Novel Anti-Neuroinflammatory Properties of a Thiosemicarbazone–Pyridylhydrazone Copper(II) Complex

Abstract

Neuroinflammation has a major role in several brain disorders including Alzheimer’s disease (AD), yet at present there are no effective anti-neuroinflammatory therapeutics available. Copper(II) complexes of bis(thiosemicarbazones) (CuII(gtsm) and CuII(atsm)) have broad therapeutic actions in preclinical models of neurodegeneration, with CuII(atsm) demonstrating beneficial outcomes on neuroinflammatory markers in vitro and in vivo. These findings suggest that copper(II) complexes could be harnessed as a new approach to modulate immune function in neurodegenerative diseases. In this study, we examined the anti-neuroinflammatory action of several low-molecular-weight, charge-neutral and lipophilic copper(II) complexes. Our analysis revealed that one compound, a thiosemicarbazone–pyridylhydrazone copper(II) complex (CuL5), delivered copper into cells in vitro and increased the concentration of copper in the brain in vivo. In a primary murine microglia culture, CuL5 was shown to decrease secretion of pro-inflammatory cytokine macrophage chemoattractant protein 1 (MCP-1) and expression of tumor necrosis factor alpha (Tnf), increase expression of metallothionein (Mt1), and modulate expression of Alzheimer’s disease-associated risk genes, Trem2 and Cd33. CuL5 also improved the phagocytic function of microglia in vitro. In 5xFAD model AD mice, treatment with CuL5 led to an improved performance in a spatial working memory test, while, interestingly, increased accumulation of amyloid plaques in treated mice. These findings demonstrate that CuL5 can induce anti-neuroinflammatory effects in vitro and provide selective benefit in vivo. The outcomes provide further support for the development of copper-based compounds to modulate neuroinflammation in brain diseases.

Patient-Derived Blood-Brain Barrier Model for Screening Copper Bis(thiosemicarbazone) Complexes as Potential Therapeutics in Alzheimer’s Disease

“…AD Patient-Derived iBEC Exhibit an Inflammatory Response to TNFα and IFNγ Stimulation. Since our previous studies demonstrated antineuroinflammatory effects of Cu(btsc) complexes in various models of neurodegeneration, 42,48,49 here we hypothesized that novel metal (btsc) complexes can achieve similar effects in iBEC and aimed to evaluate the immunomodulatory activity of selected compounds in the established AD-patient-derived platform.…”

“…CuL 1 Reverses the TNFα/IFNγ-Induced Neuroinflammatory Phenotype in AD iBEC. Given that Cu(btsc) have previously demonstrated robust antineuroinflammatory actions in preclinical models of neurodegeneration (microglia, astrocytes and neuronal in vitro cultures, and animal models), 42,48,49 we anticipated that compounds in our library could exert similar, potentially therapeutic effects. Based on compound chemistry, toxicity, cellular accumulation, and iBEC monolayer permeability, we selected Cu(ATSM), its control Ni(ATSM), and a group of five promising Cu compounds (CuL 1 , CuL 4 , CuL 6 , CuL 7 , and CuL 9 ) for their further assessment in our model.…”

“…Interestingly, at the gene expression level, TNFα/IFNγ cotreatment with selected Cu compounds led to a significant decrease of at least one of the tested (IL6, IL8, IL1A, and CCL2) proinflammatory marker genes as compared to TNFα/IFNγ alone (Figure 6A), supporting previously reported antiinflammatory properties of Cu(btsc). 42,48,49 Compound CuL 1 emerged as the most promising candidate that, in cotreatment with TNFα/IFNγ, reduced expression of all four marker genes tested (IL6: p < 0.05, CCL2: p < 0.001, IL8: p < 0.05, IL1A: p < 0.001), as compared to TNFα/IFNγ alone (Figure 6A). Intriguingly, a decrease in gene expression of proinflammatory markers did not result in changes in cytokine secretion as the levels of IL6 and MCP1 were similar between TNFα/IFNγ and TNFα/IFNγ + metal compound-treated cells at the tested 24 h time point (Figure 6B).…”

“…Correspondingly, Cu(btsc) were previously shown to act through multiple pathways involving antineuroinflammatory effects, the restoration of Cu homeostasis, inhibition of amyloid β and tau accumulation, and the reduction in lipid peroxidation and ferroptosis, ,,, with microglia, astrocytes, and neurons being suggested as the major effector cells of their therapeutic action in the brain. Here, we detected the potentially therapeutic immunomodulatory effects of selected Cu(btsc) on AD iBEC, implicating additional neuroprotective mechanisms that may be involved at the level of BBB.…”

“…This library of compounds consisted of structural derivatives of diacetylbis­( N (4)-methylthiosemicarbazonato)­copper­(II) (Cu­(atsm)), which has demonstrated broad therapeutic potential in several preclinical models of neurodegeneration. − We initially assessed the cytotoxicity of the novel metal compounds in human vascular endothelial cells, and subsequently, we investigated the toxicity, accumulation, and permeability of these compounds across the BBB using both control and familial AD patient-derived iBEC models. Considering that antineuroinflammatory actions are now recognized as one of the primary mechanisms underlying neurotherapeutic effects of Cu­(btsc) complexes, ,, we aimed to investigate the immunomodulatory properties of the tested compounds in our model. To facilitate that, we multiplexed AD patient-derived iBEC with neurologically relevant immune modulators, namely, tumor necrosis factor α (TNFα) and interferon γ (IFNγ), resulting in the development of neuroinflammatory phenotype at the patient-derived BBB in vitro .…”