Raymond Chuen-Chung Chang

The University of Hong Kong | HKU · Laboratory of Neurodegenerative Diseases, School of Biomedical Sciences

Background: The number of major operations performed in obese patients is expected to increase given the growing prevalence of obesity. Obesity is a risk factor for a range of postoperative complications including perioperative neurocognitive disorders. However, the mechanisms underlying this vulnerability are not well defined. We hypothesize that...

Postoperative cognitive dysfunction (POCD) is a common complication that affects memory, executive function, and processing speed postoperatively. The pathogenesis of POCD is linked to excessive neuroinflammation and pre-existing Alzheimer’s disease (AD) pathology. Previous studies have shown that acupuncture improves cognition in the early phase o...

Rationale: Alzheimer's disease (AD) is hallmarked by amyloid-β (Aβ) plaques and hyperphosphorylated tau (p-tau) neurofibrillary tangles. While Aβ-centric therapies have shown promise, the complex pathology of AD requires a multifaceted therapeutic approach. The weak association between Aβ levels and cognitive decline highlights the need for alterna...

Background The growing number of obese individuals is expected to create an increase in the number of major operations to be performed in those patients. Obesity is a risk factor for a range of postoperative complications including perioperative neurocognitive disorders. However, the neurotoxic effects of general anaesthesia in the obese subjects a...

Autophagy is a highly conserved catabolic mechanism by which unnecessary or dysfunctional cellular components are removed. The dysregulation of autophagy has been implicated in various neurodegenerative diseases, including Alzheimer’s disease (AD). Understanding the molecular mechanism(s)/molecules that influence autophagy may provide important ins...

Circadian rhythms regulate physiological processes in approximately 24 h cycles, and their disruption is associated with various diseases. Inflammation may perturb circadian rhythms, though these interactions remain unclear. This study examined whether systemic inflammation induced by an intraperitoneal injection of lipopolysaccharide (LPS) could a...

Aberrant activation of complement cascades plays an important role in the progress of neurological disorders. Complement C3, the central complement component, has been implicated in synaptic loss and cognitive impairment. Recent study has shown that wound injury-induced systemic inflammation can trigger the increase of C3 in the brain. Our previous...

Background Physical exercise improves cognition in human and animal studies associated with Alzheimer’s Disease (AD). However, resistance‐type regimes remain poorly investigated. Acute illness or injury can influence the rate AD progression and trigger accelerated cognitive decline. Method To evaluate the role of RE in modulating pre‐existing cogn...

CA2 region was found to have predominantly enriched α-synuclein accumulation in Parkinson’s disease dementia (PDD) with unknown pathological spreading routes. Here, we traced the novel neural circuit connecting the ventral tegmental area (VTA) to CA2 and identified the CA2 neuronal subtype involved in this circuit by viral tracing and tissue cleari...

Introduction Glucose transporter 1 (GLUT1) is essential for glucose transport into the brain and is predominantly expressed in the cerebral microvasculature. Downregulation of GLUT1 precedes the development of cognitive impairment in neurodegenerative conditions. Surgical trauma induces blood–brain barrier (BBB) disruption, neuroinflammation, neuro...

Systemic inflammation may promote neuroinflammation and neurodegeneration. The double-stranded RNA-dependent protein kinase (PKR) is a key signaling molecule that regulates immune responses. This study aims to examine the role of PKR in regulating systemic inflammation-induced neuroinflammation and cognitive dysfunctions using a laparotomy mouse mo...

Introduction Glucose transporter 1 (GLUT1) is essential for glucose transport into the brain and is predominantly expressed in the cerebral microvasculature. Downregulation of GLUT1 precedes the development of cognitive impairment in neurodegenerative conditions. Surgical trauma induces blood brain barrier (BBB) disruption, neuroinflammation, neuro...

Background Double‐stranded RNA‐dependent protein kinase (PKR) is a key signaling molecule that regulates immune responses by regulating macrophage activation, various inflammatory pathways, and the formation of inflammasomes. Meanwhile, PKR in neurons helps mediate stress responses of Aß to trigger apoptosis and affects cognitive functions. This st...

PTEN hamartoma tumour syndrome is characterised by mutations in the human PTEN gene. We performed transcriptomic and proteomic analyses of neural tissues and primary cultures from heterozygous and homozygous Pten-knockout mice. The somatosensory cortex of heterozygous Pten-knockout mice was enriched in immune response and oligodendrocyte developmen...

