We’re still a long way from knowing if we can manipulate the microbiome and if it truly presents opportunity as a new therapy. —Vijay Ramakrishnan, MD
Explore this issue:March 2019
Certain Bacteria May Be More Common in Disease States
Research suggests that particular strains of bacteria are more likely to be found in the microbiomes of patients with diseased sinuses. According to a 2016 review by Dr. Ramakrishnan and others, S. aureus, Prevotella, Fusobacterium, Bacteroides spp. and Peptostreptococcus spp. are more abundant in the microbiota of patients with CRS than in patients with healthy sinuses. (Curr Opin Otolaryngol Head Neck Surg. 2016;24:20–25). A 2017 study by Dr. Cope, Dr. Lynch, and others identified four distinct subgroups among patients with CRS. The microbiome of each subgroup was dominated by a different pathogenic family: Streptococcaceae, Pseudomonadaceae, Corynebacteriaceae, or Staphylococcaceae. The authors speculate that these different states “represent a gradient of pathogenic microbial co-colonizations that are related to patient treatment history and/or disease progression”
Indeed, it’s possible that past treatment has altered the microbiomes of many CRS patients. “People with chronic rhinosinusitis have generally already been treated with lots of antibiotics and steroids and sprays,” Dr. Ramakrishnan said. “The challenge is teasing apart whether the microbiota differences are an innocent observation–something that just happens to be different but doesn’t really have a role in anything–or an active driver of inflammation and disease.”
Dr. Cope and her team are looking for answers. “I’m interested in how microbes interact with each other in the sinuses,” she said. “If we see certain species of bacteria and fungi in our sequence data, I want to take them out into the lab and see how they play together. Is the combination causing more virulence? Could they be beneficial together?” At present, her team is using animal models to study the interplay of microbes.
Microbiome May Contribute to Asthma Development
Evidence strongly suggests that the microbiome of the lower airways may play a role in the development of asthma. Compared to people without asthma, the microbiota of people with asthma is commonly enriched for members of Proteobacteria. People with asthma also typically have a high bacterial burden and bacterial diversity in the lower airways. While no studies have yet demonstrated a direct causal link between microbial changes and the development of asthma, the composition of the airway microbiome is highly correlated with the degree of bronchial hyper-responsiveness. There’s also evidence to suggest that alterations to the oral microbiome may be associated with the development of childhood asthma. (Cell Host Microbe. 2015;17:592–602.)
“Some of these early microbial exposures during this important window of opportunity may be important in preventing asthma,” Dr. Cope said.