Abstract
High temperature and humidity (HTH) can cause diarrhea owing to food and drinking water contamination. However, their direct effects on gut microbiota and gastrointestinal inflammation are unknown. This study aimed to investigate the effects of HTH and probiotics on the microbiome. Twenty-one male mice were randomly assigned to normal control (NC), HTH, and broad-spectrum probiotic-treated (PR) groups. HTH and PR groups were regularly housed at 30 ± 0.5 °C with humidity of 85–90% for eight consecutive weeks. A broad-spectrum probiotic was administrated to PR-group mice from day 50 to 56. Clinical signs were observed and gut microbiota were analyzed via 16 S rRNA-based functional metagenomics. Intestinal pathology and the expression of defensins and pro-inflammatory cytokines were also assessed. Mice in the HTH and PR groups gradually developed sticky or loose feces. The HTH group developed a distinct microbiota profile associated with augmented metabolism and human-like pathophysiologies upon suppression of environmental sensing. Pathological assays indicated minimal enteritis, increased bacterial translocation, and elevated intestinal pro-inflammatory cytokine levels. Thus, ambient HTH directly contributes to gut dysbiosis and minimal enteritis, whereas probiotics partially normalized the microbiota and ameliorated gut inflammation. This study provides novel insights into the pathogenesis of environment-associated diseases and offers a potential therapeutic approach.
Highlights
The effect of climate on health has received increasing attention
This study aimed to investigate the effects of High temperature and humidity (HTH) and probiotics on the microbiome in 21 male mice randomly assigned to normal control (NC), HTH, and a broad-spectrum probiotic-treated (PR) groups
Mice maintained in the climate chamber (HTH and PR groups) gradually exhibited reluctance to move, reduced feeding, unkempt and dull coat, and sagging scrotum
Summary
The effect of climate on health has received increasing attention. Diarrheal disease is the leading cause of childhood morbidity and mortality worldwide, with an estimated 1.7 billion infections and 0.7 million deaths occurring annually[1]. Whether a high ambient temperature and humidity (HTH) directly affect mucosal immunity and the gut microbiota, causing diseases including diarrhea, are unclear. The Ling’nan region of South China is an ideal region to study the effect of climate on health. This region encompasses the southern region of the Nanling Mountains and covers the Guangdong, Guangxi, and Hainan provinces, representing the hottest and most humid area with the most ideal conditions for diarrhea (peak time) among 31 provinces in China[6]. The underlying pathomechanism remains unknown, according to Chinese medicine, extreme relative humidity potentially approaching 100% and lasting a month directly causes discomfort. Our results may provide novel insights into the pathogenesis of climate-associated diseases, for which the gut microbiota could be considered a promising therapeutic target
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