Anti-Inflammatory Effects of Serotonin Receptor and Transient Receptor Potential Channel Ligands in Human Small Intestinal Epithelial Cells

The dual role of dopamine and serotonin in cancer progression and inflammation: Mechanisms and therapeutic potential

This review examines the critical functions of dopamine and serotonin in the regulation of inflammation and cancer, emphasizing their potential as therapeutic targets. Traditionally recognized for their roles in neural communication, these neurotransmitters are now understood to play substantial roles in immune modulation and tumor progression. We conducted a systematic review of studies published between 2013 and 2024, using databases such as PubMed, Google Scholar, and Scopus, to assess dopamine and serotonin synthesis, receptor activity, and involvement in disease pathways. Findings indicate that dopamine, through its D1 and D2 receptors, exerts both pro- and anti-inflammatory effects, influencing tumor growth and immune responses in cancers such as breast and pancreatic. Similarly, serotonin, particularly through receptors HTR2A and HTR2B, has demonstrated dual roles in cancer progression, impacting the growth and metastasis of cancers such as gastric and colorectal. This review also addresses the interaction between dopamine and serotonin signaling pathways, which may collectively alter immune cell function and tumor microenvironment dynamics, suggesting a promising direction for combined therapeutic approaches. By synthesizing current data on dopamine and serotonin pathways, this review aims to inform the development of targeted therapies that modulate immune responses in inflammation-driven cancers. Our findings underscore the potential of neurotransmitter-based interventions as a novel strategy for managing cancer and inflammatory diseases.

The immunomodulatory effects of classical psychedelics: A systematic review of preclinical studies

Emerging evidence suggests that classical psychedelics possess immunomodulatory and anti-inflammatory properties; however, these effects are yet to be well-established. This systematic review aims to provide a timely and comprehensive overview of the immunomodulatory effects of classical psychedelics in preclinical studies. A systematic search was conducted on six databases, including CINAHL, EMBASE, MEDLINE, PsychINFO, Scopus, and Web of Science. Eligible studies targeting classical psychedelics for evaluation of their effects on inflammatory markers and immunomodulation have been included for analysis. Data was extracted from 40 out of 2822 eligible articles, and their risk of bias was assessed using the Systematic Review Center for Laboratory Animal Experimentation (SYRCLE) tool and Quality Assessment Tool for In Vitro Studies (QUIN). Studies examined 2,5-dimethoxy-4-iodoamphetamine (DOI; n = 18); psilocybin (4-PO-DMT; n = 9); N,N-dimethyltryptamine (DMT; n = 8); lysergic acid diethylamide (LSD; n = 6); 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT; n = 3); psilocin (4-HO-DMT; n = 3); and mescaline (n = 2). In 36 studies where inflammatory cytokine levels were measured following psychedelic administration, a decrease in at least one inflammatory cytokine was observed in 29 studies. Immune cell activity was assessed in 10 studies and findings were mixed, with an equal number of studies (n = 5 out of 10) reporting either an increase or decrease in immune cell activity. Classical psychedelics were found to alleviate pre-existing inflammation but promote inflammation when administered under normal physiological conditions. This information is anticipated to inform future clinical trials, exploring classical psychedelics' potential to alleviate inflammation in various pathologies.

2-(Piperidin-3-yl)phthalimides reduce classical markers of cellular inflammation in LPS-challenged RAW 264.7 cells and also demonstrate potentially relevant sigma and serotonin receptor affinity in membrane preparations

Herein, we report the synthesis of new 4-amino-2-(piperidin-3-yl)isoindoline-1,3-diones and their biological evaluation in a series of in vitro experiments. The synthetic production of these materials was initiated upon the condensation of appropriate nitrophthalic acid derivatives with various 3-aminopiperidines; subsequent reduction provided the final products in moderate to good yields. Readily available chiral pool reagents facilitated entry into optically enriched samples, while the piperidine scaffold furnished a variety of amide and alkylated entries. In total, 16 candidates were produced, and their ensuing treatment in LPS-challenged RAW cells effected slight reductions in secreted TNF-α but provided more robust and dose-dependent declines in nitrite and IL-6 levels relative to basal amounts, all concurrent with maintenance of cellular viability across the concentration ranges screened. The secondary amine cohort including rac-6, (R)-7, and (S)-8 rendered the most pronounced dose-dependent reductions in nitrite and IL-6. When dosed at 30 μM, (R)-7 demonstrated the most compelling effects, with decreases of 32 % and 40 % for nitrite and IL-6, respectively. Notable reductions in the inflammatory markers were also observed for 19 which effected declines in TNF-α (14 %), nitrite (19 %), and IL-6 (11 %) when treated at 30 μM. Additionally, four representative compounds were further evaluated against numerous CNS receptors, channels, and transporters, with 6, 9, and 19 demonstrating varying degrees of nanomolar-to-low-micromolar binding to the σ-1 and σ-2 receptors and also to serotonin receptors 5HT2A, 5HT2B and 5HT3. In this regard, 6 displayed perhaps the most noteworthy affinities, with binding at σ-2 (Ki = 2.2uM), 5HT2B (Ki = 561 nM) and 5HT3 (Ki = 536 nM). Furthermore, no pronounced or dose-dependent Cereblon/DDB1 binding was observed for the screened representative compounds 6, 9, 18 and 19.

