The inflammatory response is an unavoidable process and contributes to the destruction of cerebral tissue during the acute ischemic stroke (AIS) phase and has not been addressed fully to date. Insightful understanding of correlation of inflammatory mediators and stroke outcome may provide new biomarkers or therapeutic approaches for ischemic stroke. Here, we prospectively recruited 180 first-ever AIS patients within 72 hrs after stroke onset. We used the National Institutes of Health Stroke Scale (NIHSS) to quantify stroke severity and modified Rankin scale (mRS) to assess the 3-month outcome for AIS patients. Initially, we screened 35 cytokines, chemokines, and growth factors in sera from 75 AIS patients and control subjects. Cytokines that were of interest were further investigated in the 180 AIS patients and 14 heathy controls. We found that IL-1RA, IL-1β, IL-4, IL-5, IL-6, IL-7, IL-9, IL-10, IL-13, IL-15, EGF, G-CSF, Flt-3L, GM-CSF and Fractalkine levels were significantly decreased in severe stroke patients. In particular, IL-1β, IL-4, IL-5, IL-7, IL-9, IL-10, IL-15, G-CSF and GM-CSF were significantly reduced in AIS patients with poor outcome, compared to those with good prognosis. IL-6 was notably higher in the poor outcome group. Only IL-9 level decreased in the large infarct volume group. After adjusting for confounders, we found that IL-5 was an independent protective factor for prognosis in AIS patients with an adjusted OR of 0.042 (P = 0.007), whereas IL-6 was an independent risk predictor for AIS patients with an adjusted OR of 1.293 (P = 0.003). Our study suggests the levels of serum cytokines are related to stroke severity, short-term prognosis and cerebral infarct volume in AIS patients.

Immune checkpoint blockade (ICB) has shown long‐term survival benefits, but only in a small fraction of cancer patients. Recent studies suggest that improved vessel perfusion by ICB positively correlates with its therapeutic outcomes. However, the underlying mechanism of such a process remains unclear. Here, we show that anti‐cytotoxic T‐lymphocyte‐associated protein 4 (CTLA4) treatment‐induced tumor vessel normalization was accompanied by an increased infiltration of eosinophils into breast tumors. Eosinophil accumulation was positively correlated with the responsiveness of a breast tumor to anti‐CTLA4 therapy. Depletion of eosinophils subsequently negated vessel normalization, reduced antitumor immunity and attenuated tumor growth inhibition by anti‐CTLA4 therapy. Moreover, intratumoral accumulation of eosinophils relied on T lymphocytes and interferon γ production. Together, these results suggest that eosinophils partially mediate the antitumor effects of CTLA4 blockade through vascular remodeling. Our findings uncover an unidentified role of eosinophils in anti‐CTLA4 therapy, providing a potential new target to improve ICB therapy and to predict its efficacy.

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Stromal-derived factor-1 (SDF-1, also known as CXCL12) and its receptors CXCR4 and CXCR7 play important roles in brain repair after ischemic stroke, as SDF-1/ CXCR4/CXCR7 chemokine signaling is critical for recruiting stem cells to sites of ischemic injury. Upregulation of SDF-1/CXCR4/CXCR7 chemokine signaling in the ischemic regions has been well-documented in the animal models of ischemic stroke, but not in human ischemic brain. Here, we found that protein expression of SDF-1 and CXCR7, but not CXCR4, were significantly increased in the cortical peri-infarct regions (penumbra) after ischemic stroke in human, compared with adjacent normal tissues and control subjects. Double-label fluorescence immunohistochemistry shows that SDF-1 and CXCR4 proteins were expressed in neuronal cells and astrocytes in the normal brain tissue and peri-infarct regions. CXCR7 protein was also observed in neuronal cells and astrocytes in the normal cortical regions, but predominantly in astrocytes in the penumbra of ischemic brain. Our data suggest that ischemic stroke in human leads to an increase in the expression of SDF-1 and CXCR7, but not CXCR4, in the peri-infarct cerebral cortex. Our findings suggest that chemokine SFD-1 is expressed not only in animal models of stroke, but also in the human brain after an ischemic injury. In addition, unlike animals, CXCR7 may be the primary receptor of SDF-1 in human stroke brain.

Rationale: The systemic inflammatory milieu plays an important role in the age-related decline in functional integrity, but its contribution to age-related disease (e.g., stroke) remains largely unknown. Objective: To determine the role of systemic inflammatory milieu in ischemic stroke. Methods and Results: Here, we report that systemic administration of serum exosomes from young rats (Y-exo) into aged ischemic rats improved short- and long-term functional outcomes after ischemic stroke and reduced synaptic loss. By contract, similar injections of serum exosomes from aged rats (O-exo) into aged ischemic rats worsened sensorimotor deficits through exacerbation of synaptic dysfunction due to excessive microglial phagoptosis (primary phagocytosis). Our proteomic analysis further revealed that the expression of CD46, a C3b/C4b-inactivating factor, was higher in Y-exo, compared to O-exo. Whereas the prevalence of pro-inflammatory mediators (C1q, C3a and C3b) in serum exosomes increased with age. Microglial expression of C3a/b and C3aR increased after O-exo treatment, compared with Y-exo and vehicle groups. Administration of a selective C3aR inhibitor or microglial depletion attenuated synaptic dysfunction associated with O-exo treatment and improved post-stroke functional recovery. Conclusions: Our data suggest that the levels of pro-inflammatory mediators in serum exosomes increase with age and are associated with worsened stroke outcomes through excessive C3aR-dependent microglial phagoptosis. Modulation of this process may serve as a promising therapy for stroke and other age-related brain disorders.