Infectious causes of stroke. Lancet Infect Dis. 2014;14:869-880. [PMID: 24881525 DOI: 10.1016/s1473-3099(14)70755-8]

Microbial Modulation of Coagulation Disorders in Venous Thromboembolism

Venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), is the third leading cause of cardiovascular death in the world. Important risk factors of thrombosis include bed restraint, surgery, major trauma, long journeys, inflammation, pregnancy, and oral contraceptives, previous venous thromboembolism, cancer, and bacterial infections. Sepsis increases the risk of blood clot formation 2–20 times. In this review, we discussed various mechanisms related to the role of bacteria in venous thrombosis also taking into consideration the role of the human microbiome. Many known bacteria, such as Helicobacter pylori, Chlamydia pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae, Streptococcus pneumoniae, Staphylococcus aureus, and Escherichia coli, causing infections may increase the risk of thrombotic complications through platelet activation or may lead to an inflammatory reaction involving the fibrinolytic system. Additionally, the bacteria participate in the production of factors causing or increasing the risk of cardiovascular diseases. An example can be trimethylamine N-oxide (TMAO) but also uremic toxins (indoxyl sulfate), short-chain fatty acids (SCFA) phytoestrogens, and bile acids. Finally, we presented the involvement of many bacteria in the development of venous thromboembolism and other cardiovascular diseases.

Impact of the COVID-19 outbreak on acute stroke care

Background and purpose

There are concerns that the coronavirus disease 2019 (COVID-19) outbreak negatively affects the quality of care for acute cardiovascular conditions. We assessed the impact of the COVID-19 outbreak on trends in hospital admissions and workflow parameters of acute stroke care in Amsterdam, The Netherlands.

Methods

We used data from the three hospitals that provide acute stroke care for the Amsterdam region. We compared two 7-week periods: one during the peak of the COVID-19 outbreak (March 16th–May 3th 2020) and one prior to the outbreak (October 21st–December 8th 2019). We included consecutive patients who presented to the emergency departments with a suspected stroke and assessed the change in number of patients as an incidence-rate ratio (IRR) using a Poisson regression analysis. Other outcomes were the IRR for stroke subtypes, change in use of reperfusion therapy, treatment times, and in-hospital complications.

Results

During the COVID-19 period, 309 patients presented with a suspected stroke compared to 407 patients in the pre-COVID-19 period (IRR 0.76 95%CI 0.65–0.88). The proportion of men was higher during the COVID-19 period (59% vs. 47%, p < 0.001). There was no change in the proportion of stroke patients treated with intravenous thrombolysis (28% vs. 30%, p = 0.58) or endovascular thrombectomy (11% vs 12%, p = 0.82) or associated treatment times. Seven patients (all ischemic strokes) were diagnosed with COVID-19.

Conclusion

We observed a 24% decrease in suspected stroke presentations during the COVID-19 outbreak, but no evidence for a decrease in quality of acute stroke care.

Acute Cryptogenic Stroke During West Nile Virus Infection: Case Report

West Nile virus is an emerging infection in North America but has not traditionally been associated with acute vascular events. We report a 57-year-old healthy male who developed pharyngitis and a corporeal rash, followed 1 week later by an acute cryptogenic stroke. Following successful endovascular thrombectomy, cerebrospinal fluid analysis revealed acute West Nile virus infection. While severe cases of vasculopathy have been described with flavivirus infection, stroke associated with relatively mild symptoms has not been. Given increasing evidence that viral and bacterial infections of many varieties may be stroke triggers, West Nile virus and other flaviviruses may represent an uncommon but underappreciated trigger of cryptogenic stroke. We review indirect evidence that viral endothelial tropism or a nonspecific peri-infectious inflammatory state may be causative mechanisms.

Effect of herpes zoster vaccine and antiviral treatment on risk of ischemic stroke

OBJECTIVE

To determine whether increased risk of acute ischemic stroke (AIS) following herpes zoster (HZ) might be modified by the status of zoster vaccine live (ZVL) vaccination and antiviral treatment following HZ.

METHODS

We included 87,405 Medicare fee-for-service beneficiaries aged ≥66 years diagnosed with HZ and AIS from 2008 to 2017. We used a self-controlled case series design to examine the association between HZ and AIS, and estimated incidence rate ratios (IRRs) by comparing incidence of AIS in risk periods vs control periods. To examine effect modification by ZVL and antiviral treatment, beneficiaries were classified into 4 mutually exclusive groups: (1) no vaccination and no antiviral treatment; (2) vaccination only; (3) antiviral treatment only; and (4) both vaccination and antiviral treatment. We tested for interaction to examine changes in IRRs across 4 groups.

RESULTS

Among 87,405 beneficiaries with HZ and AIS, 22.0%, 2.0%, 70.1%, and 5.8% were in groups 1 to 4, respectively. IRRs in 0-14, 15-30, 31-90, and 91-180 days following HZ were 1.89 (95% confidence interval [CI], 1.77-2.02), 1.58 (95% CI, 1.47-1.69), 1.36 (95% CI, 1.31-1.42), and 1.19 (95% CI, 1.15-1.23), respectively. There was no evidence of effect modification by ZVL and antiviral treatment on AIS (p = 0.067 for interaction). The pattern of association between HZ and risk for AIS was largely consistent across age group, sex, and race.

CONCLUSIONS

Risk of AIS increased significantly following HZ, and this increased risk was not modified by ZVL and antiviral treatment. Our findings suggest the importance of following recommended HZ vaccination in prevention of HZ and HZ-associated AIS.

Infectious causes of stroke

PURPOSE OF REVIEW

Stroke continues to be a leading cause of debility in the world. Infections have been associated with stroke, but are not considered as directly causal, and so they are not often included in the traditional stroke workup and management. They are especially important in patients with stroke of undetermined etiology, and in certain patient populations, such as young patients without traditional risk factors, and immunocompromised patients.

RECENT FINDINGS

There has been strong evidence for infectious conditions, such as endocarditis, and pathogens, such as varicella zoster in stroke causation, and more supportive evidence is surfacing in recent years of several organisms increasing the stroke risk or being directly causal in stroke. The evidence also seems to be pointing to the role of inflammation in increasing the risk of stroke via accelerated atherosclerosis, vasculitis and vasculopathy.

SUMMARY

Infectious causes should be considered in the differential and work up of stroke in certain patient populations and appropriate treatments need to be initiated to minimize adverse stroke-related outcomes.

Risk of subsequent ischemic stroke in patients with nontyphoidal salmonellosis: A nationwide population-based cohort study

OBJECTIVES

To explore the association between nontyphoidal salmonellosis (NTS) and the risk of acute ischemic stroke (IS) by using a nationwide, population-based study.

