Interleukin-17a Induces Neuronal Differentiation of Induced-Pluripotent Stem Cell-Derived Neural Progenitors From Autistic and Control Subjects

Spatial profiling reveals tissue-specific neuro-immune interactions in gastroenteropancreatic neuroendocrine tumors

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are heterogeneous malignancies that arise from complex cellular interactions within the tissue microenvironment. Here, we sought to decipher tumor-derived signals from the surrounding microenvironment by applying digital spatial profiling (DSP) to hormone-secreting and non-functional GEP-NETs. By combining this approach with in vitro studies of human-derived organoids, we demonstrated the convergence of cell autonomous immune and pro-inflammatory proteins that suggests their role in neuroendocrine differentiation and tumorigenesis. DSP was used to evaluate the expression of 40 neural- and immune-related proteins in surgically resected duodenal and pancreatic NETs (n = 20) primarily consisting of gastrinomas (18/20). A total of 279 regions of interest were examined between tumors, adjacent normal and abnormal-appearing epithelium, and the surrounding stroma. The results were stratified by tissue type and multiple endocrine neoplasia I (MEN1) status, whereas protein expression was validated by immunohistochemistry (IHC). A tumor immune cell autonomous inflammatory signature was further evaluated by IHC and RNAscope, while functional pro-inflammatory signaling was confirmed using patient-derived duodenal organoids. Gastrin-secreting and non-functional pancreatic NETs showed a higher abundance of immune cell markers and immune infiltrate compared with duodenal gastrinomas. Compared with non-MEN1 tumors, MEN1 gastrinomas and preneoplastic lesions showed strong immune exclusion and upregulated expression of neuropathological proteins. Despite a paucity of immune cells, duodenal gastrinomas expressed the pro-inflammatory and pro-neural factor IL-17B. Treatment of human duodenal organoids with IL-17B activated NF-κB and STAT3 signaling and induced the expression of neuroendocrine markers. In conclusion, multiplexed spatial protein analysis identified tissue-specific neuro-immune signatures in GEP-NETs. Duodenal gastrinomas are characterized by an immunologically cold microenvironment that permits cellular reprogramming and neoplastic transformation of the preneoplastic epithelium. Moreover, duodenal gastrinomas cell autonomously express immune and pro-inflammatory factors, including tumor-derived IL-17B, that stimulate the neuroendocrine phenotype. © 2024 The Pathological Society of Great Britain and Ireland.

Neuroimmune mechanisms in autism etiology - untangling a complex problem using human cellular models

Autism spectrum disorder (ASD) affects 1 in 36 people and is more often diagnosed in males than in females. Core features of ASD are impaired social interactions, repetitive behaviors and deficits in verbal communication. ASD is a highly heterogeneous and heritable disorder, yet its underlying genetic causes account only for up to 80% of the cases. Hence, a subset of ASD cases could be influenced by environmental risk factors. Maternal immune activation (MIA) is a response to inflammation during pregnancy, which can lead to increased inflammatory signals to the fetus. Inflammatory signals can cross the placenta and blood brain barriers affecting fetal brain development. Epidemiological and animal studies suggest that MIA could contribute to ASD etiology. However, human mechanistic studies have been hindered by a lack of experimental systems that could replicate the impact of MIA during fetal development. Therefore, mechanisms altered by inflammation during human pre-natal brain development, and that could underlie ASD pathogenesis have been largely understudied. The advent of human cellular models with induced pluripotent stem cell (iPSC) and organoid technology is closing this gap in knowledge by providing both access to molecular manipulations and culturing capability of tissue that would be otherwise inaccessible. We present an overview of multiple levels of evidence from clinical, epidemiological, and cellular studies that provide a potential link between higher ASD risk and inflammation. More importantly, we discuss how stem cell-derived models may constitute an ideal experimental system to mechanistically interrogate the effect of inflammation during the early stages of brain development.

Exogenous IL-17A Alleviates Social Behavior Deficits and Increases Neurogenesis in a Murine Model of Autism Spectrum Disorders

Among the proposed mechanisms for autism spectrum disorders (ASD) is immune dysregulation. The proinflammatory cytokine Interleukine-17A (IL-17A) was shown to play a key role in mediating immune-related neurodevelopmental impairment of social behavior. Nevertheless, post-developmental administration of IL-17A was found to increase social behavior. In the present study, we explored the effect of post-developmental administration of IL-17A on ASD-like behaviors induced by developmental exposure to valproic acid (VPA) at postnatal day 4. At the age of seven weeks, VPA-exposed mice were intravenously injected twice with recombinant murine IL-17A (8 μg), and a week later, they were assessed for ASD-like behavior. IL-17A administration increased social behavior and alleviated the ASD-like phenotype. Behavioral changes were associated with increased serum levels of IL-17 and Th17-related cytokines. Exogenous IL-17A also increased neuritogenesis in the dendritic tree of doublecortin-expressing newly formed neurons in the dentate gyrus. Interestingly, the effect of IL-17A on neuritogenesis was more noticeable in females than in males, suggesting a sex-dependent effect of IL-17A. In conclusion, our study suggests a complex role for IL-17A in ASD. While contributing to its pathology at the developmental stage, IL-17 may also promote the alleviation of behavioral deficits post-developmentally by promoting neuritogenesis and synaptogenesis in the dentate gyrus.

Visualization of maternal IL-17a across the placental membrane

IL-17a is a pro-inflammatory cytokine produced primarily by T helper-17 cells. Several studies have shown that maternal IL-17a, associated with maternal immune activation (MIA), affects the developing brain. However, the mechanisms underlying maternal IL-17a signaling remain partially unknown. This study detected trans-placental IL-17a passage using luminescent activity studies and an in vitro transfer assay. First, the luminescent activity was observed using LiCoR dye-conjugated IL-17a injected into pregnant mice. IL-17a luminescent activity was highly detected in the placenta and isolated fetus, but positive control IgG and negative control IgM showed low or no luminescence in the placenta and fetus, respectively. Next, IL-17a transmission across the placenta was investigated using a transwell experiment with trophoblast BeWo cells and primary trophoblast cells. Significant amounts of IL-17a were detected in the lower compartment. And in various placenta cell lines, IL-17a treatment significantly increased IL-17RA mRNA expression. However, it did not affect IL-17RC mRNA expression.This study showed that elevated IL-17a increased the IL-17RA expression in the trophoblast and may accumulate in the placenta. Furthermore, these results indicate the molecular basis of an important role in IL-17a/IL-17RA in the maternal placenta.

Effects of arginine vasopressin on the transcriptome of prefrontal cortex in autistic rat model

Our previous studies have also demonstrated that AVP can significantly improve social interaction disorders and stereotypical behaviours in rats with VPA‐induced autism model. To further explore the mechanisms of action of AVP, we compared the PFC transcriptome changes before and after AVP treatment in VPA‐induced autism rat model. The autism model was induced by intraperitoneally injected with VPA at embryonic day 12.5 and randomly assigned to two groups: the VPA‐induced autism model group and the AVP treatment group. The AVP treatment group were treated with intranasal AVP at postnatal day 21 and for 3 weeks. The gene expression levels and function changes on the prefrontal cortex were measured by RNA‐seq and bioinformatics analysis at PND42 and the mRNA expression levels of synaptic and myelin development related genes were validated by qPCR. Our results confirmed that AVP could significantly improve synaptic and axon dysplasia and promote oligodendrocyte development in the prefrontal cortex in VPA‐induced autism models by regulating multiple signalling pathways.