Neutrophil respiratory burst; a determinant of the risk of infection after acute cerebrovascular infarction

Abstract

The incidence of stroke has risen over the past decade and is consideredone of the leading causes of death and disability worldwide. While a large portion of immediate death following stroke is due to cerebral infarction and neurological complications, the most common medical complication in stroke patients is infection. In fact, infections, such as pneumonia and urinary tract infections, greatly worsen the clinical outcome of stroke patients. Damage to the brain after stroke is now known to be a largely immune mediated event. As a compensatory response to the highly inflamed environment within the skull, the brain-immunity axis is a recently identified and complex pathway that induces immune suppression after stroke. This is believed to be a defensive mechanism of the brain with an attempt to lessen further cerebral damage, however rendering the host more susceptible to infections. Although the relationship between stroke and the adaptive immunity has been investigated, little is known whether innate immune system, which form the first line of antibacterial defense, is also impaired with stroke. Oxidative burst is one ofthe key mechanismsused by neutrophilsto kill bacteria. Therefore, this study aimed to determinewhether stroke altered the percentage or efficacy of oxidative burst in current study samples.

The study included the following groups: • 30 patients with acute cerebral infarction recruited from the stroke units of Ain Shams University Hospital. • 30 healthy individuals as a control group, who were group-matched with patients for age and sex, recruited from among relatives of patients, hospital workers and nursing staff. • Patients with acute cerebrovascular infarction werediagnosed according to the National Institute for Health and Care Excellence (NICE guidelines) and scored according to National Institute of Health Stroke Scale Score (NIHSS) All patients subjected to the following: 1. Magnetic resonance imaging on the brain immediately on admission, at radiology unit of Ain shams university hospital. 2. Blood sampling on day one of admission (baseline) and after 3 days of admission. Blood sample wereused for the assessment of: a- Differential leucocytic count., C Reactive Protein (CRP) b- Percentages of neutrophils showing spontaneous oxidative burst&performed by flow cytometry at the Clinical Pathology Laboratory at Ain Shams University Hospital. In addition, Differential leucocytic count.,C Reactive Protein (CRP) and percentages of neutrophils showing spontaneous oxidative burst assessed by flow cytometry for all healthy controls. In this studythat, neutrophil respiratory burst percentage was significantly lower in stroke patients than controls. Stroke patients had significantly lower Neutrophil respiratory burst (%) on day 3 of admission compared to base line value on admission. We also observed thatneutrophil respiratory burstin cases on admission (baseline) were significantlyinversely correlatedto incidence of infection following admission, and increased significantly on day 3of admission, which increase significantlythe length of hospital stay. We also observeda significant inverse correlation between neutrophil respiratory burst on day 3 in cases and stroke severity (NIHSS). There was significant relationship between neutrophilrespiratory burst (%) on days 3 in case and size of stroke in MRI finding (size of occluded cerebral vessels);The larger the occulded vessels, the lower the neutrophilrespiratory burst (%).