Active secretion of IL-33 from astrocytes is dependent on TMED10 and promotes central nervous system homeostasis.

Interleukin-33 (IL-33), secreted by astrocytes, regulates the synapse development in the spinal cord and hippocampus and suppresses autoimmune disease in the central nervous system (CNS). However, the mechanism of unconventional protein secretion of this cytokine remains unclear. In this study, we found that IFN-γ promotes the active secretion of IL-33 from astrocytes, and the active secretion of IL-33 from cytoplasm to extracellular space was dependent on interaction with transmembrane emp24 domain 10 (TMED10) via the IL-1 like cytokine domain in astrocytes. Knockout of Il-33 or its receptor St2 induced hippocampal astrocyte activation and depressive-like disorder in naive mice, as well as increased spinal cord astrocyte activation and polarization to a neurotoxic reactive subtype and aggravated passive experimental autoimmune encephalomyelitis (EAE). Our results have identified that IL-33 is actively secreted by astrocytes through the unconventional protein secretion pathway facilitated by TMED10 channels. This process helps maintain CNS homeostasis by inhibiting astrocyte activation.

Neuroprotection of N-benzyl Eicosapentaenamide in Neonatal Mice Following Hypoxic-Ischemic Brain Injury.

Maca (Lepidium meyenii) has emerged as a popular functional plant food because of its medicinal properties and nutritional value. Macamides, as the exclusively active ingredients found in maca, are a unique series of non-polar, long-chain fatty acid N-benzylamides with multiple bioactivities such as antifatigue characteristics and improving reproductive health. In this study, a new kind of macamide, N-benzyl eicosapentaenamide (NB-EPA), was identified from maca. We further explore its potential neuroprotective role in hypoxic-ischemic brain injury. Our findings indicated that treatment with biosynthesized NB-EPA significantly alleviates the size of cerebral infarction and improves neurobehavioral disorders after hypoxic-ischemic brain damage in neonatal mice. NB-EPA inhibited the apoptosis of neuronal cells after ischemic challenge. NB-EPA improved neuronal cell survival and proliferation through the activation of phosphorylated AKT signaling. Of note, the protective property of NB-EPA against ischemic neuronal damage was dependent on suppression of the p53-PUMA pathway. Taken together, these findings suggest that NB-EPA may represent a new neuroprotectant for newborns with hypoxic-ischemic encephalopathy.

Neuroprotective effect of astrocyte-derived IL-33 in neonatal hypoxic-ischemic brain injury.

BACKGROUND: Interleukin-33 (IL-33) is a well-recognized pleiotropic cytokine which plays crucial roles in immune regulation and inflammatory responses. Recent studies suggest that IL-33 and its receptor ST2 are involved in the pathogenesis of neurological diseases. Here, we explore the effect of IL-33/ST2 signaling in neonatal hypoxic-ischemic (HI) brain injury and elucidate the underlying mechanisms of action. METHODS: The brain HI model was established in neonatal C57BL/6 mice by left common carotid artery occlusion with 90 min hypoxia and treated with IL-33 at a dose of 0.2 µg/day i.p. for 3 days. TTC staining and neurobehavioral observation were used to evaluate the HI brain injury. Immunofluorescence and flow cytometry were applied to determine the expression of IL-33 and its receptor ST2 on brain CNS cells and cell proliferation and apoptosis. OGD experiment was used to assay the viability of astrocytes and neurons. RT-qPCR was used to measure the expression of neurotrophic factor-associated genes. RESULTS: The expression level of IL-33 was markedly enhanced in astrocytes 24 h after cerebral HI in neonatal mice. Exogenous delivery of IL-33 significantly alleviated brain injury 7 days after HI, whereas ST2 deficiency exacerbated brain infarction and neurological deficits post HI. Flow cytometry analyses demonstrated high levels of ST2 expression on astrocytes, and the expression of ST2 was further elevated after HI. Intriguingly, IL-33 treatment apparently improved astrocyte response and attenuated HI-induced astrocyte apoptosis through ST2 signaling pathways. Further in vitro studies revealed that IL-33-activated astrocytes released a series of neurotrophic factors, which are critical for raising neuronal survival against oxygen glucose deprivation. CONCLUSIONS: The activation of IL-33/ST2 signaling in the ischemic brain improves astrocyte response, which in turn affords protection to ischemic neurons in a glial-derived neurotrophic factor-dependent manner.

