Different Characteristics of Childhood Asthma Related to Polyhexamethylene Guanidine Hydrochloride (PHMG) Exposure

Yanghe Pingchuan granules mitigates oxidative stress and inflammation in a bronchial asthma rat model: role of the IKK/IκB/NF-κB signalling pathway

Background

Bronchial asthma (BA) is a chronic inflammatory airway disease. Previous research has shown that Yanghe Pingchuan granules (YPG), among the granules formulated by the First Affiliated Hospital of the Anhui University of Chinese Medicine, exerts a precise therapeutic effect on BA. We previously showed that YPG improves airway inflammation in BA rats. Other studies have shown that the inhibitor of kappa-B kinase (IKK)/inhibitor of NF-κB (IκB)/nuclear factor kappa-B (NF-κB) signalling pathway plays a key role in inflammation mediation. Therefore, this study explored whether YPG could intervene in BA through the IKK/IκB/NF-κB signalling pathway.

Methods

Ovalbumin-induced method was used to established BA rat model. After successful modelling, the authors used YPG to intervene the rats in BA rats. Hematoxylin-eosin (HE) staining was used to detect the bronchial pathological changes in BA rats, enzyme-linked immunosorbent assay (ELISA) was used to detect the changes of inflammatory factors (IL-1β and IL-6) and oxidative stress indexes malondialdehyde (MDA), superoxide dismutase (SOD) and nitrogen monoxide (NO), Quantitative real-time polymerase chain reactionCR and western blot were used to detect the expression of IKK/IκB/NF-κB signalling pathway.

Results

In BA model rats, YPG significantly improved the inflammatory response in bronchial tissues, reduced inflammatory factors IL-1β and IL-6, alleviated oxidative stress, reduced MDA and NO, and increased SOD. Quantitative real-time polymerase chain reaction and western blot results showed that YPG could block the IKK/IκB/NF-κB signalling pathway.

Conclusion

These findings showed that YPG had a definite therapeutic effect on BA, which may be related to blocking the IKK/IκB/NF-κB signalling pathway and improving inflammation and oxidative stress.

Dramatic reduction of toxicity of Poly(hexamethylene guanidine) disinfectant by charge neutralization

The current study aimed to investigate the toxicity of positively charged polyhexamethylene guanidine (PHMG) polymer and its complexation with different anionic natural polymers such as k-carrageenan (kCG), chondroitin sulfate (CS), sodium alginate (Alg.Na), polystyrene sulfonate sodium (PSS.Na) and hydrolyzed pectin (HP). The physicochemical properties of the synthesized PHMG and its combination with anionic polyelectrolyte complexes (PECs) namely PHMG:PECs were characterized using zeta potential, XPS, FTIR, and TG analysis. Furthermore, cytotoxic behavior of the PHMG and PHMG:PECs, respectively, were evaluated using human liver cancer cell line (HepG2). The study results revealed that the PHMG alone had slightly higher cytotoxicity to the HepG2 cells than the prepared polyelectrolyte complexes such as PHMG:PECs. The PHMG:PECs showed a significant reduction of cytotoxicity to the HepG2 cells than the pristine PHMG alone. A reduction of PHMG toxicity was observed may be due to the facile formation of complexation between the positively charged PHMG and negatively charged anionic natural polymers such as kCG, CS, Alg. Na, PSS.Na and HP, respectively, via charge balance or neutralization. The experimental results indicate that the suggested method might significantly lower PHMG toxicity while improving biocompatibility.

Comprehensive analysis of disinfectants on the horizontal transfer of antibiotic resistance genes

The propagation of antimicrobial resistance (AMR) is constantly paralyzing our healthcare systems. In addition to the pressure of antibiotic selection, the roles of non-antibiotic compounds in disseminating antibiotic resistance genes (ARGs) are a matter of great concerns. This study aimed to explore the impact of different disinfectants on the horizontal transfer of ARGs and their underlying mechanisms. First, the effects of different kinds of disinfectants on the conjugative transfer of RP4-7 plasmid were evaluated. Results showed that quaternary ammonium salt, organic halogen, alcohol and guanidine disinfectants significantly facilitated the conjugative transfer. Conversely, heavy-metals, peroxides and phenols otherwise displayed an inhibitory effect. Furthermore, we deciphered the mechanism by which guanidine disinfectants promoted conjugation, which includes increased cell membrane permeability, over-production of ROS, enhanced SOS response, and altered expression of conjugative transfer-related genes. More critically, we also revealed that guanidine disinfectants promoted bacterial energy metabolism by enhancing the activity of electron transport chain (ETC) and proton force motive (PMF), thus promoting ATP synthesis and flagellum motility. Overall, our findings reveal the promotive effects of disinfectants on the transmission of ARGs and highlight the potential risks caused by the massive use of guanidine disinfectants, especially during the COVID-19 pandemic.

