Thioredoxin-1 Protects Spinal Cord from Demyelination Induced by Methamphetamine through Suppressing Endoplasmic Reticulum Stress and Inflammation

Immunotherapeutic treatment of inflammation in mice exposed to methamphetamine

Introduction

Currently, there are no FDA-approved medications to treat methamphetamine addiction, including the inflammatory, neurotoxic, and adverse neuropsychiatric effects. We have shown that partial (p)MHC class II constructs (i.e., Recombinant T-cell receptor Ligand - RTL1000), comprised of the extracellular α1 and β1 domains of MHC class II molecules linked covalently to myelin oligodendrocyte glycoprotein (MOG)-35-55 peptide, can address the neuroimmune effects of methamphetamine addiction through its ability to bind to and down-regulate CD74 expression, block macrophage migration inhibitory factor (MIF) signaling, and reduce levels of pro-inflammatory chemokine ligand 2 (CCL2). The present study evaluated the effects of our third-generation pMHC II construct, DRmQ, on cognitive function and concentration of inflammatory cytokines in the frontal cortex, a region critical for cognitive functions such as memory, impulse control, and problem solving.

Methods

Female and male C57BL/6J mice were exposed to methamphetamine (or saline) via subcutaneous (s.c.) injections administered four times per day every other day for 14 days. Following methamphetamine exposure, mice received immunotherapy (DRmQ or ibudilast) or vehicle s.c. injections daily for five days. Cognitive function was assessed using the novel object recognition test (NORT). To evaluate the effects of immunotherapy on inflammation in the frontal cortex, multiplex immunoassays were conducted. ANOVA was used to compare exploration times on the NORT and immune factor concentrations.

Results

Post hoc analysis revealed increased novel object exploration time in MA-DRmQ treated mice, as compared to MA-VEH treated mice (non-significant trend). One-way ANOVA detected a significant difference across the groups in the concentration of macrophage inflammatory protein-2 (MIP-2) (p = 0.03). Post hoc tests indicated that mice treated with methamphetamine and DRmQ or ibudilast had significantly lower levels of MIP-2 in frontal cortex, as compared to mice treated with methamphetamine and vehicle (p > 0.05).

Discussion

By specifically targeting CD74, our DRQ constructs can block the signaling of MIF, inhibiting the downstream signaling and pro-inflammatory effects that contribute to and perpetuate methamphetamine addiction.

TRPV4 contributes to ER stress and inflammation: implications for Parkinson’s disease

Background

Parkinson’s disease (PD) is a progressive neurodegenerative disorder. Its molecular mechanism is still unclear, and pharmacological treatments are unsatisfactory. Transient receptor potential vanilloid 4 (TRPV4) is a nonselective Ca²⁺ channel. It has recently emerged as a critical risk factor in the pathophysiology of neuronal injuries and cerebral diseases. Our previous study reported that TRPV4 contributed to endoplasmic reticulum (ER) stress in the MPP⁺-induced cell model of PD. In the present study, we detected the role and the mechanism of TRPV4 in 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice.

Methods

Intracerebral injection of an adeno-associated virus (AAV) into the substantia nigra (SN) of mice was used to knockdown or upregulate the expression of TRPV4 and intraperitoneal injection of MPTP. Rotarod and pole tests were used to evaluate the locomotor ability of mice. We used immunohistochemistry, Nissl staining and Western blot to detect the alterations in the number of tyrosine hydroxylase (TH)-positive neurons, Nissl-positive neurons, the levels of ER stress-associated molecules and proinflammatory cytokines in the SN.

Results

The SN was transfected with AAV for 3 weeks and expressed the target protein with green fluorescence. Knockdown of TRPV4 via injection of a constructed AAV-TRPV4 shRNAi into the SN alleviated the movement deficits of PD mice. Upregulation of TRPV4 via injection of a constructed AAV-TRPV4 aggravated the above movement disorders. The expression of TRPV4 was upregulated in the SN of MPTP-treated mice. Injection of AAV-TRPV4 shRNAi into the SN rescued the number of TH-positive and Nissl-positive neurons in the SN decreased by MPTP, while injection of AAV-TRPV4 induced the opposite effect. Moreover, MPTP-decreased Sarco/endoplasmic reticulum Ca²⁺-ATPase 2 (SERCA2) and pro-cysteinyl aspartate specific proteinase-12 (procaspase-12), MPTP-increased Glucose-regulated protein 78 (GRP78), Glucose-regulated protein 94 (GRP94) and C/EBP homologous protein (CHOP) were inhibited by AAV-TRPV4 shRNAi infection, and enhanced by AAV-TRPV4. In the same way, MPTP-decreased procaspase-1, MPTP-increased Interleukin-18 (IL-18), Cyclooxgenase-2 (COX-2) and 5-Lipoxygenase (5-LOX) were inhibited by AAV-TRPV4 shRNAi, or further exacerbated by AAV-TRPV4.

Conclusions

These results suggest that TRPV4 mediates ER stress and inflammation pathways, contributing to the loss of dopamine (DA) neurons in the SN and movement deficits in PD mice. Moreover, this study provides a new perspective on molecular targets and gene therapies for the treatment of PD in the future.

