Associations between Particulate Matter and Otitis Media in Children: A Meta-Analysis

Early-life ozone exposure and childhood otitis media: Unveiling critical windows of risk

BACKGROUND

Despite increasing evidence of a strong correlation between air pollution and otitis media (OM), the impact of early-life ozone (O3) exposure on the development of OM in children remains uncertain.

OBJECTIVES

To explore the connection between early-life O3 exposure and OM, and to identify the critical time period(s) during which O3 exposure significantly influences the development of OM in children.

METHODS

We conducted a study involving 8689 children living in Changsha, China. Information regarding personal factors, health conditions, and the indoor environment was gathered using questionnaires. Personal exposure to outdoor O3 and other major pollutants at the place of residence during the periods before conception, prenatal periods, and after birth was calculated by applying the inverse distance weighted (IDW) method with data gathered from ten air quality monitoring stations. Multiple logistic regression analyses were employed to investigate the associations between O3 exposure and children's OM.

RESULTS

After controlling for covariates and ambient temperature, exposure to O3 during the year preceding pregnancy was correlated with childhood lifetime OM, showing ORs (95 % CI) of 1.28 (1.01-1.64). O3 exposures in the 10th-12th, 7th-9th, and 4th-6th months before pregnancy were all linked to children's lifetime OM. Within the multi-window model, we detected that O3 exposure in the 10th to 12th month prior to pregnancy was significantly related to lifetime OM, showing ORs (95 % CI) of 1.28 (1.05-1.55). A significant link was discovered between childhood OM and O3 exposure after controlling for six other pollutants (SO2, PM2.5, NO2, PM2.5-10, CO, and PM10) during the 10th to 12th month prior to conception. Exposure to O3 during the 36th gestational week significantly raised the likelihood of childhood lifetime OM. There is a significant interaction between O3 and temperature exposure during the first trimester of pregnancy and one year before pregnancy on childhood lifetime OM.

CONCLUSIONS

Preconceptional O3 exposure and its interaction with low temperature played critical roles in children's OM development, backing the hypothesis of "(pre) fetal origins of childhood OM".

Effect of diesel exhaust particles on RANK/RANKL expression in in vivo and in vitro models of middle ear inflammation

OBJECTIVE

Increasing evidence suggests a link between middle ear inflammation and the development of diesel exhaust particles (DEPs). Chronic middle ear inflammation can lead to bone damage and remodeling. This study aimed to explore the impact of DEPs on the expression of interleukin (IL)-6 and RANKL under conditions of middle ear inflammation.

METHODS

DEPs were collected by burning fuel in a diesel engine at the Gwangju Institute of Science and Technology. Human middle ear epithelial cells were cultured to 70-80% confluence in culture plates and then treated with DEPs at concentrations of 0, 5, 10, 20, 40, and 80 μg/mL for 24 h. Cell viability was assessed manually. B6.SJL mice, aged 9 weeks, were exposed to DEPs at a concentration of 200 μg/m3 for 1 h daily over a period of 28 days. The expression levels of IL-6, tumor necrosis factor α, RANKL, and RANK were evaluated using hematoxylin and eosin staining and western blot analysis of the harvested middle ear samples.

RESULTS

The viability of human middle ear epithelial cells was found to decrease in a dose-dependent manner after 24 h. The mRNA expression level of IL-6 exhibited the most significant increase at the 48-h mark. In contrast, the mRNA expression levels of RANKL and RANK showed a marked increase as early as 6 h post-exposure, with both genes subsequently displaying a time-dependent decrease. Histological analysis revealed that the middle ear mucosa was thicker in the group exposed to DEPs compared to the control group. Additionally, the protein expression levels of IL-6 and RANKL were elevated in the DEP-exposed group relative to the normal control group.

CONCLUSIONS

We confirmed the expression of osteoclast-related proteins in the mouse middle ear. These results imply that air pollutants might affect RANKL/RANK signaling, which is associated with bone remodeling.

Otitis media: Interactions between host and environment, immune and inflammatory responses

OBJECTIVE

To review and highlight progress in otitis media (OM) research in the areas of immunology, inflammation, environmental influences and host-pathogen responses from 2019 to 2023. Opportunities for innovative future research were also identified.

DATA SOURCES

PubMed database of the National Library of Medicine.

