Unraveling the potential of human chorionic gonadotropin as an approach for the treatment of multiple sclerosis using a mouse model

Abstract

Multiple sclerosis (MS) is one of the most common neuroinflammatory diseases affecting young adults. Based on observations that MS patients recover during pregnancy, it was suggested that pregnancy hormones play a role in disease amelioration. Therefore, the influence of the pregnancy hormone human chorionic gonadotropin (hCG), known to possess multiple immunomodulatory functions, was investigated in experimental autoimmune encephalomyelitis (EAE), a mouse model for MS. Female myelin oligodendrocyte glycoprotein (MOG)-immunized C57BL/6J mice were preventively and therapeutically treated with two different hCG preparations (recombinant hCG [rhCG] or urine-derived hCG [uhCG]). EAE disease severity and different immunological parameters in the CNS, inguinal lymph nodes, and spleen were analyzed during disease onset (day 10), the initial phase (day 20), and the progressive phase (day 35). Treatment with rhCG did not alter disease severity and was only able to reduce Th17 cell frequencies at the progressive EAE phase. uhCG treatment resulted in significantly less pronounced disease signs at day 13, 16, and 20. Markedly, uhCG-treated MOG-immunized animals showed approximately a 50 % lower survival rate when injection of uhCG was accompanied with EAE disease onset. During the progressive phase, a decrease in the pro-inflammatory Th17 cell population and a significant reduction in the B17 frequency was found within the CNS after uhCG treatment. However, lymphocyte populations were not altered after uhCG treatment at disease onset or the initial EAE phase. Although uhCG was able to reduce B17 cell frequencies ex vivo, it was suggested that the reduction of EAE signs at the initial disease phase is not mediated through alterations of lymphocytes during this phase in vivo. Taken together, uhCG containing various isoforms of hCG and having a purity of 70 %, but not rhCG Multiple sclerosis (MS) is one of the most common neuroinflammatory diseases affecting young adults. Based on observations that MS patients recover during pregnancy, it was suggested that pregnancy hormones play a role in disease amelioration. Therefore, the influence of the pregnancy hormone human chorionic gonadotropin (hCG), known to possess multiple immunomodulatory functions, was investigated in experimental autoimmune encephalomyelitis (EAE), a mouse model for MS. Female myelin oligodendrocyte glycoprotein (MOG)-immunized C57BL/6J mice were preventively and therapeutically treated with two different hCG preparations (recombinant hCG [rhCG] or urine-derived hCG [uhCG]). EAE disease severity and different immunological parameters in the CNS, inguinal lymph nodes, and spleen were analyzed during disease onset (day 10), the initial phase (day 20), and the progressive phase (day 35). Treatment with rhCG did not alter disease severity and was only able to reduce Th17 cell frequencies at the progressive EAE phase. uhCG treatment resulted in significantly less pronounced disease signs at day 13, 16, and 20. Markedly, uhCG-treated MOG-immunized animals showed approximately a 50 % lower survival rate when injection of uhCG was accompanied with EAE disease onset. During the progressive phase, a decrease in the pro-inflammatory Th17 cell population and a significant reduction in the B17 frequency was found within the CNS after uhCG treatment. However, lymphocyte populations were not altered after uhCG treatment at disease onset or the initial EAE phase. Although uhCG was able to reduce B17 cell frequencies ex vivo, it was suggested that the reduction of EAE signs at the initial disease phase is not mediated through alterations of lymphocytes during this phase in vivo. Taken together, uhCG containing various isoforms of hCG and having a purity of 70 %, but not rhCG Multiple sclerosis (MS) is one of the most common neuroinflammatory diseases affecting young adults. Based on observations that MS patients recover during pregnancy, it was suggested that pregnancy hormones play a role in disease amelioration. Therefore, the influence of the pregnancy hormone human chorionic gonadotropin (hCG), known to possess multiple immunomodulatory functions, was investigated in experimental autoimmune encephalomyelitis (EAE), a mouse model for MS. Female myelin oligodendrocyte glycoprotein (MOG)-immunized C57BL/6J mice were preventively and therapeutically treated with two different hCG preparations (recombinant hCG [rhCG] or urine-derived hCG [uhCG]). EAE disease severity and different immunological parameters in the CNS, inguinal lymph nodes, and spleen were analyzed during disease onset (day 10), the initial phase (day 20), and the progressive phase (day 35). Treatment with rhCG did not alter disease severity and was only able to reduce Th17 cell frequencies at the progressive EAE phase. uhCG treatment resulted in significantly less pronounced disease signs at day 13, 16, and 20. Markedly, uhCG-treated MOG-immunized animals showed approximately a 50 % lower survival rate when injection of uhCG was accompanied with EAE disease onset. During the progressive phase, a decrease in the pro-inflammatory Th17 cell population and a significant reduction in the B17 frequency was found within the CNS after uhCG treatment. However, lymphocyte populations were not altered after uhCG treatment at disease onset or the initial EAE phase. Although uhCG was able to reduce B17 cell frequencies ex vivo, it was suggested that the reduction of EAE signs at the initial disease phase is not mediated through alterations of lymphocytes during this phase in vivo. Taken together, uhCG containing various isoforms of hCG and having a purity of 70 %, but not rhCG containing 99 % of recombinant hCG, was able to reduce EAE severity. This suggests that the reduced EAE severity may be due to other components within the uhCG preparation and not by hCG itself. Thus, it remains unclear which component in the uhCG preparation is able to diminish signs of EAE and which immune cell populations contribute to the diminished EAE severity observed by uhCG. For this, the role of the B17 cell population, which was significantly reduced in the CNS after uhCG administration, as well as other cell populations in the EAE mouse model need further investigation. Finally, further studies are needed to clarify which component or components of the uhCG preparation have resulted in a significantly reduced EAE score and may represent a new potential treatment option for MS.

