Reduction of lung fungal type associated with worse illness of acute respiratory distress syndrome

Many COVID-19 patients develop acute respiratory distress syndrome (ARDS). This is a life-threatening condition in which the lungs are unable to supply sufficient oxygen to vital organs in the body. Patients with ARDS usually wear a ventilator to get enough oxygen into their body. A new study, now presented at an international conference of the “virtual” European Respiratory Society, found that the low species of fungi in the lung was associated with increased severity of ARDS patients.

of Human microbiome Consists of small organisms such as bacteria and viruses Fungi.. Presenting her work at a conference, Ms Noel Britton, Ph.D. Candidates from the University of Pittsburgh in the United States have said that so far researchers have tended to focus on studying the effects of bacteria Human healthBecause the microbiome is mainly composed of bacteria, it is technically difficult to extract enough fungi to study.

“In terms of cell numbers, fungi are orders of magnitude more than bacteria,” she said. “In addition, it is now well established that the lungs host clear and dynamic microflora, but they do not represent a rich environment for microbial growth, rather than the gut. There are far fewer, and it can be difficult to pick up signals from such low-mass fungi and to confirm that the identified sequences are not due to laboratory contamination.

“We are doing this research Acute respiratory distress syndrome We know that the fungus may be involved in the activation and regulation of the human immune system, characterized by hyperinflammatory hyperreactivity of the immune system. There is no known cure for successful treatment of ARDS, and little is known about why some patients develop a hyperinflammatory response. of Diversity Microbiomes, and especially fungi, can play an important role in understanding why some people develop ARDS and others do not. “

Britton and his colleagues enrolled 202 ventilated patients in the study between October 2011 and September 2019. To their knowledge, none of these patients have COVID-19, but they continue to enroll patients through pandemics, and see what COVID-19 has been identified in future analyses.

Of the 202 patients in this analysis, 21% were diagnosed with ARD, the average age was 50 years, and 61% were women. Researchers collected mucus-based secretions from the trachea (the major airways to the lungs) and extracted DNA for laboratory analysis using a technique called next-generation sequencing.

Ms. Briton said: “We identified about 100 fungi in the lungs of a critically ill patient wearing a ventilator. All samples were very diverse, Single species It was dominated and the diversity was very low. Many patients had samples in which a single Candida-type fungal species predominated. It accounts for over 50% of the fungi present in these samples and is known to be involved in causing human disease. “

Fungal diversity was lower in ARDS patients than in disease-free patients. Shock, sepsis, and organ failure were associated with reduced diversity in patients with ARDS. Reduced diversity was associated with worse lung damage, more intensive treatment, and elevated levels of a protein called pentraxin-3, which is an indicator of inflammation and disease severity.

“The association between lower fungal diversity and clinical markers of disease severity is lung “Microbiomes and clinical outcomes in critical illnesses,” said Briton. “Often there is no understanding of the development and treatment of ARDS, and this study is based on significant diagnostic or therapeutic findings.”

It is not known how fungal (or other microbial) diversity develops, but fungi are most likely to inhale most saliva into the lungs and enter the lungs.

“Because it’s the second largest mucosal surface area of ​​the human body, about the size of a tennis court, human lungs are always exposed to fungi by inhalation,” Ms Briton said. “Airborne fungi are particularly prevalent and contain up to 50,000 spores per cubic meter of air, which exposes the respiratory tract to a wide variety of environments. The inhaled fungus is very diverse and causes disease. Includes species known or believed to be harmless to humans.”

Not involved in the research, Tobias Welte is a former chairman of the European Respiratory Society, a professor of lung medicine, and a director of the Department of Pulmonary Infectious Diseases at the University of Hanover, Germany. He said: “In recent years, much attention has been focused on the relationship between the intestinal microbiota and its various health problems, especially fungi and other lung microbiota such as bacteria and viruses. Components are more difficult to study, but we are beginning to see more evidence that they are also involved in chronic lung disease.

“The findings of this study are compelling to discover that reduced mycobiome diversity leads to worse outcomes in patients with acute respiratory distress syndrome. It’s too early to know what this means for patients and their physicians. But leads to new diagnostic tests and better treatment.”