Sub-strain-Dependent Differences in Gut Barrier Permeability, Bacterial Translocation and Post-Stroke Inflammation in Wistar Rats

Background Stroke induces profound neuroinflammation and systemic immune dysregulation, including disturbances in gut homeostasis. Experimental evidence suggests that intestinal barrier permeability (IBP) and bacterial translocation (BT) critically influence stroke outcomes. However, biological variability among commonly used rodent sub-strains has received limited attention.

In this pilot study, we compared post-stroke immune responses in two Wistar rat sub-strains obtained from different suppliers: RccHan (Envigo) and RjHan (Janvier). Following transient middle cerebral artery occlusion, animals were assessed 72 hours later and stratified according to the presence or absence of BT. Immune cell populations in blood and bone marrow were analyzed by flow cytometry, and leukocyte infiltration into ischemic brain tissue was quantified by immunohistochemistry.

Both sub-strains developed significant infarcts and neurological deficits. RccHan rats displayed larger infarct volumes and more extensive BT across multiple organs. In contrast, RjHan rats exhibited BT mainly confined to mesenteric lymph nodes but showed greater IBP. Although dissemination was broader in RccHan rats, overall bacterial burden was slightly lower compared with RjHan, and extra-intestinal bacterial composition differed between groups. Notably, RjHan rats presented stronger systemic and central immune activation, with marked alterations in lymphocyte and monocyte populations and enhanced granulocyte and T cell infiltration within ischemic lesions.

These findings demonstrate that sub-strain origin profoundly influences post-stroke intestinal barrier integrity, bacterial dissemination, and immune responses. Considering sub-strain-related variability is essential to improve reproducibility and translational relevance in preclinical stroke research. Competing Interest Statement The authors have declared no competing interest. Footnotes E-mails: crisgran{at}ucm.es; nualfa01{at}ucm.es; manuna02{at}ucm.es; victormcuadrado.imas12{at}h12o.es; dsevill{at}ucm.es; luisalou{at}ucm.es; evalle{at}ucm.es; olhurtad{at}med.ucm.es; mariaangeles.moro{at}cnic.es.