α-Defensins are abundant antimicrobial peptides in polymorphonuclear leukocytes and play an important role in innate immunity. We have previously shown that α-defensin-1 can inhibit HIV-1 replication following viral entry. Here we examined the molecular mechanism(s) of α-defensin-1-mediated HIV-1 inhibition. α-Defensin-1 had a direct effect on HIV-1 virions at a low MOI in the absence of serum. The direct effect on HIV-1 virions was abolished by the presence of serum or an increase in virus particles. Studying the kinetics of the HIV life cycle revealed that α-defensin-1 inhibited steps following reverse transcription and integration. Analysis of PKC phosphorylation in primary CD4 + T cells in response to α-defensin-1 indicated that α-defensin-1 inhibited PKC activity. Pretreatment of infected CD4 + T cells with a PKC activator, bryostatin 1, partially reversed α-defensin-1-mediated HIV inhibition. Like α-defensin-1, the PKC isoform-selective inhibitor Go6976 blocked HIV-1 infection in a dose-dependent manner. Furthermore, kinetic studies and analysis of HIV-1 products indicated that α-defensin-1 and Go6976 blocked HIV-1 infection at similar stages in its life cycle, including nuclear import and transcription. Taken together, our studies demonstrate that, in the absence of serum, α-defensin-1 may act directly on the virus, but, in the presence of serum, its effects are on the cell, where it inhibits HIV-1 replication. At least 1 of the cellular effects associated with HIV inhibition is interference with PKC signaling in primary CD4 + T cells. Studying the complex function of α-defensin-1 in innate immunity against HIV has implications for prevention as well as therapeutics.
A prospective echocardiographic study was carried out on 55 patients with the recently described 'primary' antiphospholipid syndrome derived from three university medical centres. The prevalence of valvular lesions in patients with this syndrome was 38% compared with 4% in a control group of 55 healthy volunteers (P < 0.001). Mean age of patients with valve abnormalities was 42 +/- 12 years and of those without, 30 +/- 10 years (P < 0.05). One patient had a morphologic echocardiographic pattern suggestive of non-infective verrucous mitral endocarditis. Twenty patients had a two-dimensional or Doppler echocardiographic pattern of significant valvular dysfunction--either regurgitation or stenosis--without evidence of vegetations. Mitral and aortic regurgitation were the most common lesions in these patients. During follow-up of patients with valvular disease, haemodynamically significant clinical valve disease developed in four and surgery was required in one. Eleven patients had cerebrovascular occlusions. Thus, valvular heart disease, particularly affecting the mitral and aortic valves, is common in patients with the 'primary' antiphospholipid syndrome, especially in those over 40 years old.
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