The role of tryptophan metabolism and tolerogenic dendritic cells in maintaining immune tolerance: Insights into celiac disease pathogenesis.

BACKGROUND: In mammals, amino acid metabolism has evolved to control immune responses. Tryptophan (Trp) is the rarest essential amino acid found in food and its metabolism has evolved to be a primary regulatory node in the control of immune responses. Celiac disease (CeD) is a developed immunological condition caused by gluten intolerance and is linked to chronic small intestine enteropathy in genetically predisposed individuals. Dendritic cells (DCs), serving as the bridge between innate and adaptive immunities, can influence immunological responses in CeD through phenotypic alterations. OBJECTIVE: This review aims to highlight the connection between Trp metabolism and tolerogenic DCs, and the significance of this interaction in the pathogenesis of CeD. RESULTS: It is been recognized that various DC subtypes contribute to the pathogenesis of CeD. Tolerogenic DCs, in particular, are instrumental in inducing immune tolerance, leading to T-reg differentiation that helps maintain intestinal immune tolerance against inflammatory responses in CeD patients and those with other autoimmune disorders. T-regs, a subset of T-cells, play a crucial role in maintaining intestinal immunological homeostasis by regulating the activities of other immune cells. Notably, Trp metabolism, essential for T-reg function, facilitates T-reg differentiation through microbiota-mediated degradation and the kynurenine pathway. CONCLUSION: Therefore, alterations in Trp metabolism could potentially influence the immune response in CeD, affecting both the development of the disease and the persistence of symptoms despite adherence to a gluten-free diet.

Myrtenol Inhalation Mitigates Asthma-Induced Cognitive Impairments: an Electrophysiological, Behavioral, Histological, and Molecular Study.

Asthma is an inflammatory disorder with significant health problems. It generally affects the lungs but can also impact brain performance via several mechanisms. Some investigations have proposed that asthma impairs cognition. This study assessed the impacts of myrtenol as a monoterpene on cognitive disorders following asthma at behavioral, molecular, and synaptic levels. Asthma was induced by injection and inhalation of ovalbumin (OVA). Male Wistar rats were allocated to five groups: control, asthma, asthma/vehicle, asthma/myrtenol, and asthma/budesonide. Myrtenol (8 mg/kg) or budesonide (160 µg/kg) was administered through inhalation once a day for 1 week, and at the end of the inhalation period, behavioral tests (MWM and Open Field), field potential recording, hippocampal brain-derived neurotrophic factor (BDNF), IL1ß (ELISA), and NFκB measurement (Western blot) were performed to evaluate cognitive performance. Moreover, H&E (hematoxylin and eosin) staining was used for hippocampus histological evaluation. Myrtenol improved spatial learning, memory, LTP (long-term potentiation) impairments, and anxiety-like behaviors following asthma. Myrtenol inhalation increased the BDNF level and decreased the IL1ß level and NFκB expression in the hippocampus of the asthmatic rats. The neuronal damage in the hippocampus following allergic asthma was alleviated via myrtenol administration. Myrtenol, as an herbal extract, protects the hippocampus from asthma consequences. Our observations revealed that myrtenol can improve spatial learning, memory, synaptic plasticity impairments, and anxiety-like behaviors following asthma. We believe that these ameliorating effects of myrtenol can be attributed to inflammation suppression and increased BDNF in the hippocampus.

The effect of phonological awareness on rapid automatized naming.

Background: Phonological awareness (PA) is a fundamental predictor of reading disability. However, researches on reading have indicated that PA assessment alone is not sufficient to prevent reading problems. Rapid automatized naming (RAN) has been suggested as another influential factor in reading deficits independent of PA. This study investigated the impact of phonological awareness on rapid automatized naming. Methods: This was a randomized clinical trial study in which 62 Persian monolingual first graders were recruited from 3 schools using convenience sampling. Inclusion criteria were lack of deficits with sensory-motor skills and knowledge of the Persian alphabets. Measures of PA and RAN were utilized. The participants were randomly assigned into either the intervention or the control group. The intervention group was divided into small groups of 4-6 children who received thirty 40-minute training sessions in PA. T test, Mann-Whitney, and Wilcoxon tests were used for data analysis. Results: The results revealed that the RAN time was significantly reduced (p≤0.001), with a significant increase in PA scores (p≤0.001). In addition, there was a significant inverse relationship between some of the measures of the phonological awareness subtests and rapid automatized naming (eg, phonemic blending & RAN (numbers): ρ=-0.52 with p≤0.001). Conclusion: The findings showed that in the initial assessment, PA and RAN had a significant relationship, but RAN could be significantly improved by PA training.