Cambridge researchers announced on June 23 that they have identified three distinct biological subtypes of severe pneumonia, a discovery that may help explain why some intensive care unit patients recover faster than others while some experience life-threatening complications.
The findings, published in Nature Communications, could lead to more tailored treatments for individuals with severe pneumonia. The research team recruited patients admitted with suspected severe pneumonia to the intensive care unit at Addenbrooke's Hospital, part of Cambridge University Hospitals NHS Foundation Trust. Instead of relying solely on blood tests or scans, the team analyzed immune cells, inflammatory signals, and gene activity in fluid taken from the lungs.
They found three different 'pneumotypes' among patients. The most common pneumotype accounted for nearly half of cases and was marked by immune suppression and significant lung damage but fewer signs of inflammation. The second pneumotype involved a balanced immune response and active repair within the lungs; these patients tended to recover faster despite appearing as ill as others upon admission. The third group exhibited persistent inflammation and had prolonged critical illness; this group may be most likely to respond to anti-inflammatory therapies.
Dr. Mark Jeffrey from the Department of Medicine at the University of Cambridge said, "Even though on the surface, all of the patients seemed to have similar types of pneumonia, with comparable illness severity, oxygen levels and clinical diagnoses, their outcomes were very different. It was only when we drilled down and looked at patterns of inflammation that the differences became apparent. Severe pneumonia is not a single disease, but several biologically distinct conditions that happen to look alike. This helps explain why 'one-size-fits-all' treatments – including some immune-modulating drugs – have often failed in clinical trials."
Currently, tests used to determine these pneumotypes are too complex for rapid use in clinical settings; however, researchers hope to develop simpler tools for patient stratification and personalized treatment approaches in future studies.
Dr. Vilas Navapurkar from Addenbrooke's Hospital said, "If we know which subtype of pneumonia an individual has, we can potentially tailor their treatment more precisely, boosting the immune response in some while calming harmful inflammation in others. This has the potential to help critically ill patients, reduce deaths from pneumonia, shorten ICU stays and cut unnecessary antibiotic use."
