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Treatment of multiple sclerosis patients with interferon-beta primes monocyte-derived macrophages for apoptotic cell
J Van Weyenbergh1, J Wietzerbin, D Rouillard
1U365 INSERM, Hôpital La Pitié-Salpêtrière, Paris, France. ejomaflo@svn.com.br
Abstract:
Although interferon (IFN)-beta has shown a significant clinical benefit in multiple sclerosis (MS), its mechanism of action remains unclear. We found that IFN-beta treatment of patients with MS resulted in a significant increase in apoptotic cell death (measured by annexin V staining and nuclear fragmentation) of monocyte-derived macrophages, as compared with cells derived from patients before treatment. Stimulation of the cells with IFN-beta in vitro resulted in an even further increase of annexin V binding, as well as increased Fas (CD 95, APO-1) expression. However, no increased Fas expression, apoptotic monocytes, or monocytopenia were observed upon in vivo treatment. This indicates that IFN-beta does not deliver a death signal to monocytes but rather primes for subsequent macrophage apoptosis upon activation or differentiation.
Insights
Interferon-beta (IFN-beta) treatment increases macrophage apoptosis in multiple sclerosis (MS) patients by priming monocytes for cell death upon activation, not directly causing monocyte death in vivo.
Area of Science:
- Immunology
- Neuroimmunology
- Cell Biology
Background:
- Interferon-beta (IFN-beta) is a key therapy for multiple sclerosis (MS).
- The precise mechanism of action for IFN-beta in MS remains incompletely understood.
- Monocytes and macrophages play critical roles in MS pathogenesis.
Purpose of the Study:
- To investigate the effect of IFN-beta on monocyte and macrophage apoptosis in MS patients.
- To elucidate whether IFN-beta directly induces monocyte death or primes them for apoptosis.
Main Methods:
- Monocyte-derived macrophages from MS patients before and after IFN-beta treatment were analyzed.
- Annexin V staining and nuclear fragmentation were used to measure apoptosis.
- In vitro stimulation of monocytes with IFN-beta was performed, assessing Fas expression and apoptosis.
Main Results:
- IFN-beta treatment in MS patients significantly increased apoptotic cell death in monocyte-derived macrophages.
- In vitro IFN-beta stimulation further enhanced Annexin V binding and Fas expression in these cells.
- No significant increase in Fas expression, monocyte apoptosis, or monocytopenia was observed in patients treated with IFN-beta in vivo.
Conclusions:
- IFN-beta does not directly induce monocyte apoptosis or cause monocytopenia in vivo.
- IFN-beta appears to prime monocytes, making them susceptible to apoptosis upon subsequent activation or differentiation into macrophages.
- This priming effect may contribute to the therapeutic benefits of IFN-beta in multiple sclerosis.
