Preclinical research has established a convincing connection between changes in the gut microbiota composition and stroke outcome. However clinical data on the gut-brain axis, and its chronic characteristics, is sparse. Additional investigations in the context of ischemic stroke regarding the relationship between dysbiosis and functional changes of the microbiome, as characterized by the metabolome, are still required. The StrokeMicroBiomics study will offer insight into these mechanisms and offer new potential targets for therapeutic interventions.

The primary objective is the characterisation of gut dysbiosis in ischemic stroke patients in the acute phase after stroke and during a 3 month follow-up period.

The secondary objectives include the identification of dysregulated gut microbiome metabolites and key immune cell populations in addition to the clinical progression of the study participants during the 3 month follow-up period after disease onset.

Results of experimental, preclinical studies suggest that microbiome-targeted may improve stroke outcome as well as stroke-related comorbidities. Yet, clinical trials describing the extent and time course of microbiome changes after stroke are currently not available. Moreover, the impact of post-stroke dysbiosis on metabolic changes and the systemic immunity are unexplored.

Therefore, the primary objective of this trial is the characterization of gut dysbiosis progression in ischemic stroke patients during a 3 month follow-up period .

The secondary objectives include the identification of dysregulated gut microbiome metabolites and key immune cell populations in addition to the clinical progression of the study participants during the 3 month follow-up period after disease onset.

In order to elucidate the differential impact of lesion size on immune and microbiome homeostasis, separate patient cohorts with mild and severe stroke will be studied.

Furthermore, to control for the effects of temporary focal neurological deficits and stress induced microbiome and immune changes, patients with stroke mimics and transient ischemic attacks (TIA) are being recruited to the control group.

Inclusion Criteria:

• Written consent as submitted and approved to the human subjects review board must be gathered from the participants
• Participants must be at least 50 years of age

For the severe stroke cohort, eligibility is defined by:

• CT or MRI confirmed ischemic stroke affecting at least 1/3 of the anterior, medial or posterior cerebral arteries cortical coverage
• NIHSS of at least 10 at time of induction into emergency room
• Ischemic Stroke occured within the last 7 days

For the mild stroke cohort, eligibility is defined by:

• CT or MRI confirmed ischemic stroke affecting no more than 1/3 of the anterior, medial or posterior cerebral arteries cortical coverage
• NIHSS between 1 and 10 at time of induction into emergency room
• Ischemic Stroke occured within the last 7 days

For the TIA cohort, eligibility is defined by:

• CT or MRI confirmed absence of a lesion
• NIHSS of 0 no more than 24 hours after induction into emergency room
• TIA occured within the last 7 days

Exclusion Criteria:

• Pregnancy
• Diagnosed and malignant Tumor ailment
• Active, non-stroke related immunosuppression (i.e. HIV)
• Infection, operative procedure or antibiotics treatment within 4 weeks prior to stroke/TIA
• Relevant autoimmune disease (i.e Morbus Crohn)
• Chronic infectious diseases (i.e Hepatitis C)
• Hemorrhagic Stroke or intracranial bleeding
• Cerebellar lesions
• Other neurodegenerative diseases (i.e. Parkinson´s Disease or Alzheimers Dementia)

Participants are recruited and samples taken within 7 days of either stroke or TIA onset.