Research | Children’s Health Effect of Maternal Smoking on Breast Milk Interleukin-1α, β-Endorphin, and Leptin Concentrations Vincenzo Zanardo,1 Silvia Nicolussi,1 Stefania Cavallin,1 Daniele Trevisanuto,1 Angelo Barbato,1 Diego Faggian,2 Flaviano Favaro,2 and Mario Plebani 2 1Department of Pediatrics and 2Institute of Laboratory Medicine, Padua University School of Medicine, Padua, Italy Tobacco smoke is immunotoxic, but the effect of smoking on the immunologic function of the mammary gland of mothers who smoke cigarettes (“smoker mothers”) has not been studied. Our objective was to test, in smoker mothers, the colostral and transitional milk concentrations of interleukin-(IL)1α. The immunomodulators β-endorphin and leptin were also tested. Pregnant women who self-identiﬁed as smokers (≥ 5 cigarettes per day through pregnancy) or nonsmokers were recruited for study participation. The study population included 42 smoker and 40 non- smoker nursing mothers, with otherwise uncomplicated gestation, delivery, and puerperium, who were breast-feeding ad libitum their healthy neonates. Colostrum was obtained on the third post- partum day at 0900 hr and transitional milk on the 10th postpartum day at 0900 hr. IL-1α con- centrations were significantly reduced in the colostrum of smoker mothers compared with nonsmoker mothers (p < 0.01). Colostral β-endorphin and leptin concentrations were comparable. No signiﬁcant differences were found between smoker and nonsmoker lactating mothers in transi- tional milk concentrations of IL-1α, β-endorphin, and leptin. Moreover, β-endorphin and leptin concentrations were signiﬁcantly reduced in transitional milk samples compared with colostrum of both smoker and nonsmoker mothers (p < 0.05); also, IL-1α transitional milk concentrations were reduced compared with colostrum, but without any significance. This analysis shows that maternal smoking alters the colostral milk levels of the proinflammatory cytokine IL-1α . The altered postnatal provision of alternative source of the proinflammatory cytokine IL-1α adds understanding to how breast-feeding could be nonprotective against infections among the neonates nursed by smoker mothers. Key words: β-endorphin, cigarette smoke, colostrum, inter- leukin-1α, leptin, maternal smoking, transitional milk. Environ Health Perspect 113:1410–1413 (2005). doi:10.1289/ehp.7702 available via http://dx.doi.org/ [Online 15 June 2005] Evidence increasingly indicates that breast milk protects against gastrointestinal, respiratory tract, middle ear infections, asthma, and sud- den infant death syndrome (SIDS) (Klonoff- Cohen et al. 1995; Kovar et al. 1984; Oddy et al. 2003). Several components of human milk have been postulated to confer this pro- tective effect (Goldman et al. 1998). Breast- feeding might provide an immediate line of defense against infectious agents, which com- pensates directly for the immaturity of the newborn’s immune system and lowered ability to resist infection. Protection might also be achieved through specific and nonspecific factors in milk, including bioactive enzymes, hormones, growth factors, and immunologic agents that augment and stimulate the devel- opment of immature host defense. Thus, it is not clear which of the many components of this complex, changing biologic ﬂuid account for the protective effect. Passive smoking in the same room as the infant increases the risk for respiratory disease and SIDS (Gordon et al. 2002), whereas breast-feeding is protective for SIDS among nonsmokers, but not smokers, when adjusted for potential confounders (Klonoff-Cohen et al. 1995), raising the possibility that there are also immunologic changes in the breast milk. However, a clear negative effect of nursing by a smoker mother has not been demonstrated 1410 (Mitchell et al. 1993), and very little is known of the mechanisms by which smoke might account for the reduced protective effect of breast milk (Blizzard et al. 2003; Elliot et al. 2003). Cigarette smoke is composed of > 5,000 chemicals, including approximately 70 carcino- gens (Stedman 1968), very few of which have actually been assayed for immunosuppressive activity (Ouyang et al. 2000). Conflicting reports exist regarding the effects of nicotine on cytokine production, and little is known about the nature of the immunosuppressive compounds in cigarette smoke (Ouyang et al. 2000). Nevertheless, the major phenolic com- ponents of cigarette tar, hydroquinone and catechol, have been reported to suppress the production of interleukin-(IL)1β, IL-2, and interferon-γ (Kalf et al. 1996; Ouyang et al. 2000). Breast-feeding substantially increases absorption of nicotine compared with only environmental tobacco smoke when the mother smokes (Dahlström et al. 1990; Luck and Nau 1985; Schulte-Hobein et al. 1992). In smoker mothers, the milk:plasma con- centration ratio of nicotine is 2.9, whereas that of the primary metabolite cotinine is 1.2 (Dahlström et al. 1990). Nicotine has received much attention because it is immunotoxic, triggering the immune system and altering the humoral and cellular immunity and the levels of certain cytokines and their receptors (Sayers and Drucker 1999; Sopori et al. 1998). It has only recently been shown that human milk contains cytokines (Goldman et al. 1996). Cytokines are small soluble glyco- proteins that act in an autocrine or paracrine manner by binding to speciﬁc cellular recep- tors, operating in networks, and orchestrating the immune system’s development and func- tion. Early milk has an abundance of cytokines at a time when neonatal organ systems are immature, suggesting that these bioactive components of milk might be important in neonatal immunity development. Growth, dif- ferentiation, and immunoglobulin production by B-cells were among the ﬁrst activities found in human milk and attributed to the presence of cytokines (Bentzen 1994). IL-1α is one of the two forms, indistin- guishable in their biologic activities, of IL-1, the prototypic proinflammatory cytokine, involved in the mechanisms underlying many infectious and noninfectious inflammatory diseases. Although IL-1 can up-regulate host defenses and function as an immunoadjuvant, it is a highly proinﬂammatory cytokine. The margin between clinical beneﬁt and unaccept- able toxicity in humans is exceedingly narrow. In contrast, agents that reduce the production and/or activity of IL-1 are likely to have an impact on clinical medicine. The synthesis, processing, secretion, and activity of IL-1 are tightly regulated events. For instance, the presence of an IL-1 receptor antagonist is an important mechanism through which IL-1 signaling is down-regulated, and therefore its activity is reduced (Dinarello 1998). IL-1 is probably the first cytokine that has been quantified in human milk (Munoz et al. 1990). IL-1β, but not IL-1α, was frequently investigated and found in colostrum and early milk samples from healthy lactating mothers. To the best of our knowledge, the effect of cigarette smoking on the immunologic func- tion of the mammary gland has not been studied previously. Address correspondence to V. Zanardo, Department of Pediatrics, Padua University School of Medicine, Via Giustiniani 3, 35128 Padua, Italy. Telephone: 049-8213505. Fax: 049-8213509. E-mail: zanardo@ pediatria.unipd.it We thank M. Mead and F. Cavallin for their con- tributions to this article. The authors declare they have no competing ﬁnancial interests. Received 29 October 2004; accepted 14 June 2005. VOLUME 113 | NUMBER 10 | October 2005 • Environmental Health Perspectives