Interleukin-1beta downregulates the L-type Ca2+ channel activity by depressing the expression of channel protein in cortical neurons

Calcium Ions Aggravate Alzheimer's Disease Through the Aberrant Activation of Neuronal Networks, Leading to Synaptic and Cognitive Deficits

Alzheimer’s disease (AD) is a neurodegenerative disease that is characterized by the production and deposition of β-amyloid protein (Aβ) and hyperphosphorylated tau, leading to the formation of β-amyloid plaques (APs) and neurofibrillary tangles (NFTs). Although calcium ions (Ca²⁺) promote the formation of APs and NFTs, no systematic review of the mechanisms by which Ca²⁺ affects the development and progression of AD has been published. Therefore, the current review aimed to fill the gaps between elevated Ca²⁺ levels and the pathogenesis of AD. Specifically, we mainly focus on the molecular mechanisms by which Ca²⁺ affects the neuronal networks of neuroinflammation, neuronal injury, neurogenesis, neurotoxicity, neuroprotection, and autophagy. Furthermore, the roles of Ca²⁺ transporters located in the cell membrane, endoplasmic reticulum (ER), mitochondria and lysosome in mediating the effects of Ca²⁺ on activating neuronal networks that ultimately contribute to the development and progression of AD are discussed. Finally, the drug candidates derived from herbs used as food or seasoning in Chinese daily life are summarized to provide a theoretical basis for improving the clinical treatment of AD.

NLRP3-dependent pyroptosis is required for HIV-1 gp120-induced neuropathology

The human immunodeficiency virus-1 (HIV-1) envelope protein gp120 is the major contributor to the pathogenesis of HIV-associated neurocognitive disorder (HAND). Neuroinflammation plays a pivotal role in gp120-induced neuropathology, but how gp120 triggers neuroinflammatory processes and subsequent neuronal death remains unknown. Here, we provide evidence that NLRP3 is required for gp120-induced neuroinflammation and neuropathy. Our results showed that gp120-induced NLRP3-dependent pyroptosis and IL-1β production in microglia. Inhibition of microglial NLRP3 inflammasome activation alleviated gp120-mediated neuroinflammatory factor release and neuronal injury. Importantly, we showed that chronic administration of MCC950, a novel selective NLRP3 inhibitor, to gp120 transgenic mice not only attenuated neuroinflammation and neuronal death but also promoted neuronal regeneration and restored the impaired neurocognitive function. In conclusion, our data revealed that the NLRP3 inflammasome is important for gp120-induced neuroinflammation and neuropathology and suggest that NLRP3 is a potential novel target for the treatment of HAND.

Neuromodulatory properties of inflammatory cytokines and their impact on neuronal excitability

Increasing evidence underlines that prototypical inflammatory cytokines (IL-1β, TNF-α and IL-6) either synthesized in the central (CNS) or peripheral nervous system (PNS) by resident cells, or imported by immune blood cells, are involved in several pathophysiological functions, including an unexpected impact on synaptic transmission and neuronal excitability. This review describes these unconventional neuromodulatory properties of cytokines, that are distinct from their classical action as effector molecules of the immune system. In addition to the role of cytokines in brain physiology, we report evidence that dysregulation of their biosynthesis and cellular release, or alterations in receptor-mediated intracellular pathways in target cells, leads to neuronal cell dysfunction and modifications in neuronal network excitability. As a consequence, targeting of these cytokines, and related signalling molecules, is considered a novel option for the development of therapies in various CNS or PNS disorders associated with an inflammatory component. This article is part of a Special Issue entitled 'Neuroimmunology and Synaptic Function'.

Does brain inflammation mediate pathological outcomes in epilepsy?

Inflammation in the central nervous system (CNS) is associated with epilepsy and is characterized by the increased levels of a complex set of soluble molecules and their receptors in epileptogenic foci with profound neuromodulatory effects. These molecules activate receptor-mediated pathways in glia and neurons that contribute to hyperexcitability in neural networks that underlie seizure generation. As a consequence, exciting new opportunities now exist for novel therapies targeting the various components of the immune system and the associated inflammatory mediators, especially the IL-1β system. This review summarizes recent findings that increased our understanding of the role of inflammation in reducing seizure threshold, contributing to seizure generation, and participating in epileptogenesis. We will discuss preclinical studies supporting the hypothesis that pharmacological inhibition of specific proinflammatory signalings may be useful to treat drug-resistant seizures in human epilepsy, and possibly delay or arrest epileptogenesis.

