title: COX-2 expression in stromal fibroblasts self-limits their numbers in lymph node inflammatory responses.
abstract: We previously reported the expression of cyclooxygenase (COX)-2 in draining lymph nodes during carrageenin-induced pleurisy of rats. Here, we analyzed histological and immunohistochemical characteristics of COX-2-expressing cells. After carrageenin administration into the pleural cavity of rats, parathymic lymph nodes were enlarged beginning at 8h and peaking from 24 to 48h. Lymphatic follicles disappeared 16h after injection, and numerous macrophages and fibroblasts were observed in the cortical region. COX-2-expressing cells in the cortical region showed characteristic dendritic processes from 16 to 48h and primarily co-localized with stromal fibroblastic reticular cell markers, α-smooth muscle actin (α-SMA), and desmin. Expression of α-SMA increased following COX-2 expression. Nimesulide, a COX-2 inhibitor, increased the dendritic processes of COX-2-expressing cells as well as expression of both COX-2 and α-SMA. These results suggest that COX-2-expressing cells may be stromal fibroblastic cells, which negatively self-regulate their proliferation and modulate tissue remodeling of draining lymph nodes at inflammatory sites.
authors.affiliation: Department of Molecular Pharmacology, Kitasato University Graduate School of Medical Sciences, Sagamihara, Kanagawa, Japan. Electronic address: michikok@med.kitasato-u.ac.jp.
authors.forename: Michiko
authors.initials: M
authors.lastname: Kawamura
authors.forename: Yosihito
authors.initials: Y
authors.lastname: Tada
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kadoya
authors.forename: Shuichi
authors.initials: S
authors.lastname: Obata
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Harada
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015415:Biomarkers / Q000378:metabolism; D002351:Carrageenan / Q000009:adverse effects; D002452:Cell Count; D049109:Cell Proliferation / Q000187:drug effects; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D008198:Lymph Nodes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008297:Male; D010998:Pleurisy / Q000139:chemically induced / Q000378:metabolism; D011453:Prostaglandins / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D017154:Stromal Cells / Q000473:pathology
chemical_list: D000199:Actins; D015415:Biomarkers; D002351:Carrageenan; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D011453:Prostaglandins; C498862:Acta2 protein, rat
keywords: Carrageenin-induced pleurisy; Cyclooxygenase-2; Fibroblastic reticular cells; Lymph nodes; Tissue remodeling