Nasal Bacterial Microbiome Differs Between Healthy Controls and Those With Asthma and Allergic Rhinitis

Abstract

Perturbation of the microbiome has numerous associations with the phenotypes and progression in chronic airways disease. However, the differences in the nasal microbiome in asthma and allergic rhinitis (AR) have not been defined. We examined whether the nasal microbiome would vary among different comorbidities in asthma and AR and that those differences may be associated with the severity of asthma. Nasal lavage fluid was collected from 110 participants, including 20 healthy controls, 30 subjects with AR, 30 subjects with asthma and 30 subjects with combined asthma + AR. The Asthma Control Questionnaire (ACQ-7) was used to evaluate asthma control status. Using 16S rRNA bacterial gene sequencing, we analyzed nasal microbiome in patients with asthma, AR, combined asthma + AR, and healthy controls. Bacterial diversity was analyzed in corresponding with α diversity indices (Chao and Shannon index). Compared with healthy controls, the Chao index tended to be lower in subjects with AR (P = 0.001), asthma (P = 0.001), and combined asthma + AR (P = 0.001) when compared with healthy controls. Furthermore, the Shannon index was significantly lower in subjects with asthma (P = 0.013) and comorbid asthma with AR (P = 0.004) than the control subjects. Disparity in the structure and composition of nasal bacteria were also observed among the four groups. Furthermore, patients with combined asthma + AR and isolated asthma were divided into two groups according to the level of disease control: partially or well-controlled and uncontrolled asthma. The mean relative abundance observed in the groups mentioned the genera of Pseudoflavonifractor were dominated in patients with well and partially controlled disease, in both isolated asthma and combined asthma + AR. In subjects with uncontrolled asthma and combined asthma + AR, a lower evenness and richness (Shannon index, P = 0.040) was observed in nasal microbiome composition. Importantly, lower evenness and richness in the nasal microbiome may be associated with poor disease control in combined asthma + AR. This study showed the upper airway microbiome is associated with airway inflammation disorders and the level of asthma control.

Altered nasal microbiota in asthmatic patients is not related to changes in secretory immunity in the nasopharynx

“…15 However, knowledge on microbial variance in the upper airways of asthmatics is still fragmentary. It was shown that alpha diversity of the nasal microbiome communities is reduced in patients with asthma and comorbid allergic rhinitis (AR), 16 which is in contrast to the asthma-associated increase in alpha diversity observed in this study. However, 62% of the asthmatic patients analysed in our study exhibited asthma without AR.…”

Nasal Bacteriomes of Patients with Asthma and Allergic Rhinitis Show Unique Composition, Structure, Function and Interactions

“…The nasal bacteriomes of the studied samples were composed of four dominant phyla and 10 dominant genera ( Figure 1 and Table 1 ). All these taxa have been previously described in the nasal cavity of asthmatic, rhinitic or healthy individuals [ 35 , 37 , 38 , 47 , 48 , 49 , 51 , 52 , 69 , 103 , 104 ], where they are considered normal residents. The characterized bacteriotas were mainly comprised of commensal taxa [ 103 , 104 ], but some genera (e.g., Moraxella , Streptococcus , Haemophilus , Neisseria and Staphylococcus ) including pathogenic species associated to asthma [ 33 , 34 , 35 , 36 , 39 , 40 , 55 , 57 , 58 , 59 , 105 ] and allergic rhinitis [ 47 , 48 , 49 , 50 , 51 , 52 ] were also detected.…”

“…Multiple studies using high-throughput sequencing (HTS), mainly of the 16S rRNA gene, have already demonstrated that the bacterial communities living in the respiratory airways (i.e., airway bacteriome) play a significant role in the onset, development and severity of both asthma [ 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ] and allergic rhinitis [ 47 , 48 , 49 , 50 , 51 , 52 ]. Microbial HTS has also shown that the nasal cavity is a major reservoir for opportunistic pathogens (e.g., Moraxella , Streptococcus , Haemophilus , Neisseria , and Staphylococcus ), which can spread to other sections of the respiratory tract and potentially induce asthma, rhinitis and other respiratory illnesses [ 31 , 35 , 36 , 37 , 38 , 39 , 41 , 48 , 49 , 50 , 51 , 53 , 54 , 55 , 56 , 57 , 58 , 59 ]. The importance of the nasal microbiota as a gatekeeper to respiratory health is well known, and their intimate links to chronic airways disease are beginning to be elucidated [ 60 ...…”

“…The importance of the nasal microbiota as a gatekeeper to respiratory health is well known, and their intimate links to chronic airways disease are beginning to be elucidated [ 60 , 61 , 62 ]. Several studies (see previous references) have already characterized the nasal microbiome and shown that airway bacteriome composition and structure vary between healthy and asthmatic individuals; less is known, however, about the nasal microbiome of individuals with allergic rhinitis with and without asthma comorbidity [ 48 , 52 , 63 ]. This is particularly remarkable in some countries like Portugal, where despite the high incidence of these respiratory conditions (see statistics and references above), no study has yet characterized the airway microbiomes of healthy, asthmatic or rhinitic individuals.…”

From the nose to the lungs: the intricate journey of airborne pathogens amid commensal bacteria

“…Other examples are represented by Streptococcus pneumonia , Haemophilus influenzae , and Moraxella catarrhalis , commonly present in the nose of healthy children ( 15 ), further strengthening the idea that a healthy nasal microbiota is not only required to protect from environmental microbes but also to keep commensal opportunistic pathogens under control. Various clinical conditions, including allergic rhinitis, chronic rhinosinusitis, asthma, and respiratory tract infections from both viral and nonviral pathogens, have been associated with changes in the composition of nasal microbiome ( 8 , 16 , 17 ). Although causative relationships are difficult to draw, it is becoming increasingly clear that associations can be unveiled by combining the specific changes of the microbiota with the onset and/or the clinical course of the disease.…”