PD1+ T-cells correlate with Nerve Fiber Density as a prognostic biomarker in patients with resected perihilar cholangiocarcinoma.

Background & Aims: Perihilar cholangiocarcinoma (pCCA) is a hepatobiliary malignancy. Nerve fiber invasion (NFI) shows cancer invading the nerve and is considered an aggressive feature. Nerve fiber density (NFD) consists of small nerve fibers without cancer invasion and is divided into high NFD (high numbers of small nerve fibers) or low NFD (low numbers of small nerve fibers). We aim to explore differences in immune cell populations and survival. Approach & Results: We applied multiplex immunofluorescence (mIF) on 47 pCCA surgically resected patients and investigated immune cell composition in the tumor microenvironment (TME) of nerve fiber phenotypes (NFI, high and low NFD). Group comparison was performed and overall survival (OS) was assessed. The NFI Region of Interest (ROI) was measured with highest CD68+ macrophage levels among 3 ROIs (NFI compared to tumor free p= 0.016 and to tumor p=0.034) and PD1 expression on CD8 and were more abundant in the tumor rather than NFI ROI (p= 0.004 and p= 0.0029 respectively). NFD compared to NFI, demonstrated co-expression of CD8+PD1+ as well as CD68+PD1+ to be significantly higher in high NFD patients (p= 0.027 and p= 0.044, respectively). The high NFD OS was 92 months median OS (95% CI:41-142), for low NFD 20 months ((95% CI: 4-36) and for NFI 19 months (95% CI 7-33). High NFD OS was significantly better compared to low NFD (p= 0.046) and NFI (p= 0.032). Conclusions: PD1+ T-cells correlate with high NFD as a prognostic biomarker, the biological pathway behind this needs to be investigated.

Corneal Confocal Microscopy in the Diagnosis of Small Fiber Neuropathy: Faster, Easier, and More Efficient Than Skin Biopsy?

Chronic pain may affect 30–50% of the world’s population and an important cause is small fiber neuropathy (SFN). Recent research suggests that autoimmune diseases may be one of the most common causes of small nerve fiber damage. There is low awareness of SFN among patients and clinicians and it is difficult to diagnose as routine electrophysiological methods only detect large fiber abnormalities, and specialized small fiber tests, like skin biopsy and quantitative sensory testing, are not routinely available. Corneal confocal microscopy (CCM) is a rapid, non-invasive, reproducible method for quantifying small nerve fiber degeneration and regeneration, and could be an important tool for diagnosing SFN. This review considers the advantages and disadvantages of CCM and highlights the evolution of this technique from a research tool to a diagnostic test for small fiber damage, which can be a valuable contribution to the study and management of autoimmune disease.

Alpha-synuclein oligomers and small nerve fiber pathology in skin are potential biomarkers of Parkinson’s disease

The proximity ligation assay (PLA) is a specific and sensitive technique for the detection of αSyn oligomers (αSyn-PLA), early and toxic species implicated in the pathogenesis of PD. We aimed to evaluate by skin biopsy the diagnostic and prognostic capacity of αSyn-PLA and small nerve fiber reduction in PD in a longitudinal study. αSyn-PLA was performed in the ankle and cervical skin biopsies of PD (n = 30), atypical parkinsonisms (AP, n = 23) including multiple system atrophy (MSA, n = 12) and tauopathies (AP-Tau, n = 11), and healthy controls (HC, n = 22). Skin biopsy was also analyzed for phosphorylated αSyn (P-αSyn) and 5G4 (αSyn-5G4), a conformation-specific antibody to aggregated αSyn. Intraepidermal nerve fiber density (IENFD) was assessed as a measure of small fiber neuropathy. αSyn-PLA signal was more expressed in PD and MSA compared to controls and AP-Tau. αSyn-PLA showed the highest diagnostic accuracy (PD vs. HC sensitivity 80%, specificity 77%; PD vs. AP-Tau sensitivity 80%, specificity 82%), however, P-αSyn and 5G4, possible markers of later phases, performed better when considering the ankle site alone. A small fiber neuropathy was detected in PD and MSA. A progression of denervation not of pathological αSyn was detected at follow-up and a lower IENFD at baseline was associated with a greater cognitive and motor decline in PD. A skin biopsy-derived compound marker, resulting from a linear discrimination analysis model of αSyn-PLA, P-αSyn, αSyn-5G4, and IENFD, stratified patients with accuracy (77.8%), including the discrimination between PD and MSA (84.6%). In conclusion, the choice of pathological αSyn marker and anatomical site influences the diagnostic performance of skin biopsy and can help in understanding the temporal dynamics of αSyn spreading in the peripheral nervous system during the disease. Skin denervation, not pathological αSyn is a potential progression marker for PD.

