Cannabinoid type 2 receptor inhibition enhances the antidepressant and proneurogenic effects of physical exercise after chronic stress

Chronic stress is a major risk factor for neuropsychiatric conditions such as depression. Adult hippocampal neurogenesis (AHN) has emerged as a promising target to counteract stress-related disorders given the ability of newborn neurons to facilitate endogenous plasticity. Recent data sheds light on the interaction between cannabinoids and neurotrophic factors underlying the regulation of AHN, with important effects on cognitive plasticity and emotional flexibility. Since physical exercise (PE) is known to enhance neurotrophic factor levels, we hypothesised that PE could engage with cannabinoids to influence AHN and that this would result in beneficial effects under stressful conditions. We therefore investigated the actions of modulating cannabinoid type 2 receptors (CB2R), which are devoid of psychotropic effects, in combination with PE in chronically stressed animals. We found that CB2R inhibition, but not CB2R activation, in combination with PE significantly ameliorated stress-evoked emotional changes and cognitive deficits. Importantly, this combined strategy critically shaped stress-induced changes in AHN dynamics, leading to a significant increase in the rates of cell proliferation and differentiation of newborn neurons, overall reduction in neuroinflammation, and increased hippocampal levels of BDNF. Together, these results show that CB2Rs are crucial regulators of the beneficial effects of PE in countering the effects of chronic stress. Our work emphasises the importance of understanding the mechanisms behind the actions of cannabinoids and PE and provides a framework for future therapeutic strategies to treat stress-related disorders that capitalise on lifestyle interventions complemented with endocannabinoid pharmacomodulation.

Piwil2 (Mili) sustains neurogenesis and prevents cellular senescence in the postnatal hippocampus

Adult neural progenitor cells (aNPCs) ensure lifelong neurogenesis in the mammalian hippocampus. Proper regulation of aNPC fate has thus important implications for brain plasticity and healthy aging. Piwi proteins and the small noncoding RNAs interacting with them (piRNAs) have been proposed to control memory and anxiety, but the mechanism remains elusive. Here, we show that Piwil2 (Mili) is essential for proper neurogenesis in the postnatal mouse hippocampus. RNA sequencing of aNPCs and their differentiated progeny reveal that Mili and piRNAs are dynamically expressed in neurogenesis. Depletion of Mili and piRNAs in the adult hippocampus impairs aNPC differentiation toward a neural fate, induces senescence, and generates reactive glia. Transcripts modulated upon Mili depletion bear sequences complementary or homologous to piRNAs and include repetitive elements and mRNAs encoding essential proteins for proper neurogenesis. Our results provide evidence of a critical role for Mili in maintaining fitness and proper fate of aNPCs, underpinning a possible involvement of the piRNA pathway in brain plasticity and successful aging.

[Colchicine and non-severe ocular inflammation excluding Behcet's disease: 16 cases and literature review]

INTRODUCTION

Colchicine is a narrow therapeutic margin drug that does not have the adverse effects of corticosteroids and immunosuppressants. Its use in non-severe ocular inflammatory disease excluding Behcet's disease has not been studied.

METHODS

We included patients seen in the internal medicine department of Dijon University Hospital consecutively between September 2020 and September 2021 if they had received colchicine during their pathology. Patients with suspected Behçet's disease were excluded. Treatment efficacy was studied in patients with at least one year of disease progression who had received more than one year of colchicine. Successful treatment was defined as a 50 % reduction in the number of annual relapses on colchicine.

RESULTS

Sixteen patients were included (9 women and 7 men). They had recurrent anterior uveitis (n=10), recurrent scleritis (n=5) and intermediate uveitis. Opthalmological involvement was neither severe nor complicated. All patients combined, the annual relapse ratio (ARR) decreased from 1.8 (0.8-3.5) to 0.3 (0-1.6), (P=0.06). Colchicine was considered effective in three of 10 analyzable patients. In only one patient, treatment was stopped for adverse effects after six weeks.

