Isolation of human pluripotent stem cell-derived sensory neuron subtypes by immunopanning

Sensory neurons (SNs) detect a wide range of information from the body and the environment that is critical for homeostasis. There are three main subtypes of SNs: nociceptors, mechanoreceptors, and proprioceptors, which express different membrane proteins, such as TRKA, TRKB, or TRKC, respectively. Human pluripotent stem cell technology provides an ideal platform to study development and diseases of SNs, however there is not a viable method to isolate individual SN subtype for downstream analysis available. Here, we employ the method immunopanning to isolate each SN subtype. This method is very gentle and allows proper survival after the isolation. We use antibodies against TRKA, TRKB, and TRKC to isolate nociceptors, mechanoreceptors, and proprioceptors, respectively. We show that our cultures are enriched for each subtype and express their respective subtype markers. Furthermore, we show that the immunopanned SNs are electrically active and respond to specific stimuli. Thus, our method can be used to purify viable neuronal subtypes using respective membrane proteins for downstream studies.

Evaluating the transduction efficiency of systemically delivered AAV vectors in the rat nervous system

Gene delivery or manipulation with viral vectors is a frequently used tool in basic neuroscience studies. Adeno-associated viruses (AAV) are the most widely used vectors due to their relative safety and long-term efficacy without causing overt immunological complications. Many AAV serotypes have been discovered and engineered that preferentially transduce different populations of neurons. However, efficient targeting of peripheral neurons remains challenging for many researchers, and evaluation of peripheral neuron transduction with AAVs in rats is limited. Here, we aimed to test the efficiency of systemic AAVs to transduce peripheral neurons in rats. We administered AAV9-tdTomato, AAV-PHP.S-tdTomato, or AAV-retro-GFP systemically to neonatal rats via intraperitoneal injection. After 5 weeks, we evaluated expression patterns in peripheral sensory, motor, and autonomic neurons. No significant difference between the serotypes in the transduction of sensory neurons was noted, and all serotypes were more efficient in transducing NF200 + neurons compared to smaller CGRP + neurons. AAV-retro was more efficient at transducing motor neurons compared to other serotypes. Moreover, PHP.S was more efficient at transducing sympathetic neurons, and AAV-retro was more efficient at transducing parasympathetic neurons. These results indicate that specific AAV serotypes target peripheral neuron populations more efficiently than others in the neonatal rat.

Nox, Nox, Are You There? The Role of NADPH Oxidases in the Peripheral Nervous System

Significance: Reactive oxygen species (ROS) contribute to multiple aspects of peripheral nervous system (PNS) biology ranging from physiological processes (e.g., axonal outgrowth and regeneration) to pathophysiology (e.g., nerve degeneration). Although ROS are derived from multiple sources, NADPH oxidase (Nox) family members are dedicated to ROS generation. Noxs are expressed in the PNS, and their overexpression is associated with detrimental effects on nerve function and contributes, at least in part, to peripheral neuropathies. Recent Advances: Of the seven members, studies mostly focused on Nox1, Nox2, and Nox4, which are expressed in the PNS in a cell-specific manner. We have also recently identified human Nox5 in sural nerve biopsies. When maintained at homeostatic levels, Noxs regulate several aspects of peripheral nerve health, most notably neurite outgrowth and axonal regeneration following nerve lesion. While Nox2 and Nox4 dysregulation is a major source of oxidative stress in PNS disorders, including neuropathic pain and diabetic peripheral neuropathy, recent evidence also implicates Nox1 and Nox5. Critical Issues: Although there is compelling evidence for a direct role of Noxs on nerve function, little is known about their subcellular localization, intercellular regulation, and interaction. These, together with redox signaling, are considered crucial components of nerve redox status. In addition, the lack of isoform-specific inhibitors limits conclusions about the physiological role of Noxs in the PNS and their therapeutic potential in peripheral neuropathies. Future Directions: Future research using isoform-specific genetic and pharmacological approaches are therefore needed to better understand the significance of Nox enzymes in PNS (patho) physiology. Antioxid. Redox Signal. 37, 613-630.

