Monocyte Count on Admission Is Predictive of Shunt-Dependent Hydrocephalus After Aneurysmal Subarachnoid Hemorrhage

The Role of Serum Monocytes and Tissue Macrophages in Driving Left Ventricular Systolic Dysfunction and Cardiac Inflammation Following Subarachnoid Hemorrhage

BACKGROUND

Neurocardiogenic injury is common after aneurysmal subarachnoid hemorrhage (aSAH) despite low prevalence of preexisting cardiac disease. Potential mechanisms include autonomic dysregulation due to excess catecholamines as well as systemic inflammation. Understanding how inflammation contributes to cardiac dysfunction may aid in identifying novel therapeutic strategies. Here, we investigated serum leukocytes as predictors of left ventricular systolic dysfunction in patients with aSAH. We also investigated increased cardiac macrophages in an animal model of SAH and whether immunomodulatory treatment could attenuate this inflammatory response.

METHODS

We retrospectively analyzed 256 patients with aSAH admitted to University of Illinois Hospital between 2013 and 2019. Our inclusion criteria included patients with aSAH receiving an echocardiogram within 72 h of admission. Our primary outcome was echocardiographic evidence of systolic dysfunction. We performed multinomial regression and receiver operating curve analysis. We also used the endovascular perforation model of SAH in male Sprague-Dawley rats to assess for myocardial inflammation. Two days after surgery, hearts were collected and stained for the macrophage marker Iba-1. We compared the presence and morphology of macrophages in cardiac tissue isolated from SAH animals and sham controls treated with and without the immunomodulatory agent fingolimod.

RESULTS

Of 256 patients with aSAH, 233 (91.0%) underwent echocardiography within 72 h of admission. Of 233, 81 (34.7%) had systolic dysfunction. Patients had baseline differences in the presence of hypertension, alcohol use, and admission Glasgow Coma Scale and Hunt-Hess score. On multivariable analysis, total leukocytes (odds ratio 1.312, p < 0.001), neutrophils (odds ratio 1.242, p = 0.012), and monocytes (odds ratio 6.112, p = 0.008) were independent predictors of reduced systolic function, whereas only monocytes (odds ratio 28.014, p = 0.030) predicted hyperdynamic function. Within the rodent heart, there were increased macrophages after SAH relative to controls, and this was attenuated by fingolimod treatment (p < 0.0001).

CONCLUSIONS

Increased serum leukocytes are associated with abnormal left ventricular systolic function following aSAH. The strongest independent predictor of both reduced and hyperdynamic systolic function was increased monocytes. Increased cardiac macrophages after experimental SAH can also be targeted by using immunomodulatory drugs.

Systemic innate myeloid responses to acute ischaemic and haemorrhagic stroke

Acute ischaemic and haemorrhagic stroke account for significant disability and morbidity burdens worldwide. The myeloid arm of the peripheral innate immune system is critical in the immunological response to acute ischaemic and haemorrhagic stroke. Neutrophils, monocytes, and dendritic cells (DC) contribute to the evolution of pathogenic local and systemic inflammation, whilst maintaining a critical role in ongoing immunity protecting against secondary infections. This review aims to summarise the key alterations to myeloid immunity in acute ischaemic stroke, intracerebral haemorrhage (ICH), and subarachnoid haemorrhage (SAH). By integrating clinical and preclinical research, we discover how myeloid immunity is affected across multiple organ systems including the brain, blood, bone marrow, spleen, and lung, and evaluate how these perturbations associate with real-world outcomes including infection. These findings are placed in the context of the rapidly developing field of human immunology, which offers a wealth of opportunity for further research.

Systemic Immune-Inflammation Index Predicts Acute Symptomatic Hydrocephalus After Spontaneous Nonaneurysmal Subarachnoid Hemorrhage

OBJECTIVE

The authors sought to investigate the association between white blood cell counts and acute hydrocephalus in spontaneous nonaneurysmal subarachnoid hemorrhage (nSAH).

METHODS

We conducted a retrospective analysis of 105 consecutive patients with spontaneous nSAH. Univariate and multivariable logistic regression analyses were performed to investigate factors associated with hydrocephalus. Receiver operating characteristic curve analysis determined the optimal cutoff to differentiate between patients with and without hydrocephalus. The admission characteristics of hydrocephalic patients with aneurysmal and nSAH were compared.

RESULTS

A total of 70 patients met inclusion criteria, of which 21 (30%) presented with hydrocephalus. In univariate logistic regression, leukocytes, neutrophils, lymphocytes, neutrophil-to-lymphocyte ratio, lymphocyte-to-monocyte ratio, neutrophil-monocyte-to-lymphocyte ratio, and the systemic immune-inflammation (SII) index ([neutrophils × platelets/lymphocytes]/1000) were associated with hydrocephalus. After adjustments, the SII index independently predicted acute hydrocephalus with the highest odds among laboratory values (odds ratio 2.184, P = 0.006). Receiver operating characteristic curve analysis revealed the SII index differentiated between patients with and without hydrocephalus (area under the curve = 0.799, 95% CI: 0.688-0.909, P < 0.001) with an optimal cutoff of 1.385 103/μL. SII indices did not differ between aneurysmal and nSAH patients with hydrocephalus (3.5 vs. 3.6 103/μL, P = 0.795).

CONCLUSIONS

A SII index ≥1.385 103/μL on admission predicts acute hydrocephalus in spontaneous nSAH. Hydrocephalic patients with aneurysmal and nSAH exhibit similar SII indices, and thus, an exaggerated inflammatory and thrombotic response follows spontaneous subarachnoid hemorrhage irrespective of hemorrhage etiology.