An overview of our Research
Because animals live in a constantly changing environment (think about the fluctuations in temperature that take place seasonally or during a single day), their survival depends critically on their ability to detect and react to these alterations. To this end, the entire surface of the body, including the eyes and the mouth, and many viscera (gut, lungs, etc) are equipped with tiny nerve endings that express specialized receptors that act as miniature signal amplifiers, detecting changes in temperature, mechanical forces and a variety of chemical irritants. The general objective of our research group is to try to understand how the nervous system senses the environment, focusing on the role played by ion channels in mechanosensation, temperature sensing and pain. Detecting these signals is obviously useful and can protect our body from harm. However, in many pathological conditions (arthritis, diabetes, etc), activity in these receptors is altered, leading to exaggerated pain and other unpleasant sensations like itch. In our studies, we combine different experimental approaches. Using genetic labeling strategies, we can identify subpopulations of sensory neurons that are involved in the transduction of specific stimuli. These neurons are further characterized using electrophysiological recordings or purified for biochemical analysis or genomic profiling. We also perform behavioral characterization of animals lacking specific ion channels in different models of chronic pain. The ultimate goal of our research program is to establish the contribution of particular ion channels to somatic and viscera sensations and their role in pathological conditions like chronic pain and inflammation. Finally, we also explore the potential to develop novel analgesic drugs targeting these receptors.
To study the expression and function of ion channels, sensory ion channels, and thermoreceptors in particular, in different pathological conditions that lead to abnormal pain sensations. This knowledge is fundamental to eventually use these molecular receptors as analgesic targets.
We are also interested in understanding the cellular and molecular bases of low and high-threshold mechanotransduction by mammalian primary sensory neurons under conditions of inflammation and the effects of specific components of the extracellular matrix on articular pain.
ChemoTheRapy-Induced neuropathy: pathophysioLOGY, sex dimorphism and therapeutic intervention
Chemotherapy-induced peripheral neuropathy (CIPN) is a prevalent side effect of paclitaxel and oxaliplatin treatment of cancer (70-90% of patients receiving these drugs). Patients suffering CIPN complain of somatosensory symptoms, including paresthesia and pain that drastically affects their quality of life. Notably, this syndrome may become chronic in up to 30% of patients not resolving upon treatment cessation. Therefore, there is an urgent need to reveal the underlying molecular mechanisms leading to the sensory dysfunction characteristic of CIPN. The specific aims of Trilogy are: (i) To investigate the neuropathophysiological mechanisms underlying paclitaxel and oxaliplatin CIPN; (ii) To unveil the molecular mechanisms involved in CIPN sex dimorphism and its modulation by sex hormones; (iii) To design and pharmacologically validate lead compounds that attenuate paclitaxel and oxaliplatin CIPN sensory symptoms.
NEW PAPER IN ACTA PHYSIOL 2022 "The cold-sensing ion channel TRPM8 regulates central and peripheral clockwork and the circadian oscillations of body temperature"
TRPM8 is expressed in the retina, specifically in cholinergic amacrine interneurons and in a subset of melanopsin-positive ganglion cells which project to the central pacemaker, the suprachiasmatic nucleus (SCN) of the hypothalamus. TRPM8-positive fibres were also found innervating choroid and ciliary body vasculature, with a putative function in intraocular temperature, as shown in TRPM8-deficient mice. Interestingly, Trpm8-/- animals displayed increased expression of the clock gene Per2 and vasopressin (AVP) in the SCN, suggesting a regulatory role of TRPM8 on the central oscillator. Since SCN AVP neurons control body temperature, we studied Tc in driven and free-running conditions. TRPM8-deficiency increased the amplitude of Tc oscillations and, under dim constant light, induced a greater phase delay and instability of Tc rhythmicity. Finally, TRPM8-positive fibres innervate peripheral organs, like liver and white adipose tissue. Notably, Trpm8-/- mice displayed a dysregulated expression of Per2 mRNA in these metabolic tissues.
NEW PAPER IN BRAIN "TRPA1 modulation by Sigma-1 receptor prevents oxaliplatin-induced painful peripheral neuropathy"
Chemotherapy induced peripheral neuropathy (CIPN) is a frequent, disabling side effect of anticancer drugs. Oxaliplatin, a platinum compound used in the treatment of advanced colorectal cancer, often leads to a form of CIPN characterized by mechanical and cold hypersensitivity. Current therapies for CIPN are ineffective, often leading to the cessation of treatment. Transient receptor potential ankyrin 1 (TRPA1) is a polymodal, non-selective cation-permeable channel expressed in nociceptors, activated by physical stimuli and cellular stress products. TRPA1 has been linked to the establishment of CIPN and other painful neuropathic conditions. Sigma-1 receptor is an endoplasmic reticulum chaperone known to modulate the function of many ion channels and receptors. S1RA, a highly selective antagonist of Sigma-1 receptor has shown effectiveness in a phase II clinical trial for oxaliplatin CIPN. However, the mechanisms involved in the beneficial effects of S1RA are little understood. We combined biochemical and biophysical (i.e. intermolecular FRET) techniques to demonstrate the interaction between Sigma-1 receptor and human TRPA1. Pharmacological antagonism of Sigma-1R impaired the formation of this molecular complex and the trafficking of functional TRPA1 to the plasma membrane. Using patch-clamp electrophysiological recordings we found that antagonists of Sigma-1 receptor, including S1RA, exert a marked inhibition on plasma membrane expression and function of human TRPA1 channels. In TRPA1-expressing mouse sensory neurons, S1RA reduced inward currents and the firing of actions potentials in response to TRPA1 agonists. Finally, in a mouse experimental model of oxaliplatin neuropathy, systemic treatment with a S1RA prevented the development of painful symptoms by a mechanism involving TRPA1. In summary, the modulation of TRPA1 channels by Sigma-1 receptor antagonists suggests a new strategy for the prevention and treatment of CIPN and could inform the development of novel therapeutics for neuropathic pain.
NEW PAPER IN Int. J. Mol. Sci. "Validation of Six Commercial Antibodies for the Detection of Heterologous and Endogenous TRPM8 Ion Channel Expression"
TRPM8 is a non-selective cation channel expressed in primary sensory neurons and other tissues, including the prostate and urothelium. Its participation in different physiological and pathological processes such as thermoregulation, pain, itch, inflammation and cancer has been widely described, making it a promising target for therapeutic approaches. The detection and quantification of TRPM8 seems crucial for advancing the knowledge of the mechanisms underlying its role in these pathophysiological conditions. Antibody-based techniques are commonly used for protein detection and quantification, although their performance with many ion channels, including TRPM8, is suboptimal. Thus, the search for reliable antibodies is of utmost importance. In this study, we characterized the performance of six TRPM8 commercial antibodies in three immunodetection techniques: Western blot, immunocytochemistry and immunohistochemistry. Different outcomes were obtained for the tested antibodies; two of them proved to be successful in detecting TRPM8 in the three approaches while, in the conditions tested, the other four were acceptable only for specific techniques. Considering our results, we offer some insight into the usefulness of these antibodies for the detection of TRPM8 depending on the methodology of choice.