New research: Cow’s milk protein triggers autoimmune response in mice that damages neurons.
The immediate for the research got here from MS sufferers: “We hear repeatedly from victims that they really feel worse once they eat milk, cottage cheese or yogurt,” explains Stefanie Kürten from the Institute of Anatomy at College Hospital Bonn. “We're enthusiastic about the reason for this correlation.”
The professor of neuroanatomy is taken into account a famend knowledgeable on a number of sclerosis. She started the research in 2018 on the College of Erlangen-Nuremberg. A yr and a half in the past, she moved to Bonn, the place she continued the work collectively together with her analysis group. “We injected mice with totally different proteins from cow’s milk,” she says. “We needed to seek out out if there was a constituent that they have been responding to with signs of illness.”
In wholesome mice, the insulating myelin (black) matches snugly as a compact layer across the nerve fibers, the axons. Credit score: © Group Prof. Kürten/College of Bonn
And the researchers did certainly discover what they have been on the lookout for: After they administered the cow’s milk constituent casein along with an impact enhancer to the animals, the mice went on to develop neurological problems. Electron microscopy confirmed injury to the insulating layer across the nerve fibers, the myelin. The fat-like substance prevents brief circuits and moreover considerably accelerates stimulus conduction.
Perforated myelin layer
In a number of sclerosis, the physique’s immune system destroys the myelin sheath. The implications vary from paresthesia and imaginative and prescient issues to motion problems. In excessive instances, sufferers want a wheelchair. The insulating sheath was additionally massively perforated within the mice — apparently triggered by casein administration. “We suspected that the explanation was a misdirected immune response, much like that seen in MS sufferers,” explains Rittika Chunder, who's a postdoctoral fellow in Prof. Kürten’s analysis group. “The physique’s defenses really assault the casein, however within the course of additionally they destroy proteins concerned within the formation of myelin.”
In mice injected with casein, the construction of myelin loosens. It solely loosely covers the axons. Generally the insulating layer is even lacking altogether. Credit score: © Group Prof. Kürten/College of Bonn
Such cross-reactivity can happen when two molecules are very comparable, not less than in components. The immune system then in a way errors them for one another. “We in contrast casein to totally different molecules which are necessary for myelin manufacturing,” Chunder says. “Within the course of, we got here throughout a protein known as MAG. It appears to be like markedly much like casein in some respects — a lot in order that antibodies to casein have been additionally energetic towards MAG within the lab animals.”
Which means within the casein-treated mice, the physique’s personal defenses have been additionally directed towards MAG, destabilizing the myelin. However to what extent can the outcomes be transferred to folks with MS? To reply this query, the researchers added casein antibodies from mice to human mind tissue. These did certainly accumulate within the cells answerable for myelin manufacturing within the mind.
Self-test for antibodies towards casein
Sure white blood cells, the B cells, are answerable for antibody manufacturing. The research discovered that the B cells within the blood of individuals with MS reply notably strongly to casein. Presumably, the affected people developed an allergy to casein sooner or later because of consuming milk. Now, as quickly as they eat contemporary dairy merchandise, the immune system produces lots of casein antibodies. As a consequence of cross-reactivity with MAG, these additionally injury the myelin sheath across the nerve fibers.
The antibodies towards casein (crimson) bind to MAG (inexperienced) within the mind. They thereby intervene with the formation of myelin by particular cells, the oligodendrocytes. Credit score: © Group Prof. Kürten/College of Bonn
Nonetheless, this solely impacts MS sufferers who're allergic to cow’s milk casein. “We're presently growing a self-test with which affected people can test whether or not they carry corresponding antibodies,” says Kürten, who can be a member of the Cluster of Excellence ImmunoSensation2. “No less than this subgroup ought to chorus from consuming milk, yogurt, or cottage cheese.”
It's doable that cow’s milk additionally will increase the chance of growing MS in wholesome people. As a result of casein can even set off allergy symptoms in them — which might be not even that uncommon. As soon as such an immune response exists, cross-reactivity with myelin can in idea happen. Nonetheless, this doesn't imply that hypersensitivity to casein essentially results in the event of a number of sclerosis, the professor emphasizes. This could presumably require different threat elements. This connection is nonetheless worrying, Kürten says: “Research point out that MS charges are elevated in populations the place loads of cow’s milk is consumed.”
Reference: “Antibody cross-reactivity between casein and myelin-associated glycoprotein leads to central nervous system demyelination” by
Rittika Chunder, Alicia Weier, Hannah Mäurer, Nicolas Luber, Michael Enders, Gabriele Luber, Thorsten Heider, Alfred Spitzer, Sabine Tacke, Janine Becker-Gotot, Christian Kurts, Radhika Iyer, Peggy P. Ho, William H. Robinson, Tobias V. Lanz and Stefanie Kuerten, 2 March 2022, Proceedings of the Nationwide Academy of Sciences.
DOI: 10.1073/pnas.2117034119
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