Human amniotic epithelial stem cells inhibit microglia activation through downregulation of tumor necrosis factor-α, interleukin-1β and matrix metalloproteinase-12 in vitro and in a rat model of intracerebral hemorrhage

Role of Microglial Modulation in Therapies for Perinatal Brain Injuries Leading to Neurodevelopmental Disorders

Neurodevelopmental disorders (NDDs) encompass various conditions stemming from changes during brain development, typically diagnosed early in life. Examples include autism spectrum disorder, intellectual disability, cerebral palsy, seizures, dyslexia, and attention deficit hyperactivity disorder. Many NDDs are linked to perinatal events like infections, oxygen disturbances, or insults in combination. This chapter outlines the causes and effects of perinatal brain injury as they relate to microglia, along with efforts to prevent or treat such damage. We primarily discuss therapies targeting microglia modulation, focusing on those either clinically used or in advanced development, often tested in large animal models such as sheep, non-human primates, and piglets-standard translational models in perinatal medicine. Additionally, it touches on experimental studies showcasing advancements in the field.

Neuroinflammation of microglia polarization in intracerebral hemorrhage and its potential targets for intervention

Microglia are the resident immune cells of the central nervous system (CNS) and play a key role in neurological diseases, including intracerebral hemorrhage (ICH). Microglia are activated to acquire either pro-inflammatory or anti-inflammatory phenotypes. After the onset of ICH, pro-inflammatory mediators produced by microglia at the early stages serve as a crucial character in neuroinflammation. Conversely, switching the microglial shift to an anti-inflammatory phenotype could alleviate inflammatory response and incite recovery. This review will elucidate the dynamic profiles of microglia phenotypes and their available shift following ICH. This study can facilitate an understanding of the self-regulatory functions of the immune system involving the shift of microglia phenotypes in ICH. Moreover, suggestions for future preclinical and clinical research and potential intervention strategies are discussed.

Crescentic Glomerulonephritis: Pathogenesis and Therapeutic Potential of Human Amniotic Stem Cells

Chronic kidney disease (CKD) leads to significant morbidity and mortality worldwide. Glomerulonephritis (GN) is the second leading cause of CKD resulting in end stage renal failure. The most severe and rapidly progressive type of GN is characterized by glomerular crescent formation. The current therapies for crescentic GN, which consist of broad immunosuppressive drugs, are partially effective, non-specific, toxic and cause many serious side effects including infections, cancer, and cardiovascular problems. Therefore, new and safer therapies are needed. Human amniotic epithelial cells (hAECs) are a type of stem cell which are isolated from the placenta after birth. They represent an attractive and novel therapeutic option for the treatment of various inflammatory conditions owing to their unique and selective immunosuppressive ability, as well as their excellent safety profile and clinical applicability. In this review, we will discuss the immunopathogenesis of crescentic GN, issues with currently available treatments and how hAECs offer potential to become a new and harmless treatment option for this condition.

Microglia: A Double-Edged Sword in Intracerebral Hemorrhage From Basic Mechanisms to Clinical Research

Microglia are the resident immune cells of the central nervous system (CNS). It is well established that microglia are activated and polarized to acquire different inflammatory phenotypes, either pro-inflammatory or anti-inflammatory phenotypes, which act as a critical component in the neuroinflammation following intracerebral hemorrhage (ICH). Microglia produce pro-inflammatory mediators at the early stages after ICH onset, anti-inflammatory microglia with neuroprotective effects appear to be suppressed. Previous research found that driving microglia towards an anti-inflammatory phenotype could restrict inflammation and engulf cellular debris. The principal objective of this review is to analyze the phenotypes and dynamic profiles of microglia as well as their shift in functional response following ICH. The results may further the understanding of the body's self-regulatory functions involving microglia following ICH. On this basis, suggestions for future clinical development and research are provided.

Application of human amniotic epithelial cells in regenerative medicine: a systematic review