METHODS

A retrospective cohort study using claim data from Taiwan's National Health Insurance Research Database (NHIRD), patients aged 18 years and older with histories of NTS (N = 1618) were included from January 1, 2000-December 31, 2012, and the non-NTS group (N = 6472) without NTS were matched by propensity score. The follow-up period was defined as the time from the initial diagnosis of NTS to the date of development of IS, death or 31 December, 2013. Patients previously diagnosed with stroke were excluded. The Cox proportional hazard model with robust sandwich estimator was used to estimate the hazard ratio (HR) and 95% confidence interval (CI) of IS after adjusting for demographic and clinical covariates.

RESULTS

The adjusted hazard ratio (aHR) for the NTS group compared with the non-NTS group was 1.34 (95% confidence interval [CI], 1.10-1.65) for overall stroke. Furthermore, the NTS cohort had an increased risk of IS compared to the non-NTS groups (aHR, 1.42; 95% CI, 1.14-1.78). Stratified analysis showed that compared with propensity score matched non-NTS group, subjects aged ≥65 years, female, those with hypertension, hyperlipidemia, COPD, cancer and heart failure had higher risk of developing stroke. A 1.93-fold significant increase risk for stroke was observed during the first 3-12 months of follow-up (95% CI, 1.07-3.48).

CONCLUSIONS

Patients with NTS is associated with increased risk of developing ischemic stroke compared with non-NTS patients. Timely and mindful treatment plan about NTS may be a milestone to stroke prevention especially in some subpopulation.

COVID-19 and Stroke: Incidental, Triggered or Causative

Stroke is a serious neurological comorbidity observed during the ongoing COVID-19 (coronavirus associated disease 2019) pandemic caused by SARS-CoV-2 (severe acute respiratory syndrome, corona virus 2) and includes ischemic stroke, intracerebral haemorrhage and cerebral venous thrombosis. We reviewed factors that could potentially contribute to the occurrence of stroke among patients with COVID-19. There could be an interaction between the conventional risk factors of stroke, infection, systemic inflammatory response and plaque destabilisation. Inflammatory markers, D-dimer elevation and increased cytokine activity have been observed in patients with COVID-19. Other probable contributing factors include cardiac injury leading to embolism, a prothrombotic state and a possibility of direct neuroinvasive potential causing vasculopathy. Data from stroke patients gathered in large multicentric cohorts could help shed more light on the occurrence, behaviour, aetiology, pathophysiology, biomarkers and outcomes of stroke occurring during the ongoing pandemic.

Shunt Treatment for Coccidioidomycosis-Related Hydrocephalus: A Single-Center Series

OBJECTIVE

Coccidioidomycosis is a fungal infection endemic to the southwestern United States. Hydrocephalus can develop after intracranial dissemination, and management of this disease entity is difficult. We present our institutional experience with shunting coccidioidomycosis-related hydrocephalus.

METHODS

A cohort of patients with coccidioidomycosis-related hydrocephalus undergoing an intracranial shunt placement were retrospectively identified over a 24-year period. Demographics and treatment characteristics were obtained from the electronic medical record.

RESULTS

Thirty patients undergoing 83 procedures were identified, with a median follow-up of 19.4 months. The average age of the cohort was 43 years at the time of initial shunt placement. Most patients (66.7%) had ≥1 shunt failure, and the average number of revisions required was 2.6 for patients who had shunt failure. The average shunt valve pressure threshold required was 5.5 cm H₂O, and patients who harbored the disease for a longer period (>7 months) had a lower pressure setting for initial shunt valves. Shunts without an antisiphon component were more likely to be failure free on multivariate analysis (odds ratio, 9.2; 95% confidence interval, 2.4-35.7). Death was associated with a longer diagnosis-to-shunt time interval, and patients having been diagnosed with intracranial disease for more than 10 months before shunt placement had significantly higher rates of death on follow-up.

CONCLUSIONS

Patients with coccidioidomycosis-related hydrocephalus typically have normal to low pressure setting requirements, high shunt failure rates, prolonged hospitalizations, and mortality. In this disease context, shunt valves without an antisiphon component are associated with lower shunt failure rates.

Central Nervous System Fungal Infection-Related Stroke: A Descriptive Study of Mold and Yeast-Associated Ischemic Stroke

OBJECTIVE

Central nervous system (CNS) ischemic events caused by fungal infections are rare, and clinical characteristics of these ischemic events are largely unknown. The objective of this manuscript is to highlight characteristics of fungal-related strokes and describe possible mechanistic differences between CNS mold and yeast infection-related strokes.

METHODS

We report a single-center retrospective case series of all adult patients who presented with concurrent CNS fungal infection and stroke between 2010 and 2018. Patients believed to have a stroke etiology due to cardioembolic, atheroembolic, or strokes nontemporally associated with a CNS fungal infection and those with incomplete stroke workups were excluded from analysis.

RESULTS

Fourteen patients were identified with ischemic stroke and concurrent CNS fungal infection without other known ischemic stroke etiology. Eight patients had a CNS yeast infection, and 6 had a CNS mold infection. All patients presented with recurrent or progressive stroke symptoms. Six patients were immune-compromised. Four patients admitted to intravenous drug use. All yeast infections were identified by cerebrospinal fluid culture or immunologic studies while all but one of the mold infections required identification by tissue biopsy. Leptomeningeal enhancement was only associated with CNS yeast infections, while basal ganglia stroke was only associated with CNS mold infections.

CONCLUSION

Ischemic stroke secondary to CNS fungal infections should be considered in patients with recurrent or progressive cryptogenic stroke, regardless of immune status and cerebrospinal fluid profile. CNS yeast and mold infections have slightly different stroke and laboratory characteristics and should have a distinct diagnostic method. Depending on clinical suspicion, a thorough diagnostic approach including spinal fluid analysis and biopsy should be considered.

Cryptogenic Stroke: Anatomy of the Stroke Work-Up

Despite advances in understanding the cause of ischemic stroke, cryptogenic stroke remains a diagnostic and therapeutic challenge for clinicians. Approximately 15% to 40% of all ischemic strokes have no identifiable cause. CS is a diagnosis of exclusion after completing the standard stroke work-up. Further investigation needs to be tailored individually according to results of the clinical evaluation so appropriate secondary prevention strategies can be applied.

