ABSTRACT
Depression/anxiety (D/A) occurs in up to 50% of multiple sclerosis (MS) patients. Proinflammatory cytokines induce classical symptoms of depression. Activation of the inflammatory response also triggers production of indoleamine 2,3-dioxygenase (IDO), which catabolizes tryptophan, the amino acid precursor of serotonin and melatonin. It has been suggested that IDO is the link between the immune and serotonergic systems. This study aimed to quantify the levels of IDO and pro-inflammatory and anti-inflammatory cytokines in patients with MS and depression, according to treatment with interferon-beta (IFN-ß) or fingolimod. The study inclusion criteria were age 18-60 years and a clinical and radiological diagnosis of MS. One hundred and thirty-two patients diagnosed by McDonald's criteria and followed up at Brasília District Hospital, Brazil, with relapsing-remitting MS were identified as potential study participants. Thirty-five of these patients were identified to be receiving treatment with fingolimod or IFN-ß and to have a diagnosis of D/A. IDO and pro-inflammatory and anti-inflammatory cytokine levels were compared between these 35 patients and 18 healthy controls. The level of IL-10 (an anti-inflammatory cytokine) was lower in both the fingolimod-treated (P â< â0.001) and IFN-ß-treated (P â< â0.01) patient groups than in the control group. IFN-ß-treated patients showed increased IDO expression and decreased inflammatory cytokine levels. In contrast, fingolimod-treated patients showed significantly decreased expression of IDO and significantly increased levels of proinflammatory cytokines produced by innate immune cells, including tumor necrosis factor-alpha and interleukin-6. The agents used to treat MS maintain symptoms of D/A in patients with MS via different mechanisms.
ABSTRACT
Corticomotor excitability of peripheral muscles appears to be altered in patients with obstructive sleep apnea. However, there is no evidence of such alteration for upper airway/respiratory muscles that are involved in the pathophysiology of this disease. The aim of this study was to compare the effects of hypercapnic stimulation on diaphragm and genioglossus corticomotor excitability in awake healthy subjects versus patients with obstructive sleep apnea. Corticomotor excitability was assessed by transcranial magnetic stimulation in 12 untreated apneic men (48 ± 10 years; body mass index = 28.9 ± 4.7 kg m(-2); apnea-hypopnoea index = 41 ± 23 events per hour) and nine control men (45 ± 10 years; body mass index = 27.3 ± 3.3 kg m(-2); apnea-hypopnoea index = 7 ± 4 events per hour). Assessments included diaphragm and genioglossus expiratory motor thresholds, and transcranial magnetic stimulation-induced motor-evoked potential characteristics obtained while breathing room air or 5% CO2 (random order) and then 7% CO2 both balanced with pure O2. Transcranial magnetic stimulation twitches were applied during early inspiration and end expiration. Diaphragm motor-evoked potential amplitudes increased and expiratory diaphragm motor-evoked potential latencies decreased during CO2-induced increase in ventilatory drive, with no difference in these responses between patients with obstructive sleep apnea and control subjects. Expiratory genioglossus motor-evoked potential amplitudes were significantly lower in patients with obstructive sleep apnea than in control subjects. Baseline activity of the genioglossus increased with increasing FiCO2, this effect being significantly higher in patients with obstructive sleep apnea than in control subjects. However, neither genioglossus motor-evoked potential amplitudes nor latencies were significantly modified with increasing FiCO2 both in patients with obstructive sleep apnea and in control subjects. Corticomotor excitability of genioglossus and diaphragm are not altered during CO2-induced increase in ventilatory drive in patients with obstructive sleep apnea.
