Molecular Pathogenesis of Ischemic and Hemorrhagic Strokes: Background and Therapeutic Approaches.

Stroke represents one of the neurological diseases most responsible for death and permanent disability in the world. Different factors, such as thrombus, emboli and atherosclerosis, take part in the intricate pathophysiology of stroke. Comprehending the molecular processes involved in this mechanism is crucial to developing new, specific and efficient treatments. Some common mechanisms are excitotoxicity and calcium overload, oxidative stress and neuroinflammation. Furthermore, non-coding RNAs (ncRNAs) are critical in pathophysiology and recovery after cerebral ischemia. ncRNAs, particularly microRNAs, and long non-coding RNAs (lncRNAs) are essential for angiogenesis and neuroprotection, and they have been suggested to be therapeutic, diagnostic and prognostic tools in cerebrovascular diseases, including stroke. This review summarizes the intricate molecular mechanisms underlying ischemic and hemorrhagic stroke and delves into the function of miRNAs in the development of brain damage. Furthermore, we will analyze new perspectives on treatment based on molecular mechanisms in addition to traditional stroke therapies.

Can Hemorrhagic Stroke Genetics Help Forensic Diagnosis in Pediatric Age (<5 Years Old)?

When stroke occurs in pediatric age, it might be mistakenly interpreted as non-accidental head injury (NAHI). In these situations, a multidisciplinary approach is fundamental, including a thorough personal and familial history, along with accurate physical examination and additional investigations. Especially when the clinical picture is uncertain, it is important to remember that certain genetic conditions can cause bleeding inside the brain, which may resemble NAHI. Pediatric strokes occurring around the time of birth can also be an initial sign of undiagnosed genetic disorders. Hence, it is crucial to conduct a thorough evaluation, including genetic testing, when there is a suspicion of NAHI but the symptoms are unclear. In these cases, a characteristic set of symptoms is often observed. This study aims to summarize some of the genetic causes of hemorrhagic stroke in the pediatric population, thus mimicking non-accidental head injury, considering elements that can be useful in characterizing pathologies. A systematic review of genetic disorders that may cause ICH in children was carried out according to the Preferred Reporting Item for Systematic Review (PRISMA) standards. We selected 10 articles regarding the main genetic diseases in stroke; we additionally selected 11 papers concerning patients with pediatric stroke and genetic diseases, or studies outlining the characteristics of stroke in these patients. The disorders we identified were Moyamoya disease (MMD), COL4A1, COL4A2 pathogenic variant, Ehlers-Danlos syndrome (E-D), neurofibromatosis type 1 (Nf1), sickle cell disease (SCD), cerebral cavernous malformations (CCM), hereditary hemorrhagic telangiectasia (HHT) and Marfan syndrome. In conclusion, this paper provides a comprehensive overview of the genetic disorders that could be tested in children when there is a suspicion of NAHI but an unclear picture.

Association of MMP3, MMP14, and MMP25 gene polymorphisms with cerebral stroke risk: a case-control study.

BACKGROUND: Cerebral stroke (CS) is the leading cause of death in China, and a complex disease caused by both alterable risk factors and genetic factors. This study intended to investigate the association of MMP3, MMP14, and MMP25 single nucleotide polymorphisms (SNPs) with CS risk in a Chinese Han population. METHODS: A total of 1,348 Han Chinese were recruited in this case-control study. Four candidate loci including rs520540 A/G and rs679620 T/C of MMP3, rs2236302 G/C of MMP14, and rs10431961 T/C of MMP25 were successfully screened. The correlation between the four SNPs and CS risk was assessed by logistic regression analysis. The results were analyzed by false-positive report probability (FPRP) for chance or significance. The interactions between four SNPs associated with CS risk were assessed by multifactor dimensionality reduction (MDR). RESULTS: rs520540 A/G and rs679620 C/T SNP in MMP3 were associated with risk of CS in allele, codominant, dominant and log-additive models. Ischemic stroke risk were significantly lower in carriers with rs520540-A allele and rs679620-T allele than those with G/G or C/C genotypes. However, rs520540-A allele and rs679620-T allele were associated with higher risk of hemorrhagic stroke. Stratified analysis showed that these two SNPs were associated with reduced risk of CS in aged < 55 years, non-smoking and non-drinking participants, and rs679620 SNP also reduced CS risk in male participants. The levels of uric acid, high-density lipoprotein cholesterol, and eosinophil were different among patients with different genotypes of rs520540 and rs679620. No statistically significant association was found between MMP14 rs2236302 G/C or MMP25 rs10431961 T/C with CS even after stratification by stroke subtypes, age, gender as well as smoking and drinking conditions in all the genetic models. CONCLUSION: MMP3 rs520540 A/G and rs679620 C/T polymorphisms were associated with CS risk in the Chinese Han population, which provides useful information for the prevention and diagnosis of CS.