Therapeutic modulation of the kynurenine pathway in severe mental illness and comorbidities: A potential role for serotonergic psychedelics

Mounting evidence points towards a crucial role of the kynurenine pathway (KP) in the altered gut-brain axis (GBA) balance in severe mental illness (SMI, namely depression, bipolar disorder, and schizophrenia) and cardiometabolic comorbidities. Preliminary evidence shows that serotonergic psychedelics and their analogues may hold therapeutic potential in addressing the altered KP in the dysregulated GBA in SMI and comorbidities. In fact, aside from their effects on mood, psychedelics elicit therapeutic improvement in preclinical models of obesity, metabolic syndrome, and vascular inflammation, which are highly comorbid with SMI. Here, we review the literature on the therapeutic modulation of the KP in the dysregulated GBA in SMI and comorbidities, and the potential application of psychedelics to address the altered KP in the brain and systemic dysfunction underlying SMI and comorbidities. Psychedelics might therapeutically modulate the KP in the altered GBA in SMI and comorbidities either directly, via altering the metabolic pathway by influencing the rate-limiting enzymes of the KP and affecting the levels of available tryptophan, or indirectly, by affecting the gut microbiome, gut metabolome, metabolism, and the immune system. Despite promising preliminary evidence, the mechanisms and outcomes of the KP modulation with psychedelics in SMI and systemic comorbidities remain largely unknown and require further investigation. Several concerns are discussed surrounding the potential side effects of this approach in specific cohorts of individuals with SMI and systemic comorbidities.

Capsaicin Modulates Hepatic and Intestinal Inflammation and Oxidative Stress by Regulating the Colon Microbiota

We aimed to investigate the role of capsaicin (CAP) in modulating lipopolysaccharide (LPS)-induced hepatic and intestinal inflammation, oxidative stress, and its colonic microflora in mice. Thirty healthy male Kunming mice with similar body weights were randomly assigned to three groups: the control group (CON), the LPS group, and the CAP group, with ten mice in each group. The CON and the LPS groups received a daily dose of normal saline, respectively, while the CAP group received an equivalent dose of CAP. On the 28th day of the experiment, the LPS and the CAP groups were intraperitoneally injected with LPS, while the CON group was injected with an equal volume of normal saline. The results lead to the following conclusions. Compared to the LPS group, CAP improved the loss of hepatic lobular structure and significantly increased the duodenal villus length and ratio of villus length to crypt depth. CAP increased hepatic and colon interleukin-10 (IL-10) and decreased IL-6, IL-1β, and tumor necrosis factor (TNF-α) levels. CAP also increased hepatic catalase (CAT), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) expression, and decreased malondialdehyde (MDA) levels. CAP significantly increased the relative abundances of Mucispirillum, Helicobacter, Prevotellaceae-UCG-001, Colidextribacter, unclassified-f-Oscillospiraceae, and Odoribacter, some of which were closely related to hepatic and colonic immune and oxidative markers. CAP also decreased the overall content of short-chain fatty acids, except for propionic acid. Overall, CAP can regulate the colon microbiota and exert anti-inflammatory and antioxidant effects. Whether CAP exerts its anti-inflammatory and antioxidant effects by modulating the colonic microflora, mainly Mucispirillum spp. and Helicobacter spp., requires further investigation.

