@article{pmid40667986,

title = {Decreased KCC2 expression in the human spinal dorsal horn associated with chronic pain and long-term opioid use},

author = {Olivia C Davis and Samuel Ferland and Louis-Etienne Lorenzo and Clare Murray-Lawson and Stephanie Shiers and Muhammad Saad Yousuf and Annemarie Dedek and Eve C Tsai and Erin Vines and Peter Horton and Anna Cervantes and Tariq Khan and Geoffrey Funk and Gregory Dussor and Antoine G Godin and Francesco Ferrini and Yves De Koninck and Michael E Hildebrand and Theodore J Price},

doi = {10.1097/j.pain.0000000000003700},

issn = {1872-6623},

year  = {2025},

date = {2025-11-01},

journal = {Pain},

volume = {166},

number = {11},

pages = {e665--e673},

abstract = {Loss of GABAergic and glycinergic inhibitory efficacy in the spinal dorsal horn is associated with neuropathic pain and opioid-induced hyperalgesia in rodent models. Downregulation of the KCC2 chloride extrusion transporter is a key mechanism underlying this decreased inhibitory efficacy, but to-date there is no evidence supporting or opposing this hypothesis in humans. Here, we demonstrate that KCC2 expression is decreased in superficial dorsal horn neurons of organ donors who died with a documented history of pain, or of long-term opioid use. We show profoundly decreased KCC2 dorsal horn membrane expression in a primary cohort associated with either chronic pain or opioid use, and in a replication cohort of mixed chronic pain and opioid use history. These results show that decreased dorsal horn inhibitory efficacy likely promotes chronic pain in humans and support the development of therapeutics augmenting KCC2 function as a treatment for chronic pain and opioid use disorders.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid40553827,

title = {Differential synaptic inhibition and serotonin 5-HT receptor-mediated modulation in identified dorsal horn neurons},

author = {Chiara Salio and Francesco Ferrini and Andrea Bighinati and Enza Lacivita and Marcello Leopoldo and Rita Bardoni},

doi = {10.1016/j.neuint.2025.106011},

issn = {1872-9754},

year  = {2025},

date = {2025-09-01},

journal = {Neurochem Int},

volume = {188},

pages = {106011},

abstract = {Serotonergic modulation of pain transmission in the spinal cord involves the activation of multiple receptor types, including 5-HT receptors. Activation of spinal 5-HT receptors appears to have a predominant antinociceptive effect in various animal models. Although the serotonergic modulation of dorsal horn circuits has been extensively investigated, information about the specific effects of serotonergic receptors on identified neuron types remains limited. To address this, we have employed transgenic mice expressing channelrhodopsin-2 (ChR2) in inhibitory neurons, under the control of the vesicular GABA transporter (VGAT) promoter. Postsynaptic inhibitory responses (oIPSCs) induced by optogenetic stimulation of spinal cord slices displayed distinct properties in superficial dorsal horn VGAT+ and VGAT- neurons (inhibitory and putative excitatory neurons, respectively). While oIPSCs recorded from VGAT + neurons showed GABA- and glycine-mediated components of similar amplitudes, oIPSCs from VGAT- neurons were predominantly mediated by glycine. Consistently, immunofluorescence staining for the glycine transporter GlyT2 in mice expressing dTomato in GAD2 neurons revealed that GlyT2+ boutons primarily contact putative excitatory interneurons, which are negative for GAD2. Activation of 5-HT receptors by the agonist LP-211 significantly enhanced both the frequency of spontaneous inhibitory currents and the amplitude of oIPSCs in VGAT- neurons. In minimal optical stimulation experiments, application of LP-211 reduced the number of synaptic failures and increased the quantal content of oIPSCs, indicating presynaptic modulation mediated by 5-HT receptors. Our results suggest that enhanced synaptic inhibition of dorsal horn excitatory interneurons may contribute to the role of 5-HT receptors in suppressing pain transmission at the spinal cord level.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid39657081,

title = {Does mesenchymal stem cell's secretome affect spinal sensory circuits? Implication for pain therapies},

