Published: 18-11-2024 10:07 | Updated: 25-11-2024 16:14

New thesis sheds light on the role of immune molecules in severe bacterial infections

Portrait of Helena Alpkvist.
Helena Alpkvist. Photo: N/A

Helena Alpkvist from the Infectious Diseases and Dermatology Unit at the Department of Medicine, Huddinge, is defending her thesis titled "Damage-associated molecular patterns and pathogen-associated molecular patterns in severe bacterial infections", on 22 November, 2024. Main supervisor is Kristoffer Strålin (MedH).

What is the main focus of your thesis?

Bacterial infections can range from a mild cold to severe, life-threatening sepsis. But why do some infections become so dangerous? The key might lie in the interaction between substances produced by our own bodies and those produced by bacteria. When we fall ill with a bacterial infection, our immune system responds to molecules that signal danger—these molecules are collectively known as damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs). DAMPs are endogenous molecules released from tissue damage, while PAMPs come from the bacteria that have invaded the body. My thesis investigates the concentrations of these molecules in severe bacterial infections such as pneumonia and bacteraemia, and whether they can be linked to disease severity.

What are the most important results?

The level of pneumococcal DNA, a form of PAMP, in the airways correlated with disease severity in patients with pneumococcal pneumonia, with higher levels of bacterial DNA linked to more severe illness. In bacterial infections with bacteremia, we found that nuclear DNA (nDNA) was the DAMP most strongly linked to disease severity. Both nDNA and 16S rDNA, a PAMP, were elevated in patients with sepsis, but only nDNA remained elevated over time in those who required intensive care or died.

How can this new knowledge contribute to the improvement of people’s health?

These findings give us a better understanding of how levels of endogenous and bacterial molecules are linked to disease severity in severe bacterial infections. In the long run, this may help to explain why some infections turn severe and allow us to identify these patients in time and prevent the progression to severe illness.

What are your future ambitions? 

I will continue to work as a specialist in infectious diseases at Karolinska University Hospital, where I will be able to apply the knowledge I gained from my thesis, especially my enhanced ability to evaluate the research results of others, in my patient care. In terms of research, my goal is to further investigate whether different DAMPs could serve as biomarkers for the early identification of critically ill patients and to guide treatment strategies for patients with pneumonia and sepsis.

Dissertation

Friday, 22 November, at 09:00, Lecture hall C1:87, Karolinska University Hospital, Huddinge.

Thesis

Damage-associated molecular patterns and pathogen-associated molecular patterns in severe bacterial infections