Ischemic Stroke and Systemic Embolism in Warfarin Users With Atrial Fibrillation or Heart Valve Replacement Exposed to Dicloxacillin or Flucloxacillin

The antibiotics dicloxacillin and flucloxacillin induce cytochrome P450-dependent metabolism of warfarin. We explored the influence of these drug-drug interactions on the clinical effectiveness of warfarin therapy due to atrial fibrillation or heart valve replacement. Using the population-based Danish registers, we performed a propensity-score matched cohort study including around 50,000 episodes of dicloxacillin/flucloxacillin matched to phenoxymethylpenicillin and to no antibiotic, respectively. We estimated hazard ratios (HRs) with 95% confidence intervals (CIs) by comparing 21-day (days 7-28) risks of ischemic stroke/systemic embolism (SE) following initiation of each exposure. When compared with phenoxymethylpenicillin, dicloxacillin/flucloxacillin was associated with an HR of ischemic stroke/SE of 2.09 (95% CI 1.51-2.90; strongest for dicloxacillin (HR 2.17; 95% CI 1.56-3.02)). Use of an untreated comparator strengthened the association (HR 2.84; 95% CI 1.97-4.09). Dicloxacillin should be used with caution in patients receiving warfarin. This may also apply to flucloxacillin; however, more data on the risks associated with flucloxacillin exposure during warfarin therapy are needed.

Understanding Infection-Induced Thrombosis: Lessons Learned From Animal Models

Thrombosis is a common consequence of infection that is associated with poor patient outcome. Nevertheless, the mechanisms by which infection-associated thrombosis is induced, maintained and resolved are poorly understood, as is the contribution thrombosis makes to host control of infection and pathogen spread. The key difference between infection-associated thrombosis and thrombosis in other circumstances is a stronger inflammation-mediated component caused by the presence of the pathogen and its products. This inflammation triggers the activation of platelets, which may accompany damage to the endothelium, resulting in fibrin deposition and thrombus formation. This process is often referred to as thrombo-inflammation. Strikingly, despite its clinical importance and despite thrombi being induced to many different pathogens, it is still unclear whether the mechanisms underlying this process are conserved and how we can best understand this process. This review summarizes thrombosis in a variety of models, including single antigen models such as LPS, and infection models using viruses and bacteria. We provide a specific focus on Salmonella Typhimurium infection as a useful model to address all stages of thrombosis during infection. We highlight how this model has helped us identify how thrombosis can appear in different organs at different times and thrombi be detected for weeks after infection in one site, yet largely be resolved within 24 h in another. Furthermore, we discuss the observation that thrombi induced to Salmonella Typhimurium are largely devoid of bacteria. Finally, we discuss the value of different therapeutic approaches to target thrombosis, the potential importance of timing in their administration and the necessity to maintain normal hemostasis after treatment. Improvements in our understanding of these processes can be used to better target infection-mediated mechanisms of thrombosis.

Carotid Artery Aneurysm in HIV: A Review of Case Reports in Literature

BACKGROUND

HIV infection may affect the cardiovascular system through different physiopathological patterns. Rarely reported in HIV negative patients, aneurysms involving the carotid artery have been described for the first time in seropositive patients in 1989.

AIMS

In our study, we have focused on aneurysm pathology affecting carotid arteries in HIV patients, analyzing clinical and surgical presentation, management, and outcome, through a review of cases published in the literature.

METHODS

The MEDLINE (www.ncbi.nlm.nih.gov/pubmed) database was reviewed for "carotid artery aneurysm AND HIV OR AIDS OR immunodeficiency."

RESULTS

Nineteen articles including a total of 46 cases were included in our report. The mean age of patients was 30.6 ± 14.2 years; 30 patients (65.2%) were male. Aneurysms were localized in the intracranial carotid (41.3%) or extracranial artery (58%). Presenting features included symptoms due to compression of neck structures; positivity for neurological symptoms occurred in 36.9%. Patients were managed surgically in 58.7% of cases; surgical morbidity and mortality were of 22.2% and 7.4% respectively, higher for endovascular procedures. The overall mortality in treated and untreated cases was 26.1%.

CONCLUSIONS

Aneurysms may occur in both the extracranial and intracranial carotid artery in patients with HIV at younger age than in non-HIV patients and are linked to a high morbidity and mortality. Seropositivity must be ruled out whenever this rare vascular condition may occur in the absence of a more likely aetiology and must also be suspected in HIV patients presenting with compressive symptoms of the neck, neurological impairment or stroke.

[Rare causes of stroke-a frequent stroke etiology]

As a whole, rare stroke causes represent a frequent stroke etiology. Since rare stroke causes affect primarily young patients, early diagnosis and treatment are of high socioeconomic relevance. In our everyday clinical practice, cervical artery dissection, which is the most common stroke etiology among patients < 45 years, and vasculitis are particularly important. In the case of vasculitis, devastating disease courses and potentially harmful treatment options complicate clinical decision-making. Non-vasculitic vasculopathies, infections, hematological disorders, coagulation disorders, metabolic disorders and malignancies are further rare causes of stroke with variable clinical manifestations, thus impeding an early diagnosis. If eligible, patients with rare stroke causes should be considered for thrombectomy. Except for infective endocarditis, most rare stroke causes are not per se a contraindication to thrombolysis, so that eligible patients should also be considered for thrombolysis. Evidence based recommendations for the secondary prevention of most rare stroke causes are still missing. In many cases, treatment regimens are adapted to the patients' individual risk of stroke recurrence and bleeding complications.

Delayed Cerebral Injury in Adults With Bacterial Meningitis: A Novel Complication of Adjunctive Steroids?

OBJECTIVES

To report the prevalence of delayed cerebral injury in adults with bacterial meningitis and explore its association with adjunctive steroids.

DESIGN

Retrospective analysis of adults with bacterial meningitis between 2005 and 2016.

SETTING

Ten hospitals in the Greater Houston area.

PATIENTS

Consecutive subjects with culture proven community-acquired bacterial meningitis.

INTERVENTION

Subjects were categorized as receiving or not adjunctive steroids within 4 hours.

MEASUREMENTS AND MAIN RESULTS

A total of 120 patients were identified who were admitted with community-acquired bacterial meningitis. Delayed cerebral injury was seen in five of 120 patients (4.1%); all five patients had fever and abnormal neurologic examinations. Adjunctive steroids within 4 hours were more likely given to those with delayed cerebral injury (5/5,100% vs 43/115, 37.5%; p = 0.01). Of the patients who developed delayed cerebral injury, three had Streptococcus pneumoniae, one had methicillin-resistant Staphylococcus aureus, and one had Listeria monocytogenes isolated. We observed an adverse clinical outcome as defined by the Glasgow Outcome Scale in four of the five patients (80%).

CONCLUSIONS

Delayed cerebral injury occurred in 4.1% of adults with bacterial meningitis, and it was associated with the use of adjunctive steroids. Future studies should explore the etiology and prevention of this devastating complication.

Risk of stroke in patients with dengue fever: a population-based cohort study

BACKGROUND

Stroke is a severe neurologic complication of dengue fever, described in only a few case reports. The incidence and risk factors for stroke in patients with dengue remain unclear. We conducted a population-based retrospective cohort study to investigate the risk of stroke in patients with dengue.