The IL-33/ST2 Axis Protects Retinal Ganglion Cells by Modulating the Astrocyte Response After Optic Nerve Injury.

IL-33 and its receptor ST2 play crucial roles in tissue repair and homeostasis. However, their involvement in optic neuropathy due to trauma and glaucoma remains unclear. Here, we report that IL-33 and ST2 were highly expressed in the mouse optic nerve and retina. Deletion of IL-33 or ST2 exacerbated retinal ganglion cell (RGC) loss, retinal thinning, and nerve fiber degeneration following optic nerve (ON) injury. This heightened retinal neurodegeneration correlated with increased neurotoxic astrocytes in Il33-/- mice. In vitro, rIL-33 mitigated the neurotoxic astrocyte phenotype and reduced the expression of pro-inflammatory factors, thereby alleviating the RGC death induced by neurotoxic astrocyte-conditioned medium in retinal explants. Exogenous IL-33 treatment improved RGC survival in Il33-/- and WT mice after ON injury, but not in ST2-/- mice. Our findings highlight the role of the IL-33/ST2 axis in modulating reactive astrocyte function and providing neuroprotection for RGCs following ON injury.

HMGB1/RAGE axis in tumor development: unraveling its significance.

High mobility group protein 1 (HMGB1) plays a complex role in tumor biology. When released into the extracellular space, it binds to the receptor for advanced glycation end products (RAGE) located on the cell membrane, playing an important role in tumor development by regulating a number of biological processes and signal pathways. In this review, we outline the multifaceted functions of the HMGB1/RAGE axis, which encompasses tumor cell proliferation, apoptosis, autophagy, metastasis, and angiogenesis. This axis is instrumental in tumor progression, promoting tumor cell proliferation, autophagy, metastasis, and angiogenesis while inhibiting apoptosis, through pivotal signaling pathways, including MAPK, NF-κB, PI3K/AKT, ERK, and STAT3. Notably, small molecules, such as miRNA-218, ethyl pyruvate (EP), and glycyrrhizin exhibit the ability to inhibit the HMGB1/RAGE axis, restraining tumor development. Therefore, a deeper understanding of the mechanisms of the HMGB1/RAGE axis in tumors is of great importance, and the development of inhibitors targeting this axis warrants further exploration.

IL-33 and HMGB1 modulate the progression of EAE via oppositely regulating each other.

Interleukin-33 (IL-33) and high mobility group box 1 (HMGB1) have been reported to play crucial and distinct roles in experimental autoimmune encephalomyelitis (EAE). However, little is known about their interaction in the progression of EAE. In this study, the dynamic expression and release of IL-33 and HMGB1 in different stages of EAE in vivo, and their interaction in vitro were explored. We found that HMGB1 was dominant in pre-onset stage of EAE, while IL-33 was dominant in peak stage. Moreover, both blockade of extracellular HMGB1 in the central nervous system (CNS) and conditional knockout of HMGB1 in astrocytes decreased IL-33 release. HMGB1 promoted the release of IL-33, while IL-33 reduced the release of HMGB1 from primary astrocytes in vitro. Taken together, IL-33 and HMGB1 in the CNS jointly participate in the EAE progression and the inhibitory effect of IL-33 on HMGB1 may be involved in the self-limiting of EAE.

IL-33 Contributes to the Pathological Changes of Hair Follicles in Psoriasis: A Potential Target for Psoriatic Alopecia.