Human amniotic epithelial cells (hAECs) derived from placental tissues have gained considerable attention in the field of regenerative medicine. hAECs possess embryonic stem cell-like proliferation and differentiation capabilities, and adult stem cell-like immunomodulatory properties. Compared with other types of stem cell, hAECs have special advantages, including easy isolation, plentiful numbers, the obviation of ethical debates, and non-immunogenic and non-tumorigenic properties. During the past two decades, the therapeutic potential of hAECs for treatment of various diseases has been extensively investigated. Accumulating evidence has demonstrated that hAEC transplantation helps to repair and rebuild the function of damaged tissues and organs by different molecular mechanisms. This systematic review focused on summarizing the biological characteristics of hAECs, therapeutic applications, and recent advances in treating various tissue injuries and disorders. Relevant studies published in English from 2000 to 2020 describing the role of hAECs in diseases and phenotypes were comprehensively sought out using PubMed, MEDLINE, and Google Scholar. According to the research content, we described the major hAEC characteristics, including induced differentiation plasticity, homing and differentiation, paracrine function, and immunomodulatory properties. We also summarized the current status of clinical research and discussed the prospects of hAEC-based transplantation therapies. In this review, we provide a comprehensive understanding of the therapeutic potential of hAECs, including their use for cell replacement therapy as well as secreted cytokine and exosome biotherapy. Moreover, we showed that the powerful immune-regulatory function of hAECs reveals even more possibilities for their application in the treatment of immune-related diseases. In the future, establishing the optimal culture procedure, achieving precise and accurate treatment, and enhancing the therapeutic potential by utilizing appropriate preconditioning and/or biomaterials would be new challenges for further investigation.

Matrix Metalloproteinases in Acute Intracerebral Hemorrhage

Spontaneous intracerebral hemorrhage (ICH) accounts for 10-30% of all strokes and affects more than one million people every year worldwide, and it is the stroke subtype associated with the highest rates of mortality and residual disability. So far, clinical trials have mainly targeted primary cerebral injury and have substantially failed to improve clinical outcomes. The understanding of the pathophysiology of early and delayed injury after ICH is, hence, of paramount importance to identify potential targets of intervention and develop effective therapeutic strategies. Matrix metalloproteinases (MMPs) represent a ubiquitous superfamily of structurally related zinc-dependent endopeptidases able to degrade any component of the extracellular matrix. They are upregulated after ICH, in which different cell types, including leukocytes, activated microglia, neurons, and endothelial cells, are involved in their synthesis and secretion. The aim of this review is to summarize the available experimental and clinical evidence about the role of MMPs in brain injury following spontaneous ICH and provide critical insights into the underlying mechanisms.

Therapeutic Potential of Human Amniotic Epithelial Cells on Injuries and Disorders in the Central Nervous System

Despite recent advances in neurosurgery and pharmaceuticals, contemporary treatments are ineffective in restoring lost neurological functions in patients with injuries and disorders of the central nervous system (CNS). Therefore, novel and effective therapies are urgently needed. Recent studies have indicated that stem cells, including embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), and mesenchymal stem cells (MSCs), could repair/replace damaged or degenerative neurons and improve functional recovery in both preclinical and clinical trials. However, there are many unanswered questions and unsolved issues regarding stem cell therapy in terms of potency, stability, oncogenicity, immune response, cell sources, and ethics. Currently, human amniotic epithelial cells (hAECs) derived from the amnion exhibit considerable advantages over other stem cells and have drawn much attention from researchers. hAECs are readily available, pose no ethical concerns, and have little risk of tumorigenicity and immunogenicity. Mounting evidence has shown that hAECs can promote neural cell survival and regeneration, repair affected neurons, and reestablish damaged neural connections. It is suggested that hAECs may be the most promising candidate for cell-based therapy of neurological diseases. In this review, we mainly focus on recent advances and potential applications of hAECs for treating various CNS injuries and neurodegenerative disorders. We also discuss current hurdles and challenges regarding hAEC therapies.

Ac-YVAD-cmk improves neurological function by inhibiting caspase-1-mediated inflammatory response in the intracerebral hemorrhage of rats

OBJECTIVE

Intracerebral hemorrhage (ICH) is acknowledged as a serious clinical problem lacking effective treatments. And caspase-1-mediated inflammatory response happened during the progression of ICH. Therefore, we aimed to investigate the effects of caspase-1 inhibitor Ac-YVAD-cmk on ICH.

MATERIALS AND METHODS

Microglia cells were isolated and activated by thrombin for 24 h. Then the transcript and protein expressions of NLRP3 and inflammatory factors were assessed by RT-PCR and western blotting. Moreover, Ac-YVAD-cmk was injected into the ICH model. The mNSS and brain water content were tested at 24 h post-ICH. Finally, the pathological changes of microglia activation following ICH were discovered by the immunohistochemical and HE staining ways.

RESULTS

Ac-YVAD-cmk inhibited the activation of pro-caspase-1 and decreased brain edema, in association with decreasing activated microglia and the expression of inflammation-related factors at 24 h post-ICH. Consequently, Ac-YVAD-cmk reduced the release of mature IL-1β/IL-18 in perihematoma, improved the behavioral performance, and alleviated microglia in perihematoma region in ICH rats.