CONCLUSION

In view of the interesting benefit-risk ratio of colchicine, it seems appropriate to focus on this molecule in non-granulomatous anterior uveitis and non-severe recurrent scleritis.

Context-dependent effects of IL-2 rewire immunity into distinct cellular circuits

Interleukin 2 (IL-2) is a key homeostatic cytokine, with therapeutic applications in both immunogenic and tolerogenic immune modulation. Clinical use has been hampered by pleiotropic functionality and widespread receptor expression, with unexpected adverse events. Here, we developed a novel mouse strain to divert IL-2 production, allowing identification of contextual outcomes. Network analysis identified priority access for Tregs and a competitive fitness cost of IL-2 production among both Tregs and conventional CD4 T cells. CD8 T and NK cells, by contrast, exhibited a preference for autocrine IL-2 production. IL-2 sourced from dendritic cells amplified Tregs, whereas IL-2 produced by B cells induced two context-dependent circuits: dramatic expansion of CD8+ Tregs and ILC2 cells, the latter driving a downstream, IL-5-mediated, eosinophilic circuit. The source-specific effects demonstrate the contextual influence of IL-2 function and potentially explain adverse effects observed during clinical trials. Targeted IL-2 production therefore has the potential to amplify or quench particular circuits in the IL-2 network, based on clinical desirability.

Astrocyte-targeted gene delivery of interleukin 2 specifically increases brain-resident regulatory T cell numbers and protects against pathological neuroinflammation

The ability of immune-modulating biologics to prevent and reverse pathology has transformed recent clinical practice. Full utility in the neuroinflammation space, however, requires identification of both effective targets for local immune modulation and a delivery system capable of crossing the blood-brain barrier. The recent identification and characterization of a small population of regulatory T (Treg) cells resident in the brain presents one such potential therapeutic target. Here, we identified brain interleukin 2 (IL-2) levels as a limiting factor for brain-resident Treg cells. We developed a gene-delivery approach for astrocytes, with a small-molecule on-switch to allow temporal control, and enhanced production in reactive astrocytes to spatially direct delivery to inflammatory sites. Mice with brain-specific IL-2 delivery were protected in traumatic brain injury, stroke and multiple sclerosis models, without impacting the peripheral immune system. These results validate brain-specific IL-2 gene delivery as effective protection against neuroinflammation, and provide a versatile platform for delivery of diverse biologics to neuroinflammatory patients.

Adult Neural Stem Cell Regulation by Small Non-coding RNAs: Physiological Significance and Pathological Implications

The adult neurogenic niches are complex multicellular systems, receiving regulatory input from a multitude of intracellular, juxtacrine, and paracrine signals and biological pathways. Within the niches, adult neural stem cells (aNSCs) generate astrocytic and neuronal progeny, with the latter predominating in physiological conditions. The new neurons generated from this neurogenic process are functionally linked to memory, cognition, and mood regulation, while much less is known about the functional contribution of aNSC-derived newborn astrocytes and adult-born oligodendrocytes. Accumulating evidence suggests that the deregulation of aNSCs and their progeny can impact, or can be impacted by, aging and several brain pathologies, including neurodevelopmental and mood disorders, neurodegenerative diseases, and also by insults, such as epileptic seizures, stroke, or traumatic brain injury. Hence, understanding the regulatory underpinnings of aNSC activation, differentiation, and fate commitment could help identify novel therapeutic avenues for a series of pathological conditions. Over the last two decades, small non-coding RNAs (sncRNAs) have emerged as key regulators of NSC fate determination in the adult neurogenic niches. In this review, we synthesize prior knowledge on how sncRNAs, such as microRNAs (miRNAs) and piwi-interacting RNAs (piRNAs), may impact NSC fate determination in the adult brain and we critically assess the functional significance of these events. We discuss the concepts that emerge from these examples and how they could be used to provide a framework for considering aNSC (de)regulation in the pathogenesis and treatment of neurological diseases.

