IL-4 drives microglia and macrophages toward a phenotype conducive for tissue repair and functional recovery after spinal cord injury

Macrophages and microglia play a key role in the maintenance of nervous system homeostasis. However, upon different challenges, they can adopt several phenotypes, which may lead to divergent effects on tissue repair. After spinal cord injury (SCI), microglia and macrophages show predominantly pro-inflammatory activation and contribute to tissue damage. However, the factors that hamper their conversion to an anti-inflammatory state after SCI, or to other protective phenotypes, are poorly understood. Here, we show that IL-4 protein levels are undetectable in the spinal cord after contusion injury, which likely favors microglia and macrophages to remain in a pro-inflammatory state. We also demonstrate that a single delayed intraspinal injection of IL-4, 48 hours after SCI, induces increased expression of M2 marker in microglia and macrophages. We also show that delayed injection of IL-4 leads to the appearance of resolution-phase macrophages, and that IL-4 enhances resolution of inflammation after SCI. Interestingly, we provide clear evidence that delayed administration of IL-4 markedly improves functional outcomes and reduces tissue damage after contusion injury. It is possible that these improvements are mediated by the presence of macrophages with M2 markers and resolution-phase macrophages. These data suggest that therapies aimed at increasing IL-4 levels could be valuable for the treatment of acute SCI, for which there are currently no effective treatments

Dual Role of Lysophosphatidic Acid Receptor 2 (LPA2) in Amyotrophic Lateral Sclerosis

Lysophosphatidic acid (LPA) is a pleiotropic extracellular lipid mediator with many physiological functions that signal through six known G protein-coupled receptors (LPA1-6). In the central nervous system (CNS), LPA mediates a wide range of effects including neural progenitor cell physiology, neuronal cell death, axonal retraction, and inflammation. Since inflammation is a hallmark of most neurological conditions, we hypothesized that LPA could be involved in the physiopathology of amyotrophic lateral sclerosis (ALS). We found that LPA2 RNA was upregulated in post-mortem spinal cord samples of ALS patients and in the sciatic nerve and skeletal muscle of SOD1G93A mouse, the most widely used ALS mouse model. To assess the contribution of LPA2 to ALS, we generated a SOD1G93A mouse that was deficient in Lpar2. This animal revealed that LPA2 signaling accelerates disease onset and neurological decline but, unexpectedly, extended the lifespan. To gain insights into the early harmful actions of LPA2 in ALS, we studied the effects of this receptor in the spinal cord, peripheral nerve, and skeletal muscle of ALS mice. We found that LPA2 gene deletion increased microglial activation but did not contribute to motoneuron death, astrogliosis, degeneration, and demyelination of motor axons. However, we observed that Lpar2 deficiency protected against muscle atrophy. Moreover, we also found the deletion of Lpar2 reduced the invasion of macrophages into the skeletal muscle of SOD1G93A mice, linking LPA2 signaling with muscle inflammation and atrophy in ALS. Overall, these results suggest for the first time that LPA2 contributes to ALS, and its genetic deletion results in protective actions at the early stages of the disease but shortens survival thereafter

CSF1R blockade slows the progression of amyotrophic lateral sclerosis by reducing microgliosis and invasion of macrophages into peripheral nerves

Inflammation is a common neuropathological feature in several neurological disorders, including amyotrophic lateral sclerosis (ALS). We have studied the contribution of CSF1R signalling to inflammation in ALS, as a pathway previously reported to control the expansion and activation of microglial cells. We found that microglial cell proliferation in the spinal cord of SOD1(G93A) transgenic mice correlates with the expression of CSF1R and its ligand CSF1. Administration of GW2580, a selective CSF1R inhibitor, reduced microglial cell proliferation in SOD1(G93A) mice, indicating the importance of CSF1-CSF1R signalling in microgliosis in ALS. Moreover, GW2580 treatment slowed disease progression, attenuated motoneuron cell death and extended survival of SOD1(G93A) mice. Electrophysiological assessment revealed that GW2580 treatment protected skeletal muscle from denervation prior to its effects on microglial cells. We found that macrophages invaded the peripheral nerve of ALS mice before CSF1R-induced microgliosis occurred. Interestingly, treatment with GW2580 attenuated the influx of macrophages into the nerve, which was partly caused by the monocytopenia induced by CSF1R inhibition. Overall, our findings provide evidence that CSF1R signalling regulates inflammation in the central and peripheral nervous system in ALS, supporting therapeutic targeting of CSF1R in this disease

