Biology subjects

Castellano, B.

Publications and source records attributed to Castellano, B..

4 recordsLinked to original sources

bioRxiv2024

Chronic IL-6 overproduction induces a tolerogenic response in aged mice after peripheral nerve injury

Highlights/Main pointsO_LIAstrocyte-targeted IL-6 overproduction during aging increases basal microglial acivation in the facial nucleus. C_LIO_LIDuring aging, chronic IL-6 overproduction does not modify microglial response after peripheral nerve injury but increases T-lymphocyte infiltration. C_LIO_LIChronic IL-6 overproduction in aged mice does not modify facial motor neuron survival after facial nerve axotomy. C_LI Interleukin-6 (IL-6) is the main cytokine controlling neuroinflammation and microglial activation during aging, and the increase of IL-6 levels correlate well with chronic neuroinflammation and age-related neurodegenerative diseases. Despite the relevance of IL-6 in these conditions, the effect of this cytokine in microglia activation and neuroinflammation upon CNS injuries during aging has been scarcely explored. Previous results from our group showed that adult and aged transgenic mice with astrocyte-targeted overproduction of IL-6 (GFAP-IL6Tg) presented features of a primed microglial phenotype in basal conditions compared to wild-type (WT) mice, and that after CNS lesions, microglia showed and exacerbated response associated with increased neuronal death in adult mice. In this work, we aimed to study whether chronic IL-6 overproduction influenced microglia response to CNS injury during aging. With this aim, we performed facial nerve axotomy (FNA) in aged 21-23-month-old WT and GFAP-IL6Tg animals, and analysed facial motor neuron (FMN) survival, glial reactivity, antigen presentation, and lymphocyte infiltration both at basal conditions (non-lesioned) and after FNA. Our results showed that non-lesioned aged transgenic mice presented higher Iba1, CD11b, and CD68 levels than aged WT mice, indicative of a priming effect in the aged facial nucleus. After FNA, we detected similar levels of microglial and astroglia activation, but a remarkable increase in T-lymphocyte infiltration in GFAP-IL6Tg axotomized group. Despite slight differences in the neuroinflammatory response, aged GFAP-IL6Tg animals showed a similar rate of FMN death compared to aged WT mice. Overall, our work shows that transgenic IL-6 overproduction induces a primed microglial phenotype under basal conditions in aged animals, with a reduced fold-increase in the microglial response after FNA compared to aged WT mice and similar lesion outcomes, suggestive of a tolerant microglial phenotype. This study suggests a tolerant effect of chronic IL-6 overproduction in microglia during aging in basal conditions and after CNS lesions.

neuroscience↗

bioRxiv2023

Tau expression and phosphorylation in enteroendocrine cells

Background and objectiveThere is mounting evidence to suggest that the gut-brain axis is involved in the development of Parkinsons disease (PD). In this regard, the enteroendocrine cells (EEC), which faces the gut lumen and are connected with both enteric neurons and glial cells have received growing attention. The recent observation showing that these cells express alpha-synuclein, a presynaptic neuronal protein genetically and neuropathologically linked to PD came to reinforce the assumption that EEC might be a key component of the neural circuit between the gut lumen and the brain for the bottom-up propagation of PD pathology. Besides alpha-synuclein, tau is another key protein involved in neurodegeneration and converging evidences indicate that there is an interplay between these two proteins at both molecular and pathological levels. There are no existing studies on tau in EEC and therefore we set out to examine the isoform profile and phosphorylation state of tau in these cells. MethodsSurgical specimens of human colon from control subjects were analyzed by immunohistochemistry using a panel of anti-tau antibodies together with chromogranin A and Glucagon-like peptide-1 (two EEC markers) antibodies. To investigate tau phosphorylation and expression further, two EEC lines, namely GLUTag and NCI-H716 were analyzed by western blot after dephosphorylation with pan-tau and tau isoform specific antibodies. Eventually, GLUTag were treated with propionate and butyrate, two short chain fatty acids known to sense EEC, and analyzed at different time points by western blot with an antibody specific for tau phosphorylated at Thr205. ResultsWe found that tau is expressed and phosphorylated in EEC in adult human colon and that both EEC lines mainly express two tau isoforms that are phosphorylated under basal condition. Both propionate and butyrate regulated tau phosphorylation state by decreasing its phosphorylation at Thr205. Conclusion and inferenceOur study is the first to characterize tau in human EEC and in EEC lines. As a whole, our findings provide a basis to unravel the functions of tau in EEC and to further investigate the possibility of pathological changes in tauopathies and synucleinopathies.