Glucocorticoids Promote Fear Generalization by Increasing the Size of a Dentate Gyrus Engram Cell Population

BACKGROUND

Traumatic experiences, such as conditioned threat, are coded as enduring memories that are frequently subject to generalization, which is characterized by (re-) expression of fear in safe environments. However, the neurobiological mechanisms underlying threat generalization after a traumatic experience and the role of stress hormones in this process remain poorly understood.

METHODS

We examined the influence of glucocorticoid hormones on the strength and specificity of conditioned fear memory at the level of sparsely distributed dentate gyrus (DG) engram cells in male mice.

RESULTS

We found that elevating glucocorticoid hormones after fear conditioning induces a generalized contextual fear response. This was accompanied by a selective and persistent increase in the excitability and number of activated DG granule cells. Selective chemogenetic suppression of these sparse cells in the DG prevented glucocorticoid-induced fear generalization and restored contextual memory specificity, while leaving expression of auditory fear memory unaffected.

CONCLUSIONS

These results implicate the sparse ensemble of DG engram cells as a critical cellular substrate underlying fear generalization induced by glucocorticoid stress hormones.

Early life stress decreases cell proliferation and the number of putative adult neural stem cells in the adult hypothalamus

Stress is a potent environmental factor that can confer potent and enduring effects on brain structure and function. Exposure to stress during early life (ELS) has been linked to a wide range of consequences later in life. In particular, ELS exerts lasting effects on neurogenesis in the adult hippocampus, suggesting that ELS is a significant regulator of adult neural stem cell numbers and function. Here, we investigated the effect of ELS on cell proliferation and the numbers of neural stem/precursor cells in another neurogenic region: the hypothalamus of adult mice. We show that ELS has long-term suppressive effects on cell proliferation in the hypothalamic parenchyma and reduces the numbers of putative hypothalamic neural stem/precursor cells at 4 months of age. Specifically, ELS reduced the number of PCNA + cells present in hypothalamic areas surrounding the 3rd ventricle with a specific reduction in the proliferation of Sox2+/Nestin-GFP + putative stem cells present in the median eminence at the base of the 3rd ventricle. Furthermore, ELS reduced the total numbers of β-tanycytes lining the ventral 3rd ventricle, without affecting α-tanycyte numbers in more dorsal areas. These results are the first to indicate that ELS significantly reduces proliferation and β-tanycyte numbers in the adult hypothalamus, and may have (patho)physiological consequences for metabolic regulation or other hypothalamic functions in which β-tanycytes are involved.

Circadian glucocorticoid oscillations preserve a population of adult hippocampal neural stem cells in the aging brain

A decrease in adult hippocampal neurogenesis has been linked to age-related cognitive impairment. However, the mechanisms involved in this age-related reduction remain elusive. Glucocorticoid hormones (GC) are important regulators of neural stem/precursor cells (NSPC) proliferation. GC are released from the adrenal glands in ultradian secretory pulses that generate characteristic circadian oscillations. Here, we investigated the hypothesis that GC oscillations prevent NSPC activation and preserve a quiescent NSPC pool in the aging hippocampus. We found that hippocampal NSPC populations lacking expression of the glucocorticoid receptor (GR) decayed exponentially with age, while GR-positive populations decayed linearly and predominated in the hippocampus from middle age onwards. Importantly, GC oscillations controlled NSPC activation and GR knockdown reactivated NSPC proliferation in aged mice. When modeled in primary hippocampal NSPC cultures, GC oscillations control cell cycle progression and induce specific genome-wide DNA methylation profiles. GC oscillations induced lasting changes in the methylation state of a group of gene promoters associated with cell cycle regulation and the canonical Wnt signaling pathway. Finally, in a mouse model of accelerated aging, we show that disruption of GC oscillations induces lasting changes in dendritic complexity, spine numbers and morphology of newborn granule neurons. Together, these results indicate that GC oscillations preserve a population of GR-expressing NSPC during aging, preventing their activation possibly by epigenetic programming through methylation of specific gene promoters. Our observations suggest a novel mechanism mediated by GC that controls NSPC proliferation and preserves a dormant NSPC pool, possibly contributing to a neuroplasticity reserve in the aging brain.

