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E-cigarette consumption is under scrutiny by regulatory authorities due to concerns about product toxicity, lack of manufacturing standards, and increasing reports of e-cigarette- or vaping-associated acute lung injury. In vitro studies have demonstrated cytotoxicity, mitochondrial dysfunction, and oxidative stress induced by unflavored e-cigarette aerosols and flavoring additives. However, e-cigarette effects on the complex lung parenchyma remain unclear. Herein, the impact of e-cigarette condensates with or without menthol flavoring on functional, structural, and cellular responses was investigated using mouse precision cut lung slices (PCLS). PCLS were exposed to e-cigarette condensates prepared from aerosolized vehicle, nicotine, nicotine + menthol, and menthol e-fluids at doses from 50 to 500 mM. Doses were normalized to the glycerin content of vehicle. Video-microscopy of PCLS revealed impaired contractile responsiveness of airways to methacholine and dampened ciliary beating following exposure to menthol-containing condensates at concentrations greater than 300 mM. Following 500 mM menthol-containing condensate exposure, epithelial exfoliation in intrabronchial airways was identified in histological sections of PCLS. Measurement of lactate dehydrogenase release, mitochondrial water-soluble-tetrazolium salt-1 conversion, and glutathione content supported earlier findings of nicotine or nicotine + menthol e-cigarette-induced dose-dependent cytotoxicity and oxidative stress responses. Evaluation of PCLS metabolic activity revealed dose-related impairment of mitochondrial oxidative phosphorylation and glycolysis after exposure to menthol-containing condensates. Taken together, these data demonstrate prominent mentholinduced pulmonary toxicity and impairment of essential physiological functions in the lung, which warrants concerns about e-cigarette consumer safety and emphasizes the need for further investigations of molecular mechanisms of toxicity and menthol effects in an experimental model of disease. [ABSTRACT FROM AUTHOR]

Erythrocyte precursors produce abundant [alpha]- and [beta]-globin proteins, which assemble with each other to form hemoglobin A (HbA), the major blood oxygen carrier. [alpha]Hb-stabilizing protein (AHSP) binds free [alpha] subunits [...]

Surfactant protein D (SP-D), a member of the collectin superfamily, modulates pulmonary inflammatory responses and innate immunity. Disruption of the SP-D gene in mice induces peribronchiolar inflammation, accumulation of large, foamy macrophages, increased bronchoalveolar lavage (BAL) phospholipid, and pulmonary emphysema. We hypothesized that absence of SP-D aggravates hyperoxia-induced injury. To test this, SP-D-deficient (SP-[D.sup.-/-]) and wild-type (SP-[D.sup.+/+]) mice were exposed to 80% or 21% oxygen. Paradoxically, during 14 days of hyperoxia, SP-[D.sup.-/-] mice had 100% survival vs. 30% in SP-[D.sup.+/+]. The survival advantage in SP-[D.sup.-/-] mice was accompanied by lower histopathological injury scores at days 5 and 14, although total BAL cells (8.2 [+ or -] 1.4 x [10.sup.5] in SP-[D.sup.-/-] vs. 4.04 [+ or -] 0.25 x [10.sup.5] in SP-[D.sup.+/+] mice) and neutrophils (1.2 [+ or -] 0.4 x [10.sup.5] vs. 0.03 [+ or -] 0.02 x [10.sup.5] in SP-[D.sup.-/-] and SP-[D.sup.+/+], respectively) were increased. In addition, BAL protein and lung-to-body weight ratios were similarly elevated in both groups after 3, 5, and 14 days of continuous exposure. Biochemically, in contrast to SP-[D.sup.+/+], SP-[D.sup.-/-] mice had higher levels of surfactant phospholipid and SP-B at baseline and 5 days after hyperoxia accompanied by a preservation of surfactant biophysical activity. From a multiplex assay of nine cytokines, we found elevated levels of IL-13 in BAL fluid of normoxic SP-[D.sup.-/-] mice compared with SP-[D.sup.+/+]. We conclude that the resistance of SP-D-deficient mice to hyperoxia reflects homeostatic changes in the SP-[D.sup.-/-] phenotype involving both phospholipid and SP-B-mediated induced resistance of surfactant to inactivation as well as changes in the immunomodulatory BAL cytokine profile. surfactant protein D; inflammation; alveolar macrophages; collectin

Author(s): Liang Feng [1]; Suiping Zhou [2]; Lichuan Gu [1]; David A. Gell [3]; Joel P. Mackay [3]; Mitchell J. Weiss [2]; Andrew J. Gow (corresponding author) [2]; Yigong Shi [...]

Nitric oxide (NO), despite an apparently simple diatomic structure, has a wide variety of functions in both physiology and pathology and within every major organ system. It has become an increasingly important scientific challenge to decipher how this wide range of activity is achieved. To this end a number of investigators have begun to explore how NO-mediated posttranslational modifications of proteins may represent mechanisms of cellular signaling. These modifications include: 1) binding to metal centers; 2) nitrosylation of thiol and amine groups; 3) nitration of tyrosine, tryptophan, amine, carboxylic acid, and phenylalanine groups; and 4) oxidation of thiols (both cysteine and methionine residues) and tyrusine. However, two particular modifications have recently received much attention, nitrosylation of thiols to produce S-nitrosothiol and nitration of tyrosine residues to produce nitrotyrosine. It is the purpose of this review to examine the possibility that these modifications may play a role in NO-mediated signaling. posttranslational modification; S-nitrosothiol; nitrotyrosine; nitrosylation; nitration

Previous studies of the interactions of NO with human hemoglobin have implied the predominance of reaction channels that alternatively eliminate NO by converting it to nitrate, or tightly complex it on the [alpha] subunit ferrous hemes. Both channels could effectively quench NO bioactivity. More recent work has raised the idea that NO groups can efficiently transfer from the hemes to cysteine thiols within the [beta] subunit (cys[beta]-93) to form bioactive nitrosothiols. The regulation of NO function, through its chemical position in the hemoglobin, is supported by response to oxygen and to redox agents that modulate the molecular and electronic structure of the protein. In this article, we focus on reactions in which Fe(III) hemes could provide the oxidative requirements of this NO-group transfer chemistry. We report a detailed investigation of the reductive nitrosylation of human met-Hb, in which we demonstrate the production of S-nitroso (SNO)-Hb through a heme-Fe(III)NO intermediate. The production of SNO-Hb is strongly favored (over nitrite) when NO is gradually introduced in limited total quantities; in this situation, moreover, heme nitrosylation occurs primarily within the [beta] subunits of the hemoglobin tetramer. SNO-Hb can similarly be produced when Fe(II)NO hemes are subjected to mild oxidation. The reaction of deoxygenated hemoglobin with limited quantities of nitrite leads to the production of [beta] subunit Fe(II)NO hemes, with SNO-Hb produced on subsequent oxygenation. The common theme of these reactions is the effective coupling of heme-iron and NO redox chemistries. Collectively, they establish a connectivity between hemes and thiols in Hb, through which NO is readily dislodged from storage on the heme to form bioactive SNO-Hb.

It has been possible to identify new nitric oxide (NO) chemistry involving enzymatic activity of a haem-thiol-NO redox triad. It was established that haemoglobin of the parasitic nematode Ascaris lumbricoides enzymatically consumes oxygen in a reaction driven by NO, thus keeping the perienteric fluid hypoxic. It is suggested that Ascaris haemoglobin acts as a 'deoxygenase,' with NO being used to detoxify oxygen.