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

Procalcitonin Exerts a Mediator Role in Septic Shock Through the Calcitonin Gene-Related Peptide Receptor

OBJECTIVES

Clinically, procalcitonin represents the most widely used biomarker of sepsis worldwide with unclear pathophysiologic significance to date. Pharmacologically, procalcitonin was shown to signal through both calcitonin receptor and calcitonin gene-related peptide receptor in vitro, yet the identity of its biologically relevant receptor remains unknown.

DESIGN

Prospective randomized animal investigations and in vitro human blood studies.

SETTING

Research laboratory of a university hospital.

SUBJECTS

C57BL/6J mice and patients with post-traumatic sepsis.

INTERVENTIONS

Procalcitonin-deficient mice were used to decipher a potential mediator role in experimental septic shock and identify the relevant receptor for procalcitonin. Cecal ligation and puncture and endotoxemia models were employed to investigate septic shock. Disease progression was evaluated through survival analysis, histology, proteome profiling, gene expression, and flow cytometry. Mechanistic studies were performed with cultured macrophages, dendritic cells, and gamma delta T cells. Main findings were confirmed in serum samples of patients with post-traumatic sepsis.

MEASUREMENTS AND MAIN RESULTS

Procalcitonin-deficient mice are protected from septic shock and show decreased pulmonary inflammation. Mechanistically, procalcitonin potentiates proinflammatory cytokine expression in innate immune cells, required for interleukin-17A expression in gamma delta T cells. In patients with post-traumatic sepsis, procalcitonin positively correlates with systemic interleukin-17A levels. In mice with endotoxemia, immunoneutralization of interleukin-17A inhibits the deleterious effect of procalcitonin on disease outcome. Although calcitonin receptor expression is irrelevant for disease progression, the nonpeptide calcitonin gene-related peptide receptor antagonist olcegepant, a prototype of currently introduced antimigraine drugs, inhibits procalcitonin signaling and increases survival time in septic shock.

CONCLUSIONS

Our experimental data suggest that procalcitonin exerts a moderate but harmful effect on disease progression in experimental septic shock. In addition, the study points towards the calcitonin gene-related peptide receptor as relevant for procalcitonin signaling and suggests a potential therapeutic application for calcitonin gene-related peptide receptor inhibitors in sepsis, which warrants further clinical investigation.

Procalcitonin as a biomarker for critically ill patients with sepsis: Effects of vitamin D supplementation

Early diagnosis of sepsis is often difficult in clinical practice, whilst it can be vital for positive patient outcomes in sepsis management. Any delay in diagnosis and treatment may lead to significant organ failure and can be associated with elevated mortality rates. Early diagnosis and effective management of sepsis can allow for prompt antibiotic therapy and a potential reduction in mortality; it can also minimize the unnecessary use of antibiotics. Furthermore, vitamin D supplementation, which is commonly used in the intensive care units to reduce mortality, may interfere with the ability to use procalcitonin (PCT) as a means of assessing clinical progression. This paper aims to explore the diagnostic and prognostic value of serum levels of PCT as an early marker of sepsis and to assess whether it can be used as a guide for using antibiotic therapy. Several serum-based biomarkers such as C-reactive protein, lactate, presepsin, and cytokines, such as interleukin-1 (IL-1), and IL-6 have been evaluated as early indicators of sepsis but none have been proven sensitive and/or specific enough to make a definitive diagnosis. Finally the potential benefits and disadvantages of using serum levels of PCT to diagnose and monitor patients with sepsis and septic shock will be briefly discussed.

Association of vitamin D status of septic patients in intensive care units with altered procalcitonin levels and mortality

OBJECTIVE

The purpose of this study was to determine whether vitamin D levels correlate with procalcitonin (PCT) levels and mortality in septic patients.

METHODS

The following data were collected from 236 patients upon admission to intensive care units (ICUs): demographics; Acute Physiology and Chronic Health Evaluation (APACHE) II score; Sequential Organ Failure Assessment (SOFA) score; 25-hydroxyvitamin D (25OHD), PCT, intact PTH, albumin, creatinine, and ionized calcium (iCa) levels; 25OHD sampling seasonality; fluid load (colloid and crystalloid before 25OHD sampling); mechanical ventilation duration; and length of stay (LOS) in the ICU. The primary endpoint was all-cause mortality 28 days after ICU admission.

RESULTS

Patients with 25OHD deficiency had significantly higher APACHE II and SOFA scores, positive blood culture rates, PCT levels, intact PTH levels, and 28-day mortality rates. These patients also had lower iCa levels, longer LOS in the ICU, and longer ventilator durations than patients with 25OHD insufficiency or sufficiency. Age, sex, 25OHD sampling seasonality, serum albumin and creatinine levels, and fluid load did not vary among the 3 groups. Serum 25OHD levels at admission were significantly negatively correlated with PCT levels. PTH responders had significantly higher 28-day mortality rates than did PTH nonresponders. Cox regression showed that a 25OHD level of <20 ng/mL was an independent risk factor for 28-day mortality.

CONCLUSIONS

Lower serum 25OHD levels at ICU admission were associated with 28-day mortality in septic patients. Serum 25OHD levels were inversely correlated with PCT levels. Hypovitaminosis D was associated with higher mortality rates in PTH responders than in nonresponders.