[Use of biotherapy in the management of Behçet's disease in a department of internal medicine]

BACKGROUND

Behçet's disease (BD) is a recurrent multisystemic disease responsible for occlusive vasculitis with arterial, venous and capillary involvement. The aim of this study was to determine the frequency and the features associated with the use of biotherapy in the management of patients followed in our department for BD.

METHODS

This is a retrospective study of patients medical records followed for BD in a department of internal medicine from January 2005 to August 2018.

RESULTS

A total of 41 patients were included with a mean age at diagnosis of 42.5±12.1 years (range 16 to 63) and a sex ratio men/women of 1.05. Oral and/or genital aphtosis was present in 70.7% of the patients. Other lesions were: ocular (78.0%), articular (46.3%), cutaneous (41.5%), central neurological (34.1%), vascular (26.8%), digestive (7.3%), pericardial (2.4%) and epididymal (2.4%). A biotherapy, interferon α and monoclonal antibodies, was used in 15 patients (36.6%), after failure of conventional treatments. The monoclonal antibodies were anti-TNFα (infliximab, adalimumab, certolizumab and golimumab) except in one patient for whom ustekinumab was used. Biotherapy was used in 46.9% of the patients with ocular involvement and never used in those patients without ocular involvement (P=0.01).

CONCLUSION

Biotherapy is effective and represents a solution to the failures of conventional treatments in severe forms of Behçet's disease with ocular involvement.

Co-administration of Anti microRNA-124 and -137 Oligonucleotides Prevents Hippocampal Neural Stem Cell Loss Upon Non-convulsive Seizures

Convulsive seizures promote adult hippocampal neurogenesis (AHN) through a transient activation of neural stem/progenitor cells (NSPCs) in the subgranular zone (SGZ) of the dentate gyrus (DG). However, in a significant population of epilepsy patients, non-convulsive seizures (ncSZ) are observed. The response of NSPCs to non-convulsive seizure induction has not been characterized before. We here studied first the short-term effects of controlled seizure induction on NSPCs fate and identity. We induced seizures of controlled intensity by intrahippocampally injecting increasing doses of the chemoconvulsant kainic acid (KA) and analyzed their effect on subdural EEG recordings, hippocampal structure, NSPC proliferation and the number and location of immature neurons shortly after seizure onset. After establishing a KA dose that elicits ncSZ, we then analyzed the effects of ncSZ on NSPC proliferation and NSC identity in the hippocampus. ncSZ specifically triggered neuroblast proliferation, but did not induce proliferation of NSPCs in the SGZ, 3 days post seizure onset. However, ncSZ induced significant changes in NSPC composition in the hippocampus, including the generation of reactive NSCs. Interestingly, intrahippocampal injection of a combination of two anti microRNA oligonucleotides targeting microRNA-124 and -137 normalized neuroblast proliferation and prevented NSC loss in the DG upon ncSZ. Our results show for the first time that ncSZ induce significant changes in neuroblast proliferation and NSC composition. Simultaneous antagonism of both microRNA-124 and -137 rescued seizure-induced alterations in NSPC, supporting their coordinated action in the regulation of NSC fate and proliferation and their potential for future seizure therapies.

Glucocorticoid-mediated modulation of morphological changes associated with aging in microglia

Microglia dynamically adapt their morphology and function during increasing age. However, the mechanisms behind these changes are to date poorly understood. Glucocorticoids (GCs) are long known and utilized for their immunomodulatory actions and endogenous GC levels are described to alter with advancing age. We here tested the hypothesis that age‐associated elevations in GC levels implicate microglia function and morphology. Our data indicate a decrease in microglial complexity and a concomitant increase in GC levels during aging. Interestingly, enhancing GC levels in young mice enhanced microglial ramifications, while the knockdown of the glucocorticoid receptor expression in old mice aggravated age‐associated microglial amoebification. These data suggest that GCs increase ramification of hippocampal microglia and may modulate age‐associated changes in microglial morphology.

