Analysis of matrisome expression patterns in murine and human dorsal root ganglia.

The extracellular matrix (ECM) is a dynamic structure of molecules that can be divided into six different categories and are collectively called the matrisome. The ECM plays pivotal roles in physiological processes in many tissues, including the nervous system. Intriguingly, alterations in ECM molecules/pathways are associated with painful human conditions and murine pain models. Nevertheless, mechanistic insight into the interplay of normal or defective ECM and pain is largely lacking. The goal of this study was to integrate bulk, single-cell, and spatial RNA sequencing (RNAseq) datasets to investigate the expression and cellular origin of matrisome genes in male and female murine and human dorsal root ganglia (DRG). Bulk RNAseq showed that about 65% of all matrisome genes were expressed in both murine and human DRG, with proportionally more core matrisome genes (glycoproteins, collagens, and proteoglycans) expressed compared to matrisome-associated genes (ECM-affiliated genes, ECM regulators, and secreted factors). Single cell RNAseq on male murine DRG revealed the cellular origin of matrisome expression. Core matrisome genes, especially collagens, were expressed by fibroblasts whereas matrisome-associated genes were primarily expressed by neurons. Cell-cell communication network analysis with CellChat software predicted an important role for collagen signaling pathways in connecting vascular cell types and nociceptors in murine tissue, which we confirmed by analysis of spatial transcriptomic data from human DRG. RNAscope in situ hybridization and immunohistochemistry demonstrated expression of collagens in fibroblasts surrounding nociceptors in male and female human DRG. Finally, comparing human neuropathic pain samples with non-pain samples also showed differential expression of matrisome genes produced by both fibroblasts and by nociceptors. This study supports the idea that the DRG matrisome may contribute to neuronal signaling in both mouse and human, and that dysregulation of matrisome genes is associated with neuropathic pain.

Sensory Profiling in Classical Ehlers-Danlos Syndrome: A Case-Control Study Revealing Pain Characteristics, Somatosensory Changes, and Impaired Pain Modulation.

Pain is one of the most important yet poorly understood complaints in heritable connective tissue disorders (HCTDs) caused by monogenic defects in extracellular matrix molecules. This is particularly the case for the Ehlers-Danlos syndrome (EDS), paradigm collagen-related disorders. This study aimed to identify the pain signature and somatosensory characteristics in the rare classical type of EDS (cEDS) caused by defects in type V or rarely type I collagen. We used static and dynamic quantitative sensory testing and validated questionnaires in 19 individuals with cEDS and 19 matched controls. Individuals with cEDS reported clinically relevant pain/discomfort (Visual Analogue Scale ≥5/10 in 32% for average pain intensity the past month) and worse health-related quality of life. An altered somatosensory profile was found in the cEDS group with higher (P = .04) detection thresholds for vibration stimuli at the lower limb, indicating hypoesthesia, reduced thermal sensitivity with more (P < .001) paradoxical thermal sensations (PTSs), and hyperalgesia with lower pain thresholds to mechanical (P < .001) stimuli at both the upper and lower limbs and cold (P = .005) stimulation at the lower limb. Using a parallel conditioned pain modulation paradigm, the cEDS group showed significantly smaller antinociceptive responses (P-value .005-.046) suggestive of impaired endogenous pain modulation. In conclusion, individuals with cEDS report chronic pain and worse health-related quality of life and present altered somatosensory perception. This study is the first to systematically investigate pain and somatosensory characteristics in a genetically defined HCTD and provides interesting insights into the possible role of the ECM in the development and persistence of pain. PERSPECTIVE: Chronic pain compromises the quality of life in individuals with cEDS. Moreover, an altered somatosensory perception was found in the cEDS group with hypoesthesia for vibration stimuli, more PTSs, hyperalgesia for pressure stimuli, and impaired pain modulation.

Sensory profiling in classical Ehlers-Danlos syndrome: a case-control study revealing pain characteristics, somatosensory changes, and impaired pain modulation.