author = {Francesco Ferrini and Esri H Juárez and Adalberto Merighi},

doi = {10.4103/NRR.NRR-D-23-01967},

issn = {1673-5374},

year  = {2025},

date = {2025-01-01},

journal = {Neural Regen Res},

volume = {20},

number = {1},

pages = {181--183},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid39682771,

title = {Painful Diabetic Neuropathy: Sex-Specific Mechanisms and Differences from Animal Models to Clinical Outcomes},

author = {Emma Merlin and Chiara Salio and Francesco Ferrini},

doi = {10.3390/cells13232024},

issn = {2073-4409},

year  = {2024},

date = {2024-12-01},

journal = {Cells},

volume = {13},

number = {23},

abstract = {Diabetes is a chronic and progressive disease associated with high blood glucose levels. Several co-morbidities arise from diabetes, the most common and severe one is diabetic neuropathy whose symptoms also include pain hypersensitivity. Currently, there are no effective therapies to counteract painful diabetic neuropathy or slow down the progression of the disease, and the underlying mechanisms are yet to be fully understood. Emerging data in recent decades have provided compelling evidence that the molecular and cellular mechanisms underlying chronic pain are different across the sexes. Interestingly, relevant differences have also been observed in the course and clinical presentation of painful diabetic neuropathy in humans. Here, we reviewed the current state of the art on sex differences in diabetic neuropathy, from animal models to clinical data. Comparing the output of both preclinical and clinical studies is necessary for properly orienting future choices in pain research, refining animal models, and interpreting clinical data. The identification of sex-specific mechanisms may help to develop more targeted therapies to counteract pain symptoms in diabetes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid38277178,

title = {An improved conflict avoidance assay reveals modality-specific differences in pain hypersensitivity across sexes},

author = {Samuel Ferland and Feng Wang and Yves De Koninck and Francesco Ferrini},

doi = {10.1097/j.pain.0000000000003132},

issn = {1872-6623},

year  = {2024},

date = {2024-06-01},

journal = {Pain},

volume = {165},

number = {6},

pages = {1304--1316},

abstract = {Abnormal encoding of somatosensory modalities (ie, mechanical, cold, and heat) are a critical part of pathological pain states. Detailed phenotyping of patients' responses to these modalities have raised hopes that analgesic treatments could one day be tailored to a patient's phenotype. Such precise treatment would require a profound understanding of the underlying mechanisms of specific pain phenotypes at molecular, cellular, and circuitry levels. Although preclinical pain models have helped in that regard, the lack of a unified assay quantifying detailed mechanical, cold, and heat pain responses on the same scale precludes comparing how analgesic compounds act on different sensory phenotypes. The conflict avoidance assay is promising in that regard, but testing conditions require validation for its use with multiple modalities. In this study, we improve upon the conflict avoidance assay to provide a validated and detailed assessment of all 3 modalities within the same animal, in mice. We first optimized testing conditions to minimize the necessary amount of training and to reduce sex differences in performances. We then tested what range of stimuli produce dynamic stimulus-response relationships for different outcome measures in naive mice. We finally used this assay to show that nerve injury produces modality-specific sex differences in pain behavior. Our improved assay opens new avenues to study the basis of modality-specific abnormalities in pain behavior.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid37674016,

title = {ST2-Conditioned Medium Fosters Dorsal Horn Cell Excitability and Synaptic Transmission in Cultured Mouse Spinal Cord},

author = {Esri H Juárez and Chelsea R Wood and Rebecca Davies and Oksana Kehoe and William E B Johnson and Adalberto Merighi and Francesco Ferrini},

