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The barrier between the blood and the ventricular cerebrospinal fluid (CSF) is located at the choroid plexuses. At the interface between two circulating fluids, these richly vascularized veil-like structures display a peculiar morphology explained by their developmental origin, and fulfill several functions essential for CNS homeostasis. They form a neuroprotective barrier preventing the accumulation of noxious compounds into the CSF and brain, and secrete CSF, which participates in the maintenance of a stable CNS internal environment. The CSF circulation plays an important role in volume transmission within the developing and adult brain, and CSF compartments are key to the immune surveillance of the CNS. In these contexts, the choroid plexuses are an important source of biologically active molecules involved in brain development, stem cell proliferation and differentiation, and brain repair. By sensing both physiological changes in brain homeostasis and peripheral or central insults such as inflammation, they also act as sentinels for the CNS. Finally, their role in the control of immune cell traffic between the blood and the CSF confers on the choroid plexuses a function in neuroimmune regulation and implicates them in neuroinflammation. The choroid plexuses, therefore, deserve more attention while investigating the pathophysiology of CNS diseases and related comorbidities.

There are only few data concerning persistence of neutralizing antibodies (NAbs) among SARS-CoV-2-infected healthcare workers (HCW). These individuals are particularly exposed to SARS-CoV-2 infection and at potential risk of reinfection. We followed 26 HCW with mild COVID-19 three weeks (D21), two months (M2) and three months (M3) after the onset of symptoms. All the HCW had anti-receptor binding domain (RBD) IgA at D21, decreasing to 38.5% at M3 ( p  < 0.0001). Concomitantly a significant decrease in NAb titers was observed between D21 and M2 ( p  = 0.03) and between D21 and M3 ( p  < 0.0001). Here, we report that SARS-CoV-2 can elicit a NAb response correlated with anti-RBD antibody levels. However, this neutralizing activity declines, and may even be lost, in association with a decrease in systemic IgA antibody levels, from two months after disease onset. This short-lasting humoral protection supports strong recommendations to maintain infection prevention and control measures in HCW, and suggests that periodic boosts of SARS-CoV-2 vaccination may be required. The humoral immune response to SARS-CoV-2 infection is not yet fully understood. Here, Marot et al. monitor the longitudinal profile and neutralizing activity of IgG, IgA, and IgM among 26 healthcare workers and provide evidence for a short-lasting humoral immune protection due to a decrease of neutralizing antibody titers within 3 months.

Studying ciliary genes in the context of the human central nervous system is crucial for understanding the underlying causes of neurodevelopmental ciliopathies. Here, we use pluripotent stem cell-derived spinal organoids to reveal distinct functions of the ciliopathy gene RPGRIP1L in humans and mice, and uncover an unexplored role for cilia in human axial patterning. Previous research has emphasized Rpgrip1l critical functions in mouse brain and spinal cord development through the regulation of SHH/GLI pathway. Here, we show that RPGRIP1L is not required for SHH activation or motoneuron lineage commitment in human spinal progenitors and that this feature is shared by another ciliopathy gene, TMEM67 . Furthermore, human RPGRIP1L -mutant motoneurons adopt hindbrain and cervical identities instead of caudal brachial identity. Temporal transcriptome analysis reveals that this antero-posterior patterning defect originates in early axial progenitors and correlates with cilia loss. These findings provide important insights into the role of cilia in human neural development. Studying cilia in human neural development is key to understanding ciliopathies. Here, using stem cell-derived human and mouse spinal organoids, the authors reveal inter-species differences for ciliopathy genes and a role for cilia in human axial patterning.

Anorectal malformation (ARM) is the most common symptom in VACTERL syndrome (vertebral, anal, cardiac, tracheo-esophageal fistula, renal, and limb anomalies). The association of ARM and spinal dysraphisms (DYS) is well documented. We aim to better evaluate children with VACTERL association and ARM, considering the presence or not of DYS. Between 2000 and 2015, 279 children with VACTERL associations were identified in Necker Children’s Hospital, Paris. We identified 61 VACTERL children (22%) with ARM. A total of 52 VACTERL children with ARM were included. DYS were identified in 36/52 of cases (69.2%). A total of 33 (63.5%) VACTERL children presented with sphincterial dysfunction. We constated that 28/33 (84.8%) of them had DYS + (p < 0.0001). More children in ARM (DYS +) subgroup are presenting with initial urinary sphincter dysfunction (58 vs 19%, p < 0.009) than ARM (DYS -). We identified 29 lipoma filum in our series, which were not statistically associated with urinary disorders (p = 0.143).Conclusion: We propose to refine the definition of VACTERL association, by adding S as Spinal defect to include it as an integral part of this syndrome, resulting in a novel acronym V.A.C.TE.R.L.S.What is Known:• The VACTERL association: congenital anomalies of the bony vertebral column (V), anorectal malformation (A), congenital cardiopathy (C), tracheo-esophageal defects (TE), renal and urinary tract anomalies (R), and limb malformations (L).• VACTERL children needs a complete appraisal, as early as possible, to adopt the most appropriate therapeutic management.What is New:• Include spine dysraphism (DYS) as a part of this syndrome, resulting in a novel acronym V.A.C.TE.R.L.S.• The significant correlation between VACTERL/DYS and urinary dysfunction requires to investigate the spine cord prenatally.

