An et al. Journal of Neuroinflammation (2020) 17:147 Page 2 of 14 Page 3. H37RA (Cohesion Biosciences, CA, England). Pertussis toxin (500 ng; List Biological Laboratories Inc., CA, USA) was administered intraperitoneally on the day of immunization and 48 h later
Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system characterized by severe white matter demyelination. Because of its complex pathogenesis, there is no definite cure for MS. Experimental autoimmune encephalomyelitis (EAE) is an ideal animal model for the study of MS. Arsenic trioxide (ATO) is an ancient Chinese medicine used for its therapeutic properties with several autoimmune diseases. It is also used to inhibit acute immune rejection due to its anti-inflammatory and immunosuppressive properties. However, it is unclear whether ATO has a therapeutic effect on EAE, and the underlying mechanisms have not yet been clearly elucidated. In this study, we attempted to assess whether ATO could be used to ameliorate EAE in mice. ATO (0.5 mg/kg/day) was administered intraperitoneally to EAE mice 10 days post-immunization for 8 days. On day 22 post-immunization, the spinal cord, spleen, and blood were collected to analyze demyelination, inflammation, microglia activation, and the proportion of CD4+ T cells. In vitro, for mechanistic studies, CD4+ T cells were sorted from the spleen of naïve C57BL/6 mice and treated with ATO and then used for an apoptosis assay, JC-1 staining, imaging under a transmission electron microscope, and western blotting. ATO delayed the onset of EAE and alleviated the severity of EAE in mice. Treatment with ATO also attenuated demyelination, alleviated inflammation, reduced microglia activation, and decreased the expression levels of IL-2, IFN-γ, IL-1β, IL-6, and TNF-α in EAE mice. Moreover, the number and proportion of CD4+ T cells in the spinal cord, spleen, and peripheral blood were reduced in ATO-treated EAE mice. Finally, ATO induced CD4+ T cell apoptosis via the mitochondrial pathway both in vitro and in vivo. Additionally, the administration of ATO had no adverse effect on the heart, liver, or kidney function, nor did it induce apoptosis in the spinal cord. Overall, our findings indicated that ATO plays a protective role in the initiation and progression of EAE and has the potential to be a novel drug in the treatment of MS.
Associative and plastic thalamic signaling to the lateral amygdala controls fear behavior
Decades of research support the idea that associations between a conditioned stimulus (CS) and an unconditioned stimulus (US) are encoded in the lateral amygdala (LA) during fear learning. However, direct proof for the sources of CS and US information is lacking. Definitive evidence of the LA as the primary site for cue association is also missing. Here, we show that calretinin (Calr)-expressing neurons of the lateral thalamus (Calr+LT neurons) convey the association of fast CS (tone) and US (foot shock) signals upstream from the LA in mice. Calr+LT input shapes a short-latency sensory-evoked activation pattern of the amygdala via both feedforward excitation and inhibition. Optogenetic silencing of Calr+LT input to the LA prevents auditory fear conditioning. Notably, fear conditioning drives plasticity in Calr+LT neurons, which is required for appropriate cue and contextual fear memory retrieval. Collectively, our results demonstrate that Calr+LT neurons provide integrated CS-US representations to the LA that support the formation of aversive memories.
Human intestinal enteroids as a model of Clostridioides difficile-induced enteritis
Clostridioides difficile is an important nosocomial pathogen that produces toxins to cause life-threatening diarrhea and colitis. Toxins bind to epithelial receptors and promote the collapse of the actin cytoskeleton. C. difficile toxin activity is commonly studied in cancer-derived and immortalized cell lines. However, the biological relevance of these models is limited. Moreover, no model is available for examining C. difficile-induced enteritis, an understudied health problem. We hypothesized that human intestinal enteroids (HIEs) express toxin receptors and provide a new model to dissect C. difficile cytotoxicity in the small intestine. We generated biopsy-derived jejunal HIE and Vero cells, which stably express LifeAct-Ruby, a fluorescent label of F-actin, to monitor actin cytoskeleton rearrangement by live-cell microscopy. Imaging analysis revealed that toxins from pathogenic C. difficile strains elicited cell rounding in a strain-dependent manner, and HIEs were tenfold more sensitive to toxin A (TcdA) than toxin B (TcdB). By quantitative PCR, we paradoxically found that HIEs expressed greater quantities of toxin receptor mRNA and yet exhibited decreased sensitivity to toxins when compared with traditionally used cell lines. We reasoned that these differences may be explained by components, such as mucins, that are present in HIEs cultures, that are absent in immortalized cell lines. Addition of human-derived mucin 2 (MUC2) to Vero cells delayed cell rounding, indicating that mucus serves as a barrier to toxin-receptor binding. This work highlights that investigation of C. difficile infection in that HIEs can provide important insights into the intricate interactions between toxins and the human intestinal epithelium.NEW & NOTEWORTHY In this article, we developed a novel model of Clostridioides difficile-induced enteritis using jejunal-derived human intestinal enteroids (HIEs) transduced with fluorescently tagged F-actin. Using live-imaging, we identified that jejunal HIEs express high levels of TcdA and CDT receptors, are more sensitive to TcdA than TcdB, and secrete mucus, which delays toxin-epithelial interactions. This work also optimizes optically clear C. difficile-conditioned media suitable for live-cell imaging.
