Of sex differences in infection defence and a truly neglected tropical disease

Dr Marie Groneberg and Dr Luzia Veletzky receive doctoral prizes of the BNITM Friends Association

This year's doctoral prizes of the Association of Friends of the Tropical Institute Hamburg e.V. (VdF) go to Dr Marie Groneberg (Natural Sciences) and Dr Luzia Veletzky (Medicine). They are endowed with 1,000 euros each and honour particularly outstanding dissertations at the Bernhard Nocht Institute for Tropical Medicine.

[Translate to English:] Logo des VDF

Men fall ill differently, women too. Compared to women, men contract numerous viral, bacterial and parasitic infections much more frequently and severely. These include, for example, hepatitis B, covid-19, tuberculosis, Helicobacter and amoebic infections.

Prof. Hannelore Lotter's Molecular Infection Immunology group studies, among other things, gender-specific immune reactions in the formation and regeneration of amoebic liver abscesses. She had already shown that the sex hormone testosterone favours the development of liver abscesses.

Regulatory protein partly responsible for sex difference

Marie Groneberg and her colleagues followed up on these results. They analysed sex-specific differences in the acquired immune response in amoebic liver abscesses and carried out detailed molecular investigations of the immune response in the mouse model.

Among other things, they determined the occurrence and number of immune cells characterised in detail and the concentration of immunological messengers in the liver and blood of normal mice and mice with a targeted genetic defect.

They showed that in experimental amoeba infections in the liver, a specific immunoregulatory protein (HIF-1alpha) is partly responsible for the stronger immune response of the male mice. The protein is present in the liver cells of both sexes in response to amoebic infection, but influences the immune cell response of male and female animals to different degrees. Targeted knockdown of HIF-1alpha in the liver reduces the inflammation- and abscess-promoting immune response in male mice and leads to the abolition of the sex difference.

Portrait of Dr Marie Groneberg
Dr Marie Groneberg   ©Marie Groneberg

Loa loa infection: A truly neglected tropical disease

The second award-winning dissertation deals with the disease burden caused by infections with the nematode Loa loa. The parasite is transmitted by horseflies in West and Central Africa and migrates in the human body.

For a long time, Loa loa infection was thought to be a harmless disease. For decades, disturbing images of the symptoms caused have tended to distract from research into the real disease. The World Health Organisation (WHO) has still not recognised loiasis as a "neglected tropical disease", i.e. a disease that requires special attention and support in research and control.

Portrait of Dr Luzia Veletzky
Dr Luzia Veletzky   ©Luzia Veletzky

Luzia Veletzky and her colleagues in Michael Ramharter's Clinical Research Department, on the other hand, were able to show that this worm infection causes relevant symptoms that considerably restrict the quality of life and performance of affected patients. Not only does it cause the familiar symptoms of worm migration under the conjunctiva of the eye and itchy skin swellings (so-called calabar swellings), it can also have late effects such as damage to the central nervous system, heart and kidneys. In 2016, a study also demonstrated an increased mortality of infected persons for the first time. In addition, it has now been shown that general non-specific symptoms such as fatigue, joint pain and headaches are also associated with the disease, which significantly affect the quality of life.

Objective measurement of disease burden for the first time

The researchers investigated to what extent with the help of the so-called "DALYs" (=disability adjusted life years). DALYs are a measure of health research. It makes it possible to objectively quantify the burden of a single disease on the population and thus to make comparisons. Among other things, DALYs are used in the politically relevant "Global Burden of Disease" studies.

Prof. Rolf Horstmann, Member of the Board VdF: "Luzia Veletzky's dissertation is a significant contribution, as it will draw the attention of the WHO to the Loa loa infection. Inclusion of the infection in the official list of "Neglected Tropical Diseases" would foreseeably lead to a considerable intensification of research and control of the infection. Marie Groneberg and her colleagues have made a significant contribution to understanding the molecular basis for men's long-known greater susceptibility to infectious diseases. The results are not only of great academic interest, they also show approaches for immunotherapeutic measures. I warmly congratulate both winners and wish them every success in their future careers!"

The award winners were honoured following the annual general meeting of the VdF, as part of the BNITM's traditional summer party in the Institute's garden, the first after two years of interruption due to the pandemic.
The Vereinigung der Freunde des Tropeninstituts Hamburg e. V. (Association of Friends of the Tropical Institute Hamburg), the BNITM's sponsoring association, annually awards two prizes for outstanding dissertations at the Institute. One thesis each in medicine and the natural sciences is awarded prize money of 1,000 euros.

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