REVIEW METHODS

Key topics were assigned to each panel member for detailed review. Search of the literature was from June 2019 until February 2023. Draft reviews were collated, circulated, and discussed among panel members at the 22nd International Symposium on Recent Advances in Otitis Media in June 2023. The final manuscript was prepared and approved by all the panel members.

CONCLUSIONS

Important advances were identified in: environmental influences that enhance OM susceptibility; polymicrobial middle ear (ME) infections; the role of adaptive immunity defects in otitis-proneness; additional genes linked to OM; leukocyte contributions to OM pathogenesis and recovery; and novel interventions in OM based on host responses to infection. Innovative areas of research included: identification of novel bacterial genes and pathways important for OM persistence, bacterial adaptations and evolution that enhance chronicity; animal and human ME gene expression, including at the single-cell level; and Sars-CoV-2 infection of the ME and Eustachian tube.

Effects of air pollution on emergency visits for acute otitis media among children: a case-crossover study in Chongqing, China

Background

Many epidemiological studies have demonstrated the short-term effects of air pollution on acute otitis media (AOM) in children, but few studies have explored the association between AOM and air pollution in Chinese children. This study aimed to analyze the effects of air pollution on emergency visits for AOM among children through a time-stratified case-crossover design in Chongqing, China.

Methods

The outpatient medical records of children from nine main urban districts who presented with AOM between December 22, 2018 and December 21, 2021 were collected from the Children's Hospital of Chongqing Medical University. Data for air pollution variables, including the air quality index (AQI), particulate matter ≤ 10 μm (PM10), PM2.5, SO2, CO, NO2 and O3 from 17 monitoring sites were collected. Data for meteorological factors as confounding variables also were collected. Conditional logistic regression was used to analyze the data with single-pollutant models, multi-pollutant models, and stratified analyses.

Results

Increases in AQI, PM10, PM2.5, SO2, CO and NO2 were positively associated with emergency visits for AOM among children in single-pollutant models and stratified analyses. Increases in PM10, SO2, CO and NO2 were positively associated with emergency visits for AOM among children in multi-pollutant models. NO2 had the most statistically significant OR values in all models, whereas significant effects of O3 were observed only in seasonal stratification. In single-pollutant models, we found that the best lag periods were lag 0-7 for air pollution variables except for O3 and the largest OR values were 1.185 (95%CI: 1.129-1.245) for SO2 in single-pollutant models. In stratified analyses, there were no difference between groups in these statistically significant OR values through gender and age stratification, while the differences between seasons in these OR values of PM10, SO2, CO, NO2 and O3 were statistically significant. Children aged 0 years and 3-5 years represented the most susceptible population, and among the seasons, susceptibility was greater during Winter and Spring.

Conclusion

Short-term exposure to air pollution can increase emergency visits for AOM among children in Chongqing, China.

Effects of Particulate Matter Exposure on the Eustachian Tube and Middle Ear Mucosa of Rats

OBJECTIVES

Particulate matter (PM) is a risk factor for various diseases. Recent studies have established an association between otitis media (OM) and PM exposure. To confirm this relationship, we developed a novel exposure model designed to control the concentration of PM, and we observed the effects of PM exposure on the Eustachian tube (ET) and middle ear mucosa of rats.

METHODS

Forty healthy, 10-week-old, male Sprague-Dawley rats were divided into 3-day, 7-day, 14-day exposure, and control groups (each, n=10). The rats were exposed to incense smoke as the PM source for 3 hours per day. After exposure, bilateral ETs and mastoid bullae were harvested, and histopathological findings were compared using microscopy and transmission electron microscopy (TEM). The expression levels of interleukin (IL)-1β, IL-6, tumor necrosis factor-α, and vascular endothelial growth factor (VEGF) in the middle ear mucosa of each group were compared using real-time reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

In the ET mucosa of the exposure group, the goblet cell count significantly increased after PM exposure (P=0.032). In the middle ear mucosa, subepithelial space thickening, increased angio-capillary tissue, and inflammatory cell infiltration were observed. Moreover, the thickness of the middle ear mucosa in the exposure groups increased compared to the control group (P<0.01). The TEM findings showed PM particles on the surface of the ET and middle ear mucosa, and RT-PCR revealed that messenger RNA (mRNA) expression of IL-1β significantly increased in the 3-day and 7-day exposure groups compared to the control group (P=0.035). VEGF expression significantly increased in the 7-day exposure group compared to the control and 3-day exposure groups (P<0.01).

