The Interactions of Airway Bacterial and Fungal Communities in Clinically Stable Asthma

Abstract

Dysbiotic airway microbiota play important roles in the inflammatory progression of asthma, and exploration of airway microbial interactions further elucidates asthma pathogenesis. However, little is known regarding the airway bacterial-fungal interactions in asthma patients. We conducted a cross-sectional survey of the sputum bacterial and fungal microbiota from 116 clinically stable asthma patients and 29 healthy controls using 16S rRNA gene and ITS1 sequencing. Compared with healthy individuals, asthma patients exhibited a significantly altered microbiota and increased bacterial and fungal alpha diversities in the airway. Microbial genera Moraxella, Capnocytophaga, and Ralstonia (bacteria) and Schizophyllum, Candida, and Phialemoniopsis (fungi) were more abundant in the asthma airways, while Rothia, Veillonella and Leptotrichia (bacteria) and Meyerozyma (fungus) were increased in healthy controls. The Moraxellaceae family and their genus Moraxella were significantly enriched in asthma patients compared with healthy controls (80.5-fold, P = 0.007 and 314.7-fold, P = 0.027, respectively). Moreover, Moraxellaceae, along with Schizophyllum, Candida, and Aspergillus (fungal genera), were positively associated with fungal alpha diversity. Correlation networks revealed 3 fungal genera (Schizophyllum, Candida, and Aspergillus) as important airway microbes in asthma that showed positive correlations with each other and multiple co-exclusions with other common microbiota. Moraxellaceae members were positively associated with asthma-enriched fungal taxa but negatively related to several healthyenriched bacterial taxa. Collectively, our findings revealed an altered microbiota and complex microbial interactions in the airways of asthma patients. The Moraxellaceae family and their genus Moraxella, along with 3 important fungal taxa, showed significant interactions with the airway microbiota, providing potential insights into the novel pathogenic mechanisms of asthma.

Different Airway Inflammatory Phenotypes Correlate with Specific Fungal and Bacterial Microbiota in Asthma and Chronic Obstructive Pulmonary Disease

“…The Simpson (P = 0:035) index of the EA subjects was significantly lower compared that of NEA subjects (Figure 2 (a)), which was consistent with previous studies in the asthmatic subjects [10,25]. A comparable result had been observed in COPD subjects; the EC subjects showed lower Chao1 index (P = 0:036) and Simpson index (P = 0:031) than NEC subjects (Figure 2(c)).…”

“…In this study, NEA subjects showed higher α-diversity of bacteria compared with EA subjects (Figure 4(a), Chao1 index, P = 0:002), which coincided with the results of recent studies [8,25]. Compared with EC subjects, the NEC subjects also had significantly increased Chao1 (Figure 4(c), P = 0:004) index.…”

“…Interestingly, our research revealed that the fungal taxa associated Several studies demonstrated that fungal colonization can contribute to airway inflammatory diseases as an important allergen [27][28][29][30]. Aspergillus, Cladosporium, and Rhodotorula were previously shown to be present in healthy individuals, and their relative abundance was significantly altered in asthma patients and associated with Th2 inflammation [10,25]. Among the asthma subjects in this study, EA subjects had higher relative abundances in Aspergillus, Cladosporium, Psathyrella, and Bjerkandera adusta species.…”

Altered respiratory microbiota composition and functionality associated with asthma early in life

“…Perhaps fungal presence induces changes in the lung micro-environmental conditions that subsequently drives this compositional shift among bacterial communities to compensate. For example, enrichment of Moraxella species in asthmatic airways was found to interact negatively with multiple bacterial communities but positively with fungal communities suggesting complex interactions between the bacterial and fungal communities that may contribute to asthma pathogenesis [ 32 ] That said, it is important to note that limited fungal genome database may also explain the identified similarity between adult and pediatric groups. For example, recent check (July, 2020) of the NCBI Genome database https://www.ncbi.nlm.nih.gov/genome/browse#!/eukaryotes/fungi shown 6570 complete fungal genomes compared with > 252,000 complete bacterial genomes.…”

The respiratory microbiome and nontuberculous mycobacteria: an emerging concern in human health

“…Effect of NTM antibiotic treatment on the microbiome Antibiotics are a major cause of microbiota changes because these drugs are designed to attenuate bacterial growth and subsequently cause death. In gut and pulmonary microbiome studies, early antibiotic exposure in childhood has been identified as a risk factor for the development of obesity [71], asthma [72] and diabetes [73]. In adulthood, chronic exposure to antibiotics correlates with microbiome shifts that result in susceptibility towards pathogen colonisation, impaired host responses and chronic microbial dysbiosis [74].…”