CONCLUSIONS

These results indicate that caspase-1 could amplify the plural inflammatory responses in the ICH. Administration of Ac-YVAD-cmk has the potential to be a novel therapeutic strategy for ICH.

Role and mechanisms of cytokines in the secondary brain injury after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a common and severe cerebrovascular disease that has high mortality. Few survivors achieve self-care. Currently, patients receive only symptomatic treatment for ICH and benefit poorly from this regimen. Inflammatory cytokines are important participants in secondary injury after ICH. Increases in proinflammatory cytokines may aggravate the tissue injury, whereas increases in anti-inflammatory cytokines might be protective in the ICH brain. Inflammatory cytokines have been studied as therapeutic targets in a variety of acute and chronic brain diseases; however, studies on ICH are limited. This review summarizes the roles and functions of various pro- and anti-inflammatory cytokines in secondary brain injury after ICH and discusses pathogenic mechanisms and emerging therapeutic strategies and directions for treatment of ICH.

IL-17A induces autophagy and promotes microglial neuroinflammation through ATG5 and ATG7 in intracerebral hemorrhage

Microglial inflammation plays a vital role in intracerebral hemorrhage (ICH)-induced secondary brain injury. IL-17A has been identified to promote microglia activation, but the role in the pathology following ICH remains unclear. Autophagy is involved in modulation of cell metabolism, cell survival, and immune response. However, the role of IL-17A in autophagy following ICH has not been well defined. In this study, we assessed the role of IL-17A in microglial autophagic activity following ICH. The microglia were treated with IL-17A, and then autophagy and inflammation were detected. In addition, RNA interference in essential autophagy genes (ATG5 and ATG7) was also utilized to analyze microglial autophagy in vitro. Furthermore, ICH mice were made by injection of autologous blood model in vivo. And the IL-17A-neutralizing antibody was utilized to assess the neurological scores and brain edema. These data demonstrated that IL-17A promoted microglial autophagy and microglial inflammation. The suppression of autophagy using RNA interference in essential autophagy genes (ATG5 and ATG7) decreased microglial autophagy and inflammation. Moreover, IL-17A Ab significantly reduced brain water content and improved neurological function of ICH mice. Taken together, these data demonstrated that IL-17A promoted microglial autophagy and microglial inflammation, and IL-17A-mediated activation of autophagy might represent novel clues in ICH therapy.

Early Combined Therapy with Pharmacologically Induced Hypothermia and Edaravone Exerts Neuroprotective Effects in a Rat Model of Intracerebral Hemorrhage

In present study, we evaluated acute neuroprotective effects of combined therapy with pharmacologically induced hypothermia and edaravone in a rat model of intracerebral hemorrhage (ICH). ICH was caused by injection of 0.5 U of collagenase VII to the caudate nucleus of male Sprague-Dawley rats. Sham-treated animals receive injections of normal saline instead of collagenase VII. All animals were randomly divided into five groups: sham group, ICH group, hypothermia group, edavarone (10 mg/kg) group, and combined hypothermia + edavarone group. Hypothermia was induced by injection of the second-generation neurotensin receptor agonist HPI-201 (2 mg/kg at 1 h after ICH; 1 mg/kg at 4 and 7 h after ICH). Hypothermia was sustained for at least 6 h. The study outcomes were the extent of brain edema, permeability of the blood-brain barrier (Evan's blue dye), expression of matrix metalloproteinase-9 and inflammatory cytokines (IL-1β, IL-4, IL-6, and TNF-α), and expression of apoptosis-related proteins (caspase-3, cytochrome C, Bcl-2, and Bax). Brain edema, permeability of the blood-brain barrier, and expression of metalloproteinase-9 were increased, while expression of caspase-3 and Bcl-2 was decreased by ICH. We observed that the combined therapy was significantly more potent in reverting the above negative trends induced by ICH. In conclusion, our results indicate that a combination of pharmacologically induced hypothermia and edavarone leads to potentiation of their respective neuroprotective effects.

Amniotic Epithelial Cells: A New Tool to Combat Aging and Age-Related Diseases?

