Christian Bustamante

Background: Myocardial infarction (MI) is among the leading causes of death worldwide, and a precisely regulated inflammatory response is essential for effective cardiac repair and long-term outcome. The serotonergic system regulates immune cell functions, yet its contribution to post-MI remodeling is incompletely understood. Methods: Here, we investigated the role of serotonin receptor 7 (5-HT7R) in post-infarction inflammation and outcome after permanent left anterior coronary artery ligation in mice, and complementary analysis of peripheral blood mononuclear cells (PBMCs) obtained from patients with acute MI. Results: Three days after MI, 5-HT7R mRNA expression was significantly upregulated in the infarct region compared to remote myocardium and sham operated mice. RNA-sequencing of isolated murine CD11b ⁺ cells demonstrated high 5-HT7R expression in cardiac macrophages during the acute phase, which was confirmed by immunohistochemistry. Systemic 5-HT7R-knockout did not affect basal cardiac function but resulted in impaired left ventricular function and enhanced inflammatory signatures 14 days after MI without changes in infarct size. Pharmacological activation of 5-HT7R signaling with the selective agonist LP-211 increased survival after MI, although global systolic function among survivors was not improved. Transcriptomic profiling of cardiac macrophages 3 days after MI revealed bidirectional regulation of inflammatory and metabolic programs depending on 5-HT7R activity, including altered expression of Got1 and S100A9 . Complementary, in PBMCs from MI patients Got1 expression was reduced, while S100A9 was increased, and both correlated with 5-HT7R expression. Conclusions: These data suggest 5-HT7R as a regulator of post-MI immune responses and a potential target to improve repair and survival.

Chronic pain, a complex multidimensional disorder, remains a major healthcare issue and a therapeutic challenge. Neuropathic pain is a chronic pain condition that results from damage or dysfunction in the nervous system. While mechanisms of neuropathic pain at the peripheral and spinal cord level have been extensively studied, pain mechanisms in the brain remain underexplored. The amygdala, a limbic brain region, has emerged as a critical brain area for the emotional–affective dimension of pain and pain modulation. Amygdala neuroplasticity has been associated with pain states, but the exact molecular and cellular mechanisms underlying these states and the transition from acute to chronic pain are not well understood. Here, we used the spinal nerve ligation (SNL) model of neuropathic pain in male rats to investigate changes in gene expression in the amygdala at the chronic pain stage using RNA sequencing (RNA-Seq). Two amygdala nuclei, the basolateral (BLA) and central (CeA), were investigated in a hemisphere-dependent manner. We used an integrative approach that focuses on functional significance and cell-type specificity of differentially expressed genes (DEGs) to nominate mechanistic targets for central regulation of chronic pain. Our integrative transcriptomic and bioinformatic analyses identified individual genes (e.g., Cxcl10, Cxcl12, Mbp, Plp1, Mag, Mog, Slc17a6, Gad1, and Sst), molecular pathways (e.g., cytokine-mediated signaling pathway), biological processes (e.g., myelination, synaptic transmission), and specific cell types (e.g., oligodendrocytes, glutamatergic, and GABAergic neurons) affected by chronic pain. Our results also provide some evidence for the emerging concept of hemispheric lateralization of pain processing in the amygdala. Overall, our study proposes oligodendrocyte dysfunction in the amygdala, neuroimmune signaling in the CeA, and glutamatergic neurotransmission in the BLA as key processes and potential therapeutic targets for the management of chronic neuropathic pain.

Ketamine’s rapid neuropsychiatric actions emerge from interactions that span receptors, cells, and circuits, but their net effects on human neuronal population dynamics remain incompletely defined. Here we combine human dorsal forebrain organoids with high-density microelectrode arrays (MEAs) to quantify ketamine’s effects from spikes to networks. In 6-month-old organoids, acute ketamine (20□μg/mL) abolished population bursting while neuronal firing continued mostly unchanged. Spike sorting revealed that mean firing rates declined but not silenced after ketamine Reductions were concentrated within a subset of burst-driver units previously defined as “backbone”. Functional connectivity, estimated with the spike time tiling coefficient (STTC), decreased globally after ketamine. Backbone units displayed elevated connectivity at baseline but were functionally disconnected by ketamine. Graph construction from STTC uncovered widespread network reconfiguration, characterized by redistribution of edges from backbone to non-backbone units leading to loss of hubs and less-interconnected communities. Re-exposure after chronic ketamine treatment no longer silenced population bursting, indicating tolerance. Together, these results show that ketamine acutely silences human organoid networks by disconnecting backbone units, while chronic exposure induces tolerance to re-silencing while reducing the number of backbone units and leaving the network less active and less connected. The organoid-MEA platform provides a scalable, human-relevant system for dissecting circuit-level drug effects.

