MS immune cells produce less neuroprotective BDNF

The immune system gets blamed for a lot in MS; less appreciated are its beneficial effects on neuroprotection. Immune cells can secrete factors that help neurons and glial cells grow and survive, and these factors may help protect the central nervous system against damage.

A new study, however, indicates that production of at least one of these factors is reduced in MS subjects compared with controls. This study compared the production of brain-derived neurotrophic factor (BDNF) by T cells and monocytes drawn from untreated MS subjects and normal controls. Production of BDNF by immune cells was lower in MS subjects than in controls, and even stimulation of MS cells with CD40 (which normally increases BDNF expression) didn't help. Further tests showed that secretions from control CD40-stimulated monocytes increased the survival of a neural cell culture, but no effect on survival was seen when stimulated MS monocytes were used.

The authors speculate that in MS, perhaps the immune cells "exhaust" their neuroprotective abilities from having so much repair work to do in the CNS, or perhaps the immune cell repertoire present in MS is just naturally more inflammatory and less neuroprotective in nature. The authors also note that Copaxone (glatiramer acetate) has been shown to induce greater BDNF production. Hopefully a better understanding of why neuroprotection is inhibited in MS will lead to additional treatments that can promote this helpful aspect of the immune response.