Our results suggest a systemic immune activation in patients with ALS. The high production of CD8(+) T and NKT cells may suggest an immunological reaction to some unknown or undetected endogenous proteins or viruses. A probably dual (neurodestructive or neuroprotective) inflammatory function of Treg cells cannot be excluded.

Neuroblastoma is the second most common pediatric malignancy, characterized by a high rate of unexplained spontaneous remissions. Much progress has been made in understanding neuroblastoma differentiation triggered by certain agents such as retinoic acid. However, little is known about the signalling pathways that lead to differentiation of neuroblastoma cells due to serum withdrawal. We found that in Neuro2a neuroblastoma cells, EGFR, ERK1/2 and Akt showed increased phosphorylation after serum withdrawal, and that the activation of EGFR was necessary for the activation of Akt and ERK1/2. Inhibition of EGFR, ERK1/2 and PI3K blocked neuroblastoma differentiation after serum withdrawal. Interestingly, addition of high-density lipoprotein (HDL) abrogated serum-withdrawal induced neuroblastoma differentiation, as well as the activation of EGFR. Our results demonstrate a novel role for serum-derived lipoproteins in the control of receptor tyrosine kinase activity.

Tumor necrosis factor antagonists (anti-TNFa) are an established therapeutic option for several autoimmune and inflammatory bowel diseases. Despite their clinical effectiveness, neurological adverse events have been reported and literature data suggest a potential role of anti-TNFa in the induction of demyelination of the CNS. We present four patients treated with anti-TNFa who developed symptoms suggestive of CNS demyelination. The first patient, a 17-year-old male who received etanercept for psoriatic arthritis for eight months, presented with dysesthesias up to T4 level. The second patient, a 30-year-old male treated with adalimumab for three years due to ankylosing spondylitis, presented with right unilateral tinnitus. The third case, a 47-year-old female, received etanercept for four years because of psoriatic arthritis and developed persistent headache and left-sided face and head numbness. Finally, the fourth patient, a 57-years-old female treated with etanercept for six years due to ankylosing spondylitis, presented with difficulty in speech, swallowing, and ptosis of the right corner of the mouth. In all cases, brain MRI showed lesions suggestive of demyelination, while positive oligoclonal bands were detected in the CSF. Anti-TNFa treatments were discontinued and patients showed clinical improvement with pulsed intravenous corticosteroid therapy. CNS demyelination following anti-TNFa treatment represents a relatively rare but potential serious complication. Close follow-up and MRI monitoring of these patients is mandatory to elucidate whether the clinical manifestations represent adverse events occurring during anti-TNFa therapy or a first demyelinating episode.

Neuroblastoma cell lines are commonly used as models to study neuronal differentiation, as they retain the capacity to differentiate into a neuronal-like phenotype. Receptor tyrosine kinase (RTK) signaling is essential for neuronal differentiation during development, and cholesterol-containing lipid-rafts are important for RTK signaling. Hydroxymethylglutaryl-coenzyme A reductase inhibitors of the statin family impair cholesterol biosynthesis and are in widespread clinical use for the treatment of cardiovascular diseases. It is of great clinical interest that statin treatment also correlates with a lower incidence of malignancies. We found that mevastatin triggered neurite outgrowth of neuroblastoma cells and examined the responsible signaling pathways. Treatment of Neuro2a cells with mevastatin for 24 hr induced neurite outgrowth associated with up-regulation of the neuronal marker protein NeuN. Interestingly, we found that mevastatin triggered phosphorylation of the key kinases epidermal growth factor receptor (EGFR), ERK1/2, and Akt/protein kinase B. Inhibition of EGFR, PI3K, and the mitogen-activated protein kinase cascade blocked mevastatin-induced neurite outgrowth. Moreover, add-back experiments of cell-permeable cholesterol precursors indicated that farnesylated and geranylgeranylated proteins play a major role in statin-induced neurite outgrowth. Taken together, our results provide the first mechanistic insight into statin-triggered signaling pathways that lead to neurite outgrowth in neuroblastoma cells. Surprisingly, we revealed that mevastatin triggered the phosphorylation of the EGFR and that this was because of the inhibition of farnesylated and geranylgeranylated proteins. We propose that members of the large family of farnesylated or geranylgeranylated small GTPases (such as Rabs or Rap1) regulating the trafficking and signaling of EGFR might be responsible for the statin-induced effects on EGFR signaling.