METHODS

Using data from the Taiwan National Health Insurance Research Database, we included a total of 13 787 patients with dengue newly diagnosed between 2000 and 2012. The control cohort consisted of patients who did not have dengue, matched 1:1 by demographic characteristics and stroke-related comorbidities. We calculated the cumulative incidences and hazard ratios (HRs) of stroke in both cohorts using Kaplan-Meier curves and Cox proportional hazards regression.

RESULTS

The overall incidence rate of stroke was 5.33 per 1000 person-years in the dengue cohort and 3.72 per 1000 person-years in the control cohort, with an adjusted HR of 1.16 (95% confidence interval [CI] 1.01-1.32). The risk of stroke among patients with dengue was highest in the first 2 months after diagnosis (25.53 per 1000 person-years, adjusted HR 2.49, 95% CI 1.48-4.18).

INTERPRETATION

Dengue fever was associated with an increased risk of stroke in the first few months after diagnosis. The effect of dengue on stroke may be acute rather than chronic.

Cancer-associated stroke: Pathophysiology, detection and management (Review)

Numerous types of cancer have been shown to be associated with either ischemic or hemorrhagic stroke. In this review, the epidemiology and pathophysiology of stroke in cancer patients is discussed, while providing vital information on the diagnosis and management of patients with cancer and stroke. Cancer may mediate stroke pathophysiology either directly or via coagulation disorders that establish a state of hypercoagulation, as well as via infections. Cancer treatment options, such as chemotherapy, radiotherapy and surgery have all been shown to aggravate the risk of stroke as well. The clinical manifestation varies greatly depending upon the underlying cause; however, in general, cancer‑associated strokes tend to appear as multifocal in neuroimaging. Furthermore, several serum markers have been identified, such as high D‑Dimer levels and fibrin degradation products. Managing cancer patients with stroke is a delicate matter. The cancer should not be considered a contraindication in applying thrombolysis and recombinant tissue plasminogen activator (rTPA) administration, since the risk of hemorrhage in cancer patients has not been reported to be higher than that in the general population. Anticoagulation, on the contrary, should be carefully examined. Clinicians should weigh the benefits and risks of anticoagulation treatment for each patient individually; the new oral anticoagulants appear promising; however, low‑molecular‑weight heparin remains the first choice. On the whole, stroke is a serious and not a rare complication of malignancy. Clinicians should be adequately trained to handle these patients efficiently.

Association of herpesviruses and stroke: Systematic review and meta-analysis

BACKGROUND

Herpesviruses induce a range of inflammatory effects potentially contributing to an increased risk of stroke.

OBJECTIVES

To investigate whether patients with infection, or reactivation of, human herpesviruses are at increased stroke risk, compared to those without human herpesviruses.

DATA SOURCES

Six medical databases and grey literature sources from inception to January 2017.

STUDY ELIGIBILITY CRITERIA

Studies where the exposure was any human herpesvirus and the outcome was stroke. We included randomised controlled trials, cohort, case-control, case-crossover and self-controlled case series designs.

METHODS

Meta-analyses when sufficiently homogeneous studies were available. Quality of evidence across studies was assessed.

RESULTS

We identified 5012 publications; 41 met the eligibility criteria. Across cohort and self-controlled case series studies, there was moderate quality evidence that varicella infection in children was associated with a short-term increased stroke risk. Zoster was associated with a 1.5-fold increased stroke risk four weeks following onset (summary estimate: 1.55, 95%CI 1.46-1.65), which resolved after one year. Subgroup analyses suggested post-zoster stroke risk was greater among ophthalmic zoster patients, younger individuals and those not prescribed antivirals. Recent infection/reactivation of cytomegalovirus and herpes simplex viruses, but not past infection, was associated with increased stroke risk; however the evidence across studies was mainly derived from small, very low quality case-control studies.

CONCLUSIONS

Our review shows an increased stroke risk following zoster and suggests that recent infection or reactivation of other herpesviruses increases stroke risk, although better evidence is needed. Herpesviruses are common and potentially preventable; these findings may have implications for reducing stroke burden.

Imaging of cerebrovascular complications of infection

Cerebrovascular complications may occur in infectious diseases in the setting of infective endocarditis, central nervous system (CNS) infections, systemic bacteremia and sepsis. Cerebrovascular complications of infections include vasculitis, mycotic aneurysms, and thrombophlebitis. Infectious vasculitis of the CNS may cause cerebral hemorrhage, infarction or ischemia. Ruptured aneurysms may endanger the patient's life. Infectious thrombophlebitis may cause intracranial pressure to increase and lead to cerebral hemorrhage. These cerebrovascular complications are associated with a poor prognosis and often cause irreversible neurological deficits. Cerebrovascular events secondary to infection are not easily distinguishable from the more common cerebral infarct and non-infectious vasculitis. In addition, the clinical manifestations of cerebrovascular complications of infections are non-specific and highly variable. Therefore, early imaging, antibiotics, and anticoagulation may be lifesaving the patient's life and prevent disability. The main focus of this article is to review imaging analysis of the cerebrovascular complications of infections and imaging features that help differentiate them from non-infectious vascular diseases.

Pyogenic Meningitis Complicated with Extensive Central Nervous System Vasculitis and Moyamoya Vasculopathy

Meningitis is an uncommon complications of head trauma. Vasculitis in bacterial meningitis is seen in 9%–25% of adults. Neurological deficits in bacterial meningitis are seen in about one-third of children. Isolated cranial nerve palsies are common, whereas major deficits such as hemiparesis and quadriparesis are rare. We describe a case of a 7-year-old boy who had post-traumatic meningitis complicated with quadriparesis and severe vasculitis of bilateral anterior and posterior circulation with moyamoya vasculopathy.

Prothrombotic factors do not increase the risk of recurrent ischemic events after cryptogenic stroke at young age: the FUTURE study

BACKGROUND

The role of hypercoagulable states and preceding infections in the etiology of young stroke and their role in developing recurrent ischemic events remains unclear. Our aim is to determine the prevalence of these conditions in patients with cryptogenic stroke at young age and to assess the long-term risk of recurrent ischemic events in patients with and without a hypercoagulable state or a recent pre-stroke infection with Borrelia or Syphilis.

PATIENTS AND METHODS

We prospectively included patients with a first-ever transient ischemic attack or ischemic stroke, aged 18-50, admitted to our hospital between 1995 and 2010. A retrospective analysis was conducted of prothrombotic factors and preceding infections. Outcome was recurrent ischemic events.

