Background and Purpose: Cell-free DNA (cfDNA) and endogenous deoxyribonuclease activity are opposing mediators and might influence the inflammatory response following acute ischemic stroke. In this cohort study, we investigated the relation between these markers, circulating inflammatory mediators and clinical course including occurrence of stroke-associated infections (SAI) in patients with acute stroke. Methods: Ninety-two patients with stroke due to large vessel occlusion undergoing mechanical thrombectomy were prospectively recruited at Hannover Medical School from March 2018 to August 2019. Deoxyribonuclease activity, cfDNA, damage-associated molecular patterns, and circulating cytokines were measured in venous blood collected immediately before mechanical thrombectomy and 7 days later. Reperfusion status was categorized (sufficient/insufficient). Clinical outcome was evaluated using the modified Rankin Scale after 90 days, where a score of 3 to 6 was considered unfavorable. To validate findings regarding SAI, another stroke cohort (n=92) was considered with blood taken within 24 hours after stroke onset. Results: Patients with unfavorable clinical outcome had higher cfDNA concentrations. After adjustment for confounders (Essen Stroke Risk Score, National Institutes of Health Stroke Scale, and sex), 7-day cfDNA was independently associated with clinical outcome and especially mortality (adjusted odds ratio: 3.485 [95% CI, 1.001–12.134] and adjusted odds ratio: 9.585 [95% CI, 2.006–45.790]). No association was found between reperfusion status and cfDNA or deoxyribonuclease activity. While cfDNA concentrations correlated positively, deoxyribonuclease activity inversely correlated with distinct biomarkers. Baseline deoxyribonuclease activity was lower in patients who developed SAI compared with patients without SAI. This association was confirmed after adjustment for confounding factors (adjusted odds ratio: 0.447 [95% CI, 0.237–0.844]). In cohort 2, differences of deoxyribonuclease activity between patients with and without SAI tended to be higher with higher stroke severity. Conclusions: The interplay of endogenous deoxyribonuclease activity and cfDNA in acute stroke entails interesting novel diagnostic and potential therapeutic approaches. We confirm an independent association of cfDNA with a detrimental clinical course after stroke due to large vessel occlusion. This study provides first evidence for lower endogenous deoxyribonuclease activity as risk factor for SAI after severe stroke.

The present study in juvenile rats investigated a "two-hit model" to test the impact of prenatal stress exposure ("first hit") on the regulation of the synaptic plasticity immediate early genes Arc and Egr1 in response to a second neonatal stressor ("second hit") in a sex-specific manner. Three stress-exposed animal groups were compared at the age of 21 days in relation to unstressed controls (CON): preS animals were exposed to various unpredictable stressors during the last gestational trimester; postS animals were exposed to 45 min restraint stress at postnatal day 21, pre/postS animals were exposed to a combination of pre- and postnatal stress as described for the two previous groups. The postS and pre/postS groups were killed 2 h after exposure to the postnatal stressor, males and females were separately analyzed. In line with our hypothesis we detected sex-specific stress sensitivity for both analyzed proteins. Males did not show any significant changes in Arc expression irrespective of the stress condition. In contrast, females, which had been pre-exposed to prenatal stress, displayed an "amplified" Arc upregulation in response to postnatal stress (pre/postS group) compared to unstressed controls, which may reflect a "sensitization" effect of prenatal stress. For Egr1, the females did not show any stress-induced regulation irrespective of the stress condition, whereas in males, which were pre-exposed to prenatal stress, we observed a "protective" effect of prenatal stress on postnatal stress-induced downregulation of Egr1 expression (pre/postS group), which may indicate that prenatal stress exposure may induce "resilience".

Mechanical thrombectomy (MT) is a highly efficient treatment in patients with acute ischemic stroke due to large vessel occlusion (LVO). However, in a relevant proportion of LVO, no sufficient recanalization can be achieved. The composition of cerebral thrombi is highly heterogeneous and may constitute a relevant factor for insufficient reperfusion. We hypothesized that circulating cytokines and growth factors involved in thrombo-inflammation and platelet activation may be associated with reperfusion status and thrombus composition in patients undergoing MT. An according biomarker panel was measured in plasma specimens taken prior to MT and at a seven-day follow-up. Reperfusion status was categorized into sufficient or insufficient. Composition of retrieved thrombi was histologically analyzed. Differences of baseline biomarker-concentrations between insufficient and sufficient reperfusion were highest for interferon (IFN)-γ, epidermal growth factor (EGF), platelet derived growth factor (PDGF)-AB/BB, and interferon-γ induced protein 10 (IP-10/CXCL10). After applying correction for multiple comparisons and logistic regression analysis adjusting for stroke etiology, intravenous thrombolysis and vascular risk factors, PDGF-AB/BB was identified as an independent predictor of reperfusion status (odds ratio: 0.403 (95%-CI: 0.199–0.819). Histological analysis revealed that the majority of thrombi had a mixed composition. In conclusion, this study provides first evidence that cytokines and growth factors are potential effectors in patients undergoing MT for the treatment of acute ischemic stroke.