Skin Advanced Glycation End Products among Subjects with Type 2 Diabetes Mellitus with or without Distal Sensorimotor Polyneuropathy

Aim of the Study. To examine the correlation between skin AGEs and parameters of distal sensorimotor polyneuropathy (DSPN) in type 2 diabetes mellitus (T2DM). Materials and Methods. We included 132 subjects (88 men) with a mean age of 64.57 years and median T2DM duration of 14.5 years. Skin AGEs were measured with AGE reader mu connect (Diagnoptics) on the dominant arm. The device enables single and automated triplicate measurements: both of these were performed. DSPN was diagnosed through the neuropathy disability score (NDS). Small nerve fibre function was assessed by temperature and pinprick sensation on the foot. Bilateral measurement of the vibration perception threshold (VPT) on the hallux was carried out by using a neurothesiometer (Horwell Scientific Laboratory Supplies). Results. Single and triplicate AGE measurements were positively correlated with each other (Pearson’s correlation coefficient r = 0.991 , 95 % CI = 0.987 -0.994, p < 0.001 ). AGEs were higher among subjects with vs. those without DSPN ( p < 0.001 ). Furthermore, they were higher among subjects with reduced vs. normal temperature sensation ( p < 0.001 ), among subjects with reduced vs. normal pinprick sensation ( p = 0.002 ), among those with abnormal vs. normal monofilament examination ( p < 0.001 ), and among those with abnormal vs. normal VPT ( p < 0.001 ). AGEs were correlated with NDS, VPT, and monofilament score. Conclusions. In T2DM, skin AGEs are increased in the presence of DSPN. This holds true both for large and for small nerve function impairment. Moreover, AGEs are correlated with DSPN severity.

Integrated analysis of gene expression of solute carrier gene SLC19A3 with proven risk factors of microvascular complications in patients with type 2 diabetes

Diabetes mellitus (DM) is a chronic progressive disorder which leads to significant disability, morbidity and is likely to progress to become one of the most widespread conditions worldwide and as an additional burden to the healthcare system already reeling under the effects of the COVID-19 pandemic worldwide. Aim — to study the correlative variation in gene expression of SLC19A3 in type 2 diabetes patients with proven risk factors of diabetes complications. Materials and methods. In the study, 190 patients with type 2 DM were screened for diabetic peripheral neuropathy (DPN). DPN was confirmed in (n = 105) patients displaying symptoms of diabetic polyneuropathy with the involvement of small nerve fibers and large nerve fibers. Out of the total cohort, 45 patients with type 2 DM were shortlisted and randomized according to the severity of diabetic polyneuropathy, for assessment of the expression of the gene SLC19A3 in stage 1 of the gene expression study. Results. In the first stage of the study in patients with type 2 diabetes with diabetic polyneuropathy with the involvement of small nerve fibers and large nerve fibers we found that the difference in expression of the solute carrier gene SLC19A3 in patients with variable levels of neuropathy was not significant. As evident from the CT values and the value of ΔCT there was no statistically valid difference between the groups. The CT value of the target gene (SLC19A3) in all the three groups, in comparison to each other did not have significant difference in the initial phase of the investigation. In correlation to duration of disease the trend was similar, showing that duration of disease does not play an altering role in the expression of the target gene. In correlation to risk factor glycemic control (level of HbA1c) the expression of the target gene was slightly more profound in patients with an HbA1c of < 8.9 % as compared to the patients with HbA1c value > 9.0 %. Conclusions. Taking into consideration the results of the study it can be stated the expression of SLC19A3 is independent of the severity of diabetic polyneuropathy, duration of diabetes and the glycemic compensation in patients with type 2 diabetes.