doi = {10.1007/s12015-023-10618-x},

issn = {2629-3277},

year  = {2023},

date = {2023-11-01},

journal = {Stem Cell Rev Rep},

volume = {19},

number = {8},

pages = {2918--2928},

abstract = {Conditioned medium obtained from bone marrow-derived stem cells has been proposed as a novel cell-free therapy in spinal cord injury and neuropathic pain, yet the direct effect on spinal neuron function has never been investigated. Here, we adopted spinal cord organotypic cultures (SCOCs) as an experimental model to probe the effect of ST2 murine mesenchymal stem cells-conditioned medium (ST2-CM) on dorsal horn (DH) neuron functional properties. Three days of SCOC exposure to ST2-CM increased neuronal activity measured by Fos expression, as well as spontaneous or induced firing. We showed that the increase in neuronal excitability was associated with changes in both intrinsic membrane properties and an enhanced excitatory drive. The increased excitability at the single-cell level was substantiated at the network level by detecting synchronous bursts of calcium waves across DH neurons. Altogether, SCOCs represent a viable tool to probe mesenchymal cells' effect on intact neuronal networks. Our findings indicate that ST2-CM enhances neuronal activity and synaptic wiring in the spinal dorsal horn. Our data also support the trophic role of mesenchymal cells CM in maintaining network activity in spinal circuits.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid35058371,

title = {A Female-Specific Role for Calcitonin Gene-Related Peptide (CGRP) in Rodent Pain Models},

author = {Candler Paige and Isabel Plasencia-Fernandez and Moeno Kume and Melina Papalampropoulou-Tsiridou and Louis-Etienne Lorenzo and Eric T David and Lucy He and Galo L Mejia and Christopher Driskill and Francesco Ferrini and Andrew L Feldhaus and Leon F Garcia-Martinez and Armen N Akopian and Yves De Koninck and Gregory Dussor and Theodore J Price},

doi = {10.1523/JNEUROSCI.1137-21.2022},

issn = {1529-2401},

year  = {2022},

date = {2022-03-01},

journal = {J Neurosci},

volume = {42},

number = {10},

pages = {1930--1944},

abstract = {We aimed to investigate a sexually dimorphic role of calcitonin gene-related peptide (CGRP) in rodent models of pain. Based on findings in migraine where CGRP has a preferential pain-promoting effect in female rodents, we hypothesized that CGRP antagonists and antibodies would attenuate pain sensitization more efficaciously in female than male mice and rats. In hyperalgesic priming induced by activation of interleukin 6 signaling, CGRP receptor antagonists olcegepant and CGRP both given intrathecally, blocked, and reversed hyperalgesic priming only in females. A monoclonal antibody against CGRP, given systemically, blocked priming specifically in female rodents but failed to reverse it. In the spared nerve injury model, there was a transient effect of both CGRP antagonists, given intrathecally, on mechanical hypersensitivity in female mice only. Consistent with these findings, intrathecally applied CGRP caused a long-lasting, dose-dependent mechanical hypersensitivity in female mice but more transient effects in males. This CGRP-induced mechanical hypersensitivity was reversed by olcegepant and the KCC2 enhancer CLP257, suggesting a role for anionic plasticity in the dorsal horn in the pain-promoting effects of CGRP in females. In spinal dorsal horn slices, CGRP shifted GABA reversal potentials to significantly more positive values, but, again, only in female mice. Therefore, CGRP may regulate KCC2 expression and/or activity downstream of CGRP receptors specifically in females. However, KCC2 hypofunction promotes mechanical pain hypersensitivity in both sexes because CLP257 alleviated hyperalgesic priming in male and female mice. We conclude that CGRP promotes pain plasticity in female rodents but has a limited impact in males. The majority of patients impacted by chronic pain are women. Mechanistic studies in rodents are creating a clear picture that molecular events promoting chronic pain are different in male and female animals. We sought to build on evidence showing that CGRP is a more potent and efficacious promoter of headache in female than in male rodents. To test this, we used hyperalgesic priming and the spared nerve injury neuropathic pain models in mice. Our findings show a clear sex dimorphism wherein CGRP promotes pain in female but not male mice, likely via a centrally mediated mechanism of action. Our work suggests that CGRP receptor antagonists could be tested for efficacy in women for a broader variety of pain conditions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid33718633,