Multiple Sklerose (MS) ist eine der häufigsten neuroinflammatorischen Erkrankungen bei jungen Erwachsenen. Basierend auf vorherigen Beobachtungen kann angenommen werden, dass bei MS Patienten eine Verbesserung der Krankheitssymptome während der Schwangerschaft einhergeht. Aus diesem Grund wird ein Einfluss von Schwangerschaftshormonen auf den Krankheitsverlauf während der Schwangerschaft vermutet. Daher wurde in dieser Studie der Einfluss des humanen Choriongonadotropins (hCG), welches immunomodulatorische Wirkungen besitzt, auf den Krankheitsverlauf im experimentellen Mausmodell für MS, der Autoimmunenzephalomyelitis (EAE), untersucht. Weibliche Myelin Oligodendrocyte Glycoprotein (MOG)-immunisierte C57BL/6J Mäuse wurden präventiv und therapeutisch mit zwei unterschiedlichen hCG Präparaten (rekombinantes hCG [rhCG] oder Urin-aufgereinigtes hCG [uhCG]) behandelt. Analysen wurden direkt zu Beginn der Erkrankung (Tag 10), während der Anfangsphase (Tag 20) und während der progressiven Phase (Tag 35) durchgeführt, wobei verschiedene immunologische Parameter im zentralen Nervensystem (ZNS), den inguinalen Lymphknoten und der Milz erhoben wurden. Die Behandlung mit rhCG veränderte den EAE-Krankheitsverlauf nicht und konnte die Th17-Zellhäufigkeit nur in der progressiven EAE-Phase (Tag 35) senken. Die Behandlung mit uhCG nach EAE Induktion führte hingegen zu signifikant weniger ausgeprägten Krankheitssymptomen an Tag 13, 16 und 20. Interessanterweise zeigten uhCG-behandelte MOG-immunisierte Tiere eine um etwa 50 % niedrigere Überlebensrate, wenn die Injektion von uhCG mit Eintreten der ersten Krankheitssymptome einherging. Während der progressiven Phase wurde nach uhCG Behandlung eine Abnahme der proinflammatorischen Th17-Zellpopulation und eine signifikante Reduktion der B17-Zellpopulation im ZNS festgestellt. Die Lymphozytenpopulationen waren jedoch zu Beginn der Erkrankung und in der Anfangsphase nach uhCG-Behandlung nicht verändert. Obwohl uhCG in der Lage war ex vivo die B17-Zellfrequenzen zu reduzieren, kann vermutet werden, dass die Reduktion der Anzeichen einer EAE-Erkrankung in der anfänglichen EAE-Krankheitsphase nicht durch Veränderungen der Lymphozyten während dieser Phase in vivo vermittelt wird. Insgesamt konnte nur mit uhCG, bestehend aus verschiedenen hCG Isoformen und einer Reinheit von ungefähr 70 %, jedoch nicht mit rhCG, welches eine Reinheit von 99 % aufweist und die intakte Form von hCG enthält, eine Reduktion der EAE Symptome erreicht werden. Daher kann vermutet werden, dass der verbesserte EAE-Krankheitsverlauf durch andere Komponenten in dem uhCG-Präparat erreicht werden konnte und nicht durch das enthaltene hCG per se. Somit bleibt unklar, welche Komponenten in dem uhCG-Präparat in der Lage sind Anzeichen von EAE zu vermindern und welche Immunzellpopulationen zu den verminderten Anzeichen der EAE-Erkrankung beitragen, die durch uhCG hervorgerufen wurden. Daher muss die Rolle der B17-Zellpopulation, die nach der Verabreichung von uhCG im ZNS signifikant reduziert wurde, sowie anderer Immunzellpopulationen nach uhCG-Behandlung im EAE-Mausmodell weiter untersucht werden. Schließlich sind weitere Studien erforderlich, um zu klären, welche Komponente oder Komponenten der uhCG Präparation zu einem signifikant verringert ausgeprägten Krankheitssymptomen geführt haben und möglicherweise eine neue potenzielle Behandlungsoption für MS darstellen.