The number of elderly people is growing at an unprecedented rate and this increase of the aging population is expected to have a direct impact on the incidence of age-related diseases and healthcare-associated costs. Thus, it is imperative that new tools are developed to fight and slow age-related diseases. Regenerative medicine is a promising strategy for the maintenance of health and function late in life; however, stem cell-based therapies face several challenges including rejection and tumor transformation. As an alternative, the placenta offers an extraordinary source of fetal stem cells, including the amniotic epithelial cells (AECs), which retain some of the characteristics of embryonic stem cells, but show low immunogenicity, together with immunomodulatory and anti-inflammatory activities. Because of these characteristics, AECs have been widely utilized in regenerative medicine. This perspective highlights different mechanisms triggered by transplanted AECs that could be potentially useful for anti-aging therapies, which include: Graft and differentiation for tissue regeneration in age-related settings, anti-inflammatory behavior to combat “inflammaging,” anti-tumor activity, direct lifespan and healthspan extension properties, and possibly rejuvenation in a manner reminiscent of heterochronic parabiosis. Here, we critically discuss benefits and limitation of AECs-based therapies in age-related diseases.

Pyruvate Dehydrogenase Kinase-mediated Glycolytic Metabolic Shift in the Dorsal Root Ganglion Drives Painful Diabetic Neuropathy

The dorsal root ganglion (DRG) is a highly vulnerable site in diabetic neuropathy. Under diabetic conditions, the DRG is subjected to tissue ischemia or lower ambient oxygen tension that leads to aberrant metabolic functions. Metabolic dysfunctions have been documented to play a crucial role in the pathogenesis of diverse pain hypersensitivities. However, the contribution of diabetes-induced metabolic dysfunctions in the DRG to the pathogenesis of painful diabetic neuropathy remains ill-explored. In this study, we report that pyruvate dehydrogenase kinases (PDK2 and PDK4), key regulatory enzymes in glucose metabolism, mediate glycolytic metabolic shift in the DRG leading to painful diabetic neuropathy. Streptozotocin-induced diabetes substantially enhanced the expression and activity of the PDKs in the DRG, and the genetic ablation of Pdk2 and Pdk4 attenuated the hyperglycemia-induced pain hypersensitivity. Mechanistically, Pdk2/4 deficiency inhibited the diabetes-induced lactate surge, expression of pain-related ion channels, activation of satellite glial cells, and infiltration of macrophages in the DRG, in addition to reducing central sensitization and neuroinflammation hallmarks in the spinal cord, which probably accounts for the attenuated pain hypersensitivity. Pdk2/4-deficient mice were partly resistant to the diabetes-induced loss of peripheral nerve structure and function. Furthermore, in the experiments using DRG neuron cultures, lactic acid treatment enhanced the expression of the ion channels and compromised cell viability. Finally, the pharmacological inhibition of DRG PDKs or lactic acid production substantially attenuated diabetes-induced pain hypersensitivity. Taken together, PDK2/4 induction and the subsequent lactate surge induce the metabolic shift in the diabetic DRG, thereby contributing to the pathogenesis of painful diabetic neuropathy.

CD163/Hemoglobin Oxygenase-1 Pathway Regulates Inflammation in Hematoma Surrounding Tissues after Intracerebral Hemorrhage

BACKGROUND

The aim of the present study was to investigate changes in the expression of CD163 and hemoglobin oxygenase-1 (HO-1) in brain tissue surrounding hematomas after intracerebral hemorrhage (ICH), and correlations with other factors.

MATERIALS AND METHODS

Brain tissues in the close surrounding of ICH hematomas (n = 27, ICH group) were collected at 6 hours or less, 6-24 hours, 24-72 hours, and more than 72 hours after bleeding onset, and more distant tissues (n = 12, control group) were histologically analyzed with hematoxylin and eosin staining and transmission electron microscopy. Interleukin (IL)-1, IL-10, and tumor necrosis factor-alpha, as well as the expression of CD163 and HO-1, were assessed using immunochemistry, Western blotting, and reverse transcription-polymerase chain reaction. Apoptosis rates were determined with terminal deoxynucleotidyl transferase dUTP nick end labeling assays.

RESULTS

The expressions of the inflammatory cytokines IL-1 and tumor necrosis factor-alpha were increased at 6-24 hours (P <.05), reached a peak at 24-72 hours (P <.001 and P <.01), at which time histopathological changes became most obvious and apoptosis rates were highest, but diminished for more than 72 hours after ICH onset. The anti-inflammatory cytokine IL-10 peaked at 6-24 hours (P < .01) after ICH onset but dropped in the following periods to lower levels than the control (P <.05). CD163 and HO-1 expressions gradually increased from 6 to 24 hours to peaks at more than 72 hours after ICH onset (P <.001).

CONCLUSION

The highest inflammation level in tissues surrounding ICH hematomas occurred 2-3 days after bleeding onset, but was accompanied by an anti-inflammatory factor IL-10 expression enhancement. In the period of more than 72 hours after ICH onset, CD163 and HO-1 expressions reached peaks and inflammatory cytokine expressions dropped.