We aimed to determine whether exposure to particulate matter PM, measured as the oxidative potential (OP) of filters collected from 24 h personal samplers, is associated with increased airway inflammation in asthmatic and non-asthmatic volunteers. Forty-two adult asthmatic patients (25 women and 17 men) and 37 matched controls wore a personal sampler for a day collecting fine (PM2.5) and coarse (PM10-2.5) particles, and determining 24 h afterwards their fractional exhaled nitric oxide (FeNO). The PM-OP was determined by two methods: dithiothreitol (DTT) and ascorbic acid (AA) being OP levels dichotomized based on the median, to calculate adjusted mean differences (aMDs) and odds ratios (aORs) with sex, age, study level, body mass index and interleukin-6 (IL-6) levels as confounders. Statistically significant associations between PM-OP and FeNO levels in non-asthmatic volunteers were observed: aMD for OP-DTT PM2.5 = 11.64 ppbs; 95 %CI (0.13-22.79); aMD for OP-AA PM10-2.5 = 15.67; 95 %CI (2.91-28.43) with aORs = 4.87 and 18.18 respectively. In asthmatic patients an association was also observed in the form of aORs, but of lower magnitude (1.91 and 1.94 respectively). Non-significant higher FeNO levels (aMD = 5.22) and an aOR = 3.92 were also observed in non-asthmatic volunteers for OP-AA in the fine fraction. As a conclusion, the effect of personal PM-OP on airway inflammation appears to be differential between asthmatic and non-asthmatic volunteers suggesting a potential implication of inhaled corticosteroids diminishing the reactivity of airway epithelium since adjusted associations were higher in volunteers without asthma.

Inflammatory cell activation in asthma may lead to reactive oxygen species (ROS) overproduction with an imbalance between oxidant levels and antioxidant capacity, called oxidative stress (OS). Since particulate matter (PM) airborne exposure may also contribute to ROS generation, it is unclear whether PM contributes more to OS than inflammatory cell activation. In our ASTHMA-FENOP study, which included 44 asthma patients and 37 matched controls, we aimed to characterize OS using five serum markers: total ROS content, protein carbonyl content, oxidized low-density lipoprotein (OxLDL), 8-hydroxydeoxyguanosine, and glutathione. Volunteers wore personal samplers for 24 h, collecting fine and coarse PM fractions separately, and the oxidative potential (OP) was determined using two methods. We observed differences between asthmatic and non-asthmatic volunteers in some OS markers, such as OxLDL, with an adjusted mean difference of 50,059.8 ng/mL (p < 0.001). However, we did not find an association between higher PM-OP and increased systemic OS. This suggests that at our PM-OP exposure levels, OS generated by the inflammatory cells themselves is more relevant than that generated by airborne PM. This supports the idea that asthma is a heterogeneous disease at the molecular level, mediated by inflammatory cell activation, and that OS may have potential clinical implications.

With the rationale that the oxidative potential of particulate matter (PM-OP) may induce oxidative stress and inflammation, we conducted the ASTHMA-FENOP study in which 44 asthmatic patients and 37 matched controls wore a personal sampler for 24 h, allowing the collection of fine and coarse PM fractions separately, to determine PM-OP by the dithiothreitol (DTT) and ascorbic acid (AA) methods. The levels of Interleukin 6 (IL-6) and the IL-6/IL-10 ratio, as indicators of pro- and anti-inflammatory statuses, were determined by calculating the mean differences (MDs), odds ratios (ORs) and p-trends adjusted for sex, age, study level and body mass index. Positive associations for IL-6 levels in the form of adjusted MDs and ORs were obtained for all PM-OP metrics, reaching statistical significance for both OP-DTT and OP-AA in the fine fraction, with adjusted OR = 5.66; 95%CI (1.46 to 21.92) and 3.32; 95%CI (1.07 to 10.35), respectively, along with statistically significant dose–response patterns when restricting to asthma and adjusted also for clinical variables (adjusted p-trend = 0.029 and 0.01). Similar or stronger associations and dose–response patterns were found for the IL-6/IL-10 ratio. In conclusion, our findings on the effect of PM-OP on systemic inflammation support that asthma is a heterogeneous disease at the molecular level, with PM-OP potentially playing an important role.

