MicroRNAs as potential biomarkers for diagnosis of schizophrenia and influence of antipsychotic treatment

ABSTRACT

Characterized by positive symptoms (such as changes in behavior or thoughts, including delusions and hallucinations), negative symptoms (such as apathy, anhedonia, and social withdrawal), and cognitive impairments, schizophrenia is a chronic, severe, and disabling mental disorder with late adolescence or early adulthood onset. Antipsychotics are the most commonly used drugs to treat schizophrenia, but those currently in use do not fully reverse all three types of symptoms characterizing this condition. Schizophrenia is frequently misdiagnosed, resulting in a delay of or inappropriate treatment. Abnormal expression of microRNAs is connected to brain development and disease and could provide novel biomarkers for the diagnosis and prognosis of schizophrenia. The recent studies reviewed included microRNA profiling in blood- and urine-based materials and nervous tissue materials. From the studies that had validated the preliminary findings, potential candidate biomarkers for schizophrenia in adults could be miR-22-3p, -30e-5p, -92a-3p, -148b-5p, -181a-3p, -181a-5p, -181b-5p, -199b-5p, -137 in whole blood, and miR-130b, -193a-3p in blood plasma. Antipsychotic treatment of schizophrenia patients was found to modulate the expression of certain microRNAs including miR-130b, -193a-3p, -132, -195, -30e, -432 in blood plasma. Further studies are warranted with adolescents and young adults having schizophrenia and consideration should be given to using animal models of the disorder to investigate the effect of suppressing or overexpressing specific microRNAs.

MicroRNAs as potential biomarkers for diagnosis of attention deficit hyperactivity disorder

Inappropriate levels of hyperactivity, impulsivity, and inattention characterize attention deficit hyperactivity disorder, a common childhood-onset neuropsychiatric disorder. The cognitive function and learning ability of children with attention deficit hyperactivity disorder are affected, and these symptoms may persist to adulthood if they are not treated. The diagnosis of attention deficit hyperactivity disorder is only based on symptoms and objective tests for attention deficit hyperactivity disorder are missing. Treatments for attention deficit hyperactivity disorder in children include medications, behavior therapy, counseling, and education services which can relieve many of the symptoms of attention deficit hyperactivity disorder but cannot cure it. There is a need for a molecular biomarker to distinguish attention deficit hyperactivity disorder from healthy subjects and other neurological conditions, which would allow for an earlier and more accurate diagnosis and appropriate treatment to be initiated. Abnormal expression of microRNAs is connected to brain development and disease and could provide novel biomarkers for the diagnosis and prognosis of attention deficit hyperactivity disorder. The recent studies reviewed had performed microRNA profiling in whole blood, white blood cells, blood plasma, and blood serum of children with attention deficit hyperactivity disorder. A large number of microRNAs were dysregulated when compared to healthy controls and with some overlap between individual studies. From the studies that had included a validation set of patients and controls, potential candidate biomarkers for attention deficit hyperactivity disorder in children could be miR-140-3p, let-7g-5p, -30e-5p, -223-3p, -142-5p, -486-5p, -151a-3p, -151a-5p, and -126-5p in total white blood cells, and miR-4516, -6090, -4763-3p, -4281, -4466, -101-3p, -130a-3p, -138-5p, -195-5p, and -106b-5p in blood serum. Further studies are warranted with children and adults with attention deficit hyperactivity disorder, and consideration should be given to utilizing rat models of attention deficit hyperactivity disorder. Animal studies could be used to confirm microRNA findings in human patients and to test the effects of targeting specific microRNAs on disease progression and behavior.

Biomaterial and tissue-engineering strategies for the treatment of brain neurodegeneration

The incidence of neurodegenerative diseases is increasing due to changing age demographics and the incidence of sports-related traumatic brain injury is tending to increase over time. Currently approved medicines for neurodegenerative diseases only temporarily reduce the symptoms but cannot cure or delay disease progression. Cell transplantation strategies offer an alternative approach to facilitating central nervous system repair, but efficacy is limited by low in vivo survival rates of cells that are injected in suspension. Transplanting cells that are attached to or encapsulated within a suitable biomaterial construct has the advantage of enhancing cell survival in vivo. A variety of biomaterials have been used to make constructs in different types that included nanoparticles, nanotubes, microspheres, microscale fibrous scaffolds, as well as scaffolds made of gels and in the form of micro-columns. Among these, Tween 80-methoxy poly(ethylene glycol)-poly(lactic-co-glycolic acid) nanoparticles loaded with rhynchophylline had higher transport across a blood-brain barrier model and decreased cell death in an in vitro model of Alzheimer’s disease than rhynchophylline or untreated nanoparticles with rhynchophylline. In an in vitro model of Parkinson’s disease, trans-activating transcriptor bioconjugated with zwitterionic polymer poly(2-methacryoyloxyethyl phosphorylcholine) and protein-based nanoparticles loaded with non-Fe hemin had a similar protective ability as free non-Fe hemin. A positive effect on neuron survival in several in vivo models of Parkinson’s disease was associated with the use of biomaterial constructs such as trans-activating transcriptor bioconjugated with zwitterionic polymer poly(2-methacryoyloxyethyl phosphorylcholine) and protein-based nanoparticles loaded with non-Fe hemin, carbon nanotubes with olfactory bulb stem cells, poly(lactic-co-glycolic acid) microspheres with attached DI-MIAMI cells, ventral midbrain neurons mixed with short fibers of poly-(L-lactic acid) scaffolds and reacted with xyloglucan with/without glial-derived neurotrophic factor, ventral midbrain neurons mixed with Fmoc-DIKVAV hydrogel with/without glial-derived neurotrophic factor. Further studies with in vivo models of Alzheimer’s disease and Parkinson’s disease are warranted especially using transplantation of cells in agarose micro-columns with an inner lumen filled with an appropriate extracellular matrix material.