Serotonin's Role in Inflammatory Signaling Pathway Modulation for Colon Cancer Suppression

Background Neurons can be effectively regulated by serotonin and dopamine. Their role in anti-inflammatory pathways opens new doors for therapeutic research, particularly in chemotherapeutics. The present study investigated serotonin's role in suppressing inflammation and its potential anticancer effects in KERATIN-forming tumor cell line HeLa cells (KB cells).  Methods - in vitro and in silico analysis The study delved further into the molecular mechanisms by assessing the expression levels of key markers involved in inflammation and cancer progression, such as B-cell leukemia/lymphoma 2 protein (BCl-2), tumor necrosis factor-alpha (TNF-α) and Interleukin-6 (IL-6) using Real-time reverse-transcriptase-polymerase chain reaction at concentrations below the IC50 (50 and 100 µg/ml). The binding capability of serotonin (CID 5202) with glycoform of human interleukin 6 (PDB: 7NXZ) was analyzed with the help of Schrodinger molecular suites. Results The findings showcased serotonin's potent growth inhibition in KB cells, with an IC50 value of 225±3.1µg/ml. Additionally, it demonstrated a multifaceted impact by downregulating the expression of BCl-2, TNF-α, and IL-6, pivotal factors in cancer cell survival and inflammation regulation. The docking score was - 5.65 (kcal/mol) between serotonin and glycoform of Human Interleukin 6. It is bound with ASN 143 by two hydrogen bonds. Thus, molecular docking analysis showed an efficient bounding pattern. The research findings indicate that serotonin successfully blocks NF-κB pathways in KB cells, underscoring its therapeutic promise against colon cancer and offering vital information for additional clinical investigation.  Conclusion According to the study's conclusion, serotonin has a remarkable anticancer potential by effectively blocking NF-κB B pathways in KB cells, revealing its promising potential as a therapeutic agent against colon cancer. These comprehensive findings offer significant insights into serotonin's intricate molecular interactions and its profound impact on cancer-related signaling pathways, paving the way for further exploration and potential clinical applications in cancer treatment strategies.

Cinnamic Acid, Perillic Acid, and Tryptophan Metabolites Differentially Regulate Ion Transport and Serotonin Metabolism and Signaling in the Mouse Ileum In Vitro

Phytochemicals and tryptophan (Trp) metabolites have been found to modulate gut function and health. However, whether these metabolites modulate gut ion transport and serotonin (5-HT) metabolism and signaling requires further investigation. The aim of this study was to investigate the effects of selected phytochemicals and Trp metabolites on the ion transport and 5-HT metabolism and signaling in the ileum of mice in vitro using the Ussing chamber technique. During the in vitro incubation, vanillylmandelic acid (VMA) reduced (p < 0.05) the short-circuit current, and 100 μM chlorogenic acid (CGA) (p = 0.12) and perillic acid (PA) (p = 0.14) had a tendency to reduce the short-circuit current of the ileum. Compared with the control, PA and N-acetylserotonin treatment upregulated the expression of tryptophan hydroxylase 1 (Tph1), while 100 μM cinnamic acid, indolelactic acid (ILA), and 10 μM CGA or indoleacetaldehyde (IAld) treatments downregulated (p < 0.05) the mRNA levels of Tph1. In addition, 10 μM IAld or 100 μM ILA upregulated (p < 0.05) the expression of monoamine oxidase A (Maoa). However, 10 μM CGA or 100 μM PA downregulated (p < 0.05) Maoa expression. All selected phytochemicals and Trp metabolites upregulated (p < 0.05) the expression of Htr4 and Htr7 compared to that of the control group. VMA and CGA reduced (p < 0.05) the ratios of Htr1a/Htr7 and Htr4/Htr7. These findings may help to elucidate the effects of phytochemicals and Trp metabolites on the regulation of gut ion transport and 5-HT signaling-related gut homeostasis in health and disease.

Deciphering psilocybin: Cytotoxicity, anti-inflammatory effects, and mechanistic insights