Skeletal muscle dysfunction is common in many chronic respiratory diseases. Several clinical and biological factors contribute to its etiology. Acute exacerbations and systemic inflammation and oxidative stress are mostly responsible. Whether patients with bronchiectasis experience limb muscle dysfunction remains to be fully elucidated as well as the underlying mechanisms. In vastus lateralis (VL) of patients (n=20) with bronchiectasis and 10 healthy controls phenotypic features and in blood samples parameters of inflammation and oxidative stress were evaluated along with muscle function (upper and lower limbs). In bronchiectasis patients compared to controls, upper and lower limb muscle function and fast-twitch muscle fiber cross-sectional area were reduced, while systemic levels of myeloperoxidase, TGF-β1, VEGF-A, IL-6, protein carbonylation, superoxide dismutase activity, and reduced glutathione significantly increased. Muscle dysfunction of the upper and lower limbs in bronchiectasis patients is a relevant clinical feature, in which systemic inflammation and oxidative stress together with the predominance of a fast-twitch phenotype underlie its pathophysiology. These findings may have clinical implications when designing specific therapeutic strategies. Funding: FIS 21/00215 (FEDER, ISC-III), Intensificación INT19, CIBERES (ISC-III), SEPAR-2020.

Muscle weakness and wasting are common in patients with chronic obstructive pulmonary disease (COPD). Myostatin regulatory pathway is involved in muscle mass maintenance. Whether the expression of markers of the myostatin pathway is altered in the lower limb muscles of sarcopenic COPD patients remains to be fully elucidated. We sought to characterize gene and protein expression profile of the myostatin pathway and its downstream targets in COPD sarcopenia. In the vastus lateralis (VL) samples of 41 severe COPD patients (23 sarcopenic and 18 non-sarcopenic) and 14 healthy controls, mRNA expression levels of myostatin, activin A, activin receptors (ACVR2Aa and ACVR2B), SMAD2, SMAD3, SMAD4, AKT1, PI3KR1, IGF1 and follistatin were quantified using qRT‐PCR, and those of myostatin, SMAD2/p-SMAD2, SMAD3/p-SMAD3 and SMAD4 protein levels were measured by immunoblotting. In sarcopenic COPD patients, nutritional and muscle function status were reduced compared to non-sarcopenic and healthy controls. In muscle specimens of sarcopenic COPD, mRNA levels of myostatin, IGF1, and follistatin were greater, while those of activin A and SMAD3 were lower than in the controls and non-sarcopenic patients. Protein levels of myostatin, p-SMAD2, p-SMAD3 and SMAD4 significantly increased in sarcopenic patients compared to control subjects. The lower limb muscles of sarcopenic COPD patients exhibited an upregulation of the myostatin pathway, whereas activin was downregulated. Accelerated myostatin activity underlies sarcopenia and muscle weakness in severe COPD that should be targeted therapeutically. Funding: FIS 18/00075, FIS 21/00215 (FEDER, ISC-III), Intensificación INT19, CIBERES (ISC-III), SEPAR-2020

We aimed to demonstrate that systemic inflammation and oxidative stress and other molecular events: endoplasmic reticulum (ER) stress and proteolysis are involved in the development of sarcopenia in bronchiectasis. In blood and muscle samples (open muscle biopsy, quadriceps), prooxidants (oxidized and nitrated proteins, ELISA), antioxidants (TEAC, GSH, SOD and catalase, plasma, assays, ELISA), inflammation (MPO, COX-2, TGF-beta1, VEGF, IL-6, plasma, ELISA), ER stress (chaperones and IRE1, PERK and ATF6 pathways), proteolysis (ubiquitin proteasome system) and autophagy markers (muscle, Western blot) of sarcopenic stable patients with mild-to-moderate bronchiectasis (n=20) and controls (n=10). Patients and controls were clinically evaluated: nutritional, respiratory and muscle function (handgrip and quadriceps muscle strength). In sarcopenic patients compared to controls: 1) systemic compartment, levels of MPO, TGF-beta1, VEGF, IL-6, protein oxidation, SOD, and GSH increased, and 2) muscle compartment, levels of ER stress (XBP1, ATF4), proteolysis (MURF1, 20S proteasome) and autophagy (p62) also significantly increased. Inverse correlations were found between molecular markers and both FFMI and QMVC. In bronchiectasis patients, sarcopenia is present in upper and lower limbs. Biological events in systemic and local compartments negatively correlated with muscle mass and strength, suggesting their implications in sarcopenia development. Pulmonary rehabilitation programs should be specifically targeted. Funding: SEPAR-2020, FIS21/00215 (FEDER,ISC-III), BA21/00003, INT19/00002, INT22/00008,2021-SGR-00100, CIBERES (ISC-III), Menarini Labs, SLT028/23/000016