MicroRNA biomarkers in frontotemporal dementia and to distinguish from Alzheimer's disease and amyotrophic lateral sclerosis

Frontotemporal lobar degeneration describes a group of progressive brain disorders that primarily are associated with atrophy of the prefrontal and anterior temporal lobes. Frontotemporal lobar degeneration is considered to be equivalent to frontotemporal dementia. Frontotemporal dementia is characterized by progressive impairments in behavior, executive function, and language. There are two main clinical subtypes: behavioral-variant frontotemporal dementia and primary progressive aphasia. The early diagnosis of frontotemporal dementia is critical for developing management strategies and interventions for these patients. Without validated biomarkers, the clinical diagnosis depends on recognizing all the core or necessary neuropsychiatric features, but misdiagnosis often occurs due to overlap with a range of neurologic and psychiatric disorders. In the studies reviewed a very large number of microRNAs were found to be dysregulated but with limited overlap between individual studies. Measurement of specific miRNAs singly or in combination, or as miRNA pairs (as a ratio) in blood plasma, serum, or cerebrospinal fluid enabled frontotemporal dementia to be discriminated from healthy controls, Alzheimer's disease, and amyotrophic lateral sclerosis. Furthermore, upregulation of miR-223-3p and downregulation of miR-15a-5p, which occurred both in blood serum and cerebrospinal fluid, distinguished behavioral-variant frontotemporal dementia from healthy controls. Downregulation of miR-132-3p in frontal and temporal cortical tissue distinguished frontotemporal lobar degeneration and frontotemporal dementia, respectively, from healthy controls. Possible strong miRNA biofluid biomarker contenders for behavioral-variant frontotemporal dementia are miR-223-3p, miR-15a-5p, miR-22-3p in blood serum and cerebrospinal fluid, and miR-124 in cerebrospinal fluid. No miRNAs were identified able to distinguish between behavioral-variant frontotemporal dementia and primary progressive aphasia subtypes. Further studies are warranted on investigating miRNA expression in biofluids and frontal/temporal cortical tissue to validate and extend these findings.

MicroRNA expression in animal models of amyotrophic lateral sclerosis and potential therapeutic approaches

A review of recent animal models of amyotrophic lateral sclerosis showed a large number of miRNAs had altered levels of expression in the brain and spinal cord, motor neurons of spinal cord and brainstem, and hypoglossal, facial, and red motor nuclei and were mostly upregulated. Among the miRNAs found to be upregulated in two of the studies were miR-21, miR-155, miR-125b, miR-146a, miR-124, miR-9, and miR-19b, while those downregulated in two of the studies included miR-146a, miR-29, miR-9, and miR-125b. A change of direction in miRNA expression occurred in some tissues when compared (e.g., miR-29b-3p in cerebellum and spinal cord of wobbler mice at 40 days), or at different disease stages (e.g., miR-200a in spinal cord of SOD1(G93A) mice at 95 days vs. 108 and 112 days). In the animal models, suppression of miR-129-5p resulted in increased lifespan, improved muscle strength, reduced neuromuscular junction degeneration, and tended to improve motor neuron survival in the SOD1(G93A) mouse model. Suppression of miR-155 was also associated with increased lifespan, while lowering of miR-29a tended to improve lifespan in males and increase muscle strength in SOD1(G93A) mice. Overexpression of members of miR-17~92 cluster improved motor neuron survival in SOD1(G93A) mice. Treatment with an artificial miRNA designed to target hSOD1 increased lifespan and improved muscle strength in SOD1(G93A) animals. Further studies with animal models of amyotrophic lateral sclerosis are warranted to validate these findings and identify specific miRNAs whose suppression or directed against hSOD1 results in increased lifespan, improved muscle strength, reduced neuromuscular junction degeneration, and improved motor neuron survival in SOD1(G93A) animals.

Altered microRNA expression in animal models of Huntington's disease and potential therapeutic strategies

A review of recent animal models of Huntington's disease showed many microRNAs had altered expression levels in the striatum and cerebral cortex, and which were mostly downregulated. Among the altered microRNAs were miR-9/9*, miR-29b, miR-124a, miR-132, miR-128, miR-139, miR-122, miR-138, miR-23b, miR-135b, miR-181 (all downregulated) and miR-448 (upregulated), and similar changes had been previously found in Huntington's disease patients. In the animal cell studies, the altered microRNAs included miR-9, miR-9*, miR-135b, miR-222 (all downregulated) and miR-214 (upregulated). In the animal models, overexpression of miR-155 and miR-196a caused a decrease in mutant huntingtin mRNA and protein level, lowered the mutant huntingtin aggregates in striatum and cortex, and improved performance in behavioral tests. Improved performance in behavioral tests also occurred with overexpression of miR-132 and miR-124. In the animal cell models, overexpression of miR-22 increased the viability of rat primary cortical and striatal neurons infected with mutant huntingtin and decreased huntingtin -enriched foci of ≥ 2 µm. Also, overexpression of miR-22 enhanced the survival of rat primary striatal neurons treated with 3-nitropropionic acid. Exogenous expression of miR-214, miR-146a, miR-150, and miR-125b decreased endogenous expression of huntingtin mRNA and protein in Hdh^Q111/Hdh^Q111 cells. Further studies with animal models of Huntington's disease are warranted to validate these findings and identify specific microRNAs whose overexpression inhibits the production of mutant huntingtin protein and other harmful processes and may provide a more effective means of treating Huntington's disease in patients and slowing its progression.

MicroRNAs as diagnostic and prognostic biomarkers of age-related macular degeneration: advances and limitations

A main cause of vision loss in the elderly is age-related macular degeneration (AMD). Among the cellular, biochemical, and molecular changes linked to this disease, inflammation and angiogenesis appear as being crucial in AMD pathogenesis and progression. There are two forms of the disease: dry AMD, accounting for 80-90% of cases, and wet AMD. The disease usually begins as dry AMD associated with retinal pigment epithelium and photoreceptor degeneration, whereas wet AMD is associated with choroidal neovascularization resulting in severe vision impairment. The new vessels are largely malformed, leading to blood and fluid leakage within the disrupted tissue, which provokes inflammation and scar formation and results in retinal damage and detachment. MicroRNAs are dysregulated in AMD and may facilitate the early detection of the disease and monitoring disease progression. Two recent reviews of microRNAs in AMD had indicated weaknesses or limitations in four earlier investigations. Studies in the last three years have shown considerable progress in overcoming some of these concerns and identifying specific microRNAs as biomarkers for AMD. Further large-scale studies are warranted using appropriate statistical methods to take into account gender and age disparity in the study populations and confounding factors such as smoking status.