The Role of Extracellular Vesicles in Cancer-Nerve Crosstalk of the Peripheral Nervous System

Although the pathogenic operations of cancer–nerve crosstalk (e.g., neuritogenesis, neoneurogensis, and perineural invasion—PNI) in the peripheral nervous system (PNS) during tumorigenesis, as well as the progression of all cancer types is continuing to emerge as an area of unique scientific interest and study, extensive, wide-ranging, and multidisciplinary investigations still remain fragmented and unsystematic. This is especially so in regard to the roles played by extracellular vesicles (EVs), which are lipid bilayer-enclosed nano- to microsized particles that carry multiple-function molecular cargos, facilitate intercellular communication in diverse processes. Accordingly, the biological significance of EVs has been greatly elevated in recent years, as there is strong evidence that they could contribute to important and possibly groundbreaking diagnostic and therapeutic innovations. This can be achieved and the pace of discoveries accelerated through cross-pollination from existing knowledge and studies regarding nervous system physiology and pathology, as well as thoroughgoing collaborations between oncologists, neurobiologists, pathologists, clinicians, and researchers. This article offers an overview of current and recent past investigations on the roles of EVs in cancer–nerve crosstalk, as well as in neural development, physiology, inflammation, injury, and regeneration in the PNS. By highlighting the mechanisms involved in physiological and noncancerous pathological cellular crosstalk, we provide hints that may inspire additional translational studies on cancer–nerve interplay.

Assessing Lumbar Plexus and Sciatic Nerve Damage in Relapsing-Remitting Multiple Sclerosis Using Magnetisation Transfer Ratio

Background: Multiple sclerosis (MS) has traditionally been regarded as a disease confined to the central nervous system (CNS). However, neuropathological, electrophysiological, and imaging studies have demonstrated that the peripheral nervous system (PNS) is also involved, with demyelination and, to a lesser extent, axonal degeneration representing the main pathophysiological mechanisms. Aim: The purpose of this study was to assess PNS damage at the lumbar plexus and sciatic nerve anatomical locations in people with relapsing-remitting MS (RRMS) and healthy controls (HCs) in vivo using magnetisation transfer ratio (MTR), which is a known imaging biomarker sensitive to alterations in myelin content in neural tissue, and not previously explored in the context of PNS damage in MS. Method: Eleven HCs (7 female, mean age 33.6 years, range 24-50) and 15 people with RRMS (12 female, mean age 38.5 years, range 30-56) were recruited for this study and underwent magnetic resonance imaging (MRI) investigations together with clinical assessments using the expanded disability status scale (EDSS). Magnetic resonance neurography (MRN) was first used for visualisation and identification of the lumbar plexus and the sciatic nerve and MTR imaging was subsequently performed using identical scan geometry to MRN, enabling straightforward co-registration of all data to obtain global and regional mean MTR measurements. Linear regression models were used to identify differences in MTR values between HCs and people with RRMS and to identify an association between MTR measures and EDSS. Results: MTR values in the sciatic nerve of people with RRMS were found to be significantly lower compared to HCs, but no significant MTR changes were identified in the lumbar plexus of people with RRMS. The median EDSS in people with RRMS was 2.0 (range, 0-3). No relationship between the MTR measures in the PNS and EDSS were identified at any of the anatomical locations studied in this cohort of people with RRMS. Conclusion: The results from this study demonstrate the presence of PNS damage in people with RRMS and support the notion that these changes, suggestive of demyelination, maybe occurring independently at different anatomical locations within the PNS. Further investigations to confirm these findings and to clarify the pathophysiological basis of these alterations are warranted.

Integrin-Linked Kinase (ILK) Plays an Important Role in the Laminin-Dependent Development of Dorsal Root Ganglia during Chicken Embryogenesis

Integrin-linked kinase (ILK) is mainly localized in focal adhesions where it interacts and modulates the downstream signaling of integrins affecting cell migration, adhesion, and survival. The interaction of dorsal root ganglia (DRG) cells, being part of the peripheral nervous system (PNS), with the extracellular matrix (ECM) via integrins is crucial for proper PNS development. A few studies have focused on ILK’s role in PNS development, but none of these have focused on chicken. Therefore, we decided to investigate ILK’s role in the development of Gallus gallus domesticus’s DRG. First, using RT-PCR, Western blotting, and in situ hybridization, we show that ILK is expressed in DRG. Next, by immunocytochemistry, we show ILK’s localization both intracellularly and on the cell membrane of DRG neurons and Schwann cell precursors (SCPs). Finally, we describe ILK’s involvement in multiple aspects of DRG development by performing functional experiments in vitro. IgG-mediated interruption of ILK’s action improved DRG neurite outgrowth, modulated their directionality, stimulated SCPs migration, and impacted growth cone morphology in the presence of laminin-1 or laminin-1 mimicking peptide IKVAV. Taken together, our results show that ILK is important for chicken PNS development, probably via its exposure to the ECM.