Elevated sdLDL level and LDLR rs688 C>T mutation are independent risk factors for ischemic stroke.

PURPOSE: To investigate the level of sdLDL and the frequency of LDLR rs688 polymorphisms, as well as the correspondence between them, and to analyze the risk factors for stroke. METHODS: Between March 2019 and November 2019, 232 patients diagnosed with stroke and 96 health volunteers were enrolled in Quanzhou First Hospital. Subjects were divided into control group, ischemic stroke group (n=120) and hemorrhagic stroke group (n=112). The level of sdLDL and the genotypes and allele frequencies of LDLR rs688 were compared between groups, the correspondence was analyzed with Spearman method. Risk factors were analyzed with Binary logistic regression. RESULTS: The level of sdLDL was highest in ischemic group, followed by hemorrhagic stroke group and lowest control group. The differences of genotypes and allele frequencies of LDLR rs688 were significant in ischemic stroke group (p=0.0000 and 0.0000 respectively), while were not significant in hemorrhagic group (p=0.184 and .0137). There was no obvious correlation between the level of sdLDL and LDLR rs688 genotype by Spearman analysis (p=0.116). CONCLUSION: Elevated sdLDL level and the C>T mutation of LDLR rs688 are independent risk factors for ischemic stroke, while they are not correlative to hemorrhagic stroke. The surveillance and regulatory of sdLDL level, the detection of LDLR rs688 gene polymorphisms may contribute to the prevention of ischemic stroke.

Clonal Hematopoiesis Is Associated With Higher Risk of Stroke.

BACKGROUND AND PURPOSE: Clonal hematopoiesis of indeterminate potential (CHIP) is a novel age-related risk factor for cardiovascular disease-related morbidity and mortality. The association of CHIP with risk of incident ischemic stroke was reported previously in an exploratory analysis including a small number of incident stroke cases without replication and lack of stroke subphenotyping. The purpose of this study was to discover whether CHIP is a risk factor for ischemic or hemorrhagic stroke. METHODS: We utilized plasma genome sequence data of blood DNA to identify CHIP in 78 752 individuals from 8 prospective cohorts and biobanks. We then assessed the association of CHIP and commonly mutated individual CHIP driver genes (DNMT3A, TET2, and ASXL1) with any stroke, ischemic stroke, and hemorrhagic stroke. RESULTS: CHIP was associated with an increased risk of total stroke (hazard ratio, 1.14 [95% CI, 1.03-1.27]; P=0.01) after adjustment for age, sex, and race. We observed associations with CHIP with risk of hemorrhagic stroke (hazard ratio, 1.24 [95% CI, 1.01-1.51]; P=0.04) and with small vessel ischemic stroke subtypes. In gene-specific association results, TET2 showed the strongest association with total stroke and ischemic stroke, whereas DMNT3A and TET2 were each associated with increased risk of hemorrhagic stroke. CONCLUSIONS: CHIP is associated with an increased risk of stroke, particularly with hemorrhagic and small vessel ischemic stroke. Future studies clarifying the relationship between CHIP and subtypes of stroke are needed.

Human Milk Oligosaccharide 2'-Fucosyllactose Induces Neuroprotection from Intracerebral Hemorrhage Stroke.

Intracerebral hemorrhage (ICH) occurs when brain blood vessels rupture, causing inflammation and cell death. 2-Fucosyllactose (2FL), a human milk oligosaccharide, has potent antiapoptotic and anti-inflammatory effects. The purpose of this study was to examine the protective effect of 2FL in cellular and rodent models of ICH. Hemin was added to a primary rat cortical neuronal and BV2 microglia coculture to simulate ICH in vitro. IBA1 and MAP2 immunoreactivities were used to determine inflammation and neuronal survival. Hemin significantly increased IBA1, while it reduced MAP2 immunoreactivity. 2FL significantly antagonized both responses. The protective effect of 2FL was next examined in a rat ICH model. Intracerebral administration of type VII collagenase reduced open-field locomotor activity. Early post-treatment with 2FL significantly improved locomotor activity. Brain tissues were collected for immunohistochemistry and qRT-PCR analysis. 2FL reduced IBA1 and CD4 immunoreactivity in the lesioned striatum. 2FL downregulated the expression of ER stress markers (PERK and CHOP), while it upregulated M2 macrophage markers (CD206 and TGFß) in the lesioned brain. Taken together, our data support that 2FL has a neuroprotective effect against ICH through the inhibition of neuroinflammation and ER stress. 2FL may have clinical implications for the treatment of ICH.