MicroRNAs in laser-induced choroidal neovascularization in mice and rats: their expression and potential therapeutic targets

Choroidal neovascularization characterizes wet age-related macular degeneration. Choroidal neovascularization formation involves a primarily angiogenic process that is combined with both inflammation and proteolysis. A primary cause of choroidal neovascularization pathogenesis is alterations in pro- and anti-angiogenic factors derived from the retinal pigment epithelium, with vascular endothelium growth factor being mainly responsible for both clinical and experimental choroidal neovascularization. MicroRNAs (miRNAs) which are short, non-coding, endogenous RNA molecules have a major role in regulating various pathological processes, including inflammation and angiogenesis. A review of recent studies with the mouse laser-induced choroidal neovascularization model has shown alterations in miRNA expression in choroidal neovascularization tissues and could be potential therapeutic targets for wet age-related macular degeneration. Upregulation of miR-505 (days 1 and 3 post-laser), miR-155 (day 14) occurred in retina; miR-342-5p (days 3 and 7), miR-126-3p (day 14) in choroid; miR-23a, miR-24, miR-27a (day 7) in retina/choroid; miR-505 (days 1 and 3) in retinal pigment epithelium/choroid; downregulation of miR-155 (days 1 and 3), miR-29a, miR-29b, miR-29c (day 5), miR-93 (day 14), miR-126 (day 14) occurred in retinal pigment epithelium/choroid. Therapies using miRNA mimics or inhibitors were found to decrease choroidal neovascularization lesions. Choroidal neovascularization development was reduced by overexpression of miR-155, miR-188-5p, miR-(5,B,7), miR-126-3p, miR-342-5p, miR-93, miR-126, miR-195a-3p, miR-24, miR-21, miR-31, miR-150, and miR-184, or suppression of miR-505, miR-126-3p, miR-155, and miR-23/27. Further studies are warranted to determine miRNA expression in mouse laser-induced choroidal neovascularization models in order to validate and extend the reported findings. Important experimental variables need to be standardized; these include the strain and age of animals, gender, number and position of laser burns to the eye, laser parameters to induce choroidal neovascularization lesions including wavelength, power, spot size, and duration.

Protective effects of pharmacological therapies in animal models of multiple sclerosis: a review of studies 2014-2019

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system. The disability caused by inflammatory demyelination clinically dominates the early stages of relapsing-remitting MS and is reversible. Once there is considerable loss of axons, MS patients enter a secondary progressive stage. Disease-modifying drugs currently in use for MS suppress the immune system and reduce relapse rates but are not effective in the progressive stage. Various animal models of MS (mostly mouse and rat) have been established and proved useful in studying the disease process and response to therapy. The experimental autoimmune encephalomyelitis animal studies reviewed here showed that a chronic progressive disease can be induced by immunization with appropriate amounts of myelin oligodendrocyte glycoprotein together with mycobacterium tuberculosis and pertussis toxin in Freund's adjuvant. The clinical manifestations of autoimmune encephalomyelitis disease were prevented or reduced by treatment with certain pharmacological agents given prior to, at, or after peak disease, and the agents had protective effects as shown by inhibiting demyelination and damage to neurons, axons and oligodendrocytes. In the cuprizone-induced toxicity animal studies, the pharmacological agents tested were able to promote remyelination and increase the number of oligodendrocytes when administered therapeutically or prophylactically. A monoclonal IgM antibody protected axons in the spinal cord and preserved motor function in animals inoculated with Theiler's murine encephalomyelitis virus. In all these studies the pharmacological agents were administered singly. A combination therapy may be more effective, especially using agents that target neuroinflammation and neurodegeneration, as they may exert synergistic actions.

MicroRNAs as disease progression biomarkers and therapeutic targets in experimental autoimmune encephalomyelitis model of multiple sclerosis

Multiple sclerosis is an autoimmune neurodegenerative disease of the central nervous system characterized by pronounced inflammatory infiltrates entering the brain, spinal cord and optic nerve leading to demyelination. Focal demyelination is associated with relapsing-remitting multiple sclerosis, while progressive forms of the disease show axonal degeneration and neuronal loss. The tests currently used in the clinical diagnosis and management of multiple sclerosis have limitations due to specificity and sensitivity. MicroRNAs (miRNAs) are dysregulated in many diseases and disorders including demyelinating and neuroinflammatory diseases. A review of recent studies with the experimental autoimmune encephalomyelitis animal model (mostly female mice 6–12 weeks of age) has confirmed miRNAs as biomarkers of experimental autoimmune encephalomyelitis disease and importantly at the pre-onset (asymptomatic) stage when assessed in blood plasma and urine exosomes, and spinal cord tissue. The expression of certain miRNAs was also dysregulated at the onset and peak of disease in blood plasma and urine exosomes, brain and spinal cord tissue, and at the post-peak (chronic) stage of experimental autoimmune encephalomyelitis disease in spinal cord tissue. Therapies using miRNA mimics or inhibitors were found to delay the induction and alleviate the severity of experimental autoimmune encephalomyelitis disease. Interestingly, experimental autoimmune encephalomyelitis disease severity was reduced by overexpression of miR-146a, miR-23b, miR-497, miR-26a, and miR-20b, or by suppression of miR-182, miR-181c, miR-223, miR-155, and miR-873. Further studies are warranted on determining more fully miRNA profiles in blood plasma and urine exosomes of experimental autoimmune encephalomyelitis animals since they could serve as biomarkers of asymptomatic multiple sclerosis and disease course. Additionally, studies should be performed with male mice of a similar age, and with aged male and female mice.

