Endotoxin exposure, serum vitamin D, asthma and wheeze outcomes

Impact of rapid correction of vitamin D deficiency in asthmatic patients

BACKGROUND

Asthma is one of the most common chronic diseases, which is a growing public health concern worldwide. In recent years, there has been an increasing number of interests in the relationship between vitamin D level and asthma control. Hence, the objective of this study was to assess the effect of high doses of vitamin D₃ injection on asthmatic patient's respiratory condition and quality of life.

METHODS

This was a single arm, before and after interventional study involving 18 patients with moderate to severe asthma. Spirometry test, St George's respiratory questionnaire (SGRQ) and serum vitamin D assay were performed. Subjects with 25-hydroxyvitamin D₃ (25-(OH) D₃) < 20 ng/ml were deemed deficient (n = 18) and received 2 intramuscular injections of vitamin D₃ 300,000 IU at monthly intervals consecutively.

RESULTS

The mean changes of forced expiratory volume in the first second (FEV1) were significantly different in subjects who received vitamin D₃ injections (p = 0.008). Also, the mean changes in FEV1/forced vital capacity ratio (FEV1/FVC) were significant (p < 0.001) as well as maximum expiratory flow between 25% and 75% of FVC (MEF25-75) (p = 0.001). Interestingly, improvement in clinical parameters of SGRQ was also observed with significant differences in total score (p = 0.001). Naturally, serum vitamin D levels were increased in our patients following the injections (p < 0.001).

CONCLUSIONS

Our findings suggest that screening for serum 25-(OH) D₃ deficiency is important in asthmatic patients and correction of this deficiency with high doses of vitamin D₃ injection may lead to improvement in pulmonary function, symptoms and quality of life (QOL).

Indoor Microbial Exposures and Chronic Lung Disease: From Microbial Toxins to the Microbiome

Effects of environmental microbial exposures on human health have long been of interest. Microbes were historically assumed to be harmful, but data have suggested that microbial exposures can modulate the immune system. We focus on the effects of indoor environmental microbial exposure on chronic lung diseases. We found contradictory data in bacterial studies using endotoxin as a surrogate for bacterial exposure. Contradictory data also exist in studies of fungal exposure. Many factors may modulate the effect of environmental microbial exposures on lung health, including coexposures. Future studies need to clarify which method of assessing environmental microbial exposures is most relevant.

Factors Associated with Hospitalization and Disease Severity in a Racially and Ethnically Diverse Population of COVID-19 Patients

BACKGROUND

The coronavirus disease (COVID-19) first identified in Wuhan in December 2019 became a pandemic within a few months of its discovery. The impact of COVID-19 is due to both its rapid spread and its severity, but the determinants of severity have not been fully delineated.

OBJECTIVE

Identify factors associated with hospitalization and disease severity in a racially and ethnically diverse cohort of COVID-19 patients.

METHODS

We analyzed data from COVID-19 patients diagnosed at the University of Cincinnati health system from March 13, 2020 to May 31, 2020. Severe COVID-19 was defined as admission to intensive care unit or death. Logistic regression modeling adjusted for covariates was used to identify the factors associated with hospitalization and severe COVID-19.

RESULTS

Among the 689 COVID-19 patients included in our study, 29.2% were non-Hispanic White, 25.5% were non-Hispanic Black, 32.5% were Hispanic, and 12.8% were of other race/ethnicity. About 31.3% of patients were hospitalized and 13.2% had severe disease. In adjusted analyses, the sociodemographic factors associated with hospitalization and/or disease severity included older age, non-Hispanic Black or Hispanic race/ethnicity (compared to non-Hispanic White), and smoking. The following comorbidities: diabetes, hypercholesterolemia, asthma, COPD, chronic kidney disease, cardiovascular diseases, osteoarthritis, and vitamin D deficiency were associated with hospitalization and/or disease severity. Hematological disorders such as anemia, coagulation disorders, and thrombocytopenia were associated with both hospitalization and disease severity.

CONCLUSION

This study confirms race and ethnicity as predictors of severe COVID-19. It also finds clinical risk factors for hospitalization and severe COVID-19 not previously identified such a vitamin D deficiency, hypercholesterolemia, osteoarthritis, and anemia.

Endotoxin clustering with allergens in house dust and asthma outcomes in a U.S. national study

BACKGROUND

Endotoxin is ubiquitous in the environment, but its clustering with indoor allergens is not well characterized. This study examined the clustering patterns of endotoxin with allergens in house dust and their association with asthma outcomes.

METHODS

We analyzed data from 6963 participants of the 2005-2006 National Health and Nutrition Examination Survey. House dust sampled from bedroom floor and bedding was evaluated for endotoxin and allergens from fungi, cockroach, dog, cat, mites, and rodents. Two-step cluster analysis and logistic regressions were performed to identify the clustering patterns and their associations with current asthma and wheeze in the past 12 months, adjusting for covariates.

RESULTS

Of the homes, 17.8% had low endotoxin and allergen levels in house dust (Cluster 1). High endotoxin level clustered with Alternaria and pet allergens in the homes of participants with a high socioeconomic status who own pets (Cluster 2) (48.9%). High endotoxin clustered with Aspergillus, dust mites, cockroach, and rodent allergens in the homes of participants with low socioeconomic status (Cluster 3) (33.3%). Compared to Cluster 1, Cluster 2 was associated with higher asthma prevalence (OR 1.42, 95% CI: 1.06-1.91) and wheeze (OR 1.32, 95% CI: 1.07-1.63). Cluster 3 was positively associated with wheeze only in participants sensitized to inhalant allergens (OR 1.42, 95% CI: 1.06-1.91) or exposed to tobacco smoke (OR 1.72, 95% CI: 1.15-2.60).