Effects of SGLT2 inhibitors on stroke and its subtypes in patients with type 2 diabetes: a systematic review and meta-analysis.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have shown impressive effects in reducing major vascular events in several randomized controlled trials (RCTs). The purpose of this study was to perform a meta-analysis to evaluate the effect of SGLT2 inhibitors on the risk of stroke and its subtypes. All data from prospective RCTs up to 20 October 2020 involving SGLT2 inhibitors that reported stroke events as the primary endpoint or safety in subjects with type 2 diabetes were subjected to meta-analysis. Five eligible RCTs (EMPA-REG, CANVAS, DECLARE-TIMI 58, CREDENCE and VERTIS CV) involving 46,969 participants were included. Pooled analysis of the RCTs showed no significant effect of SGLT2 inhibitors on total stroke [risk ratio (RR) = 0.95; 95% confidence interval (CI) 0.79-1.13, P = 0.585]. Subgroup analysis indicated that SGLT2 inhibitors had no significant effect against fatal stroke, non-fatal stroke, ischemic stroke or transient ischemic attack. When only hemorrhagic stroke was included, SGLT2 inhibitors were associated with a significant 50% reduction compared with placebo (RR = 0.49, 95% CI 0.30-0.82, P = 0.007). This meta-analysis shows that SGLT2 inhibitors have a neutral effect on the risk of stroke and its subtypes but a potential protective effect against hemorrhagic stroke.

Association of ADH1B polymorphism and alcohol consumption with increased risk of intracerebral hemorrhagic stroke.

BACKGROUND: Alcohol consumption is one of the modifiable risk factors for intracerebral hemorrhage, which accounts for approximately 10-20% of all strokes worldwide. We evaluated the association of stroke with genetic polymorphisms in the alcohol metabolizing genes, alcohol dehydrogenase 1B (ADH1B, rs1229984) and aldehyde dehydrogenase 2 (ALDH2, rs671) genes based on alcohol consumption. METHODS: Data were available for 19,500 Taiwan Biobank (TWB) participants. We used logistic regression models to test for associations between genetic variants and stroke. Overall, there were 890 individuals with ischemic stroke, 70 with hemorrhagic stroke, and 16,837 control individuals. Participants with ischemic but not hemorrhagic stroke were older than their control individuals (mean ± SE, 58.47 ± 8.17 vs. 48.33 ± 10.90 years, p < 0.0001). ALDH2 rs671 was not associated with either hemorrhagic or ischemic stroke among alcohol drinkers. However, the risk of developing hemorrhagic stroke was significantly higher among ADH1B rs1229984 TC + CC individuals who drank alcohol (odds ratio (OR), 4.85; 95% confidence interval (CI) 1.92-12.21). We found that the test for interaction was significant for alcohol exposure and rs1229984 genotypes (p for interaction = 0.016). Stratification by alcohol exposure and ADH1B rs1229984 genotypes showed that the risk of developing hemorrhagic stroke remained significantly higher among alcohol drinkers with TC + CC genotype relative to those with the TT genotype (OR, 4.43, 95% CI 1.19-16.52). CONCLUSIONS: Our study suggests that the ADH1B rs1229984 TC + CC genotype and alcohol exposure of at least 150 ml/week may increase the risk of developing hemorrhagic stroke among Taiwanese adults.

Mutation analysis of the GLA gene in Chinese patients with intracerebral hemorrhage.

Fabry disease (FD) is an important underlying condition in young cryptogenic stroke patients and has also been implicated in cerebral small vessel disease. However, the contributions of causative GLA mutations in patients with intracerebral hemorrhage (ICH) remain unclear. In this study, GLA sequences were analyzed in a Chinese ICH cohort comprising 373 patients with computed tomography-confirmed ICH and 563 in-house controls and East Asians from public databases. Only one previously reported mutation, p. Ala15Val, responsible for Fabry disease was identified in a female patient with nonlobar ICH. Therefore, this definitive GLA mutation accounted for 0.27% (1/373) of Chinese patients with ICH. Another functional variant, rs2071225 (c.-10C>T), was present at minor allele frequency (MAF) of 9.1%, indicating no association with ICH, despite a trend of an association for male patients with lobar ICH. In conclusion, our results indicate that the GLA mutation is an uncommon genetic etiology of ICH in China.