MicroRNAs in blood and cerebrospinal fluid as diagnostic biomarkers of multiple sclerosis and to monitor disease progression

Multiple sclerosis is a chronic autoimmune disease of the central nervous system. It is the main cause of non-traumatic neurological disability in young adults. Multiple sclerosis mostly affects people aged 20-50 years; however, it can occur in young children and much older adults. Factors identified in the distribution of MS include age, gender, genetics, environment, and ethnic background. Multiple sclerosis is usually associated with progressive degrees of disability. The disease involves demyelination of axons of the central nervous system and causes brain and spinal cord neuronal loss and atrophy. Diagnosing multiple sclerosis is based on a patient's medical history including symptoms, physical examination, and various tests such as magnetic resonance imaging, cerebrospinal fluid and blood tests, and electrophysiology. The disease course of multiple sclerosis is not well correlated with the biomarkers presently used in clinical practice. Blood-derived biomarkers that can detect and distinguish the different phenotypes in multiple sclerosis may be advantageous in personalized treatment with disease-modifying drugs and to predict response to treatment. The studies reviewed have shown that the expression levels of a large number of miRNAs in peripheral blood, serum, exosomes isolated from serum, and cerebrospinal fluid are altered in multiple sclerosis and can distinguish the disease phenotypes from each other. Further studies are warranted to independently validate these findings so that individual or pairs of miRNAs in serum or cerebrospinal fluid can be used as potential diagnostic markers for adult and pediatric multiple sclerosis and for monitoring disease progression and response to therapy.

MicroRNAs as diagnostic and therapeutic tools for Alzheimer's disease: advances and limitations

Alzheimer’s disease (AD) is the most common age-related, progressive neurodegenerative disease. It is characterized by memory loss and cognitive decline and responsible for most cases of dementia in the elderly. Late-onset or sporadic AD accounts for > 95% of cases, with age at onset > 65 years. Currently there are no drugs or other therapeutic agents available to prevent or delay the progression of AD. The cellular and molecular changes occurring in the brains of individuals with AD include accumulation of β-amyloid peptide and hyperphosphorylated tau protein, decrease of acetylcholine neurotransmitter, inflammation, and oxidative stress. Aggregation of β-amyloid peptide in extracellular plaques and the hyperphosphorylated tau protein in intracellular neurofibrillary tangles are characteristic of AD. A major challenge is identifying molecular biomarkers of the early-stage AD in patients as most studies have been performed with blood or brain tissue samples (postmortem) at late-stage AD. Subjects with mild cognitive impairment almost always have the neuropathologic features of AD with about 50% of mild cognitive impairment patients progressing to AD. They could provide important information about AD pathomechanism and potentially also highlight minimally or noninvasive, easy-to-access biomarkers. MicroRNAs are dysregulated in AD, and may facilitate the early detection of the disease and potentially the continual monitoring of disease progression and allow therapeutic interventions to be evaluated. Four recent reviews have been published of microRNAs in AD, each of which identified areas of weakness or limitations in the reported studies. Importantly, studies in the last three years have shown considerable progress in overcoming some of these limitations and identifying specific microRNAs as biomarkers for AD and mild cognitive impairment. Further large-scale human studies are warranted with less disparity in the study populations, and using an appropriate method to validate the findings.

MicroRNAs as biomarkers of diabetic retinopathy and disease progression

Diabetes mellitus, together with its complications, has been increasing in prevalence worldwide. Its complications include cardiovascular disease (e.g., myocardial infarction, stroke), neuropathy, nephropathy, and eye complications (e.g., glaucoma, cataracts, retinopathy, and macular edema). In patients with either type 1 or type 2 diabetes mellitus, diabetic retinopathy is the leading cause of visual impairment or blindness. It is characterized by progressive changes in the retinal microvasculature. The progression from nonproliferative diabetic retinopathy to a more advanced stage of moderate to severe nonproliferative diabetic retinopathy and proliferative diabetic retinopathy occurs very quickly after diagnosis of mild nonproliferative diabetic retinopathy. The etiology of diabetic retinopathy is unclear, and present treatments have limited effectiveness. Currently diabetic retinopathy can only be diagnosed by a trained specialist, which reduces the population that can be examined. A screening biomarker of diabetic retinopathy with high sensitivity and specificity would aid considerably in identifying those individuals in need of clinical assessment and treatment. The majority of the studies reviewed identified specific microRNAs in blood serum/plasma able to distinguish diabetic patients with retinopathy from those without retinopathy and for the progresion of the disease from nonproliferative diabetic retinopathy to proliferative diabetic retinopathy. In addition, certain microRNAs in vitreous humor were dysregulated in proliferative diabetic retinopathy compared to controls. A very high percentage of patients with diabetic retinopathy develop Alzheimer’s disease. Thus, identifying diabetic retinopathy by measurement of suitable biomarkers would also enable better screening and treatment of those individuals at risk of Alzheimer’s disease.

Amelioration of Alzheimer's disease pathology and cognitive deficits by immunomodulatory agents in animal models of Alzheimer's disease

The most common age-related neurodegenerative disease is Alzheimer’s disease (AD) characterized by aggregated amyloid-β (Aβ) peptides in extracellular plaques and aggregated hyperphosphorylated tau protein in intraneuronal neurofibrillary tangles, together with loss of cholinergic neurons, synaptic alterations, and chronic inflammation within the brain. These lead to progressive impairment of cognitive function. There is evidence of innate immune activation in AD with microgliosis. Classically-activated microglia (M1 state) secrete inflammatory and neurotoxic mediators, and peripheral immune cells are recruited to inflammation sites in the brain. The few drugs approved by the US FDA for the treatment of AD improve symptoms but do not change the course of disease progression and may cause some undesirable effects. Translation of active and passive immunotherapy targeting Aβ in AD animal model trials had limited success in clinical trials. Treatment with immunomodulatory/anti-inflammatory agents early in the disease process, while not preventive, is able to inhibit the inflammatory consequences of both Aβ and tau aggregation. The studies described in this review have identified several agents with immunomodulatory properties that alleviated AD pathology and cognitive impairment in animal models of AD. The majority of the animal studies reviewed had used transgenic models of early-onset AD. More effort needs to be given to creat models of late-onset AD. The effects of a combinational therapy involving two or more of the tested pharmaceutical agents, or one of these agents given in conjunction with one of the cell-based therapies, in an aged animal model of AD would warrant investigation.