Background Systemic activation of the immune system can exert detrimental effects on the central nervous system. Periodontitis, a chronic disease of the oral cavity, is a common source of systemic inflammation. Neuroinflammation might be a result of this to accelerate progressive deterioration of neuronal functions during aging or exacerbate pre-ex...

The increasing amount of particulate matter (PM) in the ambient air is a pressing public health issue globally. Epidemiological studies involving data from millions of patients or volunteers have associated PM with increased risk of dementia and Alzheimer’s disease in the elderly and cognitive dysfunction and neurodegenerative pathology across all...

Adult mammalian injured axons regenerate over short-distance in the peripheral nervous system (PNS) while the axons in the central nervous system (CNS) are unable to regrow after injury. Here, we demonstrated that Lycium barbarum polysaccharides (LBP), purified from Wolfberry, accelerated long-distance axon regeneration after severe peripheral nerv...

Background Systemic activation of the immune system can exert detrimental effects on the central nervous system. Periodontitis, a chronic disease of the oral cavity, is a common source of systemic inflammation. Neuroinflammation might be a result of this to accelerate progressive deterioration of neuronal functions during aging or exacerbate pre-ex...

Background The incidence of perioperative neurocognitive disorders (PNDs) is reportedly higher in older patients. Mitochondrial and synaptic dysfunctions have consistently been demonstrated in models of aging and neurodegenerative diseases; nonetheless, their role in PND is not well understood.Methods The Morris water maze and elevated plus maze te...

Metals have been investigated as biomaterials for a wide range of medical applications. At nanoscale, some metals, such as gold nanoparticles, exhibit plasmonics, which have motivated researchers’ focus on biosensor development. At the device level, some metals, such as titanium, exhibit good physical properties, which could allow them to act as bi...

Metals have been investigated as biomaterials for a wide range of medical applications. At nanoscale, some metals, such as gold nanoparticles, exhibit plasmonics, which have motivated researchers’ focus on biosensor development. At the device level, some metals, such as titanium, exhibit good physical properties, which could allow them to act as bi...

Alzheimer’s disease (AD) is the most common form of dementia. Although previous studies have selectively investigated the localization of amyloid-beta (Aβ) deposition in certain brain regions, a comprehensive characterization of the rostro-caudal distribution of Aβ plaques in the brain and their inter-regional correlation remain unexplored. Our res...

Despite well-known systemic immune reactions in peripheral trauma, little is known about their roles in posttraumatic neurological disorders, such as anxiety, sickness, and cognitive impairment. Leukocyte invasion of the brain, a common denominator of systemic inflammation, is involved in neurological disorders that occur in peripheral inflammatory...

Background Postoperative neurocognitive dysfunction remains a significant problem in vulnerable groups such as the elderly. While experimental data regarding its possible pathogenic mechanisms accumulate, therapeutic options for this disorder are limited. In this study, we evaluated the neuroprotective effect of a period of preconditioning resistan...

Perioperative neurocognitive disorders are frequently observed in postoperative patients and previous reports have shown that pre-existing mild cognitive impairment with accumulated neuropathology may be a risk factor. Sevoflurane is a general anesthetic agent which is commonly used in clinical practice. However, the effects of sevoflurane in posto...

Objectives: It has long been considered that accumulation of pathological alpha-synuclein (aSyn) leads to synaptic/neuronal loss which then results in behavioural and cognitive dysfunction. To investigate this claim, we investigated effects downstream of aSyn preformed fibrils (PFF) and 6-hydroxydopamine (6-OHDA), because aSyn PFFs induce spreadin...

Background: PTEN Hamartoma Tumor Syndrome (PHTS) is characterized by frequent mutation in PTEN gene. PHTS patients have numerous neurological defects including macrocephaly and autism spectrum disorder. While clinical features of PHTS are likely the result of PTEN haploinsufficiency, the role of PTEN gene dosage in driving transcriptomic changes in...

Emerging evidence suggests that both disruption of circadian rhythms and gut dysbiosis are closely related to aging-associated neurodegenerative diseases. Over the last decade, the microbiota-gut-brain axis has been an emerging field and revolutionized studies in pathology, diagnosis, and treatment of neurological disorders. Crosstalk between the b...

Neuroinflammation is closely related to the pathogenesis of perioperative neurocognitive disorders (PNDs), which is characterized by the activation of microglia, inflammatory pathways and the release of inflammatory mediators. Sigesbeckia orientalis L. (SO) is a traditional Chinese medicine which demonstrates anti-inflammatory activities in differe...