Dipeptidyl Peptidase-4 deficiency effectively protects the brain and neurological function in rodent after acute Hemorrhagic Stroke.

This study tested the hypothesis that abrogated dipeptidyl peptidase-4 (DPP4) activity played a crucial role on reducing stroke volume and preserving neurological function in rodent after acute hemorrhagic stroke (AHS). Animals (n=6/each group) were categorized into group 1 (sham-control of F344 rat), group 2 (sham-control of DPP4-deficiency rat), group 3 [AHS by right cerebral injection of autologous blood (100 µL) in F344 rat], group 4 (AHS + sitagliptin/600 mg/kg 3 h prior to and at 3 h then once per day after AHS) and group 5 (AHS in DPP4-deficiency rat). The results of corner test showed the neurological function was significantly improved from days 3, 7, and 14 in groups 4 and 5 than in group 3 (all p<0.001). By days 1 and 14 after AHS procedure, the circulating levels of SDF-1α and GLP-1 were significantly increased from groups 1/2 to group 5 (all p<0.001), whereas circulating DPP4 activity was significantly increased in group 3 than other groups (all p<0.001). The brain ischemic area (BIA) was highest in group 3, lowest in groups 1/2 and significantly lower in group 5 than in group 4 (all p<0.0001). The protein expressions of oxidative-stress/inflammatory/apoptotic/cell-proliferation signaling, and the cellular expressions of inflammatory/DNA-damaged biomarkers exhibited a similar pattern to BIA among the groups (all p<0.01). In conclusion, deprivation of DPP4 activity protected the brain from AHS damage and preserved neurological function.

Fgr contributes to hemorrhage-induced thalamic pain by activating NF-κB/ERK1/2 pathways.

Thalamic pain, a type of central poststroke pain, frequently occurs following ischemia/hemorrhage in the thalamus. Current treatment of this disorder is often ineffective, at least in part due to largely unknown mechanisms that underlie thalamic pain genesis. Here, we report that hemorrhage caused by microinjection of type IV collagenase or autologous whole blood into unilateral ventral posterior lateral nucleus and ventral posterior medial nucleus of the thalamus increased the expression of Fgr, a member of the Src family nonreceptor tyrosine kinases, at both mRNA and protein levels in thalamic microglia. Pharmacological inhibition or genetic knockdown of thalamic Fgr attenuated the hemorrhage-induced thalamic injury on the ipsilateral side and the development and maintenance of mechanical, heat, and cold pain hypersensitivities on the contralateral side. Mechanistically, the increased Fgr participated in hemorrhage-induced microglial activation and subsequent production of TNF-α likely through activation of both NF-κB and ERK1/2 pathways in thalamic microglia. Our findings suggest that Fgr is a key player in thalamic pain and a potential target for the therapeutic management of this disorder.

Sleep Duration and Stroke: Prospective Cohort Study and Mendelian Randomization Analysis.

BACKGROUND AND PURPOSE: Studies of sleep duration in relation to specific types of stroke are scarce. Moreover, the results are inconclusive and causality remains unclear. Our objective was to investigate whether sleep duration is associated with risk of stroke and its types using observational and Mendelian randomization designs. METHODS: The prospective study included 79 881 women and men (45-79 years of age) who were followed up for incident stroke or death over a mean follow-up of 14.6 years (1 164 646 person-years) through linkage to Swedish Registers. For the Mendelian randomization study, single-nucleotide polymorphisms associated with sleep duration were identified from a genome-wide association study. Summarized data for genetic associations with stroke were obtained from publicly available data of the MEGASTROKE and the International Stroke Genetics Consortia. RESULTS: Compared with normal sleep duration, long sleep (≥9 hours per day) was associated with increased risk of total and ischemic stroke (hazard ratios [95% CI], 1.12 [1.03-1.22] and 1.14 [1.03-1.24], respectively), whereas short sleep (<7 h/d) was linked to higher risk of intracerebral hemorrhage (hazard ratio [95% CI], 1.21 [1.03-1.41]). The 2-sample Mendelian randomization analysis supported no causal association of short or long sleep duration with ischemic stroke as a whole. CONCLUSIONS: In a prospective study, long sleep duration was associated with increased risk of total and ischemic stroke, whereas short sleep was linked to increased risk of intracerebral hemorrhage. However, the Mendelian randomization analysis did not show a significant detrimental effect of short or long sleep duration on the risk of total stroke or stroke types.