[Ocular tuberculosis]

Despite extensive investigations, including the use of Interferon-gamma release assays (IGRA), the diagnosis of intraocular tuberculosis (TB) remains challenging. Ocular evidence of Mycobacterium tuberculosis in low endemic countries for TB is extremely rare, leading mostly to a TB-related ocular inflammation presumptive diagnosis. This present work aims: to highlights the main clinical patterns suggestive of ocular TB; and the latest recommended guidelines for diagnosing ocular TB to clarify interferon-gamma release assay (IGRA) contribution and accuracy to the management of intraocular TB and its diagnosis, in addition to other available diagnostic tools, such as tuberculin skin test, bacteriologic and histologic analysis from intra/extra ocular sample and radiographic investigations; to define the accuracy of these diagnostic tools according to the endemic TB prevalence; and finally to identify therapeutic strategies adapted to the main clinical presentations of ocular TB. Our review of the literature shows that management of suspected ocular TB differs significantly based on whether patients are from high or low TB prevalence countries since accuracy of chest X-ray, tuberculin skin test and IGRA is significantly different. Taking into account these discrepancies, distinct guidelines should be determined for managing patients with suspected ocular TB, taking into consideration home prevalence of TB-patients.

Associated arterial and venous cerebral manifestations in Behçet's disease

Behçet's disease is a rare multisystemic vasculitis with an etiology that is still unknown. Neurological manifestations may be seen in approximately 5-15% of patients, and both parenchymal and extraparenchymal neurological involvement has been described. When cerebral venous thrombosis (CVT) is the main extraparenchymal manifestation of Behçet's disease, the condition is then dubbed "angio-Behçet's syndrome". However, arterial involvement is extremely rare, with only one reported case of vasculo-neuro-Behçet's disease, characterized by both venous and intracranial arterial involvement - until now. This report is of two patients diagnosed with Behçet's disease characterized by the concomitant presence of both cerebral arterial manifestations and CVT.

[Therapeutic strategy for the treatment of non-infectious uveitis proposed by an expert panel]

Conventional immunosuppressive drugs, anti-TNF alpha and other biotherapies used in clinical practice are capable of controlling non-infectious anterior uveitis, posterior uveitis and panuveitis. The present work has been led by a multidisciplinary panel of experts, internists, rheumatologists and ophthalmologists and is based on a review of the literature. In case of corticodependency or sight-threatening disease, conventional immunosuppressive drugs (methotrexate, azathioprine and mycophenolate mofetil) and/or anti-TNF alpha (adalimumab, infliximab) are used to achieve and maintain remission. Interferon is an efficient immunomodulatory treatment, as a second-line therapy, for some therapeutic indications (refractory macular edema, Behçet's vascularitis). Other biologics, especially tocilizumab, are showing promising results. Local treatments (corticosteroids, sirolimus etc.) are adjuvant therapies in case of unilateral inflammatory relapse. Therapeutic response must be evaluated precisely by clinical examination and repeated complementary investigations (laser flare photometry, multimodal imaging, perimetry, electroretinography measures).

[Scleritis and systemic diseases: What should know the internist?]

Scleritis is an inflammatory disease of the sclera; outer tunic of the eye on which the oculomotor muscles are inserted. It can be associated with a systemic disease up to one time out of 3. These associated diseases are mainly rheumatoid arthritis, vasculitis, including granulomatosis with polyangiitis in the first line and spondyloarthropathies. Before mentioning such an etiology, it is necessary to eliminate an infectious cause, mainly herpetic, which is regularly underestimated. The classification of scleritis is clinical. We distinguish between anterior scleritis and posterior scleritis. Anterior scleritis is diffuse or nodular, usually of good prognosis. Anterior necrotizing scleritis with inflammation is often associated with an autoimmune disease, necrotizing scleritis without inflammation usually reflects advanced rheumatoid arthritis. The treatment of these conditions requires close collaboration between internists and ophthalmologists to decide on the use of corticosteroid therapy with or without immunosuppressors or biotherapies.

