Inflammatory biotype of ADHD is linked to chronic stress: a data-driven analysis of the inflammatory proteome.

The association between Attention Deficit Hyperactivity Disorder (ADHD) and low-grade inflammation has been explored in children but rarely in adults. Inflammation is characteristic of some, but not all, patients with ADHD and might be influenced by ADHD medication but also lifestyle factors including nutrition, smoking, and stress. It is also still unclear if any specific symptoms are related to inflammation. Therefore, we assessed 96 inflammatory proteins in a deeply phenotyped cohort of 126 adult ADHD participants with a stable medication status using OLINK technology. A data-based, unsupervised hierarchical clustering method could identify two distinct biotypes within the 126 ADHD participants based on their inflammatory profile: a higher inflammatory potential (HIP) and a lower inflammatory protein potential (LIP) group. Biological processes that differed strongest between groups were related to the NF-κB pathway, chemokine signaling, IL-17 signaling, metabolic alterations, and chemokine attraction. A comparison of sample characteristics revealed that the HIP group was more likely to have higher levels of chronic stress (p < 0.001), a higher clinical global impression scale score (p = 0.030), and a higher risk for suicide (p = 0.032). Medication status did not influence protein levels significantly (p ≥ 0.074), but psychotropic co-medication (p ≤ 0.009) did. In conclusion, our data suggest the presence of two distinct biotypes in adults with ADHD. Higher levels of inflammatory proteins in ADHD are linked to higher levels of chronic perceived stress in a linear fashion. Further research on inflammation in adults with ADHD should take stress levels into account.

Immuno-inflammatory in vitro hepatotoxicity models to assess side effects of biologicals exemplified by aldesleukin.

Introduction: Hepatotoxicity induced by immunotherapeutics is an appearing cause for immune-mediated drug-induced liver injury. Such immuno-toxic mechanisms are difficult to assess using current preclinical models and the incidence is too low to detect in clinical trials. As hepatotoxicity is a frequent reason for post-authorisation drug withdrawal, there is an urgent need for immuno-inflammatory in vitro models to assess the hepatotoxic potential of immuno-modulatory drug candidates. We developed several immuno-inflammatory hepatotoxicity test systems based on recombinant human interleukin-2 (aldesleukin). Methods: Co-culture models of primary human CD8+ T cells or NK cells with the hepatocyte cell line HepaRG were established and validated with primary human hepatocytes (PHHs). Subsequently, the HepaRG model was refined by increasing complexity by inclusion of monocyte-derived macrophages (MdMs). The main readouts were cytotoxicity, inflammatory mediator release, surface marker expression and specific hepatocyte functions. Results: We identified CD8+ T cells as possible mediators of aldesleukin-mediated hepatotoxicity, with MdMs being implicated in increased aldesleukin-induced inflammatory effects. In co-cultures of CD8+ T cells with MdMs and HepaRG cells, cytotoxicity was induced at intermediate/high aldesleukin concentrations and perforin was upregulated. A pro-inflammatory milieu was created measured by interleukin-6 (IL-6), c-reactive protein (CRP), interferon gamma (IFN-γ), and monocyte chemoattractant protein-1 (MCP-1) increase. NK cells responded to aldesleukin, however, only minor aldesleukin-induced cytotoxic effects were measured in co-cultures. Results obtained with HepaRG cells and with PHHs were comparable, especially regarding cytotoxicity, but high inter-donor variations limited meaningfulness of the PHH model. Discussion: The in vitro test systems developed contribute to the understanding of potential key mechanisms in aldesleukin-mediated hepatotoxicity. In addition, they may aid assessment of immune-mediated hepatotoxicity during the development of novel immunotherapeutics.

The Roles of Long-Term Hyperhomocysteinemia and Micronutrient Supplementation in the AppNL-G-F Model of Alzheimer's Disease.

A causal contribution of hyperhomocysteinemia to cognitive decline and Alzheimer's disease (AD), as well as potential prevention or mitigation of the pathology by dietary intervention, have frequently been subjects of controversy. In the present in vivo study, we attempted to further elucidate the impact of elevated homocysteine (HCys) and homocysteic acid (HCA) levels, induced by dietary B-vitamin deficiency, and micronutrient supplementation on AD-like pathology, which was simulated using the amyloid-based AppNL-G-F knock-in mouse model. For this purpose, cognitive assessment was complemented by analyses of ex vivo parameters in whole blood, serum, CSF, and brain tissues from the mice. Furthermore, neurotoxicity of HCys and HCA was assessed in a separate in vitro assay. In confirmation of our previous study, older AppNL-G-F mice also exhibited subtle phenotypic impairment and extensive cerebral amyloidosis, whereas dietary manipulations did not result in significant effects. As revealed by proximity extension assay-based proteome analysis, the AppNL-G-F genotype led to an upregulation of AD-characteristic neuronal markers. Hyperhomocysteinemia, in contrast, indicated mainly vascular effects. Overall, since there was an absence of a distinct phenotype despite both a significant amyloid-ß burden and serum HCys elevation, the results in this study did not corroborate the pathological role of amyloid-ß according to the "amyloid hypothesis," nor of hyperhomocysteinemia on cognitive performance. Nevertheless, this study aided in further characterizing the AppNL-G-F model and in elucidating the role of HCys in diverse biological processes. The idea of AD prevention with the investigated micronutrients, however, was not supported, at least in this mouse model of the disease.