Platelets are critical for survival and tissue integrity during murine pulmonary Aspergillus fumigatus infection
Tischler, BY;Tosini, NL;Cramer, RA;Hohl, TM;
Plos Pathogens16e1008544May 1, 2020
Product: Diphtheria Toxin, Unnicked, from Corynebacterium diphtheriae
To model thrombocytopenia by diphtheria toxin receptor-mediated megakaryocyte depletion, PF4-iCre mice were crossed to ROSA26iDTR (iDTR) mice (iDTR Pf4 ). On the first day of depletion, 400 ng of diphtheria toxin (DT) (List Biological Laboratories, Cat. No Cached
Beyond their canonical roles in hemostasis and thrombosis, platelets function in the innate immune response by interacting directly with pathogens and by regulating the recruitment and activation of immune effector cells. Thrombocytopenia often coincides with neutropenia in patients with hematologic malignancies and in allogeneic hematopoietic cell transplant recipients, patient groups at high risk for invasive fungal infections. While neutropenia is well established as a major clinical risk factor for invasive fungal infections, the role of platelets in host defense against human fungal pathogens remains understudied. Here, we examined the role of platelets in murine Aspergillus fumigatus infection using two complementary approaches to induce thrombocytopenia without concurrent neutropenia. Thrombocytopenic mice were highly susceptible to A. fumigatus challenge and rapidly succumbed to infection. Although platelets regulated early conidial phagocytosis by neutrophils in a spleen tyrosine kinase (Syk)-dependent manner, platelet-regulated conidial phagocytosis was dispensable for host survival. Instead, our data indicated that platelets primarily function to maintain hemostasis and lung integrity in response to exposed fungal antigens, since thrombocytopenic mice exhibited severe hemorrhage into the airways in response to fungal challenge in the absence of overt angioinvasion. Challenge with swollen, heat-killed, conidia was lethal in thrombocytopenic hosts and could be reversed by platelet transfusion, consistent with the model that fungus-induced inflammation in platelet-depleted mice was sufficient to induce lethal hemorrhage. These data provide new insights into the role of platelets in the anti-Aspergillus host response and expand their role to host defense against filamentous molds.
NAD+ attenuates experimental autoimmune encephalomyelitis through induction of CD11b+ gr-1+ myeloid-derived suppressor cells
Louis, MO) containing 400 μg of Mycobacterium tuberculosis H37Ra. Furthermore, an intraperitoneal injection of 0.5 ml pertussis toxin (PT) (List Biological Labs, Inc, San Josa, CA) was given at the beginning of the induction and 48 h later
Abstract Objective: To investigate the effects of nicotinamide adenine dinucleotide (NAD+) on the pathogenesis of the animal model for multiple sclerosis (MS)-experimental autoimmune encephalomyelitis (EAE). Methods: EAE model was induced by myelin oligodendrocyte protein (MOG 35-55). Clinical scores of EAE were measured in mice with or without NAD+ treatment. Hematoxylin and Eosin (HE) and Luxol Fast Blue (LFB) staining were performed to assess inflammation and demyelination, respectively. Expressions of target proteins were measured by Western blot. The numbers of myeloid-derived suppressor cells (MDSCs) were measured by immunofluorescent staining and flow cytometry. Enzyme-linked immunosorbent assay (ELISA) was used to measure the expressions of inflammatory cytokine in serum. Results: NAD+ treatment could decrease inflammatory cells and demyelination foci, attenuate the clinical scores of EAE and slightly delay disease onset. Western blot showed that NAD+ treatment up-regulated the expression of phosphorylated-STAT6 (p-STAT6) and SIRT1. Besides, NAD+ treatment up-regulated the expression of p-IκB and down-regulated the expression of p-NF-κB. In addition, NAD+ treatment could increase the numbers of CD11b+ gr-1+ MDSCs and the expression of Arginase-1. Moreover, NAD+ treatment up-regulated the expressions of IL-13 and down-regulated the expression of IFN-γ and IL-17. Conclusions: The present study demonstrated that NAD+ treatment may induce the CD11b+ gr-1+ MDSCs to attenuate EAE via activating the phosphorylation of STAT6 expression. Therefore, NAD+ should be considered as a potential novel therapeutic strategy for MS.