RESULTS

Prevalence of prothrombotic factors did not significantly differ between patients with a cryptogenic stroke and with an identified cause (24/120 (20.0%) and 32/174 (18.4%) respectively). In patients with a cryptogenic stroke the long-term risk [mean follow-up of 8.9 years (SD 4.6)] of any recurrent ischemic event or recurrent cerebral ischemia did not significantly differ between patients with and without a hypercoagulable state or a recent infection. In patients with a cryptogenic stroke 15-years cumulative risk of any recurrent ischemic event was 24 and 23% in patients with and without any prothrombotic factor respectively.

CONCLUSIONS

The prevalence of prothrombotic factors and preceding infections did not significantly differ between stroke patients with a cryptogenic versus an identified cause of stroke and neither is significantly associated with an increased risk of recurrent ischemic events after cryptogenic stroke.

Why does my patient's basilar artery continue to grow? A four-year case study of a patient with symptoms of vertebrobasilar dolichoectasia

BACKGROUND

Vertebrobasilar dolichoectasia (VBD) is a clinical entity associated with ischemic stroke, compression of cranial nerves or brainstem, and hydrocephalus. There have been relatively few studies following the progression of VBD in patients presenting with a variety of diverse clinical features.

CASE PRESENTATION

Here, we report a case study of a male with progressive VBD who was followed from November 2012 to December 2016. The patient had diagnosed hypertension for several years and suffered from left peripheral facial paralysis, recurrent ischemic attacks in the brainstem and cerebellum, obstructive hydrocephalus and frequent pneumonia. A series of cranial CT and multi-modal MRI scans were performed to explore the brain imaging features of the patient during follow-up.

CONCLUSIONS

The presented case study suggests that aging, uncontrolled hypertension, arterial dissection and infection may contribute to the exacerbation of VBD and recurrent ischemic stroke.

Risk of stroke associated with use of nonsteroidal anti-inflammatory drugs during acute respiratory infection episode

BACKGROUND

Previous studies suggested that acute respiratory infection (ARI) could trigger stroke and that use of nonsteroidal anti-inflammatory drugs (NSAIDs) was associated with increased risk of stroke. In many countries, NSAIDs have been widely used among patients with ARI or common cold for pain and fever relief. However, studies evaluating whether NSAIDs use during ARI episodes may further increase the risk of stroke were very limited.

METHODS AND RESULTS

During 2007 to 2011, 29 518 patients with an incident hospitalization of stroke were identified. The date of admission was defined as the index date. Using case-crossover design, we compared the following exposure status between the case period (1- to 7-d period before the index date) and matched control period (366- to 372-d period before the index date): NSAIDs use during ARI episodes, ARI episodes without NSAIDs use, NSAIDs use only, or no exposure. Multivariable conditional regression models were used to estimate odds ratios adjusting potential confounders. The results suggested that NSAIDs use during ARI episodes was associated with a 2.3-fold increased risk of stroke (ischemic: adjusted odds ratio, aOR 2.27, 95% confidence interval, 95% CI, 2.00-2.58; hemorrhagic: aOR 2.28, 95% CI, 1.71-3.02). We also determined that parenteral NSAIDs were associated with much higher risk of stroke in patients with ARI.

CONCLUSIONS

Nonsteroidal anti-inflammatory drugs use during ARI episodes, especially parenteral NSAIDs use, was associated with a further increased risk of stroke.

Increase of Meningitis Risk in Stroke Patients in Taiwan

Background and purpose

The blood–brain barrier (BBB) not only provides a physical obstruction but also recruits and activates neutrophils in cases of infection. Hemorrhagic or ischemic stroke reportedly induces the disruption of the BBB. However, few studies have reported a correlation between the incidence of meningitis in patients with a history of stroke. This study tested the hypothesis that patients with a history of stroke may be more vulnerable to meningitis.

Methods

Stroke and age-matched comparison (n = 29,436 and 87,951, respectively) cohorts were recruited from the Taiwan National Health Insurance database (2000–2011). Correlations between the two cohorts were evaluated by Cox proportional hazard regression model, Kaplan–Meier curve, and log-rank tests.

Results

The incidence of meningitis was higher in the stroke cohort compared to that in the comparison cohort [hazard ratio (HR), 2.89; 95% confidence interval (CI), 2.23–3.74, p < 0.001]. After adjusting for age, sex, and comorbidities, the estimated HR in the stroke cohort was 2.55-fold higher than that in the comparison cohort (CI, 1.94–3.37; p < 0.001). Notably, patients who had experienced hemorrhagic stroke had a higher incidence rate of meningitis than those with a history of ischemic stroke, except for patients older than 75 years (incidence rates in hemorrhagic/ischemic stroke patients, 3.14/1.48 in patients younger than 45 years, 1.52/0.41 in 45- to 64-year group, 1.15/0.90 in 65- to 74-year group, 0.74/0.93 in patients older than 75 years). Moreover, stroke patients who had undergone head surgery had the highest meningitis risk (adjusted HR, 8.66; 95% CI, 5.55–13.5; p < 0.001) followed by stroke patients who had not undergone head surgery (adjusted HR, 2.11; 95% CI, 1.57–2.82; p < 0.001).

Conclusion

Our results indicated that stroke patients have higher risks of meningitis. Compromised BBB integrity in stroke patients may lead to increased vulnerability to infectious pathogens. In summary, our study provided new evidence of the clinical relationship between stroke and meningitis, and our findings suggest the need for precautions to prevent meningitis in stroke patients.

Infections of the Nervous System

Microorganisms can affect the entire neuraxis, producing a variety of neurologic complications that frequently entail prolonged hospitalizations and complicated treatment regimens. The spread of pathogens to new regions and the reemergence of opportunistic organisms in immunocompromised patients pose increasing challenges to health care professionals. Because rapid diagnosis and treatment may prevent long-term neurologic sequelae, providers should approach these diseases with a structured, neuroanatomic framework, incorporating a thorough history, examination, laboratory analysis, and neuroimaging in their clinical reasoning and decision-making.

Hepatitis E virus infection and acute non-traumatic neurological injury: A prospective multicentre study

BACKGROUND & AIMS

Hepatitis E virus (HEV) has been associated with a number of neurological syndromes, but causality has not yet been established. The aim of this study was to explore the relationship between HEV and neurological illness by prospective HEV testing of patients presenting with acute non-traumatic neurological injury.

METHODS

Four hundred and sixty-four consecutive patients presenting to hospital with acute non-traumatic neurological illnesses were tested for HEV by serology and PCR from four centres in the UK, France and the Netherlands.

RESULTS

Eleven of 464 patients (2.4%) had evidence of current/recent HEV infection. Seven had HEV RNA identified in serum and four were diagnosed serologically. Neurological cases in which HEV infection was found included neuralgic amyotrophy (n=3, all PCR positive); cerebral ischemia or infarction (n=4); seizure (n=2); encephalitis (n=1); and an acute combined facial and vestibular neuropathy (n=1). None of these cases were clinically jaundiced and median ALT at presentation was 24IU/L (range 8-145). Cases of HEV-associated neuralgic amyotrophy were found in each of the participating countries: all were middle-aged males with bilateral involvement of the brachial plexus.