High-Throughput Screening for CEBPD-Modulating Compounds in THP-1-Derived Reporter Macrophages Identifies Anti-Inflammatory HDAC and BET Inhibitors.

This study aimed to identify alternative anti-inflammatory compounds that modulate the activity of a relevant transcription factor, CCAAT/enhancer binding protein delta (C/EBPδ). C/EBPδ is a master regulator of inflammatory responses in macrophages (Mϕ) and is mainly regulated at the level of CEBPD gene transcription initiation. To screen for CEBPD-modulating compounds, we generated a THP-1-derived reporter cell line stably expressing secreted alkaline phosphatase (SEAP) under control of the defined CEBPD promoter (CEBPD::SEAP). A high-throughput screening of LOPAC®1280 and ENZO®774 libraries on LPS- and IFN-γ-activated THP-1 reporter Mϕ identified four epigenetically active hits: two bromodomain and extraterminal domain (BET) inhibitors, I-BET151 and Ro 11-1464, as well as two histone deacetylase (HDAC) inhibitors, SAHA and TSA. All four hits markedly and reproducibly upregulated SEAP secretion and CEBPD::SEAP mRNA expression, confirming screening assay reliability. Whereas BET inhibitors also upregulated the mRNA expression of the endogenous CEBPD, HDAC inhibitors completely abolished it. All hits displayed anti-inflammatory activity through the suppression of IL-6 and CCL2 gene expression. However, I-BET151 and HDAC inhibitors simultaneously upregulated the mRNA expression of pro-inflammatory IL-1ß. The modulation of CEBPD gene expression shown in this study contributes to our understanding of inflammatory responses in Mϕ and may offer an approach to therapy for inflammation-driven disorders.

An in vitro test system for compounds that modulate human inflammatory macrophage polarization.

Macrophages undergo activation by pathophysiological stimuli to pro-inflammatory and bactericidal, or wound-healing and anti-inflammatory phenotypes, termed M1 or M2, respectively. Dysregulation of the M1-M2 balance is often associated with inflammatory diseases. Therefore, mechanisms of macrophage polarization may reveal new drug targets. We profiled six compounds with claimed modulatory effects on macrophage polarization using peripheral blood monocyte-derived macrophages. Based on the distinct mRNA or protein expression in macrophages stimulated either with M1 [lipopolysaccharide (LPS) + interferon-γ, IFNγ] or M2 interleukin-4 (IL-4) stimuli, we selected a combination of M1 (IL1ß, tumor necrosis factor-α,TNFα, CC chemokine receptor 7, CCR7 and CD80) and M2 (chemokine (C-C motif) ligand 22, CCL22, CD200R and mannose receptor C type 1, MRC1) markers to monitor drug effects on "M1 polarization" or cells "pre-polarized to M1". Azithromycin (25-50 µM), tofacitinib (2.5-5 µM), hydroxychloroquine (40 µg/ml) and pioglitazone (15-60 µM) exhibit an anti-inflammatory profile because they downregulated M1 markers and upregulated some M2 markers when given both before and after M1 polarization. Lovastatin given before M1 polarization downregulated M1 marker genes but enhanced the M1 phenotype in macrophages pre-polarized with LPS and IFNγ. Methotrexate (1.25-5 µM) did not modulate macrophage polarization. We have, thus, established a test system suitable to identify novel compounds or repurposed drugs that modulate inflammatory macrophage plasticity. Compounds with potential to reduce expression of molecules involved in inflammatory T cell activation (IL-1ß, TNFα, CD80), while enhancing production of a major chemokine involved in recruitment of Tregs (CCL22) may be of interest for treating chronic inflammatory diseases.

THP-1 and human peripheral blood mononuclear cell-derived macrophages differ in their capacity to polarize in vitro.

Macrophages (Mφ) undergo activation to pro-inflammatory (M1) or anti-inflammatory (M2) phenotypes in response to pathophysiologic stimuli and dysregulation of the M1-M2 balance is often associated with diseases. Therefore, studying mechanisms of macrophage polarization may reveal new drug targets. Human Mφ polarization is generally studied in primary monocyte-derived Mφ (PBMC Mφ) and THP-1-derived Mφ (THP-1 Mφ). We compared the polarization profile of THP-1 Mφ with that of PBMC Mφ to assess the alternative use of THP-1 for polarization studies. Cellular morphology, the expression profiles of 18 genes and 4 cell surface proteins, and phagocytosis capacity for apoptotic cells and S. aureus bioparticles were compared between these Mφ, activated towards M1, M2a, or M2c subsets by stimulation with LPS/IFNγ, IL-4, or IL-10, respectively, for 6h, 24h and 48h. The Mφ types are unique in morphology and basal expression of polarization marker genes, particularly CCL22, in a pre-polarized state, and were differentially sensitive to polarization stimuli. Generally, M1 markers were instantly induced and gradually decreased, while M2 markers were markedly expressed at a later time. Expression profiles of M1 markers were similar between the polarized Mφ types, but M2a cell surface markers demonstrated an IL-4-dependent upregulation only in PBMC Mφ. Polarized THP-1 Mφ but not PBMC Mφ showed distinctive phagocytic capacity for apoptotic cells and bacterial antigens, respectively. In conclusion, our data suggest that THP-1 may be useful for performing studies involving phagocytosis and M1 polarization, rather than M2 polarization.