves short-term survival. To explore further the pathophysiological role of N-PCT in sepsis, we developed an antibody raised against a highly conserved amino acid sequence of human N-PCT [N-PCT-(44-57)]. This sequence differs by only one amino acid from rat N-PCT. First, we demonstrated the specificity of this antibody in a well-proven model of anorexia induced in rats by central administration of human N-PCT-(1-57). Next we explored further the therapeutic potential of anti-N-PCT-(44-57) in a rat model of lethal endotoxaemia and determined how this immunoneutralization affected LPS-induced lethality and cytokine production. We show that this specific antibody inhibited the LPS-induced early release of TNF-α and IL-1β and increased survival, even if treatment began after the cytokine response had occurred. In addition, anti-N-PCT-(44-57) may increase long-term survival in LPS-treated rats by up-regulating the late production of counter-regulatory anti-inflammatory mediators such as ACTH (adrenocorticotropic hormone) and IL-10. In conclusion, these results support N-PCT as a pro-inflammatory factor in both the early and the late stages of lethal endotoxaemia, and suggest anti-N-PCT as a candidate for septic shock therapy.

Immunoneutralization of procalcitonin or its component peptides: a promising treatment of sepsis

Sepsis and the severe systemic response syndrome are very common illnesses that are responsible for a great amount of morbidity and death. These closely related conditions are characterized by a remarkable increase in the prohormone ProCT (procalcitonin). ProCT is both a marker of sepsis and a harmful mediator of the disease. In the present issue of Clinical Science, in a study in rats with endotoxin shock, Tavares and Miñano used an antibody to a segment of N-ProCT (aminoprocalcitonin) that is part of the ProCT molecule, and confirmed that immunoneutralization of ProCT saves the animals from this severe illness. Furthermore, they extensively studied the epiphenomena associated with this immunoneutralization.

Procalcitonin in 759 patients clinically suspected of infective endocarditis

BACKGROUND

diagnostic delay contributes to high morbidity and mortality in infective endocarditis. A readily available diagnostic marker of infective endocarditis is desirable. S-procalcitonin has been proposed as a candidate, but data on its yield are conflicting. We tested its diagnostic value in a large population of patients seen in a tertiary center.

METHODS

this prospective study included 759 consecutive patients referred for echocardiographic examination on clinical suspicion of infective endocarditis. Transthoracic echocardiography was followed by immediate transesophageal examination, and a blood sample was obtained for procalcitonin analysis. Infective endocarditis was diagnosed by an interdisciplinary team and confirmed according to the Duke criteria. The team was unaware of the results of procalcitonin analyses.

RESULTS

infective endocarditis was present in 147 patients (19%). Procalcitonin was higher in these patients than in those in whom infective endocarditis was rejected (median, 0.21 ng/mL vs. 0.13 ng/mL; P <.0005). Multivariate analysis identified significant independent determinants of high procalcitonin: blood culture with endocarditis-typical microorganisms (odds ratio [OR], 2.81), temperature ≥ 38°C (OR, 2.61), symptoms ≤ 5 days (OR, 2.39), immunocompromised status (OR, 1.74), and male gender (OR, 1.61). Tests at various procalcitonin thresholds yielded an acceptable sensitivity of 95% at 0.04 ng/mL, but specificity was only 14%. Only 12% had procalcitonin below this threshold, which might justify postponement of further examinations for infective endocarditis.

CONCLUSIONS

procalcitonin was significantly higher in patients with infective endocarditis than in patients without infective endocarditis and bacteremia with endocarditis-typical organisms was the strongest independent determinant of high procalcitonin. The clinical importance of this is questionable, because a suitable procalcitonin threshold for diagnosing or excluding infective endocarditis was not established.

Additional benefit of procalcitonin to C-reactive protein to assess disease activity and severity in Crohn's disease

BACKGROUND

Serum procalcitonin level may reflect non-infectious inflammation.

AIM

To assess the correlation of serum procalcitonin level with clinical, biological, endoscopic and radiological markers of disease activity in inflammatory bowel diseases (IBD), and to evaluate the additional diagnostic benefit of measuring serum procalcitonin level to that of C-reactive protein (CRP) for disease activity appraisal.

METHODS

We performed a prospective observational study. Spearman's rank correlation and receiver operating characteristic analysis were used to evaluate correlation and diagnostic accuracy respectively.

RESULTS

In Crohn's disease (CD) (n = 30), serum procalcitonin level was strongly correlated with clinical, biological, endoscopic and radiological disease activity markers. In CD, the serum procalcitonin level >0.14 μg/L demonstrated a high accuracy for detecting severe disease (Sensitivity = 100%; Specificity = 96%; AUROC = 0.963; P = 0.0001). The diagnostic accuracy of the 'serum procalcitonin level-CRP strategy' (CRP >5 mg/L and serum procalcitonin level >0.05 μg/L) was significantly superior to that of CRP alone for diagnosing severe CD (AUROC = 0.783 vs. 0.674; P = 0.01). In ulcerative colitis (UC) (n = 27), serum procalcitonin level was correlated with CRP and with endoscopic and radiological disease activity markers.

CONCLUSIONS

In CD, the serum procalcitonin level was correlated with all disease activity markers and a cut-off of 0.14 μg/L could distinguish severe forms of the disease. The 'serum procalcitonin level-CRP strategy' was superior to CRP alone for diagnosing active or severe CD.