CONCLUSIONS

In this cohort of patients with non-traumatic neurological injury, 2.4% had evidence of HEV infection. Symptoms of hepatitis were mild or absent and no patients were jaundiced. The cases of HEV-associated neuralgic amyotrophy had similarities with other HEV-associated cases described in a large retrospective study. This observation supports a causal relationship between HEV and neuralgic amyotrophy. To further understand the relevance of HEV infection in patients with acute neurological illnesses, case-control studies are warranted. Lay summary: Hepatitis E virus (HEV), as its name suggests, is a hepatotropic virus, i.e. it causes damage to the liver (hepatitis). Our findings show that HEV can also be associated with a range of injury to the nervous system.

Severe infections and subsequent delayed cardiovascular disease

Background Severe infections in adulthood are associated with subsequent short-term cardiovascular disease. Whether hospital admission for sepsis or pneumonia is associated with persistent increased risk (over a year after infection) is less well established. Design The design of this study was as a register-based cohort study. Methods Some 236,739 men born between 1952-1956 were followed from conscription assessments in adolescence to 2010. All-cause cardiovascular disease ( n = 46,754), including coronary heart disease ( n = 10,279) and stroke ( n = 3438), was identified through national registers 1970-2010 (at ages 18-58 years). Results Sepsis or pneumonia in adulthood (resulting in hospital admission) are associated with increased risk of cardiovascular disease in the years following infection. The risk is highest during the first year after the infection, with an adjusted hazard ratio (and 95% confidence intervals) of 6.33 (5.65-7.09) and a notably increased risk persisted with hazard ratios of 2.47 (2.04-3.00) for the second and 2.12 (1.71-2.62) for the third year after infection. The risk attenuated with time, but remained raised for at least five years after infection; 1.87 (1.47-2.38). The results are adjusted for characteristics in childhood, cardiovascular risk factors and medical history in adolescence. Similar statistically significant associations were found for coronary heart disease and stroke. Conclusions Raised risks of cardiovascular disease following hospital admission for sepsis or pneumonia were increased for more than five years after the infection, but with the highest magnitude during the first three years following infection, suggesting a period of vulnerability when health professionals and patients should be aware of the heightened risk for cardiovascular disease.

Effect of Influenza Vaccination on Risk of Stroke: A Systematic Review and Meta-Analysis

Background: Despite the presence of a strong association between influenza infection and stroke, whether influenza vaccination reduces the risk of stroke is yet a matter of controversy. We conducted a meta-analysis to determine whether influenza vaccination protects against stroke. Methods: We searched PubMed, EMBASE, and the Cochrane Library from database inception date to November 18, 2016, without language restrictions, to identify studies investigating the effect of influenza vaccination on subsequent risk of stroke. We conducted a meta-analysis to quantify the risk of stroke in overall and subgroup analyses and calculated a pooled OR for developing stroke with a 95% CI. Publication bias was assessed by Begg's rank correlation test. Results: Eleven studies fulfilled our inclusion criteria. In a random-effects model, vaccinated individuals had a decreased risk of stroke compared with unvaccinated individuals (OR 0.82; 95% CI 0.75-0.91; p < 0.001). The relationship between influenza vaccination and stroke risk remained robust in subgroup analyses. The significant effect of influenza vaccination was associated with ascertainment of vaccination status and stage of prevention. Conclusion: Vaccination against influenza is associated with a lower risk of stroke. Well-designed prospective studies are needed to provide stronger evidence of the protective effect of influenza vaccination against stroke.

Stroke in HIV-infected individuals with and without HCV coinfection in Spain in the combination antiretroviral therapy era

The incidence of stroke in human immunodeficiency virus (HIV)–infected individuals has been well analyzed in recent epidemiological studies. However, little is known about the specific contribution of hepatitis C virus (HCV) infection to stroke among HIV-infected individuals. The aims of this study were to analyze trends in the incidence rates of stroke in HIV-infected individuals during the combination antiretroviral (cART) era in Spain and to categorize them by the presence or absence of HCV coinfection. We analyzed hospital discharges with a diagnosis of stroke in Spain according to ICD-9-CM during 1997–2013. The study period was divided into four calendar periods (1997–1999, 2000–2003, 2004–2007, and 2008–2013). Patients were classified according to HCV serology. The number of HIV-infected patients was estimated based on data from the National Centre of Epidemiology. We calculated incidence rates (events per 10,000 patient-years) and in-hospital case fatality rates (CFR). The incidence of hemorrhagic stroke (HS) decreased in HIV-monoinfected patients (15.8 [1997–1999] to 6.5 [2008–2013]; P<0.001) and increased in HIV/HCV-coinfected patients (1.3 [1997–1999] to 5.5 [2008–2013]; P<0.001). The incidence of ischemic stroke (IS) decreased in HIV-monoinfected patients (27.4 [1997–1999] to 21.7 [2008–2013]; P = 0.005) and increased in HIV/HCV-coinfected patients (1.8 [1997–1999] to 11.9 [2008–2013]; P<0.001). The CFR was 3.3 times higher for HS than for IS for the whole study period. The CFR of HS in HIV-monoinfected patients decreased significantly (47.4% [1997–1999] to 30.6% [2008–2013]; P = 0.010) but did not change significantly among HIV/HCV-coinfected patients (41.4% [1997–1999] to 44.7% [2008–2013]; P = 0.784). The CFR of IS in the whole HIV-infected population decreased significantly (14.6% [1997–1999] to 10.9% [2008–2013]; P = 0.034), although no significant differences were found when each group was analyzed separately. In conclusion, after the introduction of cART, HS and IS rates decreased in HIV-monoinfected individuals, but increased steadily in HIV/HCV-coinfected individuals.

Cerebrovascular injury in cryptococcal meningitis

Background

Cryptococcal meningitis continues to be one of the common causes of chronic central nervous system infection worldwide. Individuals with cryptococcal meningitis can occasionally present with small vessel vasculitis causing infarcts primarily in the basal ganglia, internal capsule, and thalamus. Literature regarding patterns of cerebrovascular injury among patients with cryptococcal meningitis is scanty, and outcome following these vascular involvements is unknown.