Neuroprotection by immunomodulatory agents in animal models of Parkinson's disease

Parkinson's disease (PD) is an age-related neurodegenerative disease for which the characteristic motor symptoms emerge after an extensive loss of dopamine containing neurons. The cell bodies of these neurons are present in the substantia nigra, with the nerve terminals being in the striatum. Both innate and adaptive immune responses may contribute to dopaminergic neurodegeneration and disease progression is potentially linked to these. Studies in the last twenty years have indicated an important role for neuroinflammation in PD through degeneration of the nigrostriatal dopaminergic pathway. Characteristic of neuroinflammation is the activation of brain glial cells, principally microglia and astrocytes that release various soluble factors. Many of these factors are proinflammatory and neurotoxic and harmful to nigral dopaminergic neurons. Recent studies have identified several different agents with immunomodulatory properties that protected dopaminergic neurons from degeneration and death in animal models of PD. All of the agents were effective in reducing the motor deficit and alleviating dopaminergic neurotoxicity and, when measured, preventing the decrease of dopamine upon being administered therapeutically after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, 6-hydroxydopamine, rotenone-lesioning or delivery of adeno-associated virus-α-synuclein to the ventral midbrain of animals. Some of these agents were shown to exert an anti-inflammatory action, decrease oxidative stress, and reduce lipid peroxidation products. Activation of microglia and astrocytes was also decreased, as well as infiltration of T cells into the substantia nigra. Pretreatment with fingolimod, tanshinoine I, dimethyl fumarate, thalidomide, or cocaine- and amphetamine-regulated transcript peptide as a preventive strategy ameliorated motor deficits and nigral dopaminergic neurotoxicity in brain-lesioned animals. Immunomodulatory agents could be used to treat patients with early clinical signs of the disease or potentially even prior to disease onset in those identified as having pre-disposing risk, including genetic factors.

Immunomodulators and microRNAs as neurorestorative therapy for ischemic stroke

Most of all strokes are ischemic due to occlusion of a vessel, and comprise two main types, thrombotic and embolic. Inflammation and immune response play an important role in the outcome of ischemic stroke. Pharmaceutical and cell-based therapies with immunomodulatory properties could be of benefit in treating ischemic stroke. Possible changes in microRNAs brought about by immunomodulatory treatments may be important. The pharmaceutical studies described in this review have identified several differentially regulated miRNAs associated with disregulation of mRNA targets or the upregulation of several neuroprotective genes, thereby highlighting the potential neuroprotective roles of specific miRNAs such as miR-762, -1892, -200a, -145. MiR-124, -711, -145 are the strongly associated miRNAs predicted to mediate anti-inflammatory pathways and microglia/macrophage M2-like activation phenotype. The cell-based therapy studies reviewed have mainly utilized mesenchymal stem cells or human umbilical cord blood cells and shown to improve functional and neurological outcomes in stroke animals. MiR-145 and miR-133b were implicated in nerve cell remodeling and functional recovery after stroke. Human umbilical cord blood cells decreased proinflammatory factors and promoted M2 macrophage polarization in stroke diabetic animals.

Blood microRNAs as potential diagnostic markers for hemorrhagic stroke

Proper medical treatment of a stroke victim relies on accurate and rapid differentiation between ischemic and hemorrhagic stroke, which in current practice is performed by computerized tomography (CT) or magnetic resonance imaging (MRI) scans. A panel of microRNAs could be an extremely useful clinical tool for distinguishing between hemorrhagic and ischemic stroke. This review has shown that blood miRNA profile can distinguish hemorrhagic from ischemic stroke in patients and in experimental animal models. It also seems likely they can differentiate between intracerebral and subarachnoid hemorrhage stroke. The miRNA profile in cerebrospinal fluid could be a useful diagnostic tool for subarachnoid hemorrhagic stroke. Decreased or increased miRNA levels may be needed either as prevention or treatment of stroke. Administration in vivo of miR-130a inhibitor or miRNA mimic (miR-367, miR-223) in an intracerebral hemorrhage animal model improved neurological outcomes.

MicroRNAs in Parkinson's disease and emerging therapeutic targets

Parkinson's disease (PD) is the second most common age-related neurodegenerative disorder, with the clinical main symptoms caused by a loss of dopaminergic neurons in the substantia nigra, corpus striatum and brain cortex. Over 90% of patients with PD have sporadic PD and occur in people with no known family history of the disorder. Currently there is no cure for PD. Treatment with medications to increase dopamine relieves the symptoms but does not slow down or reverse the damage to neurons in the brain. Increasing evidence points to inflammation as a chief mediator of PD with inflammatory response mechanisms, involving microglia and leukocytes, activated following loss of dopaminergic neurons. Oxidative stress is also recognized as one of the main causes of PD, and excessive reactive oxygen species (ROS) and reactive nitrogen species can lead to dopaminergic neuron vulnerability and eventual death. MicroRNAs control a range of physiological and pathological functions, and may serve as potential targets for intervention against PD to mitigate damage to the brain. Several studies have demonstrated that microRNAs can regulate oxidative stress and prevent ROS-mediated damage to dopaminergic neurons, suggesting that specific microRNAs may be putative targets for novel therapeutic strategies in PD. Recent human and animal studies have identified a large number of dysregulated microRNAs in PD brain tissue samples, many of which were downregulated. The dysregulated microRNAs affect downstream targets such as SNCA, PARK2, LRRK2, TNFSF13B, LTA, SLC5A3, PSMB2, GSR, GBA, LAMP-2A, HSC. Apart from one study, none of the studies reviewed had used agomirs or antagomirs to reverse the levels of downregulated or upregulated microRNAs, respectively, in mouse models of PD or with isolated human or mouse dopaminergic cells. Further large-scale studies of brain tissue samples collected with short postmortem interval from human PD patients are warranted to provide more information on the microRNA profiles in different brain regions and to test for gender differences.