CONCLUSION

The ET and middle ear mucosa of rats showed histopathologic changes after acute exposure to PM that directly reached the ET and middle ear mucosa. Therefore, acute exposure to PM may play a role in the development of OM.

Recurrent Acute Otitis Media Environmental Risk Factors: A Literature Review from the Microbiota Point of View

Acute otitis media (AOM) constitutes a multifactorial disease, as several host and environmental factors contribute to its occurrence. Prevention of AOM represents one of the most important goals in pediatrics, both in developing countries, in which complications, mortality, and deafness remain possible consequences of the disease, compared to in developed countries, in which this condition has an important burden in terms of medical, social, and economical implications. The strategies for AOM prevention are based on reducing the burden of risk factors, through the application of behavioral, environmental, and therapeutic interventions. The introduction of culture-independent techniques has allowed high-throughput investigation of entire bacterial communities, providing novel insights into the pathogenesis of middle ear diseases through the identification of potential protective bacteria. The upper respiratory tract (URT) is a pivotal region in AOM pathogenesis, as it could act as a source of pathogens than of protective microorganisms for the middle ear (ME). Due to its direct connection with the external ambient, the URT is particularly exposed to the influence of environmental agents. The aim of this review was to evaluate AOM environmental risk factors and their impact on URT microbial communities, and to investigate AOM pathogenesis from the microbiota perspective.

Effect of Angiogenesis and Lymphangiogenesis in Diesel Exhaust Particles Inhalation in Mouse Model of LPS Induced Acute Otitis Media

Lymphangiogenesis and angiogenesis might have significant involvement in the pathogenesis of otitis media with effusion. This study investigated the effect of diesel exhaust particles (DEP) on inflammation and lymphangiogenesis in a mouse model of acute otitis media (AOM). BALB/c mice were injected with LPS and exposed to 100 µg/m³ DEP. The mice were divided into four groups: control (no stimulation), AOM, AOM + DEP, and DEP + AOM.

The effects of DEP inhalation pre- and post-DEP induction were estimated based on measurements of the auditory brainstem response, mRNA levels of lymphangiogenesis-related genes and cytokines, and histology of the middle ear. Cell viability of human middle ear epithelial cells decreased in a dose-response manner at 24 and 48 hours post-DEP exposure. DEP alone did not induce AOM. AOM-induced mice with pre- or post-DEP exposure showed thickened middle ear mucosa and increased expression of TNF-α and IL1-β mRNA levels compared to the control group, but increased serum IL-1β levels were not found in the AOM + Post DEP. The mRNA expression of TLR4, VEGFA, VEGFAC, and VEGFR3 was increased by pre-AOM DEP exposure.

The expression of VEFGA protein was stronger in the AOM + Post DEP group than in any other group. The expression of CD31 and CD45 markers in the mouse middle ear tissue was higher in the Pre DEP + AOM group than in the AOM group. This result implies that pre-exposure to DEP more strongly increases inflammation and lymphangiogenesis in a mouse model of acute otitis media.

Stochastic and Self-Organisation Patterns in a 17-Year PM10 Time Series in Athens, Greece

This paper utilises statistical and entropy methods for the investigation of a 17-year PM₁₀ time series recorded from five stations in Athens, Greece, in order to delineate existing stochastic and self-organisation trends. Stochastic patterns are analysed via lumping and sliding, in windows of various lengths. Decreasing trends are found between Windows 1 and 3500-4000, for all stations. Self-organisation is studied through Boltzmann and Tsallis entropy via sliding and symbolic dynamics in selected parts. Several values are below -2 (Boltzmann entropy) and 1.18 (Tsallis entropy) over the Boltzmann constant. A published method is utilised to locate areas for which the PM₁₀ system is out of stochastic behaviour and, simultaneously, exhibits critical self-organised tendencies. Sixty-six two-month windows are found for various dates. From these, nine are common to at least three different stations. Combining previous publications, two areas are non-stochastic and exhibit, simultaneously, fractal, long-memory and self-organisation patterns through a combination of 15 different fractal and SOC analysis techniques. In these areas, block-entropy (range 0.650-2.924) is significantly lower compared to the remaining areas of non-stochastic but self-organisation trends. It is the first time to utilise entropy analysis for PM₁₀ series and, importantly, in combination with results from previously published fractal methods.