15(s)-15-methylprostaglandin-e1 and Inflammation

Prostaglandins are important regulators of inflammatory responses. The rat subcutaneous air pouch, a model for synovial inflammation, was used to study the effect of systemic injections of prostaglandin E1 (PGE1) and its stable analog 15S,15 methyl prostaglandin E1 (15M PGE1) on nonimmunologically induced acute inflammation. The 15M PGE1 analog was a more effective longer-lasting antiinflammatory agent. Acute inflammatory responses were induced with three diverse stimuli including monosodium urate crystals, leukotriene B4 and formylmethionylleucyl-phenylalanine. Animals were treated with 15 M PGE1 for 2 days before induction of inflammation. Analysis of pouch fluid 6 hours after injection of the inflammatory stimulus indicates that 15M PGE1 treatment suppressed exudate volume and protein concentration, polymorphonuclear leucocyte accumulation and activity of the lysosomal enzyme beta-galactosidase. Treatment with 15M PGE1 was least effective in preventing the fluid phase of inflammation (exudate volume and protein concentration) when leukotriene B4 was used to induce inflammation. Direct observation (dissecting microscope) of pouch lining vessels indicated that 15M PGE1 reduced markedly the intense vascular reactivity (increased number of dilated vessels and filamentous, corkscrew-shaped vessels) usually seen in an acute inflammatory response. The antiinflammatory effect of 15M PGE1 was also documented by histopathology of pouch lining tissue. Treatment with 15M PGE1 reduced substantially the invasion of pouch tissue by polymorphonuclear leucocytes which was induced by all three stimuli of inflammation. Results of these experiments show that systemic administration of 15M PGE1 is capable of suppressing acute inflammation induced by monosodium urate crystals, by the potent soluble naturally occurring mediator of inflammation leukotriene B4, and by the synthetic chemotactic peptide, formylmethionylleucylphenylalanine.

Topics: Acute Disease; Alprostadil; Animals; Inflammation; Leukotriene B4; Male; N-Formylmethionine Leucyl-Phenylalanine; Rats; Rats, Inbred Strains; Uric Acid

Brown-Norway (BN) rats develop tubulointerstitial nephritis (TIN) after immunization with bovine tubular basement membrane (TBM) and adjuvants. Daily subcutaneous injections (either on Days 0-7 or Days 0-14) of (15S)-15-methyl prostaglandin E1 (M-PGE1) at a dose of 1 mg/kg/day markedly inhibited or completely abrogated the development of both the acute polymorphonuclear (Day 10) and the subsequent mononuclear (Day 14) inflammatory phases of BN rat TIN. Circulating anti-TBM antibody in Days 0-7 M-PGE1-treated rats was moderately diminished on Day 8 after immunization but not on Day 14. Circulating anti-TBM antibody in Days 0-14 M-PGE1-treated rats was only slightly diminished on Day 14. In experiments to test the effect of M-PGE1 on the elicitation phase of humorally mediated inflammation, M-PGE1 inhibited the acute inflammatory response observed 6 hours after intradermal injection of particulate TBM into TBM-sensitized BN rats. The inflammation in these skin tests was demonstrated by passive transfer experiments to be humorally mediated. The inhibition of acute humorally mediated intradermal inflammation was not attributable to neutropenia, because M-PGE1 caused a significant neutrophilia as demonstrated by peripheral blood smears. Although the inhibition of TIN in Days 0-14 M-PGE1-treated rats may have been due, in part, to dysfunction of the elicitation phase of humorally mediated inflammation, the inhibition of TIN in Days 0-7 M-PGE1-treated rats was more likely secondary to the diminished induction of either humoral or cellular immunity.

Topics: Alprostadil; Animals; Antibody Formation; Autoimmune Diseases; Basement Membrane; Cattle; Immunization; Inflammation; Kidney Tubules; Male; Nephritis, Interstitial; Rats; Rats, Inbred BN