The functions of the complement system to both innate and adaptive immunity through opsonization, cell lysis, and inflammatory activities are well known. In contrast, the role of complement in the central nervous system (CNS) which extends beyond immunity, is only beginning to be recognized as important to neurodevelopment and neurodegeneration. In...

In Alzheimer's disease (AD), amyloid β deposition-induced hippocampal synaptic dysfunction generally begins prior to neuronal degeneration and memory impairment. Lycium barbarum extracts (LBE) have been demonstrated to be neuroprotective in various animal models of neurodegeneration. In this study, we aimed to investigate the effects of LBE on the...

Background Periodontitis, a chronic systemic inflammatory disease, is a common health problem in the elderly. With increasing recognition that inflammation plays a key role in the pathophysiology of Alzheimer's disease (AD), our research team has been studying how systemic inflammation affects the brain immune responses. Aging is a major risk facto...

Background Major depressive disorder (MDD) is a prevalent neuropsychiatric condition, affecting approximately 264 million people worldwide. While various hypotheses have been proposed for MDD, the full extent of the neuropathology underlying depression has not yet been elucidated. Nonetheless, evidence suggests that inflammation is a key pathologic...

Background Systemic inflammation has been linked to neuroinflammation and the progression of neurodegenerative diseases. Double‐stranded RNA‐dependent protein kinase (PKR) is a key signaling molecules that regulates immune responses by regulating macrophage activation, various inflammatory pathways, and formation of inflammasomes. This study aims a...

Background Perioperative neurocognitive dysfunction remains a significant problem in vulnerable groups such as the elderly. While experimental data regarding its possible pathogenic mechanisms accumulates, therapeutic options for this disorder are limited. In this study, we evaluated the neuroprotective effect of a period of preconditioning resista...

Recent research into meningeal lymphatics has revealed a never-before appreciated role of type II innate lymphoid cells (ILC2s) in modulating neuroinflammation in the central nervous system (CNS). To date, the role of ILC2-mediated inflammation in the periphery has been well studied. However, the exact distribution of ILC2s in the CNS and therefore...

Neurodegeneration is the most common disease in the elderly population due to its slowly progressive nature of neuronal deterioration, eventually leading to executive dysfunction. The pathological markers of neurological disorders are relatively well-established, however, detailed molecular mechanisms of progression and therapeutic targets are need...

Introduction Cognitive impairment is a common complication in chronic kidney disease (CKD) patients. Currently, limited types of animal models are available for studying cognitive impairment in CKD. We used unilateral ureteral obstruction (UUO) in mice as an animal model to study the cognitive changes and related pathology under prolonged renal imp...

Although it is known that stronger cell-extracellular matrix interactions will be developed as neurons mature, how such change influences their response against traumatic injury remains largely unknown. In this report, by transecting axons with a sharp atomic force microscope tip, we showed that the injury-induced retracting motion of axon can be t...

Cellular senescence, a state of irreversible growth arrest triggered by various stressors, engages in a category of pathological processes, whereby senescent cells accumulate in mitotic tissues. Senolytics as novel medicine against aging and various diseases through the elimination of senescent cells has emerged rapidly in recent years. Exercise is...

Background Increasing lines of evidence demonstrate that systemic immune responses triggered by either sterile or infectious inflammation can activate neuroimmune responses, resulting in developing Alzheimer’s pathology, such as phosphorylation of tau protein. Systemic inflammation can be a risk factor for developing cognitive dysfunctions and even...

Background To date, different techniques were developed for mapping neural connections, including diffusion tensor imaging (DTI) and neural tracers. DTI allows tracing of connections in macroscale but with low resolution. While neural tracers can allow visualization at single cell level, their signals are usually visualized in 2D sections. This res...

Background Autophagy via formation of the autophagosome is a major cellular degradation pathway for long‐lived proteins and organelles. Dysfunction in autophagic processes are prominently linked to neurodegenerative disorders associated with an aggregation of misfolded protein. However, the underlying cellular mechanisms of how amyloid‐β (Aβ) promo...

Background Increasing lines of evidence have shown that systemic inflammation may contribute to neuroinflammation and accelerate the progression of neurodegenerative diseases. In this study, a non‐bacterial endotoxin mouse model of laparotomy is adopted to address the systemic inflammation triggered by surgery. We aim at investigating whether lapar...

Background Chronic kidney disease is associated with cognitive impairment. While the pathophysiology remains unclear, it has been suggested that it shares some similarity to those in Alzheimer’s disease. Currently, most studies in this area used the 5/6 nephrectomy and high adenine diet to induce renal impairment in rat or mice. Our group had succe...

