Autonomic function testing in multiple system atrophy: a prognostic biomarker? and other updates on recent autonomic research

Clinical Autonomic Research -     

Cannabinoid receptor 2 positions and retains marginal zone B cells within the splenic marginal zone

Specialized B cells residing in the splenic marginal zone (MZ) continuously survey the blood for antigens and are important for immunity to systemic infections. However, the cues that uniquely attract cells to the MZ have not been defined. Previous work demonstrated that mice deficient in cannabinoid receptor 2 (CB2) have decreased numbers of MZ B cells but it has been unclear whether CB2 regulates MZ B cell development or positioning. We show that MZ B cells are highly responsive to the CB2 ligand 2-arachidonylglycerol (2-AG) and that CB2 antagonism rapidly displaces small numbers of MZ B cells to the blood. Antagonism for longer durations depletes MZ B cells from the spleen. In mice deficient in sphingosine-1-phosphate receptor function, CB2 antagonism causes MZ B cell displacement into follicles. Moreover, CB2 overexpression is sufficient to position B cells to the splenic MZ. These findings establish a role for CB2 in guiding B cells to the MZ and in preventing their loss to the blood. As a consequence of their MZ B cell deficiency, CB2-deficient mice have reduced numbers of CD1d-high B cells. We show that CB2 deficiency results in diminished humoral responses to a CD1d-restricted systemic antigen.     

Sleep disorders in patients with postural tachycardia syndrome

Objective

Patients with postural tachycardia syndrome (POTS) often describe symptoms of fatigue, sleepiness, and lack of refreshing sleep. We aimed to provide further objective measures of sleep in patients with POTS.

Methods

POTS patients (n = 18) were selected based on autonomic testing and evaluation at our center. Controls (n = 16) of similar age, gender, and BMI were selected from new patients referred to the Stanford Sleep Disorders Clinic for any sleep-related complaint. All patients underwent polysomnography and completed several sleep questionnaires and a 2-week sleep diary.

Results

POTS patients and control subjects were of similar age (27 ± 10.2 vs. 29 ± 5.4 years, p = 0.92) and Body Mass Index (21 ± 3.8 vs. 24 ± 4.1, p = 0.14). The majority of subjects in both groups were females (72 % POTS vs. 81 % controls). POTS patients scored higher on subjective fatigue scales but not sleepiness scales. POTS patients scored in the normal range on the BDI and the “evening” category on the MEQ. Their sleep diaries were not different from controls. With the exception of mild OSA, slightly reduced %REM and prolonged REM latency, their PSG data were normal and no different from controls.

Conclusions

It is unlikely that the sleep-related complaints of POTS patients are the result of a primary sleep disorder unique to POTS. We propose that a combination of factors such as body fatigue, chronic pain, and other somatic symptoms common in POTS patients might be the underlying reason for sleep-related symptoms in POTS.

     

Towards more evidenced-based therapies for postural tachycardia syndrome and other updates on recent autonomic research

Clinical Autonomic Research -     

Autonomic function test during the COVID-19 pandemic: the Stanford experience

Clinical Autonomic Research -     

Life and death decisions: secondary complexes and lipid rafts in TNF receptor family signal transduction

Signaling by receptors in the TNF receptor (TNFR) superfamily mediate biological outcomes ranging from inflammation to apoptosis and other forms of programmed cell death. How receptor signaling mediates these divergent responses is just beginning to be understood. Here, we discuss how receptor submembrane localization and the formation of alternate signaling complexes can alter the fate of cells stimulated through TNFRs with a death domain, also known as "death receptors."     

Synuclein in red blood cells: a potential biomarker for multiple system atrophy,and other updates on recent autonomic research

Clinical Autonomic Research -