Immune-endothelial-nerve interaction: an explanation for the failure of the gastrointestinal system in systemic sclerosis?

Autophagy is a key feature in the pathogenesis of systemic sclerosis

Autophagosomes are formed during autophagy, which is activated by hypoxia and starvation. Autophagy is important for mast cell degranulation. We hypothesized that autophagy is a key feature in the pathogenesis of systemic sclerosis (SSc). We examined SSc clinical features and mast cell density across the presence and severity of autophagy. Skin punch biopsy was performed on 33 SSc patients and 6 healthy controls (HC). Autophagy was evaluated by immunofluorescence on paraffin sections using LC3-FITC staining on these patients. The intensity of staining and mast cell density was examined across clinical features in 19 of the SSc patients. Presence of autophagosome formation was assessed by EM in 17 of the SSc patients and 4 HC. In our SSc study population, 29 of subjects were female and 23 were limited cutaneous. Twenty-nine of 33 SSc patients had autophagy by LC3-FITC staining. Intensity of staining decreased with longer duration of SSc (p = 0.09) and RP (p = 0.10). Bloating and distention differed across level of intensity staining (Wilcoxon signed-rank test, p = 0.05), with the greatest levels among those with moderate intensity. On EM, autophagosome formation was present in 16 of 17 SSc patients and no HC. All SSc patients had perivascular mast cells. Autophagy was present in 29 of 33 SSc patients, and none of our HC suggesting importance in pathogenesis. Autophagy staining was greater among those with shorter duration of SSc. Bloating and distention were higher in patients with moderate autophagy staining. Perivascular mast cells were present in all SSc patients. The role of autophagy in vasculopathy and mast cell activation in SSc warrants further studies.

Peripheral neuropathy: a complication of systemic sclerosis

We performed bedside testing for peripheral neuropathy in our systemic sclerosis (SSc) population to determine whether foot care guidelines should be developed for SSc. Twenty consecutive SSc patients and 20 healthy control (HC) patients were evaluated for peripheral neuropathy in both feet using the 10-g Semmes-Weinstein monofilament examination (SWME) and 128 Hz vibration sensation using the on-off method. Independent, blinded, vibratory sensation, and SWME evaluations were performed on each subject by two investigators who had completed a training session to standardize each exam. An additional consecutive 20 patients with type 2 diabetes mellitus (DM) were examined by a diabetologist to compare with peripheral neuropathy prevalence in SSc patients. We examined the inter-rater variability using Cohen's kappa. We compared SWME and vibratory sensation in SSc to HC using Fisher's exact. The t test was used to compare duration of disease and modified Rodnan skin score (mRSS) for those with abnormal SWME or vibratory sensation. Two of 20 SSc patients reported sensory foot symptoms consistent with peripheral neuropathy prior to the examination. Inter-rater agreement for both SWME and vibratory sensation was strong (kappa: 0.72 and 0.83, respectively). Two HC and 12 SSc patients demonstrated abnormal vibratory sense (one-sided Fishers' exact, p < 0.002). No HC and four SSc patients had abnormal monofilament exams (one-sided Fisher's exact, p = 0.053). Neither mRSS (p = 0.28) nor duration of non-Raynauds (p = 0.07) symptoms differed between those with peripheral neuropathy and those without. Duration of Raynaud's symptoms were clinically significantly associated with presence of peripheral neuropathy (p = 0.04). The prevalence of sensory loss to monofilament in SSc was identical to DM patients (4/20). SSc patients have a considerable prevalence of pedal peripheral neuropathy as detected by loss of vibratory sensation or inability to sense the 10-g SWME. Further studies are indicated to determine if routine screening for neuropathy and subsequent podiatric care for SSc patients with abnormalities can reduce pedal complications.