Pain is one of the most important, yet poorly understood complaints in heritable connective tissue disorders (HCTD) caused by monogenic defects in extracellular matrix molecules. This is particularly the case for Ehlers-Danlos syndromes (EDS), paradigm collagen-related disorders. This study aimed to identify the pain signature and somatosensory characteristics in the rare classical type of EDS (cEDS) caused by defects in type V or rarely type I collagen. We used static and dynamic quantitative sensory testing and validated questionnaires in 19 individuals with cEDS and 19 matched controls. Individuals with cEDS reported clinically relevant pain/discomfort (VAS ≥5/10 in 32% for average pain intensity the past month) and worse health -related quality of life. Altered sensory profile was found in the cEDS group with higher (p=0.04) detection thresholds for vibration stimuli at the lower limb indicating hypoesthesia, reduced thermal sensitivity with more (p<0.001) paradoxical thermal sensations, and hyperalgesia with lower pain thresholds to mechanical (p<0.001) stimuli at both the upper and lower limbs and to cold (p=0.005) stimulation at the lower limb. Using a parallel conditioned pain paradigm, the cEDS group showed significantly smaller antinociceptive responses (p-value between 0.005 and 0.046) suggestive of impaired endogenous central pain modulation. In conclusion, Individuals with cEDS report chronic pain and worse health-related quality of life, and present altered somatosensory perception. This study is the first to systematically investigate pain and somatosensory characteristics in a genetically defined HCTD and provides interesting insights on the possible role of the ECM in the development and persistence of pain.

Kyphoscoliotic Ehlers-Danlos syndrome caused by pathogenic variants in FKBP14: Further insights into the phenotypic spectrum and pathogenic mechanisms.

The Ehlers-Danlos syndromes (EDS) are a heterogeneous group of heritable connective tissue diseases. The autosomal recessive kyphoscoliotic EDS results from deficiency of either lysyl hydroxylase 1 (encoded by PLOD1), crucial for collagen cross-linking; or the peptidyl-prolyl cis-trans isomerase family FK506-binding protein 22 kDa (FKBP22 encoded by FKBP14), a molecular chaperone of types III, IV, VI, and X collagen. This study reports the clinical manifestations of three probands with homozygous pathogenic FKBP14 variants, including the previously reported c.362dupC; p.(Glu122Argfs*7) variant, a novel missense variant (c.587A>G; p.(Asp196Gly)) and a start codon variant (c.2T>G; p.?). Consistent clinical features in the hitherto reported individuals (n = 40) are kyphoscoliosis, generalized joint hypermobility and congenital muscle hypotonia. Severe vascular complications have been observed in 12.5%. A previously unreported feature is microcornea observed in two probands reported here. Both the c.587A>G and the c.362dupC variant cause complete loss of FKBP22. With immunocytochemistry on dermal fibroblasts, we provide the first evidence for intracellular retention of types III and VI collagen in EDS-FKBP14. Scratch wound assays were largely normal. Western blot of proteins involved in the unfolded protein response and autophagy did not reveal significant upregulation in dermal fibroblasts.

Pain-related behaviors and abnormal cutaneous innervation in a murine model of classical Ehlers-Danlos syndrome.

Classical Ehlers-Danlos syndrome (cEDS) is a connective tissue disorder caused by heterozygous mutations in one of the type V collagen-encoding genes, COL5A1 or COL5A2. cEDS is characterized by generalized joint hypermobility and instability, hyperextensible, fragile skin, and delayed wound healing. Chronic pain is a major problem in cEDS patients, but the underlying mechanisms are largely unknown, and studies in animal models are lacking. Therefore, we assessed pain-related behaviors in haploinsufficient Col5a1 mice, which clinically mimic human cEDS. Compared to wild-type (WT) littermates, 15 to 20-week-old Col5a1 mice of both sexes showed significant hypersensitivity to mechanical stimuli in the hind paws and the abdominal area, but responses to thermal stimuli were unaltered. Spontaneous behaviors, including distance travelled and rearing, were grossly normal in male Col5a1 mice, whereas female Col5a1 mice showed altered climbing behavior. Finally, male and female Col5a1 mice vocalized more than WT littermates when scruffed. Decreased grip strength was also noted. In view of the observed pain phenotype, Col5a1 mice were crossed with NaV1.8-tdTomato reporter mice, enabling visualization of nociceptors in the glabrous skin of the footpad. We observed a significant decrease in intraepidermal nerve fiber density, with fewer nerves crossing the epidermis, and a decreased total nerve length of Col5a1 mice compared to WT. In summary, male and female Col5a1 mice show hypersensitivity to mechanical stimuli, indicative of generalized sensitization of the nervous system, in conjunction with an aberrant organization of cutaneous nociceptors. Therefore, Col5a1 mice will provide a useful tool to study mechanisms of pain associated with cEDS.