TGFβ1 and POSTN as biomarkers of postinfectious bronchiolitis obliterans and asthma in children

RATIONALE

Asthma and postinfectious bronchiolitis obliterans (PIBO) are common chronic lung diseases in company with wheezing in children. However, it is not clear what is common and unique mechanisms between the two diseases. Thus, we used proteomic analysis to compare differences in biomarkers between children with asthma and PIBO.

METHODS

Overall, 30 healthy children without respiratory underlying diseases, 18 children with asthma and 15 with PIBO were included for this study. Sequential window acquisition of all theoretical mass spectra (SWATH)-mass spectrometry (MS) was used to measure proteins in plasma samples. To identify specific pathways of each groups, we used the ingenuity pathway analysis (IPA) software.

RESULTS

We identified and quantified 354 proteins across all 63 samples in the SWATH-MS analysis. Forty eight proteins were significantly different among 3 groups. The upstream analysis of IPA suggested that inhibitor of nuclear factor kappa B kinase subunit beta (IKBKB) was the upstream inhibitor of 4 differentially expressed proteins (DEPs) in asthma, while the upstream activator in PIBO subjects. Among 4 DEPs, TGF-β1 in PIBO and periostin in asthma were negatively correlated with forced expiratory volume in 1 s (FEV1), FEV1/forced vital capacity, maximal med-expiratory flow, and PC20, respectively.

CONCLUSION

These findings demonstrate that transforming growth factor β1 and periostin were unique biomarkers of PIBO and asthma in children, respectively. The mechanism regulated by IKBKB may be therapeutically relevant for PIBO and asthma.

Reduced Diffusing Capacity in Humidifier Disinfectant-Associated Asthma Versus Typical Asthma: A Retrospective Case Control Study

BACKGROUND

Humidifier disinfectant-related lung injury (HDLI) is a severe form of toxic inhalational pulmonary parenchymal damage found in residents of South Korea previously exposed to specific guanidine-based compounds present in humidifier disinfectants (HD). HD-associated asthma (HDA), which is similar to irritant-induced asthma, has been recognized in victims with asthma-like symptoms and is probably caused by airway injury. In this study, diffusing capacity of the lung for carbon monoxide (DL_CO) in individuals with HDA was compared to that in individuals with pre-existing asthma without HD exposure.

METHODS

We retrospectively compared data, including DL_CO values, of 70 patients with HDA with that of 79 patients having pre-existing asthma without any known exposure to HD (controls). Multiple linear regression analysis and logistic regression analysis were performed to confirm the association between HD exposure and DL_CO after controlling for confounding factors. The correlation between DL_CO and several indicators related to HD exposure was evaluated in patients with HDA.

RESULT

The mean DL_CO was significantly lower in the HDA group than in the control group (81.9% vs. 88.6%; P = 0.021). The mean DL_CO of asthma patients with definite HD exposure was significantly lower than that of asthma patients with lesser exposure (P for trend = 0.002). In multivariable regression models, DL_CO in the HDA group decreased by 5.8%, and patients with HDA were 2.1-fold more likely to have a lower DL_CO than the controls. Pathway analysis showed that exposure to HD directly affected DL_CO values and indirectly affected its measurement through a decrease in the forced vital capacity (FVC). Correlation analysis indicated a significant inverse correlation between DL_CO% and cumulative HD exposure time.

CONCLUSION

DL_CO was lower in patients with HDA than in asthma patients without HD exposure, and decreased FVC partially mediated this effect. Therefore, monitoring the DL_CO may be useful for early diagnosis of HDA in patients with asthma symptoms and history of HD exposure.

Health Effects Associated With Humidifier Disinfectant Use: A Systematic Review for Exploration

BACKGROUND

It has been 10 years since the outbreak of lung disease caused by humidifier disinfectants in Korea, but the health effects have not yet been summarized. Therefore, this study aims to systematically examine the health effects of humidifier disinfectants that have been discovered so far.

