Quantitative Real-Time PCR detection of TRPV1–4 gene expression in human leukocytes from healthy and hyposensitive subjects

<p>Abstract</p> <p>Background</p> <p>Besides functioning as chemosensors for a broad range of endogenous and synthetic ligands, transient receptor potential vanilloid (TRPV) 1–4 channels have also been related to capsaicin (TRPV1), pain, and thermal stimuli perception, and itching sensation (TRPV1–4). While the expression of the TRPV1–4 genes has been adequately proved in skin, sensory fibres and keratinocytes, less is known about TRPV3 and TRPV4 expression in human blood cells.</p> <p>Results</p> <p>To study the gene expression of TRPV1–4 genes in human leukocytes, a quantitative Real-Time PCR (qRT-PCR) method, based on the calculation of their relative expression, has been developed and validated. The four commonly used house-keeping genes (HKGs), β-Actin (Act-B), glyceraldehyde-3P-dehydrogenase (GAPDH), hypoxanthine ribosyltransferase (HPRT1), and cyclophilin B (hCyPB), were tested for the stability of their expression in several human leukocyte samples, and used in the normalization procedure to determine the mRNA levels of the TRPV 1–4 genes in 30 healthy subjects. cDNAs belonging to all the TRPV1–4 genes were detected in leukocytes but the genes appear to be expressed at different levels. Our analysis did not show significant sex differences in TRPV1–4 cDNA levels in the 30 healthy subjects. The same qRT-PCR assay was used to compare TRPV1–4 expression between healthy controls and patients hyposensitive to capsaicin, pain and thermal stimuli: an almost doubled up-regulation of the TRPV1 gene was found in the pathological subjects.</p> <p>Conclusion</p> <p>The qRT-PCR assay developed and tested in this study allowed us to determine the relative expression of TRPV1–4 genes in human leukocytes: TRPV3 is the least expressed gene of this pool, followed by TRPV4, TRPV1 and TRPV2. The comparison of TRPV1–4 gene expression between two groups of healthy and hyposensitive subjects highlighted the evident up-regulation of TRPV1, which was almost doubly expressed (1.9× normalized fold induction) in the latter group. All the four house-keeping genes tested in this work (Act-B, GAPDH, hCyPB, HPRT1) were classified as optimal controls and showed a constant expression in human leukocytes samples. We recommend the use of these genes in similar qRT-PCR studies on human blood cells.</p

Sensory phenotype assessment in a young girl affected by congenital insensitivity to pain (CIPA)

Sensory phenotype was assessed in a young girl affected by congenital insensitivity to pain (CIPA) scheduled for an open surgical drainage. The sensory profile showed that only the Abeta fibers were functioning normally, whereas Adelta and C fibers did not respond to nociceptive stimuli. On the basis of these findings and the results of cardiovascular reflexes, she was submitted to abscess incision and debridement under midazolam sedation alone. She did not report pain or other discomfort during surgery. The sensory (and sympathetic) assessment may have a high potential value in planning anesthesia and analgesia in children with CIPA. This psychophysical procedure could be introduced as standard component of clinical evaluation before surgery

Headache and muscle-skeletal pain in children and adolescents

Headache and muscle-skeletal pain are among the most diffuse kinds of pain in children and adolescents. To know the prevalence of these kinds of pain and the possible association with life habits in modern society, a study on 110 children attending a Tuscany secondary school has been carried out. Twenty-six students referred headache or muscle-skeletal pain and sixty-nine both of them. Headache had a higher prevalence in females (53% vs 46%), while muscle-skeletal pain was prevalent in males (54% vs 46%). Low back pain was present especially at the awakening (24%) or following sitting position (11,5%), while the transport of school books was often accompanied by muscular pain (47%). Sport activity was associated to muscleskeletal pain (72%), as well as the forced and prolonged hypermotility (63%). From this study emerges that the presence of pain is particularly high in subjects in school age, and that some life habits are associated with its appearance

Pain Study in X-Linked Adrenoleukodystrophy in Males and Females

Introduction X-linked adrenoleukodystrophy (ALD) is a metabolic disorder in which very long chain fatty acids (VLCFAs) are accumulated in the nervous system and adrenal cortex, impairing their functions. Three main variants are described in males: adrenomyeloneuropathy (AMN), a cerebral form (cALD or cAMN) and Addison's disease only (AD), while for females no classification is used. To evaluate pain and the functional state of afferent fibers, a series of tests was carried out in male and female patients. Methods Chronic pain occurrence and sensory phenotype profile were assessed in 30 patients (20 male: 10 AMN, 1 cAMN, 1 cALD, 8 AD; and 10 female). A set of instruments assessed the intensity, quality and extent of pain, while a battery of quantitative sensory testing (QST) procedures examined the functional status of A beta and A delta fibers. Principal component analysis and hierarchical clustering with sensory responses input were used to identify distinct clusters. Results Nearly half of the subjects reported pain, with a high prevalence in females and male AMN patients. No sex differences in pain dimensions were found. The sensory responses were heterogeneous, differing among the clinical variants and between genders. Male AMN/cAMN/cALD patients showed the worst impairment. A beta and A delta fibers were affected in males and females, but A beta fibers appeared undamaged in females when tactile sensitivity was tested. Abnormal responses were localized in the lower body district, according to the dying-back pattern of the neuropathy. Cluster analysis showed discrete clusters for each function examined, with well-interpretable sensory and clinical phenotypes. Conclusion The study of pain and of the sensory profile appears to indicate a difference in the mechanisms underlying the AMN/cAMN/cALD and AD clinical forms and in the treatment of the respective generated pain types

A novel human pain insensitivity disorder caused by a point mutation in ZFHX2

Chronic pain is a major global public health issue causing a severe impact on both the quality of life for sufferers and the wider economy. Despite the significant clinical burden, little progress has been made in terms of therapeutic development. A unique approach to identifying new human-validated analgesic drug targets is to study rare families with inherited pain insensitivity. Here we have analysed an otherwise normal family where six affected individuals display a pain insensitive phenotype that is characterized by hyposensitivity to noxious heat and painless bone fractures. This autosomal dominant disorder is found in three generations and is not associated with a peripheral neuropathy. A novel point mutation in ZFHX2, encoding a putative transcription factor expressed in small diameter sensory neurons, was identified by whole exome sequencing that segregates with the pain insensitivity. The mutation is predicted to change an evolutionarily highly conserved arginine residue 1913 to a lysine within a homeodomain. Bacterial artificial chromosome (BAC) transgenic mice bearing the orthologous murine p.R1907K mutation, as well as Zfhx2 null mutant mice, have significant deficits in pain sensitivity. Gene expression analyses in dorsal root ganglia from mutant and wild-type mice show altered expression of genes implicated in peripheral pain mechanisms. The ZFHX2 variant and downstream regulated genes associated with a human pain-insensitive phenotype are therefore potential novel targets for the development of new analgesic drugs.awx326media15680039660001.</p