MicroRNAs as diagnostic markers and therapeutic targets for traumatic brain injury

Traumatic brain injury (TBI) is characterized by primary damage to the brain from the external mechanical force and by subsequent secondary injury due to various molecular and pathophysiological responses that eventually lead to neuronal cell death. Secondary brain injury events may occur minutes, hours, or even days after the trauma, and provide valuable therapeutic targets to prevent further neuronal degeneration. At the present time, there is no effective treatment for TBI due, in part, to the widespread impact of numerous complex secondary biochemical and pathophysiological events occurring at different time points following the initial injury. MicroRNAs control a range of physiological and pathological functions such as development, differentiation, apoptosis and metabolism, and may serve as potential targets for progress assessment and intervention against TBI to mitigate secondary damage to the brain. This has implications regarding improving the diagnostic accuracy of brain impairment and long-term outcomes as well as potential novel treatments. Recent human studies have identified specific microRNAs in serum/plasma (miR-425-p, -21, -93, -191 and -499) and cerebro-spinal fluid (CSF) (miR-328, -362-3p, -451, -486a) as possible indicators of the diagnosis, severity, and prognosis of TBI. Experimental animal studies have examined specific microRNAs as biomarkers and therapeutic targets for moderate and mild TBI (e.g., miR-21, miR-23b). MicroRNA profiling was altered by voluntary exercise. Differences in basal microRNA expression in the brain of adult and aged animals and alterations in response to TBI (e.g., miR-21) have also been reported. Further large-scale studies with TBI patients are needed to provide more information on the changes in microRNA profiles in different age groups (children, adults, and elderly).

Treatment of insulin resistance by acupuncture: a review of human and animal studies

BACKGROUND

Numerous experimental studies have demonstrated that acupuncture can correct various metabolic disorders such as hyperglycaemia, overweight, hyperphagia, hyperlipidaemia, inflammation, altered activity of the sympathetic nervous system, and insulin signalling defects, all of which contribute to the development of insulin resistance.

OBJECTIVE

To review human and animal studies investigating acupuncture as a treatment for insulin resistance, and to evaluate its potential to increase insulin sensitivity.

METHODS

PubMed was searched for relevant articles published between January 2008 and October 2015. Search terms used were 'acupuncture', 'insulin resistance', 'insulin sensitivity', and 'blood glucose'. Additional secondary sources of information included reference lists from retrieved papers and pertinent papers identified by hand searches of relevant journals not found in the database.

RESULTS

In total, 31 articles were included in this review and comprised studies of the following insulin resistant conditions: obesity (n=9); diabetes mellitus (n=12); polycystic ovarian syndrome (n=7); skeletal muscle atrophy (n=1); ischaemic heart disease (n=1); and fatty liver disease (n=1). Of these articles, seven were human trials and 24 animal experiments. Collectively, the studies suggest that electroacupuncture (EA) at low intensity and low frequency can reduce insulin resistance and increase insulin sensitivity in a range of different insulin-resistant conditions.

CONCLUSIONS

EA, used alone or in combination with other therapies, such as Chinese herbs or diet-exercise interventions, has the potential to be an effective treatment for insulin resistance. Additional controlled clinical studies of acupuncture are needed in subjects with diabetes mellitus, ischaemic heart disease, muscle atrophy, and fatty liver disease.

Differential Effect of Electroacupuncture on Inflammatory Adipokines in Two Rat Models of Obesity

Chronic inflammation is known to be associated with visceral obesity and insulin resistance which are characterized by altered levels of production of pro- and anti-inflammatory adipokines. The dysregulation of the production of inflammatory adipokines and their functions in obese individuals leads to a state of chronic low-grade inflammation and may promote obesity-linked metabolic disorders and cardiovascular diseases such as insulin resistance, metabolic syndrome, and atherosclerosis. Electroacupuncture (EA) was tested to see if there was a difference in its effect on pro- and anti-inflammatory adipokine levels in the blood serum and the white adipose tissue of obese Zucker fatty rats and high-fat diet-induced obese Long Evans rats. In the two rat models of obesity, on Day 12 of treatment, repeated applications of EA were seen to have had a significant differential effect for serum tumor necrosis factor-α, adiponectin, the adiponectin:leptin ratio, and blood glucose. For the adipose tissue, there was a differential effect for adiponectin that was on the borderline of significance. To explore these changes further and how they might affect insulin resistance would require a modification to the research design to use larger group sizes for the two models or to give a greater number of EA treatments.

Blood microRNAs as potential diagnostic and prognostic markers in cerebral ischemic injury

MicroRNAs are a family of small, genome-encoded endogenous RNAs that are transcribed but are not translated into proteins. They serve essential roles in virtually every aspect of brain function, including neurogenesis, neural development, and cellular responses leading to changes in synaptic plasticity. They are also implicated in neurodegeneration and neurological disorders, in responses to hypoxia and ischemia, and in ischemic tolerance induced by ischemic preconditioning. In recent developments, miRNA expression profiling has been examined in stroke, and these studies indicate that miRNAs have emerged as key mediators in ischemic stroke biology. Both increased and decreased miRNA levels may be needed either as prevention or treatment of stroke. Novel approaches are being developed to get miRNA related therapeutics into the brain across an intact blood-brain barrier, including chemical modification, use of targeting molecules and methods to disrupt the blood-brain barrier.

Neuroimmunomodulatory effects of transcranial laser therapy combined with intravenous tPA administration for acute cerebral ischemic injury

At present, the only FDA approved treatment for ischemic strokes is intravenous administration of tissue plasminogen activator within 4.5 hours of stroke onset. Owing to this brief window only a small percentage of patients receive tissue plasminogen activator. Transcranial laser therapy has been shown to be effective in animal models of acute ischemic stroke, resulting in significant improvement in neurological score and function. NEST-1 and NEST-2 clinical trials in human patients have demonstrated the safety and positive trends in efficacy of transcranial laser therapy for the treatment of ischemic stroke when initiated close to the time of stroke onset. Combining intravenous tissue plasminogen activator treatment with transcranial laser therapy may provide better functional outcomes. Statins given within 4 weeks of stroke onset improve stroke outcomes at 90 days compared to patients not given statins, and giving statins following transcranial laser therapy may provide an effective treatment for patients not able to be given tissue plasminogen activator due to time constraints.