METHODS

All literature with humidifier disinfectants and their representative components as the main words were collected based on the web, including PubMed, Research Information Sharing Service, and government publication reports. A total of 902 studies were searched, of which 196 were selected. They were divided into four groups: published human studies (group 1), published animal and cytotoxicology studies (group 2), technical reports (group 3), and gray literature (group 4).

RESULTS

Out of the 196 studies, 97 (49.5%) were published in peer-reviewed journals as original research. Group 1 consisted of 49 articles (50.5%), while group 2 consisted of 48 articles (49.5%). Overall, respiratory diseases such as humidifier disinfectant associated lung injury, interstitial lung disease, and asthma have a clear correlation, but other effects such as liver, heart, thymus, thyroid, fetal growth, metabolic abnormalities, and eyes are observed in toxicological experimental studies, but have not yet been identified in epidemiologic studies.

CONCLUSION

The current level of evidence does not completely rule out the effects of humidifier disinfectants on extrapulmonary disease. Based on the toxicological evidence so far, it is required to monitor the population of humidifier disinfectant exposure continuously to see if similar damage occurs.

Need for individual-based evaluation to determine the association between humidifier disinfectants and health injuries

Background

Injuries caused by humidifier disinfectants (HDs) can no longer be grouped under the concept of HD lung injury. Focusing on individual cases, we were able to evaluate the relevance not only of diseases for which epidemiological correlation is recognized but also all diseases and symptoms that the victims complain of.

Methods

In-depth interviews and reassessment of 113 HD-exposed patients who had not been acknowledged as victims by the government were conducted, and their medical records were reviewed. Based on these processes, an assessment questionnaire for the injuries related to HDs was completed and the involvement of HDs was assessed either as “strong association,” “association,” or “no association.”

Results

In this study, of the 113 patients included who claimed damages, 78 (69.0%) had HD-related injuries. Among the cases of 22 patients who applied for injury acknowledgment due to upper respiratory inflammation that was not included among the acknowledged diseases, 17 (77.3%) were judged to be HD-related injuries (strong association vs. association: 10 [45.5%] vs. 7 [31.8%]). When the cases of 12 rhinitis patients were reassessed, 9 were HD-related injuries (strong association vs. association: 4 [33.3%] vs. 5 [41.7%]). When the cases of 18 asthma patients unacknowledged as a victim were reassessed, 17 (94.4%) were humidifier-related injuries (strong association vs. association: 12 [66.6%] vs. 5 [27.8%]). Among 4 interstitial lung disease patients unacknowledged as a victim, 2 (50.0%) were HD-related injuries.

Conclusions

HD-related health injuries should be assessed through both individual interviews and detailed chart reviews for more accurate injury acknowledgment. In the future, efforts should go beyond existing methods based on the adherence to acknowledgment criteria to directly listen to the victims.

Characteristics of the Molecular Weight of Polyhexamethylene Guanidine (PHMG) Used as a Household Humidifier Disinfectant

(1) Background: Household humidifier disinfectant (HD) brands containing polyhexamethylene guanidine (PHMG) have been found to cause the most HD-associated lung injuries (HDLIs) in the Republic of Korea. Nevertheless, no study has attempted to characterize the potential association of the health effects, including HDLI, with the physicochemical properties of PHMG dissolved in different HD brands. This study aimed to characterize the molecular weight (MW) distribution, the number-average molecular weight (M_n), the weight-average molecular weight (M_w), and the structural types of PHMG used in HD products. (2) Methods: Quantitative measurements were made using matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry (MALDI-TOF MS). The M_n, M_w, and MW distributions were compared among various HD products. (3) Results: The mean M_n and M_w were 542.4 g/mol (range: 403.0–692.2 g/mol) and 560.7 g/mol (range: 424.0–714.70 g/mol), respectively. The degree of PHMG oligomerization ranged from 3 to 7. The MW distribution of PHMG indicated oligomeric compounds regardless of the HD brands. (4) Conclusions: Based on the molecular weight distribution, the average molecular weight of PHMG, and the degree of polymerization, the PHMG collected from HDLI victims could be regarded as an oligomer. PHMG, as used in household humidifiers, should not be exempted from toxic chemical registration as a polymer. Further study is necessary to examine the association of PHMG oligomeric compounds and respiratory health effects, including HDLI.