Prolactin, cortisol and heat shock proteins in early sepsis: preliminary data

Introduction

Besides cortisol, prolactin might also be important in maintaining normal immune response in stress states. Its role in the hypothalamus-pituitary-adrenal axis hormonal and immune stress response in sepsis has hardly been investigated in a critically ill setting. The aims of the study were to evaluate the early (first 48 hours) ACTH, cortisol and prolactin plasma levels in ICU patients with severe sepsis/ septic shock (SS) or systemic inflammatory response syndrome (SIRS) compared with healthy control subjects (C) and to correlate their expression with heat shock proteins (HSPs), interleukins (ILs) and outcome.

Methods

Thirty consecutively admitted patients with SS, 22 with SIRS, and 15 C were enrolled in the study. Patients' demographics, laboratory examinations, and APACHE II, SOFA and SAPS III scores were recorded on ICU admission. Blood sampling was performed between 9:00 and 10:00 a.m. Prolactin and cortisol were measured using the ADVIA centaur system, ACTH using the Immulite 2000. Intracellular monocyte HSP (iHSP) was determined after staining with surface antigens CD33- PE/Cy5 and CD45 PE/Cy7 followed by either HSP72-FITC or HSP90a-PE intracellular staining (four-color flow cytometry). Mean fluorescence intensity values for each HSP were noted and analyzed. ELISA was used to determine extracellular (e) HSP, IL-6 and IL-10 levels.

Results

Prolactin (P < 0.034), cortisol (P < 0.0001), and ACTH (P < 0.02) levels differed among groups. Prolactin, cortisol, IL-6, and eHSP90 were higher in SS (P < 0.03) and SIRS (P < 0.04) compared with C. Cortisol and eHSP90 were higher in SS compared with SIRS (P < 0.005; P < 0.03); iHSP72 and iHSP90 were higher in SIRS compared with SS (P < 0.05; P < 0.05) or C (iHSP72, P < 0.02). Cortisol related with eHSP90 (r = 0.45, P < 0.02), lactate (r = 0.33, P < 0.02) and HCO³ (r = -0.45), and prolactin with SAPS III (r = 0.34, P < 0.02), but not with mortality or LOS.

Conclusion

Prolactin seems to be a stress hormone, probably related to the severity of illness, increased along with IL-6 and eHSP90 levels in SS. Also in these patients, cortisol correlates to lactate and eHSP90, but in contrast to SIRS the iHSP72 and iHSP90 immune response is depressed.

Acknowledgements

This research has been co-financed by the European Union (European Social Fund) and Greek national funds through the Operational Program 'Education and Lifelong Learning' of the National Strategic Reference Framework Research Funding Program: THALES.