Calcium dysregulation and neuroinflammation: discrete and integrated mechanisms for age-related synaptic dysfunction

Some of the best biomarkers of age-related cognitive decline are closely linked to synaptic function and plasticity. This review highlights several age-related synaptic alterations as they relate to Ca(2+) dyshomeostasis, through elevation of intracellular Ca(2+), and neuroinflammation, through production of pro-inflammatory cytokines including interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α). Though distinct in many ways, Ca(2+) and neuroinflammatory signaling mechanisms exhibit extensive cross-talk and bidirectional interactions. For instance, cytokine production in glial cells is strongly dependent on the Ca(2+) dependent protein phosphatase calcineurin, which shows elevated activity in animal models of aging and disease. In turn, pro-inflammatory cytokines, such as TNF, can augment the expression/activity of L-type voltage sensitive Ca(2+) channels in neurons, leading to Ca(2+) dysregulation, hyperactive calcineurin activity, and synaptic depression. Thus, in addition to discussing unique contributions of Ca(2+) dyshomeostasis and neuroinflammation, this review emphasizes how these processes interact to hasten age-related synaptic changes.

Interleukin-6 inhibits L-type calcium channel activity of cultured cerebellar granule neurons

Our previous work has shown that interleukin-6 (IL-6) implements its neuroprotective effect by inhibiting the intracellular Ca(2+) overload in neurons. Here, we examined whether regulation of L-type calcium channels (LCCs) activities is involved in the neuroprotective action of IL-6. In cultured cerebellar granule neurons (CGNs), patch-clamp recording showed that the whole-cell Ca(2+) current and LCC current were significantly reduced by IL-6 pretreatment (120 ng/ml, for 24 h). Calcium imaging data indicated that IL-6 significantly suppressed high K(+)-induced intracellular Ca(2+) overload and LCC Ca(2+) influx. Moreover, expression of the LCC subunit, Ca(v)1.2, was remarkably downregulated by IL-6 in cultured CGNs. These findings suggest that IL-6 exerts a neurotrophic effect by preventing Ca(2+) overload, at least partly through inhibition of LCC activity in cultured CGNs.

Inhibition of NMDA-induced outward currents by interleukin-1beta in hippocampal neurons

There is increasing evidence that a functional interaction exists between interleukin-1beta (IL-1beta) and N-methyl-D-aspartate (NMDA) receptors. The present study attempted to elucidate the effect of IL-1beta on the NMDA-induced outward currents in mechanically dissociated hippocampal neurons using a perforated patch recording technique. IL-1beta (30-100 ng/ml) inhibited the mean amplitude of the NMDA-induced outward currents that were mediated by charybdotoxin (ChTX)-sensitive Ca(2+)-activated K(+) (K(Ca)) channels. IL-1beta (100 ng/ml) also significantly increased the mean ratio of the NMDA-induced inward current amplitudes measured at the end to the beginning of a 20-s application of NMDA. In hippocampal neurons from acute slice preparations, IL-1beta significantly inhibited ChTX-sensitive K(Ca) currents induced by a depolarizing voltage-step. IL-1 receptor antagonist antagonized effects of IL-1beta. These results strongly suggest that IL-1beta increases the neuronal excitability by inhibition of ChTX-sensitive K(Ca) channels activated by Ca(2+) influx through both NMDA receptors and voltage-gated Ca(2+) channels.

Interleukin-1beta regulation of N-type Ca2+ channels in cortical neurons

Interleukin-1beta (IL-1beta) has been found to play an important role in various diseases in the central nervous system (CNS) and exhibit neuroprotective effects in some conditions. The transmitter release in brain is controlled by voltage-gated Ca(2+) channels (VGCCs), predominantly N-type Ca(2+) channels (NCCs). Although both IL-1beta and NCCs are implicated regulating excitotoxicity and Ca(2+) homeostasis, it is not known whether IL-1beta modulates NCCs directly. In present study, we examined the effects of IL-1beta treatment (10 ng/ml, 24 h) on NCCs in cultured cortical neurons using patch-clamp recording and immunoblot assay. Our results showed that IL-1beta decreased NCC currents by approximately 50%, which made up 40% of the whole-cell Ca(2+) current demonstrated by omega-conotoxin-GVIA, and also significantly downregulated the expression of NCC protein. The residual Ca(2+) currents except L-type Ca(2+) channel currents and NCC currents were not affected by IL-1beta. Our finding, IL-1beta inhibits the activity of NCC via suppressing NCC protein expression provides new insight into the neuroprotective role of IL-1beta in CNS.