Oral administration of gammalinolenic acid, an unsaturated fatty acid with anti-inflammatory properties, modulates interleukin-1beta production by human monocytes.

Administration of gammalinolenic acid (GLA), an unsaturated fatty acid, reduces joint inflammation in patients with rheumatoid arthritis. Addition of GLA in vitro suppresses release of interleukin-1beta (IL-1beta) from human monocytes stimulated with lipopolysaccharide (LPS). LPS-induced IL-1beta release is followed by IL-1-induced IL-1beta release, an amplification process termed "autoinduction." We show here, using IL-1alpha stimulation to simulate autoinduction, that administration of GLA to healthy volunteers and to patients with inflammatory arthritis reduces LPS-induced IL-1beta secretion mainly by reducing autoinduction of IL-1beta. GLA reduces LPS-induced pro-IL-1beta mRNA modestly and IL-la-induced pro-IL-1beta gene expression markedly. In addition to reducing amplification of IL-1beta, GLA increases the amount of IL-1 receptor antagonist (IL-1Ra) secreted from stimulated cells, thereby facilitating an increase in the secreted IL-1Ra/IL-1beta ratio. IL-1beta is important to host defense, but the amplification mechanism may be excessive in genetically predisposed individuals. Thus, reduction of IL-1beta autoinduction may be protective in some patients with endotoxic shock and with diseases characterized by chronic inflammation.

Effect of Misoprostol on Acute and Chronic Inflammation.

Prostaglandins and their fatty acid precursors are important to regulation of cell function, and immune and inflammatory responses. Prostaglandin E compounds in particular have been shown to reduce inflammation and tissue injury. We examined the ability of misoprostol, the orally active analog of Prostaglandin E1, to influence inflammation in two animal models. In the subcutaneous air pouch model, acute inflammation was induced by tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta). Misoprostol reduced pouch leukocyte counts in a dose dependent manner (33--49% v control), but did not alter fluid accumulation. The non-steroidal antiinflammatory agent, diclofenac, also reduced leukocyte counts in a dose dependent manner (28--66%) without affecting pouch fluid volume. Low dose misoprostol and low dose diclofenac used together reduced leukocyte counts by 39%, suggesting an advantageous snyergy in suppression of acute inflammation. Collagen induced arthritis (CIA) is a model of chronic inflammation. Misoprostol had no effect on the severity or course of CIA. Diclofenac reduced significantly all indices of inflammation tested, including joint swelling, number of affected joints and ability to walk. Misoprostol interfered with the antiinflammatory effect of diclofenac when the two compounds were administered together in the CIA model. These studies suggest that Misoprostol suppresses neutrophil mediated acute inflammation.