**8. Conclusion**

There is increasing evidence that implicates the involvement of the innate immune system in the progression of ALS. In particular, the inappropriate activation or dysregulation of the complement system may play a role in ALS pathology. Evidence for this includes elevated levels of complement activation fragments in the serum, CSF, spinal cord and motor cortex of ALS patients. This has also been supported with elevated levels of complement activation fragments in various animal models of ALS. Moreover, inhibition of the C5a receptor using a specific C5a receptor antagonist ameliorated disease symptoms in a rat model of ALS. Collectively, these studies suggest that complement activation may play a crucial role in the progression of ALS. Hence reducing complement-induced inflammation using inhibitors to target complement factors could be an important therapeutic strategy to treat ALS.