Background/Aims: Including women of childbearing age in a clinical trial makes it necessary to consider two factors from a bioethical perspective: first, the lack of knowledge about the potential teratogenic effects of an investigational product, and also, the principle of justice not to exclude any population from the benefits of research. The most common way to address this issue is by requiring volunteers to use contraceptives before, during, and a few weeks after the clinical trial. This work presents all the strategies used to promote contraception use and prevent pregnancy during the Alzheimer’s Prevention Initiative Autosomal-Dominant Alzheimer’s Disease (API ADAD) Colombia clinical trial. Two characteristics of this trial make it of special interest for closely monitoring contraception use. One is that the trial lasted more than 7 years, and the other is that participants could be carriers of the E280A PSEN1 mutation, leading to a mild cognitive impairment as early as their late 30s. Methods: An individual medical evaluation to select the contraception method that best fits the volunteer was carried out during the screening visit, remitting to the gynecologist when necessary. All non-surgical contraception methods were supplied by the sponsor. Staff were trained on contraception counseling, correctly dispensing contraceptive drugs to volunteers, and identifying, reporting, and following up on pregnancies. Two comprehensive educational campaigns on contraception use were performed, and the intervention included all volunteers. In addition, volunteers were asked on an annual survey to evaluate the dispensing procedure. Finally, the effectiveness of these strategies was retrospectively evaluated, comparing by extrapolation the number of pregnancies presented throughout the trial with the General Fertility Rate in Colombia. Results: A total of 159 female volunteers were recruited. All strategies were implemented as planned, even during the COVID-19 contingency. Ten pregnancies occurred during the evaluation period (2015–2021). Two were planned; the rest were associated with a potential therapeutic failure or incorrect use of contraceptive methods for a contraceptive failure of 0.49% per year. Sixty percent of pregnancies led to an abortion, either miscarriage or therapeutic abortion. However, there was not enough data to associate the pregnancy outcome with the administration of the investigational product. Finally, we observed a lower fertility rate in women participating in the trial compared to the Colombian population. Conclusion: The lower rates of contraceptive failure and the decrease in the incidence of pregnancies in women participating in the trial compared to the Colombian population across the 7 years of evaluation suggest that the strategies used in API ADAD Colombia were adequate and effective in addressing contraception use.

The lack of therapeutic alternatives for the treatment of Chagas disease, a neglected disease, drives the discovery of new drugs with trypanocidal activity. Consequently, we conducted in vitro studies using UBMC-4, a potential Trypanosoma cruzi AKT-like pleckstrin homology (PH) domain inhibitory compound found using bioinformatics tools. The half effective concentration (EC₅₀) on intracellular amastigotes was determined at 1.85 ± 1 μM showing low cytotoxicity (LC₅₀) > 40 μM on human cell lines tested. In order to study the lethal effect caused by the compound on epimastigotes, morphological changes were assessed by scanning and transmission electron microscopy. Progressive alterations such as flagellum inactivation, cell size reduction, nuclear structure alteration, condensation of chromatin towards the nuclear periphery, vacuole formation, and mitochondrial swelling with kinetoplast integrity loss were evidenced. In addition, apoptosis-like markers in T. cruzi were assessed by flow cytometry, demonstrating that the effect of UBMC-4 on T. cruzi AKT-like kinase reduced the tolerance to nutritional stress-triggered, apoptosis-like events, including DNA fragmentation, mitochondrial damage, and loss of plasma membrane integrity. After this, UBMC-4 was formulated for oral administration and pharmacokinetics were analyzed in a mouse model. Finally, upon oral administration of 200 mg/kg in mice, we found that a UBMC-4 plasma concentration remaining in circulation beyond 24 h after administration is well described by the two-compartment model. We conclude that UBMC-4 has an effective trypanocidal activity in vitro at low concentrations and this effect is evident in T. cruzi cell structures. In mice, UBMC-4 was well absorbed and reached plasma concentrations higher than the EC₅₀, showing features that would aid in developing a new drug to treat Chagas disease.