Effect of Electroacupuncture on Inflammation in the Obese Zucker Fatty Rat Model of Metabolic Syndrome

Chronic inflammation is known to be associated with visceral obesity and insulin resistance and is characterized by altered levels of production of adipokines such as tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), IL-6, leptin, and adiponectin. Metabolic syndrome (MetS) is a major and escalating public health and clinical challenge worldwide, and patients with MetS have an increased risk of developing cardiovascular disease and type 2 diabetes mellitus. Electroacupuncture (EA) was tested as a means of decreasing inflammation in genetically obese Zucker fatty rats, which serve as a model of MetS. Repeated application of EA at the Zhongwan/Guanyuan acupoints decreased serum TNF-α, but produced no significant alterations in serum leptin, adiponectin, or IL-10. EA had no significant effect on the levels of these four adipokines in white adipose tissue. These findings are consistent with the supposition that EA inhibits proliferation and/or infiltration of macrophages into the adipose tissue of obese rats and stimulates the release of IL-10 from the decreased numbers of macrophages present in adipose tissue. Compared with the control animals, no significant change in body weight occurred. The blood glucose (BG) level over a 30-minute interval in Week 2 was relatively the same as that in Week 1, suggesting that EA treatment does not increase the likelihood of developing hyperglycemia.

Repeated electroacupuncture: an effective treatment for hyperglycemia in a rat model

The effect of electroacupuncture (EA) in lowering blood glucose (BG) in eight fasted male obese Zucker diabetic rats aged 21-24 weeks was investigated. Group 1 (n = 4) received no EA and Group 2 (n = 4) received EA at the Zhongwan and Guanyuan acupoints on Day 1, Day 3, Day 6, Day 8, and Day 10. The BG level of the rats was measured at 10 minutes and 20 minutes after their nose had been inserted into the nose cone of an anesthetic apparatus; then, EA was applied for 30 minutes, and BG was measured again. At the end of the study, the animals were injected with sodium pentobarbitone (60 mg/mL, intraperitoneally), and blood and white adipose tissue were collected. On statistical analysis, Group 2 showed a significant decrease in mean BG at 20 minutes (baseline) and 50 minutes on Day 8 and Day 10 compared with Day 1 and Day 3, but such a decrease was not observed in Group 1. For Group 2, the baseline BG and the change in BG over 30 minutes were significantly lower on Day 8 and Day 10 compared with Day 1, Day 3, and Day 6, but not for Group 1. No significant differences were noted between the groups in serum insulin, glucose, insulin-to-glucose ratio, adiponectin, leptin, adiponectin-to-leptin ratio, and white adipose tissue.

Growth factor- and cytokine-stimulated endothelial progenitor cells in post-ischemic cerebral neovascularization

Endothelial progenitor cells are resident in the bone marrow blood sinusoids and circulate in the peripheral circulation. They mobilize from the bone marrow after vascular injury and home to the site of injury where they differentiate into endothelial cells. Activation and mobilization of endothelial progenitor cells from the bone marrow is induced via the production and release of endothelial progenitor cell-activating factors and includes specific growth factors and cytokines in response to peripheral tissue hypoxia such as after acute ischemic stroke or trauma. Endothelial progenitor cells migrate and home to specific sites following ischemic stroke via growth factor/cytokine gradients. Some growth factors are less stable under acidic conditions of tissue ischemia, and synthetic analogues that are stable at low pH may provide a more effective therapeutic approach for inducing endothelial progenitor cell mobilization and promoting cerebral neovascularization following ischemic stroke.

Defining a therapeutic window for laser irradiation (810 nm) applied to the inguinal region to ameliorate diabetes in diabetic mice

OBJECTIVE

The purpose of this study was to determine a therapeutic window of antidiabetic effect by laser irradiating the left inguinal region of diabetic mice (810 nm 20.4 and 40.8 J/cm(2)) for 7 days.

BACKGROUND DATA

Irradiation of 810 nm 10.2 J/cm(2) to the left inguinal region of diabetic mice for 7 days significantly decreased blood plasma fructosamine compared with nonirradiated controls.

METHODS

Forty-seven diabetic mice were used. Body weight and water intake of the mice were measured daily for 7 days prior to start of treatment (day 0). Mice were irradiated on the left inguinal region with 810 nm laser 20.4 J/cm(2) (n=15) or 40.8 J/cm(2) (n=15) for 7 days, or were not irradiated (control, n=17). Body weight and water intake were measured to day 7. On day 7, mice were fasted for 5 h, anesthetized with sodium pentobarbitone (i.p.), and blood plasma was collected. The blood plasma was assayed for glucose and fructosamine.

RESULTS

Water intake was significantly increased on day 7 compared with day 0 for diabetic mice receiving laser treatment. Blood plasma glucose levels on day 7 for diabetic mice irradiated 20.4 and 40.8 J/cm(2) were not significantly different than for nonirradiated controls. The blood plasma fructosamine level of diabetic mice irradiated with 20.4 J/cm(2) was significantly lower than for nonirradiated controls, whereas that for diabetic mice irradiated with 40.8 J/cm(2) was not significantly different than for nonirradiated controls.

CONCLUSIONS

Irradiation (810 nm laser 10.2-20.4 J/cm(2)) to the left inguinal region of diabetic mice for 7 days has the potential to ameliorate diabetes, as is shown by decreased blood plasma fructosamine.

Repeated electroacupuncture in obese Zucker diabetic fatty rats: adiponectin and leptin in serum and adipose tissue

Fasted, male, obese, Zucker, diabetic fatty rats aged 10-16 weeks were anesthetized with 1% halothane in nitrous oxide-oxygen (3:1) on alternate weekdays over 2 weeks. Group 1 (n = 4) did not receive electroacupuncture (controls); Group 2 (n = 4) received electroacupuncture using the Zhongwan and the Guanyuan acupoints; Group 3 (n = 4) received electroacupuncture using the bilateral Zusanli acupoints; Group 4 (n = 6) received neither halothane in nitrous oxide:oxygen nor electroacupuncture. At the end of study, animals were injected with sodium pentobarbitone (60 mg/mL, i.p.), and blood and white adipose tissue were collected. Analysis of variance and Duncan's tests showed that the mean leptin in serum was significantly lower and the adiponectin:leptin ratio was significantly higher in Group 2 than in Group 1 (p < 0.05); for Group 4, the serum leptin was significantly higher than it was for Groups 1-3 (p < 0.05), and the adiponectin:leptin ratio was significantly lower than it was for Group 2 (p < 0.05). Similar changes occurred for the leptin levels in the pelvic adipose tissue. In addition, for Group 2, the mean serum insulin: glucose ratio was significantly higher than it was for Group 1 (p < 0.05); for Group 4 the mean serum insulin and insulin: glucose ratio were significantly higher than they were for Groups 1 and 3 (p < 0.05), but not Group 2 (p > 0.05). No significant differences in the serum or the adipose-tissue measurements between Groups 1 and 3 were observed (p > 0.05).

