Indoor Mycotoxin Exposure on Atopic Dermatitis in Companion Dogs

Over 90% of the global population is exposed to poor air quality, with indoor air pollutant (IAP) concentrations exceeding the World Health Organization (WHO) air quality guidelines. The impact of particulate matter (PM) on atopic dermatitis (AD) has been studied for decades, revealing significant associations between the two. However, few studies have specifically investigated the substances constituting PM. This study aimed to identify mycotoxins as PM components and assess their effects on companion dogs with AD [1-4].

Dogs were divided into two groups: the AD group (n = 44) and the healthy control group (n = 29). Additionally, based on the presence or absence of mold on the walls, as indicated in a questionnaire, the AD group was further divided into the mold (n = 26) and non-mold (n = 18) subgroups. To evaluate IAP concentrations, PM_2.5, PM₁₀, and volatile organic compounds (VOCs) were measured using a real-time ambient air quality monitoring system (IAQ Station-CL1, Kweather Co., Seoul, Korea). Owners were instructed to collect dust samples from their homes, which were stored at −70°C until an ELISA was performed to quantify the Aflatoxin B1 concentrations. The Aflatoxin B1 concentrations were measured using an ELISA kit (10002123; AgraQuant, Romer Labs, Austria).

Demographic and clinical details for this cohort are summarized in Table S1. No statistically significant associations were observed between AD and specific factors such as age, sex, breed. Clinical parameters were significantly higher in the AD group compared with the control group (p < 0.01). Additionally, within the AD group, these parameters were significantly elevated in the subgroup with visible mold on the walls (p < 0.01) (Figure S1). The concentration of PM₁₀ was also significantly higher in the AD group compared with the control group. Within the AD group, the PM₁₀ concentrations were significantly higher in the mold subgroup compared with the non-mold subgroup (p < 0.01) (Figure 1A,B). Furthermore, Aflatoxin B1 concentrations were significantly higher in the AD group compared with the control group (p < 0.05). Within the AD group, the Aflatoxin B1 concentrations were significantly greater in the mold subgroup compared with the non-mold subgroup (p < 0.01) (Figure 1C,D).

The comparison of reactive oxygen metabolites (d-ROMs) and immunoglobulin E (IgE) showed that the d-ROM and IgE levels were significantly elevated in the AD group compared with the control group (p < 0.05). Within the AD group, both values were significantly higher in the mold-exposed subgroup compared with the non-mold subgroup (p < 0.01) (Figure S2). A positive correlation was observed between Aflatoxin B1 and IgE (r = 0.3065, p < 0.05) and between Aflatoxin B1 and d-ROMs (r = 0.3185, p < 0.05) (Figure 2A,B).

Additionally, there was a positive correlation between d-ROM concentrations and the severity of clinical indicators in the AD group, with the pruritus visual analog scale (PVAS) scores showing a statistically significant positive correlation (Figure 2C–E). This suggests that exposure to mycotoxins increases d-ROM levels and enhances immune responses, such as elevated IgE. Furthermore, the indicators (Aflatoxin B1, d-ROMs, and IgE) that exhibited significant differences between the mold and non-mold groups were positively correlated with the PM₁₀ concentrations (Figure S3), reinforcing the role of PM as an IAP.

This study is the first to examine the relationship between mold as an indoor environmental factor and the mechanisms by which it exacerbates AD in companion dogs. These findings suggest that dogs could serve as a spontaneous disease model for IAPs associated with AD, mainly due to their shared indoor environments with humans.

The authors declare no conflicts of interest.