[Management of orbital inflammation in internal medicine. Proposal for a diagnostic work-up]

Inflammatory orbitopathies relate to an inflammatory state originating within the orbit and its adnexes, except the inner ocular globe. Orbital inflammation (OI) may be either localized manifestation of a proven or like autoimmune disease, or local response from immune system against infectious, structural or tumoral antigens. We review the clinical manifestations of OI, which provide helpful clues to the diagnosis and describe the inflammatory, infectious and neoplastic conditions classically associated with OI. Autoimmune diseases are probably the most common causes of OI associated with a bilateral dacryoadenitis (e.g., sarcoidosis, granulomatosis with polyangiitis, IgG4-related disease). We focused on a major part of the IgG4-RD spectrum, the IgG4-related orbital disease which has been recently described and the idiopathic orbital inflammation syndrome that one should consider in patients 40 years of age or older with non specific inflammation OI on biopsy but without underlying local or systemic disease. An algorithm for the diagnostic approach of OI was proposed. If systemic explorations fail to diagnose an underlying disease, histopathologic control is required for distinguishing non-specific OI from other differential diagnosis, especially lymphoma. In the cases of pure myositic locations and posteriorly located tumours where biopsy could damage to the optic nerve, analysis of orbital lesions in T2W IRM sequence may be helpful to distinguish idiopathic OI (IOI) from lymphoma. When the diagnostic work-up fails, a corticosteroid trial could be used, but its beneficial effect has to be cautiously interpretated before definitively diagnosing IOI. Finally, treatments used in main infllammatory orbitopathies were also reviewed.

[Hyper-IgE in internal medicine]

Hyper-IgE may be found under many pathological conditions. The role of IgE is essentially associated with the occurrence of allergic manifestations, which may be accompanied by an increase of their serum levels. Elevation of total IgE has also been reported in association with certain rare genetic immune deficiencies called hyper-IgE syndromes. Other circumstances such as infectious diseases, tumors or autoimmune diseases may also be accompanied by an excessive synthesis of IgE. Considering the diversity of these situations, discussion of the prognostic value of total IgE is useful to the internist.

miRNA-Mediated Regulation of Adult Hippocampal Neurogenesis; Implications for Epilepsy

Hippocampal neural stem/progenitor cells (NSPCs) proliferate and differentiate to generate new neurons across the life span of most mammals, including humans. This process takes place within a characteristic local microenvironment where NSPCs interact with a variety of other cell types and encounter systemic regulatory factors. Within this microenvironment, cell intrinsic gene expression programs are modulated by cell extrinsic signals through complex interactions, in many cases involving short non-coding RNA molecules, such as miRNAs. Here we review the regulation of gene expression in NSPCs by miRNAs and its possible implications for epilepsy, which has been linked to alterations in adult hippocampal neurogenesis.

[Quality of life measures in SLE: An update]

Systemic lupus erythematosus (SLE) is a chronic disease that considerably hampers patient's daily living. Qualitative studies with patients' interviews have been conducted to describe the experiences and perspectives of adults living with SLE. Among existing generic and disease-specific quality of life (QOL) questionnaires, none succeeded to exhaustively measure patient's preoccupations. However, these tools are useful to quantify the burden of the disease. Social precariousness, socioeconomic status and education level are intimately correlated to QOL measures, either generic or disease-specific. Musculoskeletal disease activity is also associated with a lower QOL. Using disease-specific tools may be useful because of a better aptitude to record an improvement in health status. Moreover, using generic and disease-specific questionnaires together may help to identify factors associated with a lower quality of life but not related to SLE from the patient's perspective (such as smoking or obesity). Developing new ways of recording QOL data in the future may help to evaluate the real benefit of using QOL scales in daily practice.