Background Ocular abnormalities were reported in patients with Alzheimer’s disease (AD). The Lycium barbarum extracts (LBE) have been demonstrated to be neuroprotective. The current study aim to investigate the effect of oral feeding LBE on structural and functional changes of retina in the 3xTg AD mouse model. Method 6 months old 3xTg‐AD and C57/...

Background Alzheimer’s disease (AD) is a devastating neurodegenerative disease characterized by the presence of tau tangles, amyloid beta plaques and neuroinflammation. Although the mechanisms underlying AD are not fully understand, several key risk factors for developing AD have been identified, such as depression. Previous work from our group, us...

Background Alzheimer’s disease (AD) is the most common form of dementia characterized by the presence of amyloid plaques, neurofibrillary tangles and the activation of the brain immune system. Studies from the public health have shown that activation of the immune cells in the periphery can lead to neuroimmune responses, which can initiate or perpe...

Background: Infiltration of macrophages into the central nervous system (CNS) is involved in many neurological disorders, such as Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS) and autism. Despite extensive studies into neuroinflammation associated macrophage infiltration into the CNS, its underlying mechanisms and pathological roles...

Ras‐related C3 botulinum toxin substrate 1 (Rac1) is a member of the Rho family of GTPases that functions as a molecular switch to regulate many important cellular events including actin cytoskeleton remodeling during neurite outgrowth. Engulfment and cell motility 1 (ELMO1)‐dedicator of cytokinesis 1 (DOCK180) is a bipartite guanine nucleotide exc...

Aims A variety of tissue clearing techniques have been developed to render intact tissue transparent. For thicker samples, additional partial tissue delipidation is required before immersion into the final refractive index (RI)‐matching solution, which alone is often inadequate to achieve full tissue transparency. However, it is difficult to determ...

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiological agent of coronavirus disease 2019 (COVID-19). SARS-CoV-2, is a positive-sense single-stranded RNA virus with epithelial cell and respiratory system proclivity. Like its predecessor, SARS-CoV, COVID-19 can lead to life-threatening disease. Due to wide geographic impact a...

The formation of multiple beads along an injured axon will lead to blockage of axonal transport and eventually neuron death, and this has been widely recognized as a hallmark of nervous system degeneration. Nevertheless, the underlying mechanisms remain poorly understood. Here, we report a combined experimental and theoretical study to reveal key f...

Background: The mesencephalic trigeminal nucleus (Vmes) is not only anatomically adjacent to the locus coeruleus (LC) but is also tightly associated with the function of the LC. The LC can be the first area in which Alzheimer's disease (AD) develops, although it is unclear how LC neuronal loss occurs. Objective: We investigated whether neuronal...

Tight connection between neural cells and their micro-environment is crucial for processes such as neurite outgrowth and nerve regeneration. However, characterizing neuron adhesion remains challenging because of its rate-dependent nature as well as its coupling with the viscoelastic cellular response. In this study, by conducting successive forced...

The formation of multiple beads along an injured axon will lead to blockage of axonal transport and eventually neuron death, and this has been widely recognized as a hallmark of nervous system degeneration. Nevertheless, the underlying mechanisms remain poorly understood. Here, we report a combined experimental and theoretical study to reveal key f...

1-phenyl 2-thiourea (PTU) is a Tyr (tyrosinase) inhibitor that is extensively used to block pigmentation and improve optical transparency in zebrafish (Danio rerio) embryo. Here, we reported a previously undescribed effect of PTU on macroautophagy/autophagy in zebrafish embryos. Upon 0.003% PTU treatment, aberrant autophagosome and autolysosome for...

Germline mutation in the PTEN gene is the genetic basis of PTEN hamartoma tumor syndrome with the affected individuals harboring features of autism spectrum disorders. Characterizing a panel of 14 autism‐associated PTEN missense mutations revealed reduced protein stability, catalytic activity, and subcellular distribution. Nine out of 14 (64%) PTEN...

A current bottleneck in the advance of neurophysics is the lack of reliable methods to quantitatively measure the interactions between neural cells and their microenvironment. Here, we present an experimental technique to probe the fundamental characteristics of neuron adhesion through repeated peeling of well-developed neurite branches on a substr...

Postoperative cognitive dysfunction (POCD) is a common sequela following surgery and hospitalization. The prevention and management of POCD are important during clinical practice. POCD more commonly affects elderly patients who have undergone major surgery and can result in major decline in quality of life for both patients and their families. Acup...