A measurement in saliva is a much better indicator of the severity of recurrent respiratory infections in children than a standard blood measurement. If there are too few protective antibodies in the saliva, a child will have more pneumonia. This is what researchers from the Children’s Hospital Radboudumc Amalia and the Children’s Hospital UMC Utrecht Wilhelmina write in the European Respiratory Journal. So measuring saliva provides valuable information for treatment and is also more enjoyable for children.
About ten to fifteen percent of all children suffer from recurrent respiratory infections. When they arrive at the hospital, blood is taken to look for antibodies and underlying conditions or causes. But that rarely yields any results. “That’s difficult for pediatricians, because we really want to help children,” says pediatric infectious disease specialist/psychiatrist Lilly Verhagen from the Radboud university medical center. “So we did a study to see if we can get more find out about the severity of an illness in another way. That would be extremely valuable in determining which children need more care and when it makes sense to give antibiotics.’
Comprehensive protection
Now a study of one hundred children with recurrent respiratory infections shows that saliva measurements indicate the severity of the disease much better than blood measurements. “As expected, we found no relationship between substances in the blood and disease burden. But in saliva we saw very broad protective antibodies that work against all kinds of different pathogens. Children who have fewer such antibodies do worse and get more serious infections. So these substances are a good indicator of disease burden,’ explained PhD candidate Mischa Koenen.
Everyone has these broad protective antibodies in their respiratory tract, the researchers also found them in brothers, sisters and parents of sick children, and in healthy caregivers. A large number of these are beneficial. These substances provide such broad protection that researchers already found substances in children’s saliva before the corona pandemic that could be linked to the SARS-CoV-2 virus.
Bacteria
These broad protective antibodies hardly appear in the blood. “And that’s very logical,” says Verhagen. “Because you breathe in all kinds of things throughout the day, including all kinds of pathogens, and that’s why you need a wide range of antibodies in your airways. This is very different in the blood: not many pathogens get into the bloodstream through the intestines or the respiratory tract. If that happens, your body will benefit much more from a strong, targeted immune response.’
In addition to antibodies, the researchers also looked at the balance between healthy and potentially pathogenic bacteria on the mucous membrane of the respiratory tract. They saw that a specific type of bacteria on the mucous membrane in the nasopharynx is strongly associated with the severity of respiratory infections. This bacterium, called Haemophilus influenzae, can also live in healthy airways. But children who have a lot of this bacteria on the mucous membrane of the respiratory tract are much more likely to be sick in winter. The bacterium has been associated with pneumonia in the past.
To come
Therefore, the measurements in saliva and nasal mucosa are of great help in diagnosing these children. Koenen: ‘This allows us to estimate the amount of care and medicine we need to give to children. And also which antibiotic, because the current level that is given at the moment does not work against the bacterium Haemophilus influenzae. In addition, I expect the initial blood test to follow, but in follow-up appointments a more appropriate saliva and nasopharyngeal sample can be used as an indicator of the expected disease burden.’
The saliva measurement also provides insight into new treatments and therapies. For example, researchers observed in healthy health care providers that the flu vaccine increases the amount of broad protective antibodies in the saliva. In the long term, the researchers are also looking at whether they can obtain these antibodies so that they can be used in the treatment of respiratory diseases in the future.
About the publication
This research was published in the European Respiratory Journal: Salivary polyreactive antibodies and Haemophilus influenzae are associated with severity of respiratory infections in young children with recurrent respiratory infections. Mischa H. Koenen, WAA de Steenhuijsen Piters, Marien I. de Jonge, Jeroen D. Langereis, Stefan Nierkens, Mei Ling JN Chu, Roosmarijn van der Woude, Robert P. de Vries, Elisabeth AM Sanders, Debby Bogaert, Erhard van der Vries, Marianne Boes, Lilly M. Verhagen. DOI: 10.1183/13993003.00317-2024.
Photo: Pediatric infectious disease specialist/immunologist Lilly Verhagen
2024-08-08 14:39:12
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