title = {Mesenchymal stem cell conditioned medium increases glial reactivity and decreases neuronal survival in spinal cord slice cultures},

author = {Chelsea R Wood and Esri H Juárez and Francesco Ferrini and Peter Myint and John Innes and Laura Lossi and Adalberto Merighi and William E B Johnson},

doi = {10.1016/j.bbrep.2021.100976},

issn = {2405-5808},

year  = {2021},

date = {2021-07-01},

journal = {Biochem Biophys Rep},

volume = {26},

pages = {100976},

abstract = { spinal cord slice cultures (SCSC) allow study of spinal cord circuitry, maintaining stimuli responses comparable to live animals. Previously, we have shown that mesenchymal stem/stromal cell (MSC) transplantation  reduced inflammation and increased nerve regeneration but MSC survival was short-lived, highlighting that beneficial action may derive from the secretome. Previous  studies of MSC conditioned medium (CM) have also shown increased neuronal growth. In this study, murine SCSC were cultured in canine MSC CM (harvested from the adipose tissue of excised inguinal fat) and cell phenotypes analysed via immunohistochemistry and confocal microscopy. SCSC in MSC CM displayed enhanced viability after propidium iodide staining. GFAP immunoreactivity was significantly increased in SCSC in MSC CM compared to controls, but with no change in proteoglycan (NG2) immunoreactivity. In contrast, culture in MSC CM significantly decreased the prevalence of βIII-tubulin immunoreactive neurites, whilst Ca transients per cell were significantly increased. These  results contradict previous  and  reports of how MSC and their secretome may affect the microenvironment of the spinal cord after injury and highlight the importance of a careful comparison of the different experimental conditions used to assess the potential of cell therapies for the treatment of spinal cord injury.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32579747,

title = {Cytoarchitectural analysis of the neuron-to-glia association in the dorsal root ganglia of normal and diabetic mice},

author = {Elisa Ciglieri and Maurizia Vacca and Francesco Ferrini and Mona A Atteya and Patrizia Aimar and Elisa Ficarra and Santa Di Cataldo and Adalberto Merighi and Chiara Salio},

doi = {10.1111/joa.13252},

issn = {1469-7580},

year  = {2020},

date = {2020-11-01},

journal = {J Anat},

volume = {237},

number = {5},

pages = {988--997},

abstract = {Dorsal root ganglia (DRGs) host the somata of sensory neurons which convey information from the periphery to the central nervous system. These neurons have heterogeneous size and neurochemistry, and those of small-to-medium size, which play an important role in nociception, form two distinct subpopulations based on the presence (peptidergic) or absence (non-peptidergic) of transmitter neuropeptides. Few investigations have so far addressed the spatial relationship between neurochemically different subpopulations of DRG neurons and glia. We used a whole-mount mouse lumbar DRG preparation, confocal microscopy and computer-aided 3D analysis to unveil that IB4 non-peptidergic neurons form small clusters of 4.7 ± 0.26 cells, differently from CGRP peptidergic neurons that are, for the most, isolated (1.89 ± 0.11 cells). Both subpopulations of neurons are ensheathed by a thin layer of satellite glial cells (SGCs) that can be observed after immunolabeling with the specific marker glutamine synthetase (GS). Notably, at the ultrastructural level we observed that this glial layer was discontinuous, as there were patches of direct contact between the membranes of two adjacent IB4 neurons. To test whether this cytoarchitectonic organization was modified in the diabetic neuropathy, one of the most devastating sensory pathologies, mice were made diabetic by streptozotocin (STZ). In diabetic animals, cluster organization of the IB4 non-peptidergic neurons was maintained, but the neuro-glial relationship was altered, as STZ treatment caused a statistically significant increase of GS staining around CGRP neurons but a reduction around IB4 neurons. Ultrastructural analysis unveiled that SGC coverage was increased at the interface between IB4 cluster-forming neurons in diabetic mice, with a 50% reduction in the points of direct contacts between cells. These observations demonstrate the existence of a structural plasticity of the DRG cytoarchitecture in response to STZ.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}