Aim

To study the clinical profile, imaging findings, and details of vascular territory involved among patients admitted with cryptococcal meningitis and central nervous system infarct in a tertiary care center from India. And to compare the outcomes of patients of cryptococcal meningitis with or without central nervous system infarcts in terms of mortality and morbidity,

Methodology

A total of 151 patients with microbiologically proven cryptococcal meningitis over a time span of 11 years were retrospectively enrolled into the study. Of these, 66 patients met the inclusion criteria of having appropriate imaging of the brain. The presence of infarct in the imaging was analyzed by two independent radiologists. Patterns of central nervous system involvement and types of vascular injury were ascertained based on radiological parameters. Clinical parameters and outcomes of patients with and without infarcts were compared.

Results

Twenty (13%) of these patients had evidence of central nervous system infarcts on imaging. The mean age of patients with and without infarcts was 41 years and 38 years, respectively. Male predominance was present among both the groups. The presence of fever, neck stiffness, positive blood culture, and hydrocephalus in central nervous system imaging was similar among patients with or without infarct. Longer duration of illness, low sensorium at the time of presentation, low Glasgow Coma Scale score, presence of meningeal inflammation, cryptococcomas, and basal exudates in imaging were higher in patients with infarct. All the infarcts were of the lacunar type. Sixty percent of the cerebrovascular infarcts were acute in nature, 50% of these being multiple. Unilateral infarcts were seen in 70% of the patients. The most common site of infarct was the basal ganglia, others being distributed over the thalamus, frontal, temporal, parieto-occipital regions in the descending order. The presence of neurovascular involvement in the form of infarcts to the risk of morbidity and mortality had an odds ratio of 9.1 and 2.6, respectively.

Conclusion

Neurovascular involvement in chronic cryptococcal meningitis is a rare entity. These tend to present as multiple lacunar infarcts. Mortality and morbidity associated with these patients is higher when compared to patients who do not have infarcts. This result suggests that vascular injury plays a role in predicting outcome of patients with cryptococcal meningitis. Future studies are needed to understand the mechanism by which vascular events (infarcts) occur and result in poor outcome.

Stroke caused by an inflammatory thrombus: a case report

Background

Stroke is the leading cause of mortality and disability worldwide. Several definite risk factors have been identified for stroke, although infectious factors might also contribute to stroke episodes through increased susceptibility or direct induction.

Case presentation

A 46-year-old Chinese male initially presented with fever, headache, and impaired memory and developed disturbance of consciousness after admission. A clinical diagnosis of Staphylococcus aureus sepsis, massive cerebral infarction and haemorrhagic transformation (left internal carotid arterial system, inflammatory thrombus) were made based on brain radiography, blood culture and postoperative pathological examinations. These symptoms improved following antibiotic therapy with vancomycin and conventional treatments for stroke.

Conclusion

For stroke patients without traditional cerebrovascular risk factors but with signs of infection, infectious causes should be considered.

Impact of HIV on inpatient mortality and complications in stroke in Thailand: a National Database Study

The co-existence of stroke and HIV has increased in recent years, but the impact of HIV on post-stroke outcomes is poorly understood. We examined the impact of HIV on inpatient mortality, length of acute hospital stay and complications (pneumonia, respiratory failure, sepsis and convulsions), in hospitalized strokes in Thailand. All hospitalized strokes between 1 October 2004 and 31 January 2013 were included. Data were obtained from a National Insurance Database. Characteristics and outcomes for non-HIV and HIV patients were compared and multivariate logistic and linear regression models were constructed to assess the above outcomes. Of 610 688 patients (mean age 63·4 years, 45·4% female), 0·14% (866) had HIV infection. HIV patients were younger, a higher proportion were male and had higher prevalence of anaemia (P < 0·001) compared to non-HIV patients. Traditional cardiovascular risk factors, hypertension and diabetes, were more common in the non-HIV group (P < 0·001). After adjusting for age, sex, stroke type and co-morbidities, HIV infection was significantly associated with higher odds of sepsis [odds ratio (OR) 1·75, 95% confidence interval (CI) 1·29-2·4], and inpatient mortality (OR 2·15, 95% CI 1·8-2·56) compared to patients without HIV infection. The latter did not attenuate after controlling for complications (OR 2·20, 95% CI 1·83-2·64). HIV infection is associated with increased odds of sepsis and inpatient mortality after acute stroke.

Pathogenesis of Taenia solium taeniasis and cysticercosis

Taenia solium infections (taeniasis/cysticercosis) are a major scourge to most developing countries. Neurocysticercosis, the infection of the human nervous system by the cystic larvae of this parasite, has a protean array of clinical manifestations varying from entirely asymptomatic infections to aggressive, lethal courses. The diversity of clinical manifestations reflects a series of contributing factors which include the number, size and location of the invading parasites, and particularly the inflammatory response of the host. This manuscript reviews the different presentations of T. solium infections in the human host with a focus on the mechanisms or processes responsible for their clinical expression.

Nontyphoidal Salmonellosis, Human Immunodeficiency Virus Infection, and Ischemic Stroke

Nontyphoidal Salmonella infection and stroke are major causes of morbidity and mortality worldwide, with increased risk in the human immunodeficiency virus (HIV)-infected population. We report a rare case of ischemic stroke associated with Salmonella enteritidis subdural empyema in an older HIV-infected patient with multimorbidity, despite surgery and treatment with susceptible antimicrobial drugs.

Arterial ischemic stroke in HIV: Defining and classifying etiology for research studies

HIV infection, and potentially its treatment, increases the risk of an arterial ischemic stroke. Multiple etiologies and lack of clear case definitions inhibit progress in this field. Several etiologies, many treatable, are relevant to HIV-related stroke. To fully understand the mechanisms and the terminology used, a robust classification algorithm to help ascribe the various etiologies is needed. This consensus paper considers the strengths and limitations of current case definitions in the context of HIV infection. The case definitions for the major etiologies in HIV-related strokes were refined (e.g., varicella zoster vasculopathy and antiphospholipid syndrome) and in some instances new case definitions were described (e.g., HIV-associated vasculopathy). These case definitions provided a framework for an algorithm to help assign a final diagnosis, and help classify the subtypes of HIV etiology in ischemic stroke.

Longitudinal Study of the Effects of Bacteremia and Sepsis on 5-year Risk of Cardiovascular Events

BACKGROUND

The long-term and cumulative effect of multiple episodes of bacteremia and sepsis across multiple hospitalizations on the development of cardiovascular (CV) events is uncertain.

METHODS

We conducted a longitudinal study of 156 380 hospitalizations in 47 009 patients (≥18 years old) who had at least 2 inpatient admissions at an academic tertiary care center in St Louis, Missouri, from 1 January 2008 through 31 December 2012. We used marginal structural models, estimated by inverse probability weighting (IPW) of bacteremia or sepsis and IPW of censoring, to estimate the marginal causal effects of bacteremia and sepsis on developing the first observed incident CV event, including stroke, transient ischemic attack, and myocardial infarction (MI), during the study period.

