The Clinical Value of Procalcitonin and Neopterin in Predicting Sepsis and Organ Failure After Major Trauma

Characterization of circulating monocytes expressing HLA-DR or CD71 and related soluble factors for 2 weeks after severe, non-thermal injury

BACKGROUND

Severe injury is associated with changes in monocytes that may contribute to poor outcomes. Longitudinal characterization of monocyte response patterns after trauma may provide added insight into these immunological alterations.

METHODS

Venous blood obtained seven times during post-injury days 1 through 13 from 61 patients with an injury severity score >20 was assessed by flow cytometry for monocytes (CD14+) expressing HLA-DR or CD71 (transferrin receptor) and for circulating levels of interleukin (IL) 1alpha, IL-1beta, IL-6, soluble CD14 (sCD14), tumor necrosis factor-alpha (TNF-alpha), prostaglandin E(2) (PGE(2)), thromboxane B(2) (TXB(2)), and endotoxin. Urine neopterin was measured by high-pressure liquid chromatography, expressed as a neopterin-creatinine ratio.

RESULTS

Trauma patients had leucocytosis days 1 through 13, monocytosis days 5 through 13, reduced proportions of CD14+HLA-DR+ cells days 2 through 5, and elevated proportions of CD14+CD71+ cells days 1 through 13. Neopterin was elevated all days, peaking on day 10. sCD14 was elevated days 2 through 13, and there were sporadic elevations of IL-1alpha, IL-1beta, IL-6, TNF-alpha, PGE(2), TXB(2), and endotoxin. Sepsis syndrome patients (n = 6) had larger and more prolonged reductions in CD14+HLA-DR+ cells and higher neopterin values, in comparison with uneventful patient outcomes.

CONCLUSIONS

Altered proportions of monocytes expressing HLA-DR and CD71 and elevated sCD14 and urine neopterin levels, for up to 2 weeks after severe injury, underscores an extended period of profound immunological effects. Additional studies to more fully assess temporal monocyte response patterns after severe injury, including activation, may be warranted.

Improved diagnostic approaches to infection/sepsis detection

Sepsis is a major healthcare problem from the perspective of mortality and economics. Advances in diagnostic detection of infection and sepsis have been slow, but recent advances in both soluble biomarker detection and quantitative cellular measurements promise the availability of improved diagnostic techniques. Though the promise of cytokine measurements reaching clinical practice have not matured, procalcitonin levels are currently available in many countries and appear to offer enhanced diagnostic distinction between bacterial and viral etiologies. Cellular diagnostics is poised to enter clinical laboratory practice in the form of neutrophil CD64 measurements, which offer superior sensitivity and specificity to conventional laboratory assessment of sepsis. Neutrophil CD64 expression is negligible in the healthy state. However, it increases as part of the systemic response to severe infection or sepsis. The combination of cellular proteomics, as in the case of neutrophil CD64 quantification, and selected soluble biomarkers of the inflammatory response, such as procalcitonin or triggering receptor expressed on myeloid cells (TREM)-1, is predicted to remove the current subjectivity and uncertainty in the diagnosis and therapeutic monitoring of infection and sepsis.

Toward resolving the challenges of sepsis diagnosis

Sepsis in the United States has an estimated annual healthcare cost of 16.7 billion dollars and leads to 120,000 deaths. Insufficient development in both medical diagnosis and treatment of sepsis has led to continued growth in reported cases of sepsis over the past two decades with little improvement in mortality statistics. Efforts over the last decade to improve diagnosis have unsuccessfully sought to identify a "magic bullet" proteic biomarker that provides high sensitivity and specificity for infectious inflammation. More recently, genetic methods have made tracking regulation of the genes responsible for these biomarkers possible, giving current research new direction in the search to understand how host immune response combats infection. Despite the breadth of research, inadequate treatment as a result of delayed diagnosis continues to affect approximately one fourth of septic patients. In this report we review past and present diagnostic methods for sepsis and their respective limitations, and discuss the requirements for more timely diagnosis as the next step in curtailing sepsis-related mortality. We also present a proposal toward revision of the current diagnostic paradigm to include real-time immune monitoring.