The nervous system is divided into the central nervous system (CNS) composed of the brain, the brainstem, the cerebellum, and the spinal cord and the peripheral nervous system (PNS) made up of the different nerves arising from the CNS. The PNS is divided into the cranial nerves III to XII supplying the head and the spinal nerves that supply the upper and lower limbs. The general anatomy of the PNS is organized according to the arrangement of the fibers along the rostro-caudal axis. The control of the development of the PNS has been unravelled during the last 30 years. Motor nerves arise from the ventral neural tube. This ventralization is induced by morphogenetic molecules such as sonic hedgehog. In contrast, the sensory elements of the PNS arise from a specific population of cells originating from the roof of the neural tube, namely the neural crest. These cells give rise to the neurons of the dorsal root ganglia, the autonomic ganglia and the paraganglia including the adrenergic neurons of the adrenals. Furthermore, the supportive glial Schwann cells of the PNS originate from the neural crest cells. Growth factors as well as myelinating proteins are involved in the development of the PNS.

Cerebellar hypoplasia and dysplasia are hallmark features of neurodevelopmental ciliopathies such as Joubert syndrome. These disorders are caused by biallelic mutations in genes regulating the function of the primary cilium, a near-ubiquitous antenna-like organelle involved in signal reception and transduction. However, the pathogenetic mechanisms linking ciliary gene dysfunction to Joubert syndrome neurodevelopmental defects are poorly understood. Here, we generate cerebellar organoids from human induced pluripotent stem cells carrying either null mutations or patient-derived variants in RPGRIP1L, a Joubert syndrome-associated gene encoding a scaffold protein crucial for ciliary function. While control organoids robustly express markers of cerebellar glutamatergic and GABAergic lineages including Purkinje cells, RPGRIP1L-deficient organoids display a consistent and severe reduction in Purkinje cell markers, accompanied by impaired neurogenesis and increased progenitor proliferation. These defects coincide with prolonged overactivation of the FGF/MAPK signaling pathway, consistent with the enrichment of MEK1/2 pathway effector at cilia base. Pharmacological inhibition of FGF receptors reduces MEK1/2 activation at cilia base and rescues both the proliferative-neurogenic balance and Purkinje lineage formation in RPGRIP1L-deficient organoids. Together, our findings reveal FGF/MAPK signaling modulation at the ciliary base in neural progenitors and identify early FGF pathway overactivation as a key driver of cerebellar differentiation defects in an in vitro human model of Joubert syndrome. This provides new insight into the developmental origin of cerebellar impairment in neurodevelopmental ciliopathies.

Primary cilia are essential signaling organelles that mediate key developmental pathways, including Sonic Hedgehog (SHH) and WNT, and are crucial for tissue patterning and homeostasis. Ciliary dysfunction underlies a spectrum of human ciliopathies - such as Joubert syndrome (JBTS) and Meckel syndrome (MKS) - which present with profound neurodevelopmental abnormalities. Although the role of cilia in SHH-dependent ventral spinal cord patterning is well established, their contribution to dorsal spinal cord development, particularly in human systems, remains poorly defined. To address this gap, we utilized human spinal organoids to investigate the function of a ciliopathy-associated protein in dorsal neural tube patterning downstream of BMP4, independent of exogenous SHH. Using TMEM67 knockout human iPSC-derived dorsal spinal organoids, we demonstrate that loss of TMEM67 disrupts the specification of dorsal interneurons, most notably within the dI1 lineage, while concomitantly expanding intermediate dorsal progenitor populations (dI4-dI6). These patterning defects are associated with defective roof plate induction and attenuated BMP4 signaling. Mechanistically, TMEM67 deficiency alters ciliary morphology, decreases cilia number, and impairs recruitment of BMPR2 to the ciliary base, suggesting a direct role for cilia in modulating BMP-induced dorsal spinal patterning. Together, these findings provide new mechanistic insights into the pathogenesis of ciliopathies and underscore the value of human organoid models for elucidating human-specific aspects of neurodevelopmental disorders.Competing Interest StatementThe authors have declared no competing interest.