Purpose: IL-33 is constitutively expressed in skin tissues. Alopecia, a T cells-driven disorder of the hair follicles (HFs), is a common complication in the development of psoriasis. However, the role of IL-33 in psoriatic alopecia remains uncovered. Here, we investigated the roles of IL-33 in inducing pathological changes of hair follicles in psoriasis. Patients and Methods: Clinical samples and imiquimod (IMQ)-induced psoriatic mice samples were used to investigate the pathological changes and T-cell infiltration of HFs. By using immunohistochemistry staining, the distribution and expression alteration of IL-33 in HFs were determined. Next, by using IL-33 and ST2 knockout mice, we investigated the role of IL-33/ST2 axis in the pathological changes of HFs in psoriasis. Meanwhile, recombinant IL-33 protein was subcutaneous injected to confirm its effect. Finally, RNA sequencing was used to clarify the genes and signaling pathways that involved in this process. Differentially expressed genes were further verified by RT-PCR in cultured HFs in vitro. Results: We found that the pathological changes of HFs and T cells infiltration in imiquimod-induced psoriatic mice were similar to that in psoriasis patients. The IL-33 positive keratinocytes in the outer root sheath of HFs were increased in both psoriasis patients and psoriatic model mice compared with the controls. By using gene knockout mice, we found that the pathological changes and T cell infiltration were attenuated in IL-33-/- and ST2-/- psoriatic model mice. In addition, subcutaneous injection of recombinant IL-33 exacerbated the pathological changes of HFs and T cell infiltration. RNA sequencing and RT-RCR revealed that IL-33 upregulated the transcription of genes related to keratinocytes proliferation and T lymphocytes chemotaxis. Conclusion: Our study identifies that IL-33 promotes the pathological changes of HFs in psoriasis, which contributes to psoriatic alopecia. Inhibition of IL-33 may be a potential therapeutic approach for psoriatic alopecia.

HMGB1 from Astrocytes Promotes EAE by Influencing the Immune Cell Infiltration-Associated Functions of BMECs in Mice.

High mobility group box 1 (HMGB1) has been reported to play an important role in experimental autoimmune encephalomyelitis (EAE). Astrocytes are important components of neurovascular units and tightly appose the endothelial cells of microvessels by their perivascular endfeet and directly regulate the functions of the blood-brain barrier. Astrocytes express more HMGB1 during EAE while the exact roles of astrocytic HMGB1 in EAE have not been well elucidated. Here, using conditional-knockout mice, we found that astrocytic HMGB1 depletion decreased morbidity, delayed the onset time, and reduced the disease score and demyelination of EAE. Meanwhile, there were fewer immune cells, especially pathogenic T cells infiltration in the central nervous system of astrocytic HMGB1 conditional-knockout EAE mice, accompanied by up-regulated expression of the tight-junction protein Claudin5 and down-regulated expression of the cell adhesion molecules ICAM1 and VCAM1 in vivo. In vitro, HMGB1 released from astrocytes decreased Claudin5 while increased ICAM1 and VCAM1 expressed by brain microvascular endothelial cells (BMECs) through TLR4 or RAGE. Taken together, our results demonstrate that HMGB1 derived from astrocytes aggravates EAE by directly influencing the immune cell infiltration-associated functions of BMECs.

Allograft or Recipient ST2 Deficiency Oppositely Affected Cardiac Allograft Vasculopathy via Differentially Altering Immune Cells Infiltration.

The role of IL-33/ST2 signaling in cardiac allograft vasculopathy (CAV) is not fully addressed. Here, we investigated the role of IL-33/ST2 signaling in allograft or recipient in CAV respectively using MHC-mismatch murine chronic cardiac allograft rejection model. We found that recipients ST2 deficiency significantly exacerbated allograft vascular occlusion and fibrosis, accompanied by increased F4/80+ macrophages and CD3+ T cells infiltration in allografts. In contrast, allografts ST2 deficiency resulted in decreased infiltration of F4/80+ macrophages, CD3+ T cells and CD20+ B cells and thus alleviated vascular occlusion and fibrosis of allografts. These findings indicated that allografts or recipients ST2 deficiency oppositely affected cardiac allograft vasculopathy/fibrosis via differentially altering immune cells infiltration, which suggest that interrupting IL-33/ST2 signaling locally or systematically after heart transplantation leads different outcome.

Identification of proteins in housefly (Musca domestica) larvae powder by LC-MS/MS and their potential medical relevance.

