title: Immunomodulatory effect of Hawthorn extract in an experimental stroke model.
abstract: BACKGROUND
  Recently, we reported a neuroprotective effect for Hawthorn (Crataegus oxyacantha) ethanolic extract in middle cerebral artery occlusion-(MCAO) induced stroke in rats. The present study sheds more light on the extract's mechanism of neuroprotection, especially its immunomodulatory effect.
  
  
  METHODS
  After 15 days of treatment with Hawthorn extract [100 mg/kg, pretreatment (oral)], male Sprague Dawley rats underwent transient MCAO for 75 mins followed by reperfusion (either 3 or 24 hrs). We measured pro-inflammatory cytokines (IL-1β, TNF-α, IL-6), ICAM-1, IL-10 and pSTAT-3 expression in the brain by appropriate methods. We also looked at the cytotoxic T cell sub-population among leukocytes (FACS) and inflammatory cell activation and recruitment in brain (using a myeloperoxidase activity assay) after ischemia and reperfusion (I/R). Apoptosis (TUNEL), and Bcl-xL- and Foxp3- (T(reg) marker) positive cells in the ipsilateral hemisphere of the brain were analyzed separately using immunofluorescence.
  
  
  RESULTS
  Our results indicate that occlusion followed by 3 hrs of reperfusion increased pro-inflammatory cytokine and ICAM-1 gene expressions in the ipsilateral hemisphere, and that Hawthorn pre-treatment significantly (p ≤ 0.01) lowered these levels. Furthermore, such pre-treatment was able to increase IL-10 levels and Foxp3-positive cells in brain after 24 hrs of reperfusion. The increase in cytotoxic T cell population in vehicle rats after 24 hrs of reperfusion was decreased by at least 40% with Hawthorn pretreatment. In addition, there was a decrease in inflammatory cell activation and infiltration in pretreated brain. Hawthorn pretreatment elevated pSTAT-3 levels in brain after I/R. We also observed an increase in Bcl-xL-positive cells, which in turn may have influenced the reduction in TUNEL-positive cells compared to vehicle-treated brain.
  
  
  CONCLUSIONS
  In summary, Hawthorn extract helped alleviate pro-inflammatory immune responses associated with I/R-induced injury, boosted IL-10 levels, and increased Foxp3-positive T(regs) in the brain, which may have aided in suppression of activated inflammatory cells. Such treatment also minimizes apoptotic cell death by influencing STAT-3 phosphorylation and Bcl-xL expression in the brain. Taken together, the immunomodulatory effect of Hawthorn extract may play a critical role in the neuroprotection observed in this MCAO-induced stroke model.
authors.affiliation: Department of Biochemistry, University of Madras, Chennai, Tamil Nadu, India.
authors.forename: Chinnasamy
authors.initials: C
authors.lastname: Elango
authors.forename: Sivasithambaram Niranjali
authors.initials: SN
authors.lastname: Devaraj
mesh_terms: D000328:Adult; D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism / Q000473:pathology; D027825:Crataegus / Q000737:chemistry*; D016207:Cytokines / Q000276:immunology; D004195:Disease Models, Animal; D004660:Encephalitis / Q000188:drug therapy / Q000276:immunology / Q000473:pathology; D006801:Humans; D007155:Immunologic Factors / Q000627:therapeutic use*; D020244:Infarction, Middle Cerebral Artery; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D016753:Interleukin-10 / Q000276:immunology; D008297:Male; D018696:Neuroprotective Agents / Q000627:therapeutic use*; D009195:Peroxidase / Q000378:metabolism; D010936:Plant Extracts / Q000627:therapeutic use*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000276:immunology / Q000517:prevention & control; D050796:STAT3 Transcription Factor / Q000378:metabolism; D020521:Stroke / Q000188:drug therapy* / Q000276:immunology* / Q000473:pathology; D051020:bcl-X Protein / Q000378:metabolism
chemical_list: C494813:Bcl2l1 protein, rat; D016207:Cytokines; D007155:Immunologic Factors; D018696:Neuroprotective Agents; D010936:Plant Extracts; D050796:STAT3 Transcription Factor; C494088:Stat3 protein, rat; D051020:bcl-X Protein; D018799:Intercellular Adhesion Molecule-1; D016753:Interleukin-10; D009195:Peroxidase