Neuregulin-1 promotes functional improvement by enhancing collateral sprouting in SOD1G93A ALS mice and after partial muscle denervation

Altres ajuts: Fundació La Marato-TV3(TV3201428-10), AFM-Telethon (Nrg14ALS)Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive degeneration of motoneurons, which is preceded by loss of neuromuscular connections in a "dying back" process. Neuregulin-1 (Nrg1) is a neurotrophic factor essential for the development and maintenance of neuromuscular junctions, and Nrg1 receptor ErbB4 loss-of-function mutations have been reported as causative for ALS. Our main goal was to investigate the role of Nrg1 type I (Nrg1-I) in SOD1G93A mice muscles. We overexpressed Nrg1-I by means of an adeno-associated viral (AAV) vector, and investigated its effect by means of neurophysiological techniques assessing neuromuscular function, as well as molecular approaches (RT-PCR, western blot, immunohistochemistry, ELISA) to determine the mechanisms underlying Nrg1-I action. AAV-Nrg1-I intramuscular administration promoted motor axon collateral sprouting by acting on terminal Schwann cells, preventing denervation of the injected muscles through Akt and ERK1/2 pathways. We further used a model of muscle partial denervation by transecting the L4 spinal nerve. AAV-Nrg1-I intramuscular injection enhanced muscle reinnervation by collateral sprouting, whereas administration of lapatinib (ErbB receptor inhibitor) completely blocked it. We demonstrated that Nrg1-I plays a crucial role in the collateral reinnervation process, opening a new window for developing novel ALS therapies for functional recovery rather than preservation

Modulation of the inflammatory response in amyotrophic lateral sclerosis

L’esclerosi lateral amiotròfica (ELA) és una malaltia neurodegenerativa que causa la paràlisi i la mort dels pacients arrel de la pèrdua de les motoneurones de la medul·la espinal i el cervell. Malauradament, els únics tractaments actuals que hi ha són pal·liatius i no endarrereixen la progressió de la malaltia. Una de les característiques de l’ELA és l’activació aberrant del sistema immunològic: (i) activació de les cèl·lules glials (microglia i astròcits) a nivell del sistema nerviós central i (ii) infiltració dels leucòcits, principalment macròfags, al sistema nerviós perifèric. La resposta inflamatòria és un procés fisiològic que s’encarrega de l’eliminació de detritus cel·lulars així com de l’activació de processos de reparació tissular en teixits que han patit un dany o infecció. No obstant, les cèl·lules immunològiques també poden secretar mediadors citotòxics que causen danys i fins i tot la mort de les cèl·lules circumdants. La regulació d’aquests processos però, es deu a la presencia de diverses molècules que es troben en el teixit afectat. En l’ELA, diversos estudis han demostrat que aquesta resposta inflamatòria no té un rol protector, sinó deleteri. Basant-nos en aquestes evidències, en la present tesi doctoral vam avaluar si la modulació de la resposta inflamatòria podia millorar la progressió de la malaltia. En concret, ens vam centrar en l’estudi de tres dianes inflamatòries: (i) el receptor del factor estimulador de colònies tipus 1; (ii) la citocina anti-inflamatòria, interleuquina-37; (iii) el lípid immunoresolutor, Maresina-1. En aquest treball, mostrem que la modulació de la resposta inflamatòria per les tres vies confereix neuroprotecció i endarrereix el curs clínic de l’ELA.Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that causes progressive paralysis and death to patients due to the degeneration of motor neurons in the spinal cord and the brain. At present, therapy is mainly symptomatic and fails to halt disease progression. A common feature of ALS, and other neurological disorders, is the occurrence of an inflammatory reaction consisting of activated glial cells (microglia and astrocytes) within the central nervous system, and leukocytes, mainly macrophages, in the peripheral nerves. The inflammatory response is a physiological process with very precise control and plays an essential role in the removal of cell debris and the activation of repair processes in infected or injured tissues. However, immune cells also secrete cytotoxic mediators that exert damage in healthy neighboring cells and even lead to cell death. This dual sword edge of immune cells likely depends on regulatory mediators that are present in the milieu. However, in ALS, as well as, in other neurological conditions inflammatory response is believed to trigger greater hazardous than protective actions. Based on these evidences, in the present thesis we aimed at assessing whether modulation of key aspects of inflammation could ameliorate the clinical course of ALS disease. In particular, we have focused our interest in three main targets: (i) the proinflammatory colony stimulating factor 1 receptor; (ii) the anti-inflammatory cytokine, interleukin-37; (iii) the immunoresolvent agent, Maresin-1. We provide novel data demonstrating that these approaches confer neuroprotection against the clinical course of ALS disease