Thioredoxin-1 inhibits amyloid-β25-35-induced activation of NLRP1/caspase-1/GSDMD pyroptotic pathway in PC12 cells

BACKGROUND

Alzheimer's disease (AD), the most common neurodegenerative disease, is charactered by these accepted pathological features, such as β-amyloid (Aβ) plaques outside the neurons and neurofibrillary tangles inside the neurons. In recent years, several studies have demonstrated that pyroptosis is associated with the development of AD process. However, whether Aβ_25-35 induces pyroptosis is still unclear. Thioredoxin-1 (Trx-1), an intracellular multifunctional protein, showed neuroprotective roles by inhibiting the neurotoxicity of Aβ, attenuating the apoptosis of brain neurons and improving the spatial learning and memory ability in AD models. Whether Trx-1 could inhibit pyroptosis in AD needs to be further investigated.

METHODS AND RESULTS

In the present study, MTT assay was employed to detected the viability. Western blotting was employed to detect the protein levels. Enzyme linked immunosorbent assay was used to examine the intracellular and extracellular levels of IL-18 and IL-1β. Chronic Aβ_25-35 treatment remarkedly compromised the viability of PC12 cells, increased the expression of NOD-like receptor pyrin domain containing 1 (NLRP-1), caspase-1 and gasdermin D (GSDMD), and promoted the extracellular release of interleukin (IL)-18 and IL-1β. Simultaneously, Aβ_25-35 treatment also significantly reduced the intracellular protein levels of Trx-1. Pharmacological inhibition of Trx-1 activity further decreased the cell viability, activated the NLRP-1/caspase-1/GSDMD pyroptotic pathway, and exacerbated the extracellular release of IL-18 and IL-1β.

CONCLUSIONS

These data suggest that Trx-1 may play a potential inhibitory effect on Aβ_25-35-induced pyroptosis.

Thioredoxin-1 blocks methamphetamine-induced injury in brain through inhibiting endoplasmic reticulum and mitochondria-mediated apoptosis in mice

Methamphetamine (METH) has been reported to induce endoplasmic reticulum (ER) stress and neuronal apoptosis in the central nervous system (CNS) during the development of addiction. Thioredoxin-1 (Trx-1) is a redox regulating protein and plays an important role in inhibiting apoptosis and protects neurons from cytotoxicity through ER and mitochondria-mediated pathways. Our previous study has been reported that Trx-1 protects mice from METH-induced rewarding effect. However, whether Trx-1 plays the role in resisting METH injury is still unclear. Here, we aim to investigate whether Trx-1 participates in the regulation of METH-induced CNS injury via ER stress and mitochondria-mediated pathways. Our study first repeated the conditioned place preference expression induced by METH. Then we detected and found that METH increased the expression of N-methyl-d-asparate (NMDA) receptor subunit 2B (NR2B) and the level of glutamate (Glu) in the ventral tegmental area (VTA) and nucleus accumbens (NAc), while Trx-1 overexpression suppressed the increases. We further examined ER stress-related proteins and mitochondrial apoptosis pathway in the VTA and NAc, and found that METH increased the expressions of glucose regulated protein 78 (GRP78), C/EBP homologous protein (CHOP), and Bax, as same time decreased the expressions of procaspase12, Bcl-2, and procaspase3, while Trx-1 overexpression blocked these changes. These results indicate that Trx-1 blocks METH-induced injury by suppressing ER stress and mitochondria-mediated apoptosis in the VTA and NAc via targeting glutamatergic system.

Overexpression of Thioredoxin-1 Blocks Morphine-Induced Conditioned Place Preference Through Regulating the Interaction of γ-Aminobutyric Acid and Dopamine Systems

Morphine is one kind of opioid, which is currently the most effective widely utilized pain relieving pharmaceutical. Long-term administration of morphine leads to dependence and addiction. Thioredoxin-1 (Trx-1) is an important redox regulating protein and works as a neurotrophic cofactor. Our previous study showed that geranylgeranylaceton, an inducer of Trx-1 protected mice from rewarding effects induced by morphine. However, whether overexpression of Trx-1 can block morphine-induced conditioned place preference (CPP) in mice is still unknown. In this study, we first examined whether overexpression of Trx-1 affects the CPP after morphine training and further examined the dopamine (DA) and γ-aminobutyric acid (GABA) systems involved in rewarding effects. Our results showed that morphine-induced CPP was blocked in Trx-1 overexpression transgenic (TG) mice. Trx-1 expression was induced by morphine in the ventral tegmental area (VTA) and nucleus accumbens (NAc) in wild-type (WT) mice, which was not induced in Trx-1 TG mice. The DA level and expressions of tyrosine hydroxylase (TH) and D1 were induced by morphine in WT mice, which were not induced in Trx-1 TG mice. The GABA level and expression of GABA_BR were decreased by morphine, which were restored in Trx-1 TG mice. Therefore, Trx-1 may play a role in blocking CPP induced by morphine through regulating the expressions of D1, TH, and GABA_BR in the VTA and NAc.