neuroscience↗

bioRxiv2022

Cholecystokinin exerts a major control on corticostriatal synapse and motor behavior

Cholecystokinin (CCK) is a neuropeptide detected and produced at high concentrations in the brain. To date it was mainly used as a neuronal marker of neuronal subtypes and its role as a neuromodulator was poorly known. However, few studies showed that it could be an essential neuromodulator in various brain structures, playing a role on synaptic plasticity and memory consolidation. In order to better understand the processes by which CCK impacts plasticity, we focus our attention on the striatum, a nucleus involved in procedural learning and motor behavior, with a rich expression of CCK receptor type 2 (CCK2R). By using in-vivo and ex-vivo electrophysiological approaches, we show that CCK is involved in the corticostriatal synaptic transmission and has a key role in its plasticity. Using in-vivo optopatch-clamp of identified MSNs, we observe a decrease of corticostriatal synaptic transmission after an injection of CCK2R antagonist, leading to a reduction of evoked excitatory post synaptic potential recorded on both MSNs populations (direct and indirect pathways). In addition, we evaluate the impact of CCK2R antagonist on corticostriatal synaptic plasticity using Spike Timing Dependent Plasticity (STDP) protocols on MSNs of acute rat brain slices. Results demonstrate that the CCK2R antagonist is able to reverse the corticostriatal synaptic plasticity (i.e. LTP protocol leads to LTD). Finally, we evaluate the effect of CCK2R antagonist on the motor behavior of juvenile rats challenged with different locomotor tests and show a sex-dependent impairment of motor behavior. Overall, our results demonstrate that CCK and its receptor CCK2R are essential for inputs processing encoding in the corticostriatal network with consequences on motor activity. Significant statementCholecystokinin (CCK) is considered to be one of the most abundant neuropeptides in the brain but its role as a neuromodulator is not well understood. In our study we investigate its role on the corticostriatal transmission which is a well characterized synapse highly involved in motor and cognitive functions. Here, we show that CCK2R is crucial for the corticostriatal synaptic transmission and plasticity. Indeed, CCK binding on CCK2R is essential for LTP induction by STDP. Finally, we demonstrate that the blockage of CCK2R affects corticostriatal synaptic transmission and motor ability in male rats.

neuroscience↗

bioRxiv2022

Epigenetic alterations in gut and brain of adult rats after oral administration of miR-320-3p and miR-375-3p at mid-lactation, and preventive potential of miR-320-3p on early weaning stress.

AimTo investigate if the artificial delivery of microRNAs naturally present in the breastmilk can impact the gut and brain of young rats according to weaning. MethodsAnimals from a new transgenic rat line expressing green-fluorescent protein in the endocrine lineage (cholecystokinin expressing cells) received at Day-12, near neural diversification, a single oral bolus of mir-320-3p or miR-375-3p, embedded in DiOleyl-Succinyl-Paromomycin (DOSP), and were further early (Day-15) or regularly (Day-30) weaned. Relevant miRNA (miR-320-3p, miR-375-3p, miR-375-5p, miR-16-5p, miR-132-3p, miR-504), polr3d, hspb6, inflammation, enteroendocrine, and circadian clock-related mRNAs, chromatin complexes, and duodenal cell density were assayed at 8h post-inoculation and at Day-45. ResultsThe miR-320-3p/DOSP induced immediate effects on H3K4me3 chromatin complexes with polr3d promoter (p<0.05) but no long-term effects. On regular weaning, at Day-45, both miR-320-3p and 375-3p were down-regulated in the stomach, up-regulated in the hypothalamus (p<0.001) but only miR-320-3p was up-regulated in the duodenum. After early weaning, the miR-320-3p and miR-375-3p levels were down-regulated in the stomach and the duodenum, but up-regulated in the hypothalamus and the hippocampus. Combining miR-320-3p/DOSP with early weaning enhanced miR-320-3p and chromogranin A expression in the duodenum. In the hippocampus, the miR-504 was down-regulated for both sexes, but in the brain stem, up regulated only for females, along with miR-320-3p and miR-16-5p levels. In the hypothalamus, clock levels were up regulated for both sexes. In the miR-375-3p/DOSP group, the density of enteroendocrine duodenal cells increased. The long-term effect of miR-375-3p/DOSP was more limited, according to the fourfold lower number of predicted targets than with miR-320-3p. ConclusionAddressing oral miRNA-320-3p loads to duodenal cell lineage is paving the way for the design of new therapeutics, manipulating long term consequences of early life stress.

genetics↗