CONCLUSIONS

The clustering of endotoxin with allergens in dust from homes with pets or of people with low socioeconomic status is associated with asthma and wheeze.

The Impact of Ambient Environmental Exposures to Microbial Products on Asthma Outcomes from Birth to Childhood

Purpose of Review

Asthma is a chronic respiratory condition with increasing domestic and worldwide prevalence that burdens individuals and the healthcare system with high costs associated with long-term treatments and acute emergency room (ER) visits. It can be triggered by ambient microbes, including bacteria, viruses, and fungi. In this review, we examine the outcomes of asthma patients in relation to environmental exposures to ambient microbe products, focusing on whether exposure leads to asthma development from birth to childhood and if particular microbes are associated with worsened asthma exacerbations.

Recent Findings

Bacterial endotoxin is more prominent in homes with pets and may cause cytokine cascades that lead to asthma exacerbation. However, some studies have demonstrated a protective effect with early exposure. Patients with positive Aspergillus skin testing are more prone to moderate-severe or severe-uncontrolled asthma. Fungal sensitization is also associated with earlier onset of asthma and demonstrates a dose-dependent relationship of symptom severity and duration. Among viruses, rhinovirus has the greatest association with decreased lung function, severe asthma, and asthma-related hospital admissions. Distribution of microbial products and associated asthma symptoms depends on the geographical climate. Genetic variations among individuals also mitigate the effects of microbial products on asthma development and symptom severity.

Summary

Microbial products of bacteria, fungi, and viruses are associated with the development of asthma, more severe asthma symptoms, and worse outcomes. However, some early exposure studies have also demonstrated a protective effect. Bacterial and fungal products are related to decreased lung function and earlier onset of asthma. Viral products are related to asthma-associated hospital admissions; and the climate and patient genetics can also temper or intensify the relationships between microbial products, asthma development, and asthma symptom severity. Further research should focus on the effects of early microbe exposure and its interaction with human immune systems and asthma-related outcomes.

Microwave-induced release and degradation of airborne endotoxins from Escherichia coli bioaerosol

Endotoxins are widely distributed toxins in the outer cell-wall membranes of Gram-negative bacteria and other microorganisms. Chronic exposure to endotoxins can induce and exacerbate airway symptoms and diseases. However, the release and degradation of airborne endotoxins from bioaerosol by microwave (MW) irradiation have not yet been reported. This study investigated the distribution and fate of airborne endotoxins during MW irradiation process, as well as the kinetics and thermodynamics of the degradation of airborne endotoxins. Results showed that MW irradiation induced cell lysis, thus considerably increasing the proportion of cells with ruptured membranes. Furthermore, MW irradiation changed the distribution of airborne endotoxins, sharply decreased the concentration of bound endotoxins from 230 EU/m3 to 68 EU/m3, and increased the concentration of free endotoxins from 21 EU/m3 to 122 EU/m3. These results indicated that MW irradiation released endotoxins from cells into the atmosphere. MW irradiation likely degraded endotoxins by exerting thermal effects, which achieved a total endotoxin removal efficiency of as high as 35%. Endotoxin degradation was a first-order reaction and required the activation energy of 26.3 kJ/mol.

Inactivation of airborne bacteria using different UV sources: Performance modeling, energy utilization, and endotoxin degradation

Airborne bacteria-containing bioaerosols have attracted increased research attention on account of their adverse effects on human health. Ultraviolet germicidal irradiation (UVGI) is an effective method to inactivate airborne microorganisms. The present study models and compares the inactivation performance of three UV sources in the UVGI for aerosolized Escherichia coli. Inactivation efficiency of 0.5, 2.2 and 3.1 logarithmic order was obtained at an exposure UV dose of 370 J/m³ under UVA (365 nm), UVC (254 nm) and UVD (185 nm) sources, respectively. A Beer-Lambert law-based model was developed and validated to compare the inactivation performances of the UV sources, and modeling enabled prediction of inactivation efficiency and analysis of the sensitivity of several parameters. Low influent E. coli concentrations and high UV doses resulted in high energy consumption (EC). The change in airborne endotoxin concentration during UV inactivation was analyzed, and UVC and UVA irradiation showed no marked effect on endotoxin degradation. By contrast, both free and bound endotoxins could be removed by UVD treatment, which is attributed to the ozone generated by the UVD source. The results of this study can provide a better understanding of the air disinfection and airborne endotoxin removal processes.

Environmental determinants of allergy and asthma in early life

Allergic disease prevalence has increased significantly in recent decades. Primary prevention efforts are being guided by study of the exposome (or collective environmental exposures beginning during the prenatal period) to identify modifiable factors that affect allergic disease risk. In this review we explore the evidence supporting a relationship between key components of the external exposome in the prenatal and early-life periods and their effect on atopy development focused on microbial, allergen, and air pollution exposures. The abundance and diversity of microbial exposures during the first months and years of life have been linked with risk of allergic sensitization and disease. Indoor environmental allergen exposure during early life can also affect disease development, depending on the allergen type, dose, and timing of exposure. Recent evidence supports the role of ambient air pollution in allergic disease inception. The lack of clarity in the literature surrounding the relationship between environment and atopy reflects the complex interplay between cumulative environmental factors and genetic susceptibility, such that no one factor dictates disease development in all subjects. Understanding the effect of the summation of environmental exposures throughout a child's development is needed to identify cost-effective interventions that reduce atopy risk in children.