A decade of clinical research has indicated psilocybin's effectiveness in treating various neuropsychiatric disorders, such as depression and substance abuse. The correlation between increased pro-inflammatory cytokines and the severity of neuropsychiatric symptoms, along with the known anti-inflammatory potential of some psychedelics, suggests an immunomodulatory role for psilocybin. This study aims to understand the mechanism of action of psilocybin by investigating the cytotoxic and immunomodulatory effects of psilocybin and psilocin on both resting and LPS-activated RAW 264.7 murine macrophages. The study evaluated the cytotoxicity of psilocybin and psilocin using an LDH assay across various doses and assessed their impact on cytokine production in RAW 264.7 cells, measuring cytokine expression via ELISA. Different doses, including those above and below the LC50, were used in both pre-treatment and post-treatment approaches. The LDH assay revealed that psilocybin is almost twice as cytotoxic as psilocin, with an LC50 of 12 ng/ml and 28 ng/ml, respectively. In resting macrophages, both psilocybin and psilocin triggered significant release of TNF- α after 4 h, with the lowest doses inducing higher levels of the cytokine than the highest doses. IL-10 expression in resting cells was only triggered by the highest dose of psilocin in the 4-hour incubation group. In LPS-stimulated cells, psilocin reduced TNF- α levels more than psilocybin in pre-treatment and post-treatment, with no significant effects on IL-10 in pre-treatment. Psilocin, but not psilocybin, induced a significant increase of IL-10 in post-treatment, leading to the conclusion that psilocin, but not psilocybin, exerts anti-inflammatory effects on classically activated macrophages.

Do the therapeutic effects of psilocybin involve actions in the gut?

The psychedelic compound psilocybin has recently emerged as a therapeutic intervention for various mental health conditions. Psilocybin is a potent agonist of serotonin (5-HT) receptors (5-HTRs), which are expressed in the brain and throughout peripheral tissues, with particularly high expression in the gastrointestinal (GI) tract. However, no studies have investigated the possibility that peripheral actions of psilocybin may contribute to improvements in mental health outcomes. This is despite strong evidence for disturbed gut-brain signalling in conditions in which psilocybin is being tested clinically. In this Opinion, we highlight the likely actions of psychedelics in the gut and provide initial support for the premise that peripheral actions may be involved in rapid and long-term therapeutic effects. A greater understanding of all sites and modes of action will guide more targeted approaches to drug development.

Psilocybin and Eugenol Reduce Inflammation in Human 3D EpiIntestinal Tissue

Inflammation plays a pivotal role in the development and progression of inflammatory bowel disease (IBD), by contributing to tissue damage and exacerbating the immune response. The investigation of serotonin receptor 2A (5-HT2A) ligands and transient receptor potential (TRP) channel ligands is of significant interest due to their potential to modulate key inflammatory pathways, mitigate the pathological effects of inflammation, and offer new avenues for therapeutic interventions in IBD. This study investigates the anti-inflammatory effects of 5-HT2A ligands, including psilocybin, 4-AcO-DMT, and ketanserin, in combination with TRP channel ligands, including capsaicin, curcumin, and eugenol, on the inflammatory response induced by tumor necrosis factor (TNF)-α and interferon (IFN)-γ in human 3D EpiIntestinal tissue. Enzyme-linked immunosorbent assay was used to assess the expression of pro-inflammatory markers TNF-α, IFN-γ, IL-6, IL-8, MCP-1, and GM-CSF. Our results show that psilocybin, 4-AcO-DMT, and eugenol significantly reduce TNF-α and IFN-γ levels, while capsaicin and curcumin decrease these markers to a lesser extent. Psilocybin effectively lowers IL-6 and IL-8 levels, but curcumin, capsaicin, and 4-AcO-DMT have limited effects on these markers. In addition, psilocybin can significantly decrease MCP-1 and GM-CSF levels. While ketanserin lowers IL-6 and GM-CSF levels, there are no effects seen on TNF-α, IFN-γ, IL-8, or MCP-1. Although synergistic effects between 5-HT2A and TRP channel ligands are minimal in this study, the results provide further evidence of the anti-inflammatory effects of psilocybin and eugenol. Further research is needed to understand the mechanisms of action and the feasibility of using these compounds as anti-inflammatory therapies for conditions like IBD.

A Comprehensive Review of the Current Status of the Cellular Neurobiology of Psychedelics

Psychedelic substances have gained significant attention in recent years for their potential therapeutic effects on various psychiatric disorders. This review delves into the intricate cellular neurobiology of psychedelics, emphasizing their potential therapeutic applications in addressing the global burden of mental illness. It focuses on contemporary research into the pharmacological and molecular mechanisms underlying these substances, particularly the role of 5-HT2A receptor signaling and the promotion of plasticity through the TrkB-BDNF pathway. The review also discusses how psychedelics affect various receptors and pathways and explores their potential as anti-inflammatory agents. Overall, this research represents a significant development in biomedical sciences with the potential to transform mental health treatments.