Vitronectin, fibronectin, and gp120 antibody enhance macrophage release of TNF-alpha in response to Pneumocystis carinii.

Alveolar macrophages (AMS) initiate inflammation during Pneumocystis carinii pneumonia by releasing cytokines including TNF-alpha. Recent studies suggest that macrophage responses to P. carinii are enhanced by serum opsonization, but the mechanisms of enhancement are not well defined. To determine whether macrophage release of TNF-alpha in response to P. carinii was augmented by immune opsonization, alveolar macrophages obtained from rabbits were cultured with P. carinii that had been opsonized with either nonimmune rabbit serum, immune serum generated against P. carinii, or an affinity-purified polyclonal Ab recognizing the major P. carinii surface Ag gp120. Each experiment also included organisms maintained in media alone (nonopsonized P. carinii). Opsonization of P. carinii with immune serum or gp120 Ab significantly enhanced macrophage TNF-alpha release. Interestingly, however, opsonization with nonimmune serum also increased TNF-alpha response to the organism. Because P. carinii is known to interact with the adhesive glycoproteins, vitronectin (VN) and fibronectin (FN), we hypothesized that they might also augment TNF-alpha release. Opsonization of P. carinii with VN or FN resulted in significant potentiation of macrophage TNF-alpha liberation. We further determined that VN and FN were present in increased quantities in the lower respiratory tract of patients with P. carinii pneumonia compared with normal volunteers. Additionally, VN and FN were demonstrated on the surface of freshly isolated P. carinii organisms by immunoblot analysis. Our study suggests that immune and nonimmune opsonins contribute to host defenses during P. carinii pneumonia by enhancing regional TNF-alpha release in response to the organism.

Nicotine patch therapy for smoking cessation combined with physician advice and nurse follow-up. One-year outcome and percentage of nicotine replacement.

OBJECTIVE: To determine the efficacy of a 22-mg nicotine patch combined with the National Cancer Institute program for physician advice and nurse follow-up in providing withdrawal symptom relief, 1-year smoking cessation outcome, and percentage of nicotine replacement. DESIGN: Randomized, double-blind, placebo-controlled trial. SUBJECTS: Two-hundred forty healthy volunteers who were smoking at least 20 cigarettes per day. INTERVENTIONS: Based on the National Cancer Institute program, subjects received smoking cessation advice from a physician. Follow-up and relapse prevention were provided by a study nurse during individual counseling sessions. Subjects were randomly assigned to 8 weeks of a 22-mg nicotine or placebo patch. MAIN OUTCOME MEASURES: Abstinence from smoking was verified by expired air carbon monoxide levels. Withdrawal symptoms were recorded during patch therapy, and the percentage of nicotine replacement was calculated by dividing serum nicotine and cotinine levels at week 8 of patch therapy by levels obtained while smoking. RESULTS: Higher smoking cessation rates were observed in the active nicotine patch group at 8 weeks (46.7% vs 20%) (P < .001) and at 1 year (27.5% vs 14.2%) (P = .011). Higher smoking cessation rates were also observed in subjects assigned to the active patch who had lower serum levels of nicotine and cotinine at baseline, and withdrawal symptom relief was better in the active patch group compared with placebo. CONCLUSIONS: Clinically significant smoking cessation can be achieved using nicotine patch therapy combined with physician intervention, nurse counseling, follow-up, and relapse prevention. Smokers with lower baseline nicotine and cotinine levels had better cessation rates, which provides indirect evidence that they had more adequate nicotine replacement with this fixed dose of transdermal nicotine than those smokers with higher baseline levels.

Vitronectin binds to Pneumocystis carinii and mediates organism attachment to cultured lung epithelial cells.

Pneumocystis carinii attaches to alveolar epithelial cells during the development of pneumonia. Adhesive proteins found within the alveolar space have been proposed to mediate P. carinii adherence to lung cells. Vitronectin (Vn), a 75-kDa glycoprotein present in the lower respiratory tract, has substantial cell-adhesive properties and might participate in the host-parasite interaction during P. carinii pneumonia. To address whether Vn binds to P. carinii, we studied the interaction of radiolabeled Vn with purified P. carinii organisms. Vn bound to P. carinii, occupying an estimated 5.47 x 10(5) binding sites per organism, with an affinity constant, Kd, of 4.24 x 10(-7) M. Interestingly, the interaction of Vn with P. carinii was not mediated through the Arg-Gly-Asp cell-adhesive domain of Vn. Addition of Arg-Gly-Asp-Ser (RGDS) peptides did not inhibit binding. In contrast, Vn binding to P. carinii was substantially inhibited by the addition of heparin or by digesting the organisms with heparitinase, suggesting that P. carinii may interact with the glycosaminoglycan-binding domain of Vn. To determine whether Vn might enhance P. carinii attachment to lung epithelial cells, we studied the binding of 51Cr-labeled P. carinii to cultured A549 lung cells. Addition of Vn resulted in significantly increased binding of P. carinii to A549 cells, whereas a neutralizing anti-Vn serum substantially reduced the binding of P. carinii to A549 cells. These data suggest that Vn binds to P. carinii and that Vn might provide an additional means by which P. carinii attaches to respiratory epithelial cells.