RESULTS

Bacteremia and sepsis occurred during 4923 (3.1%) and 5544 (3.5%) hospitalizations among 3932 (8.4%) and 4474 (9.5%) patients, respectively. CV events occurred in 414 (10.5%) and 538 (12.0%) patients with prior episodes of bacteremia or sepsis, respectively, vs 3087 (7.2%) and 2963 (7.0%) patients without prior episodes of bacteremia or sepsis. The causal odds of experiencing a CV event was 1.52-fold (95% confidence interval [CI], 1.21- to 1.90-fold) and 2.39-fold (95% CI, 1.88- to 3.03-fold) higher in patients with prior instances of bacteremia or sepsis, respectively, compared to those without. Prior instances of septic shock resulted in a 6.91-fold (95% CI, 5.34- to 8.93-fold) increase in the odds of MI.

CONCLUSIONS

Prior instances of bacteremia and sepsis substantially increase the 5-year risk of CV events.

Clinical management of infectious cerebral vasculitides

A wide range of infections (virus, bacteria, parasite and fungi) may cause cerebral vasculitides. Headache, seizures, encephalopathy and stroke are common forms of presentation. Infection and inflammation of intracranial vessels may cause pathological vascular remodelling, vascular occlusion and ischemia. Vasculitis in chronic meningitis may cause ischemic infarctions, and is associated with poor outcome. Appropriate neuroimaging (CT-angiography, MR-angiography, conventional 4-vessel angiography) and laboratory testing (specific antibodies in blood and CSF, CSF culture and microscopy) and even brain biopsy are needed to quickly establish the aetiology. Enhancement of contrast, wall thickening and lumen narrowing are radiological signs pointing to an infectious vasculitis origin. Although corticosteroids and prophylactic antiplatelet therapy have been used in infectious cerebral vasculitis, there are no randomized clinical trials that have evaluated their efficacy and safety. Stable mycotic aneurysms can be treated with specific antimicrobial therapy. Endovascular therapy and intracranial surgery are reserved for ruptured aneurysms or enlarging unruptured aneurysms.

Simvastatin Reduces Lipopolysaccharides-Accelerated Cerebral Ischemic Injury via Inhibition of Nuclear Factor-kappa B Activity

Preceding infection or inflammation such as bacterial meningitis has been associated with poor outcomes after stroke. Previously, we reported that intracorpus callosum microinjection of lipopolysaccharides (LPS) strongly accelerated the ischemia/reperfusion-evoked brain tissue damage via recruiting inflammatory cells into the ischemic lesion. Simvastatin, 3-hydroxy-3-methylgultaryl (HMG)-CoA reductase inhibitor, has been shown to reduce inflammatory responses in vascular diseases. Thus, we investigated whether simvastatin could reduce the LPS-accelerated ischemic injury. Simvastatin (20 mg/kg) was orally administered to rats prior to cerebral ischemic insults (4 times at 72, 48, 25, and 1-h pre-ischemia). LPS was microinjected into rat corpus callosum 1 day before the ischemic injury. Treatment of simvastatin reduced the LPS-accelerated infarct size by 73%, and decreased the ischemia/reperfusion-induced expressions of pro-inflammatory mediators such as iNOS, COX-2 and IL-1β in LPS-injected rat brains. However, simvastatin did not reduce the infiltration of microglial/macrophageal cells into the LPS-pretreated brain lesion. In vitro migration assay also showed that simvastatin did not inhibit the monocyte chemoattractant protein-1-evoked migration of microglial/macrophageal cells. Instead, simvastatin inhibited the nuclear translocation of NF-κB, a key signaling event in expressions of various proinflammatory mediators, by decreasing the degradation of IκB. The present results indicate that simvastatin may be beneficial particularly to the accelerated cerebral ischemic injury under inflammatory or infectious conditions.

Synthetic Oligodeoxynucleotides Containing Multiple Telemeric TTAGGG Motifs Suppress Inflammasome Activity in Macrophages Subjected to Oxygen and Glucose Deprivation and Reduce Ischemic Brain Injury in Stroke-Prone Spontaneously Hypertensive Rats

The immune system plays a fundamental role in both the development and pathobiology of stroke. Inflammasomes are multiprotein complexes that have come to be recognized as critical players in the inflammation that ultimately contributes to stroke severity. Inflammasomes recognize microbial and host-derived danger signals and activate caspase-1, which in turn controls the production of the pro-inflammatory cytokine IL-1β. We have shown that A151, a synthetic oligodeoxynucleotide containing multiple telemeric TTAGGG motifs, reduces IL-1β production by activated bone marrow derived macrophages that have been subjected to oxygen-glucose deprivation and LPS stimulation. Further, we demonstrate that A151 reduces the maturation of caspase-1 and IL-1β, the levels of both the iNOS and NLRP3 proteins, and the depolarization of mitochondrial membrane potential within such cells. In addition, we have demonstrated that A151 reduces ischemic brain damage and NLRP3 mRNA levels in SHR-SP rats that have undergone permanent middle cerebral artery occlusion. These findings clearly suggest that the modulation of inflammasome activity via A151 may contribute to a reduction in pro-inflammatory cytokine production by macrophages subjected to conditions that model brain ischemia and modulate ischemic brain damage in an animal model of stroke. Therefore, modulation of ischemic pathobiology by A151 may have a role in the development of novel stroke prevention and therapeutic strategies.

The dormant blood microbiome in chronic, inflammatory diseases

Blood in healthy organisms is seen as a ‘sterile’ environment: it lacks proliferating microbes. Dormant or not-immediately-culturable forms are not absent, however, as intracellular dormancy is well established. We highlight here that a great many pathogens can survive in blood and inside erythrocytes. ‘Non-culturability’, reflected by discrepancies between plate counts and total counts, is commonplace in environmental microbiology. It is overcome by improved culturing methods, and we asked how common this would be in blood. A number of recent, sequence-based and ultramicroscopic studies have uncovered an authentic blood microbiome in a number of non-communicable diseases. The chief origin of these microbes is the gut microbiome (especially when it shifts composition to a pathogenic state, known as ‘dysbiosis’). Another source is microbes translocated from the oral cavity. ‘Dysbiosis’ is also used to describe translocation of cells into blood or other tissues. To avoid ambiguity, we here use the term ‘atopobiosis’ for microbes that appear in places other than their normal location. Atopobiosis may contribute to the dynamics of a variety of inflammatory diseases. Overall, it seems that many more chronic, non-communicable, inflammatory diseases may have a microbial component than are presently considered, and may be treatable using bactericidal antibiotics or vaccines.

Atopobiosis of microbes (the term describing microbes that appear in places other than where they should be), as well as the products of their metabolism, seems to correlate with, and may contribute to, the dynamics of a variety of inflammatory diseases.