Influence of growth factors and cytokines on angiogenic function of endothelial progenitor cells: a review of in vitro human studies

Growth factors and cytokines released at sites of injury and inflammation play an important role in stimulating endothelial progenitor cell (EPC) migration to these sites. A comparative analysis of the literature shows under neutral in vitro conditions (pH 7.4), several growth factors and cytokines influenced favorably indices of EPC angiogenic function. They included SDF-1, VEGF, PlGF, FGF-2, NGF and IL-1β. Others, e.g. TNF-α, have an unfavorable influence. SDF-1 and VEGF in combination increased chemotactic cell migration and reduced apoptosis caused by serum starvation. Under acidic conditions (pH 6.5), the biological activity of certain growth factors may be impaired, although TPO, SCF and IL-3 were each able to rescue EPCs from acidic exposure apoptosis, a combination of these three factors stimulated cell proliferation and prevented apoptosis. Possible combinations of growth factors and cytokines together with EPC transplantation may provide for a greater extent of vessel repair and new vessel formation.

Electroacupuncture for control of blood glucose in diabetes: literature review

Electrical stimulation at acupuncture points (acupoints) has been investigated for its utility in lowering blood glucose in hyperglycemic humans and animal models. Only two studies were found using electroacupuncture in human subjects, and in both of these, the participants were normal (nondiabetic) and electrical stimulation was carried out at several acupoints. It had a hypoglycemic effect in obese women with calorific restriction diet using electrical stimulation of 2 Hz for 30 minutes/day for 20 days, but no change occurred in blood glucose of fasted patients in the other study using 1 Hz for 15 minutes. Fourteen animal studies were found, of which, 11 were performed in diabetic and normal rats. A hypoglycemic effect was observed in fasted type 1 diabetic rats using the Zusanli (ST36) leg acupoint with electrical stimulation of 15 Hz for 30 minutes and 60 minutes. In fasted type 2 diabetic rats, blood glucose was lowered using the Zusanli acupoint with electrical stimulation parameters of 15 Hz and 10 mA for 30 minutes. Also, using the Zhongwan (CV12) abdomen acupoint with electrical stimulation parameters of 15 Hz and 10 mA for 90 minutes had a hypoglycemic effect in fasted type 2 diabetic rats. In fasted normal rats, electrical stimulation of 2 Hz or 15 Hz for 30 minutes at the Zusanli or Zhongwan acupoint caused a decrease in blood glucose. Future studies are required in fasted diabetic rats to determine the effect of electroacupuncture on blood levels of insulin, lipids, fatty acids and β-endorphin, and blood flow and nerve conduction velocity. Studies with fasted normal and diabetic human subjects treated by electroacupuncture are warranted using data from animal experiments to inform such studies.

Laser photostimulation (660 nm) of wound healing in diabetic mice is not brought about by ameliorating diabetes

BACKGROUND AND OBJECTIVES

We have used a 660-nm laser diode in genetic diabetic mice to stimulate the healing of wounds covered with a Tegaderm HP dressing that causes a retardation of contraction (splinted wounds). It is possible that the stimulation of healing could be due to possible diabetes-modifying properties of laser light. This has been examined by using the 660 nm laser to irradiate non-wounded diabetic mice with the same dose and at same location as for wounded diabetic mice.

MATERIALS AND METHODS

Twenty-two diabetic mice were used and divided into two equal groups. Body weight and water intake of mice were measured daily for 7 days prior to the start of treatment (Day 0). The left flank of mice in the experimental group was irradiated with 660 nm laser, 100 mW, 20 seconds/day, 7 days; for mice in the control group, the left flank was sham-treated with the laser power supply not switched on. Body weight and water intake of mice were measured to Day 14. On Day 14, the mice were fasted for 4 hours, anaesthetized with sodium pentobarbitone (i.p.) and blood collected by cardiac puncture into heparinized tubes. The plasma was assayed for glucose and glycated hemoglobin A1c.

RESULTS

There were no significant differences in body weight and water intake over 22 days between mice in the experimental group and control group. On day 14, the mean blood plasma glucose level was not significantly different between the two groups; glycated hemoglobin A1c was not detected in the samples.

CONCLUSION

Irradiation of the left flank in diabetic mice with 660 nm laser system does not have a significant hypoglycemic effect, and the laser-stimulated healing of wounds in diabetic mice is due to cellular and biochemical changes in the immediate wound environment.

Testing photobiomodulatory effects of laser irradiation on wound healing: development of an improved model for dressing wounds in mice

OBJECTIVE

To develop a suitable method for dressing skin wounds in BKS.Cg-m(+)/(+)Lepr(db) mice for subsequent use in laser irradiation of wounds. The healing of nonirradiated wounds (controls) was examined histologically to provide essential reference data.

BACKGROUND DATA

Dressing excisional skin wounds in mice has many advantages. However, previous studies using dressings such as Tegaderm W or OpSite, with or without adhesives, have shown that this is not easily achieved.

MATERIALS AND METHODS

In a pilot study, a full-thickness wound was made on the left flank in six diabetic and six nondiabetic mice, and five different methods were tried for dressing the wounds with Tegaderm HP to develop an optimized procedure. The optimized procedure was used in subsequent studies, with a total of 23 diabetic and 13 nondiabetic mice being controls for laser-irradiated mice. Measurements of healing outcomes from histologic sections of controls were statistically analyzed.

RESULTS

The optimized procedure used Tegaderm HP with Cavilon and Fixomull Stretch strips for the first dressing, and with Mastisol for subsequent dressings. Wound closure by contraction was retarded in a large proportion of diabetic mice (approximately 80%) and a small proportion of nondiabetic mice. These wounds, described as "splinted," healed mainly by epithelial regeneration and granulation tissue formation.

CONCLUSION

A simple, easy-to-perform procedure was developed for dressing wounds in diabetic and nondiabetic mice. It was found to cause splinting with wound healing mimicking that in human patients. This model is suitable for examining the effects of different therapies on wound healing, including lasers.