Unraveling the pathogenesis of HIV peripheral neuropathy: insights from a simian immunodeficiency virus macaque model

Peripheral neuropathy (PN) is the most frequent neurologic complication in individuals infected with human immunodeficiency virus (HIV). It affects over one third of infected patients, including those receiving effective combination antiretroviral therapy. The pathogenesis of HIV-associated peripheral neuropathy (HIV-PN) remains poorly understood. Clinical studies are complicated because both HIV and antiretroviral treatment cause damage to the peripheral nervous system. To study HIV-induced peripheral nervous system (PNS) damage, a unique simian immunodeficiency virus (SIV)/pigtailed macaque model of HIV-PN that enabled detailed morphologic and functional evaluation of the somatosensory pathway throughout disease progression was developed. Studies in this model have demonstrated that SIV induces key pathologic features that closely resemble HIV-induced alterations, including inflammation and damage to the neuronal cell bodies in somatosensory ganglia and decreased epidermal nerve fiber density. Insights generated in the model include: finding that SIV alters the conduction properties of small, unmyelinated peripheral nerves; and that SIV impairs peripheral nerve regeneration. This review will highlight the major findings in the SIV-infected pigtailed macaque model of HIV-PN, and will illustrate the great value of a reliable large animal model to show the pathogenesis of this complex, HIV-induced disorder of the PNS.

Dynamic transcriptional events in distal sural nerve revealed by transcriptome analysis

Compared with biochemical information available about the diseases in the central nervous system, that for peripheral neuropathy is quite limited primarily due to the difficulties in obtaining samples. Characterization of the core pathology is a prerequisite to the development of personalized medicine for genetically heterogeneous diseases, such as hereditary motor and sensory neuropathy (HMSN). Here, we first documented the transcriptome profile of distal sural nerve obtained from HMSN patients. RNA-seq analysis revealed that over 12,000 genes are expressed in distal sural nerve. Among them 4,000 transcripts are novel and 10 fusion genes per sample were observed. Comparing dataset from whole exome sequencing revealed that over 1,500 transcriptional base modifications occur during transcription. These data implicate that dynamic alterations are generated when genetic information are transitioned in distal sural nerve. Although, we could not find significant alterations associated with HMSN, these data might provide crucial information about the pathophysiology of HMSN. Therefore, next step in the development of therapeutic strategy for HMSN might be unveiling biochemical and biophysical abnormalities derived from those potent variation.

If Neurologists Establish The Diagnosis of Primary Sjogren's Syndrome?

INTRODUCTION

Neurological involvements were shown in 20% of patients with Primary Sjogren's Syndrome (pSS). Neurological symptoms may be the first signs of pSS in 57% of the cases. In addition, early diagnosis and treatment of neurological disorders may save or improve the quality of life of these cases. There have been reports about the neurologic manifestations of pSS but little is known about the details of neurologically presented cases.

METHOD

In this study, we described 11 pSS patients who presented with neurological manifestations.

RESULTS

Central nervous system (CNS) involvement was recorded in 7 (63.7%) and peripheric nervous system (PNS) involvement in 4 cases (36.4%).

CONCLUSION

Our findings regarding the cases with neurological manifestations leading to the diagnosis of pSS suggest that: 1) The frequency of CNS involvement was higher than that of PNS, and the most frequent clinical pictures of CNS involvement are Multiple Sclerosis (MS)-like illnesses and optic neuritis, 2) Guillain Barre Syndrome (GBS) was the most frequent disease of PNS involvement; 3) Mononeuropathy multiplex (MM) might be the first sign of pSS; 4) Neurologists should consider pSS in the differential diagnosis of cases with MS, optic neuritis, GBS and neuropathies of unknown causes including MM; 5) There is an urgent need of therapeutical guidelines for the cases with neurological involvement associated with pSS.