Modulation of the inflammatory response in amyotrophic lateral sclerosis

L’esclerosi lateral amiotròfica (ELA) és una malaltia neurodegenerativa que causa la paràlisi i la mort dels pacients arrel de la pèrdua de les motoneurones de la medul·la espinal i el cervell. Malauradament, els únics tractaments actuals que hi ha són pal·liatius i no endarrereixen la progressió de la malaltia. Una de les característiques de l’ELA és l’activació aberrant del sistema immunològic: (i) activació de les cèl·lules glials (microglia i astròcits) a nivell del sistema nerviós central i (ii) infiltració dels leucòcits, principalment macròfags, al sistema nerviós perifèric. La resposta inflamatòria és un procés fisiològic que s’encarrega de l’eliminació de detritus cel·lulars així com de l’activació de processos de reparació tissular en teixits que han patit un dany o infecció. No obstant, les cèl·lules immunològiques també poden secretar mediadors citotòxics que causen danys i fins i tot la mort de les cèl·lules circumdants. La regulació d’aquests processos però, es deu a la presencia de diverses molècules que es troben en el teixit afectat. En l’ELA, diversos estudis han demostrat que aquesta resposta inflamatòria no té un rol protector, sinó deleteri. Basant-nos en aquestes evidències, en la present tesi doctoral vam avaluar si la modulació de la resposta inflamatòria podia millorar la progressió de la malaltia. En concret, ens vam centrar en l’estudi de tres dianes inflamatòries: (i) el receptor del factor estimulador de colònies tipus 1; (ii) la citocina anti-inflamatòria, interleuquina-37; (iii) el lípid immunoresolutor, Maresina-1. En aquest treball, mostrem que la modulació de la resposta inflamatòria per les tres vies confereix neuroprotecció i endarrereix el curs clínic de l’ELA.Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that causes progressive paralysis and death to patients due to the degeneration of motor neurons in the spinal cord and the brain. At present, therapy is mainly symptomatic and fails to halt disease progression. A common feature of ALS, and other neurological disorders, is the occurrence of an inflammatory reaction consisting of activated glial cells (microglia and astrocytes) within the central nervous system, and leukocytes, mainly macrophages, in the peripheral nerves. The inflammatory response is a physiological process with very precise control and plays an essential role in the removal of cell debris and the activation of repair processes in infected or injured tissues. However, immune cells also secrete cytotoxic mediators that exert damage in healthy neighboring cells and even lead to cell death. This dual sword edge of immune cells likely depends on regulatory mediators that are present in the milieu. However, in ALS, as well as, in other neurological conditions inflammatory response is believed to trigger greater hazardous than protective actions. Based on these evidences, in the present thesis we aimed at assessing whether modulation of key aspects of inflammation could ameliorate the clinical course of ALS disease. In particular, we have focused our interest in three main targets: (i) the proinflammatory colony stimulating factor 1 receptor; (ii) the anti-inflammatory cytokine, interleukin-37; (iii) the immunoresolvent agent, Maresin-1. We provide novel data demonstrating that these approaches confer neuroprotection against the clinical course of ALS disease

Combined intramuscular and intraspinal transplant of bone marrow cells improves neuromuscular function in the SOD1G93A mice

