Much debate has focused on the relative importance of interleukin 1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha) in the pathophysiology of rheumatoid arthritis (RA). The production of these cytokines by synovial macrophages is tightly regulated by cell-cell contact with T cells. During this contact, several surface molecules are implicated in contact mediated cytokine production, including CD40 ligand, CD11b/c, and CD69. Apolipoprotein A-I, an acute phase reactant (APR) that declines during systemic inflammation (reverse APR), inhibits cytokine production by interfering in the T cell-monocyte interaction. Although the effects of IL-1 and TNF-alpha overlap, they have somewhat differing roles in RA on the basis of evidence from several animal models. TNF-alpha appears to play a more important role in triggering events leading to inflammation both locally and systemically, whereas IL-1 is more involved at the local level in processes leading to cartilage and bone destruction and in impeding cartilage repair. However, IL-1 and TNF-alpha strongly synergize in numerous biological functions, both in vitro and in vivo. Blockade of IL-1 and TNF-alpha simultaneously provides favorable effects in collagen and adjuvant induced arthritis, illustrating the importance of both cytokines.
Heart failure is frequently the cause. Pressures in the heart rise when a sick or overworked left ventricle can't pump out enough of the blood it receives from the lungs. Fluid is pushed past the blood vessel walls and into the air sacs by the increasing pressure.
