The inflammatory factors IL-36 and soluble B7-H3 may play a role in community-acquired pneumonia in children, often caused by Mycoplasma pneumoniae, a study reported. One may even serve as a prognostic marker of pneumonia caused by this pathogen.
Recent research has confirmed that, in contrast to previous beliefs, M. pneumoniae infections also occur in small children and infants. Although the infection is often handled well by the immune system, limiting its spread, it can be life threatening. A better understanding of the mechanisms underlying infection and immune responses might lead to better treatment, reducing the risk of death.
Scientists do not have a clear picture of key molecular processes involved in microbe invasion and the immune responses toward it. Researchers at the Children’s Hospital of Soochow University, China, explored these issues in 35 children, ages 1 month to 14 years, with pneumonia caused by M. pneumoniae, as well as 15 control individuals.
Earlier studies have indicated that IL-36 — a proinflammatory cytokine — mediated airway inflammation and regulated the responses of Th1 cells, initiators of immune reactions, setting off an array of other inflammatory factors to fight an infection. B7-H3 is a co-factor, known to modify the development of immune Th1 cells triggered by other cytokines, including IL-36.
The study “Increased concentrations of soluble B7-H3 and interleukin 36 in bronchoalveolar lavage fluid of Children with Mycoplasma pneumoniae pneumonia,“ published in the journal BMC Infectious Diseases, analyzed the bronchoalveolar lavage fluid and found higher levels of both molecules in the lungs of infected children. Levels of IL-36 and soluble B7-H3 were also higher in patients with pleural effusion — an excessive accumulation of liquid in the fluid-filled pleural cavity surrounding the lungs, representing a state of increased inflammation.
Researchers also noted that the levels of the two factors seemed linked, so that the higher were the levels of IL-36, the higher was the concentration of soluble B7-H3. Soluble B7-H3 levels were also indicative of duration of fever and length of hospital stay, suggesting that the molecule could be used as a prognostic marker of the condition.
Since the concentration of both factors dropped after specific M. pneumoniae treatment, the researchers believe that the factors are involved in the disease-causing mechanisms of this microbe.