Housefly larvae (HL) powder was used to cure wounds centuries ago for its good nutritional and pharmacological values. At present, most of the medical studies are about the crude extracts of HL, while the specific pharmacological material basis is still unclear. We ground third-instar Musca domestica larvae into a powder, degreasing and preparing the protein extract. The protein extract was subjected to enzymatic hydrolysis, and the enzymatic hydrolysis products were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). We identified a variety of highly trusted proteins (false discovery rate is less than or equal to 1%), including catalysis-related proteins, antioxidant proteins and antimicrobial peptides, which may be closely related to the anti-tumor, anti-bacterial, anti-oxidant and other pharmacological effects of HL. We identified the amino acid sequences of these proteins, and further confirmed HL's protective effect on APP/PS1 transgenic Alzheimer's mice. The results of this work provide material basis for further medical research on HL.

Correction: Housefly (Musca domestica) larvae powder, preventing oxidative stress injury via regulation of UCP4 and CyclinD1 and modulation of JNK and P38 signaling in APP/PS1 mice.

Correction for 'Housefly (Musca domestica) larvae powder, preventing oxidative stress injury via regulation of UCP4 and CyclinD1 and modulation of JNK and P38 signaling in APP/PS1 mice' by Yinru He et al., Food Funct., 2019, 10, 235-243.

Housefly (Musca domestica) larvae powder, preventing oxidative stress injury via regulation of UCP4 and CyclinD1 and modulation of JNK and P38 signaling in APP/PS1 mice.

Housefly (Musca domestica) Larvae powder (HL) is rich in antioxidants. As oxidative stress is considered as one of the main pathogenesis in Alzheimer's Disease (AD), this study was designed to explore the protective effects of HL as an antioxidant on APP/PS1 mice. 2-Month-old APP/PS1 mice were divided into a model control (MC) group, a Donepezil group and a HL group, and C57BL/6 mice were used as the normal control (NC) group. After 180 days of treatment, the memory ability was measured by Morris Water Maze (MWM). The presence of Aß and the expression of Uncoupling Protein 4 (UCP4) and CyclinD1 were detected by immunohistochemistry. The expressions of Superoxide Dismutase 1 (SOD1), Catalase (CAT) and Mitogen-activated Protein Kinase (MAPK) signal pathways were measured by western blotting. Compared with untreated APP/PS1 mice, the memory abilities of the HL-treated mice were significantly improved. Furthermore, the HL treatment not only down-regulated the deposition of Aß and the expression of CylinD1, but also increased both the mRNA and protein levels of SOD, CAT, and UCP4, and enhanced the phosphorylation of JNK and P38 MAPK activation. In conclusion, these results suggest that HL may have a protective effect against memory impairment and prevent oxidative stress-induced injury via the regulation of UCP4 and CyclinD1 and the modulation of JNK and P38 MAPK signaling in AD.

Interleukin-33 regulates hematopoietic stem cell regeneration after radiation injury.

BACKGROUND: IL-33 is a pleiotropic cytokine of the IL-1 family, which has been reported to implicate in both innate and adaptive immune responses. Recent studies suggest IL-33 is crucial for regulation of myelopoiesis and myeloid cell activity. Here, we explore the potential effect of IL-33 against hematopoietic injury after total body irradiation (TBI). METHODS: C57BL/6 mice were irradiated with a sublethal dose of radiation (600 cGy) and treated with IL-33 at a dose of 3 µg/dose i.p. once a day for seven consecutive days. H&E staining was used to determine the bone marrow cellularity. A flow cytometer was used to quantify the hematopoietic stem cell (HSC) population, cell proliferation, and apoptosis. The colony-forming assay was used to evaluate the clonogenic function of HSCs. RT-qPCR was used to determine the expression of apoptosis-associated genes. RESULTS: Bone marrow HSCs from wild-type mice expressed functional IL-33 receptor (ST2), and treatment with IL-33 promoted the recovery of the HSC pool in vivo and improved the survival of mice after TBI. Conversely, mice with ST2 deficiency showed decreased HSC regeneration and mouse survival after TBI. Of note, IL-33 reduced radiation-induced apoptosis of HSCs and mediated this effect through repression of the p53-PUMA pathway. CONCLUSIONS: IL-33 regulates HSC regeneration after myelosuppressive injury through protecting HSCs from apoptosis and enhancing proliferation of the surviving HSCs.