Procalcitonin: improved biochemical severity stratification and postoperative monitoring in severe abdominal inflammation and sepsis

BACKGROUND

Infections and sepsis are among the most devastating complications in abdominal surgery and significantly contribute to morbidity and mortality. Early and reliable diagnosis of septic complications is notoriously difficult, and the search for novel approaches to overcome this problem is still a compelling issue for clinicians. Among a large array of inflammatory parameters, procalcitonin (PCT), the 116-amino-acid pro-peptide of calcitonin, has gained considerable importance in identifying patients at risk of developing infection and sepsis in clinical practice.

METHODS

Along with the latest insights into pathophysiological aspects of this pro-hormone, the literature as well as our own experience on the usefulness of PCT determinations in patients with severe inflammatory abdominal disorders was reviewed.

RESULTS

Although the term "sepsis" does not embrace the integral properties of PCT, a remarkable number of clinical studies have demonstrated the pivotal role of this parameter in the host response to microbial and fungal infections. In acute pancreatitis PCT allows early severity stratification and closely correlates with the development of subsequent pancreatic infections. In patients with peritonitis PCT reflects overall disease severity and is an early and reliable indicator of overall prognosis. Postoperative monitoring of PCT is a helpful tool to identify patients with evolving or persisting septic complications after elective and emergency abdominal surgery.

CONCLUSIONS

Compared with established biochemical routine variables, PCT significantly contributes to earlier and better stratification of patients at risk of developing septic complications and provides excellent prognostic assessment in severe abdominal inflammation. The currently available test systems render PCT an applicable and readily available parameter under clinical routine and emergency conditions.

Cytometric bead assay of cytokines in sepsis: A clinical evaluation

BACKGROUND

The clinical relevancy of an attractive new multiparametric method, cytometric beads assay (CBA), was evaluated for the monitoring of cytokines in sepsis.

METHODS

A total of 52 samples (26 patients) were simultaneously tested by CBA and chemiluminescence (IL-6, IL-8, IL-1beta, and TNFalpha) or ELISA (IL-10, IL-12 p40, IL-12 p70, and soluble TNFalpha-RI).

RESULTS

CBA standard curves were linear from 20-5,000 ng/L except for IL-1beta (40-5,000 ng/L). IL-6 and IL-8 were detected in 41 and 48 samples (44-5,000 ng/L and 22-5,000 ng/L), respectively, and out of range in six samples. IL-10 and IL-1beta were detected in 14 and 15 samples (21-1,548 ng/L and 29-582 ng/L), respectively. TNFalpha was rarely detected, and IL-12 p70 was never detected. Accuracy and repeatability were good (CV for IL-6 was 2.1-8.7%; for IL-8 3.7-5.3%; for IL-10 2.5-9.1%; for IL-12 5.2-6.5%; for IL-1 beta 4-12%; and for TNFalpha 3-19.3%). Reproducibility of four standard curves and 20 samples (-1.1 to +1.03%) was excellent between tests done at two- to six-week intervals. CBA values were correlated (r2 > 0.89; P < 0.001) with our reference methods, but were lower on CBA (TNFalpha 45% +/- 8; IL-6 49% +/- 7), probably due to interactions with patients' serum, as confirmed by spiking diluted standards in one patient's serum with end stage renal failure and high levels of TNF soluble receptor (i.e., TNFalpha levels 34 and 21%).

CONCLUSIONS

Finally, these results suggest that IL-6, IL-8, IL-1beta, and Il-10 are clinically promising for sepsis evaluation. However, sensitivity of TNFalpha has to be improved and IL-12 p70 should be replaced with more relevant parameters such as TNF-R, procalcitonin, or neopterin.