[Background]: The simultaneous contribution of several etiopathogenic disturbances makes amyotrophic lateral sclerosis (ALS) a fatal and challenging disease. Here, we studied two different cell therapy protocols to protect both central and peripheral nervous system in a murine model of ALS.[Methods]: Since ALS begins with a distal axonopathy, in a first assay, we performed injection of bone marrow cells into two hindlimb muscles of transgenic SOD1G93A mice. In a second study, we combined intramuscular and intraspinal injection of bone marrow cells. Fluorescence-activated cell sorting was used to assess the survival of the transplanted cells into the injected tissues. The mice were assessed from 8 to 16 weeks of age by means of locomotion and electrophysiological tests. After follow-up, the spinal cord was processed for analysis of motoneuron survival and glial cell reactivity.[Results]: We found that, after intramuscular injection, bone marrow cells were able to engraft within the muscle. However, bone marrow cell intramuscular injection failed to promote a general therapeutic effect. In the second approach, we found that bone marrow cells had limited survival in the spinal cord, but this strategy significantly improved motor outcomes. Moreover, we also found that the dual cell therapy tended to preserve spinal motoneurons at late stages of the disease and to reduce microgliosis, although this did not prolong mice survival.[Conclusion]: Overall, our findings suggest that targeting more than one affected area of the motor system at once with bone marrow cell therapy results in a valuable therapeutic intervention for ALS.This study was supported by the Spanish State Research Agency “Severo Ochoa” Program for Centers of Excellence in R&D (SEV-2013-0317) and Instituto de Salud Carlos III Red de Terapia Celular, TERCEL, co-funded by the European Union (ERDF/ESF, “Investing in your future”).Peer reviewe

Modulation of the inflammatory response in amyotrophic lateral sclerosis /

L'esclerosi lateral amiotròfica (ELA) és una malaltia neurodegenerativa que causa la paràlisi i la mort dels pacients arrel de la pèrdua de les motoneurones de la medul·la espinal i el cervell. Malauradament, els únics tractaments actuals que hi ha són pal·liatius i no endarrereixen la progressió de la malaltia. Una de les característiques de l'ELA és l'activació aberrant del sistema immunològic: (i) activació de les cèl·lules glials (microglia i astròcits) a nivell del sistema nerviós central i (ii) infiltració dels leucòcits, principalment macròfags, al sistema nerviós perifèric. La resposta inflamatòria és un procés fisiològic que s'encarrega de l'eliminació de detritus cel·lulars així com de l'activació de processos de reparació tissular en teixits que han patit un dany o infecció. No obstant, les cèl·lules immunològiques també poden secretar mediadors citotòxics que causen danys i fins i tot la mort de les cèl·lules circumdants. La regulació d'aquests processos però, es deu a la presencia de diverses molècules que es troben en el teixit afectat. En l'ELA, diversos estudis han demostrat que aquesta resposta inflamatòria no té un rol protector, sinó deleteri. Basant-nos en aquestes evidències, en la present tesi doctoral vam avaluar si la modulació de la resposta inflamatòria podia millorar la progressió de la malaltia. En concret, ens vam centrar en l'estudi de tres dianes inflamatòries: (i) el receptor del factor estimulador de colònies tipus 1; (ii) la citocina anti-inflamatòria, interleuquina-37; (iii) el lípid immunoresolutor, Maresina-1. En aquest treball, mostrem que la modulació de la resposta inflamatòria per les tres vies confereix neuroprotecció i endarrereix el curs clínic de l'ELA.Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that causes progressive paralysis and death to patients due to the degeneration of motor neurons in the spinal cord and the brain. At present, therapy is mainly symptomatic and fails to halt disease progression. A common feature of ALS, and other neurological disorders, is the occurrence of an inflammatory reaction consisting of activated glial cells (microglia and astrocytes) within the central nervous system, and leukocytes, mainly macrophages, in the peripheral nerves. The inflammatory response is a physiological process with very precise control and plays an essential role in the removal of cell debris and the activation of repair processes in infected or injured tissues. However, immune cells also secrete cytotoxic mediators that exert damage in healthy neighboring cells and even lead to cell death. This dual sword edge of immune cells likely depends on regulatory mediators that are present in the milieu. However, in ALS, as well as, in other neurological conditions inflammatory response is believed to trigger greater hazardous than protective actions. Based on these evidences, in the present thesis we aimed at assessing whether modulation of key aspects of inflammation could ameliorate the clinical course of ALS disease. In particular, we have focused our interest in three main targets: (i) the proinflammatory colony stimulating factor 1 receptor; (ii) the anti-inflammatory cytokine, interleukin-37; (iii) the immunoresolvent agent, Maresin-1. We provide novel data demonstrating that these approaches confer neuroprotection against the clinical course of ALS disease