Sepsis is a life-threatening organ dysfunction caused through a dysregulated host response to an infection. Septic shock, a subset of sepsis, is associated with abnormalities in many areas of the body and poses a high risk of mortality when it occurs.
Sepsis is a major healthcare issue throughout the world and a team of Researchers from Spain have created a novel patent-pending multiple reaction monitoring targeted mass spectrometry and a multiple reaction monitoring approach (MRM-MS) to detect circulating H3 and H2B histones in the plasma of septic shock patients.
Sepsis, aka blood poisoning, affects millions of people worldwide and has been categorized as a global healthcare problem. Part of the issue surrounding sepsis is that it is a growing problem due to ageing populations, immuno-senescence and the resulting impaired immunity. Sepsis is often documented as the most common cause of death in intensive care units (ICUs) and accounts for more than $20 billion (5.2% of total hospital costs) in the US alone in 2011. Despite the high cost and mortality rates of sepsis, most of the population are unaware of the damage it can impose.
Currently, mortality rates for sepsis range between 10% and 40%, but for cases where septic shock is induced the mortality rate jumps up to anywhere between 30% and 60%, depending on the severity and overall health of the patient. Therapeutic advances have helped to curb the mortality rate in recent years, but the dangerous nature of sepsis requires efficient detection and monitoring equipment to help improve mortality rates even further.
The Researchers from Spain have created a novel mass spectrometry method which detects circulating H3 and H2B histones in a patient’s blood sample. The Researchers took plasma from the blood of septic shock patients with bacteraemia using the new technique, which known as multiple reaction monitoring targeted mass spectrometry (MRM-MS).
The Researchers included 10 healthy subjects as a control group in the study and applied the same exclusion criteria as the patients. The patient group included 17 patients from the medical ICU of the Clinical University Hospital of Valencia (HCUV) who had been clinically admitted for septic shock. For the patients to be used in the study, the plasma had to also contain bacteraemia.
For this study, the exclusion criteria set by the Researchers was as follows:
- Patients with a life expectancy under 24 hours
- Patients beyond the age range of 18–85 years
- Patients with an active neoplastic process or treated with antioxidants
- Patients with a stay in hospital ward prior to ICU admission longer than 24 hours or were transferred from another hospital
- Surgical patients
The MRM experiments were performed using a 5500 QTRAP hybrid triple quadrupole/linear ion trap mass spectrometer (ABSciex), with an Eksigent 1D+plus NanoLC chromatographic system. The area ratios for the transitions in the mass spectrometer were analyzed using Analyst 1.5.2 and MultiQuant 2.0.2 software (ABsciex). The new mass spectrometry method calculated the concentrations of both histones in the plasma samples from the average signal peak sample/signal peak Spike-In ratios.
By measuring against known internal standards, the Researchers found that it was possible to quantify the concentration of the histones in the circulating plasma. The results showed a high histone concentration in the patients with septic shock but not in the healthy control samples, and such a discovery has allowed the histones to be biomarkers for diagnosing septic shock.
The Researchers compared the patients who survived with those who did not and found a correlation between the histone concentration and the survival outcome- the consensus being that a higher concentration of circulating histones represented a more unfavorable outcome. Of the two histones, the H3 histone was found to be a more efficient and sensitive biomarker for septic shock diagnosis.
However, despite having a novel method which can efficiently and sensitively detect septic shock, the Researchers state that limitations should be considered. The main concern being clinical validation. Further research in this case would need to include a larger sample size, more sever septic patients and to test with critically ill non-infected patients rather than completely healthy control volunteers.
Overall, the presence of these histones can be used for clinical purposes and the novel method is currently undergoing a patent application process. The new mass spectrometry method, should it materialize commercially in the clinic, could be used as a first triage criterion when patients arrive into an ICU. Aside from helping to detect early septic shock, the method also has the potential to become a useful prognostic biomarker for the prognosis of fatal septic shock outcomes.
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“A new mass spectrometry-based method for the quantification of histones in plasma from septic shock patients”- García-Giménez J. L. et al, Scientific Reports, 2017, DOI:10.1038/s41598-017-10830-z