Mitochondrial mechanisms in Alzheimer's disease: Quest for therapeutics.

Mitochondrial function is essential for maintaining neuronal integrity, because neurons have a high energy demand. Neurodegenerative diseases, such as Alzheimer's disease (AD), are exacerbated by mitochondrial dysfunction. Mitochondrial autophagy (mitophagy) attenuates neurodegenerative diseases by eradicating dysfunctional mitochondria. In neurodegenerative disorders, there is disruption of the mitophagy process. High levels of iron also interfere with the mitophagy process and the mtDNA released after mitophagy is proinflammatory and triggers the cGAS-STING pathway that aids AD pathology. In this review, we critically discuss the factors that affect mitochondrial impairment and different mitophagy processes in AD. Furthermore, we discuss the molecules used in mouse studies as well as clinical trials that could result in potential therapeutics in the future.

Exercise mitigates calpain induced Purkinje cell loss in diabetes.

Calpain-1 is a ubiquitous calcium dependent cysteine protease and found in cytoplasm as well as mitochondria. We have earlier reported that active calpain-1 is translocated from cytosol to mitochondria and activates MMP9. Calpain-1 activation is detrimental to the heart in several different ways, but there is little evidence that it can degrade Purkinje cell protein (PCP-4) and impair contractility in diabetes. Our hypothesis is that in diabetes, PCP-4 is degraded by calpain-1, causing contractile dysfunction that can be mitigated by exercise. To test this hypothesis, we recruited four groups of mice, 1) db/+ control, 2) db/+ with exercise, 3) db/db, 4) db/db with exercise. The mice were exercised on treadmill for 8 weeks as per American Veterinary Research Guidelines. Adding calcium to isolated cardiomyocytes caused them to lose shape and die. Compared with live myocytes, we observed high calpain-1 levels as well as significantly lower levels of PCP-4 and increased levels of calmodulin and calmodulin kinase II (CaMKII) in dead myocytes. We used the CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats) plasmid to knock down calpain-1 in HL-1 myocytes which restored the levels of PCP-4 along with calmodulin and CaMKII. In vivo, we found upregulated levels of calpain-1 in db/db mice (diabetic) as compared to db/+ which were mitigated in the exercised mice. Conclusively our data strongly suggests that in diabetes there is high induction of calpain-1 with degrades PCP-4, a protein important for contractility and exercise can mitigate this.

Brain-derived neurotrophic factor levels in acute stroke and its clinical implications.

BACKGROUND: Brain-derived neurotrophic factor (BDNF) has a very important role in repairing intact and injured brain, also known as neuroplasticity. Risk factors may affect neuroplasticity. OBJECTIVES: In this study, our aim was to delineate the levels of BDNF in acute stroke with different etiology and impact of risk factors on its levels. METHODS: In this prospective study, 208 patients with first-ever stroke, between 18 and 75 years, were included. All individuals were assessed for severity and type of stroke, risk factors, levels of BDNF in the acute stroke, and its association with outcome of stroke. RESULTS: The mean age of the patients in our study was 55.29 ± 11.6 years. Compared to healthy controls, a significant decline in the levels of BDNF was observed after stroke (P < 0.01). Patients with National Institutes of Health Stroke Scale (NIHSS) <6 on the 1st day of stroke had significantly higher levels of BDNF than those with NIHSS >6 (9.8 ng/ml ± 3.8; P < 0.01). A significant difference in the levels of BDNF was observed on comparing the stroke patients and healthy individuals of age <55 and >55 years (<55 years: 10.4 ng/ml ± 3.2; >55 years: 9.8 ng/ml ± 4.5 and in healthy individuals <55 years: 22.97 ± 3.8, >55 years: 15.4 ± 4.9; P < 0.01). Risk factors have negative impact on levels of BDNF (diabetics, P = 0.001; alcoholics, P = 0.003; both diabetes mellitus + hypertension, P = 0.002; smokers, P = 0.001). The difference was not significant between hypertensives and nonhypertensives (P = 0.06). CONCLUSION: BDNF level is significantly reduced in acute stroke. The presence of risk factors further affects its level.

Post-stroke BDNF concentration changes following proprioceptive neuromuscular facilitation (PNF) exercises.

BACKGROUND: Brain-derived neurotrophic factor (BDNF) plays an important role in repairing normal as well as in the injured brain. Physical exercise may have a positive impact on the release of BDNF. OBJECTIVE: PNF is a neurophysiological approach that facilitates the stimulation of central and peripheral nervous systems. In this study, our aim was to assess the levels of BDNF as well as functional recovery before and after the intervention of PNF in patients with acute stroke. METHODS: A total of 208 patients with first time confirmed stroke were recruited and assessed for stroke severity, type, mini-mental state exam (MMSE), functional independence measure scale, and BDNF levels before and after PNF intervention. BDNF levels were also assessed in healthy individuals for control values. RESULTS: A significant decline in levels of BDNF was observed after in stroke. BDNF levels in patients (with different risk factors) with diabetes, hypertension and DM+ HTN, alcohol, and smoking history were 8.8 ± 4.04 ng/mL, 8.86 ± 4.68 ng/mL, 8.65 ± 3.26 ng/mL, 8.51 ± 4.26 ng/mL, and 8.9 ± 3.4 ng/mL, respectively. A decline in BDNF levels was observed in accordance with the severity of stroke in both ischemic and hemorrhagic stroke with the least level being in severe stroke (NIHSS >15 and ICH >3). Despite the type of stroke and the presence of risk factors, a significant improvement in BDNF levels and FIM scale scores was seen in all subjects who received PNF exercises. CONCLUSION: Thus, PNF is efficient in improving functional level in acute stroke irrespective of the type of stroke and risk factors.

Depression impedes neuroplasticity and quality of life after stroke.

BACKGROUND AND PURPOSE: Depression following a stroke/poststroke depression (PSD) has been newly recognized as one of the most common complications after stroke. PSD may affect neuroplasticity and quality of life. The purpose of present study was to find out effects of depression on functional recovery, quality of life and neuroplasticity in patients with acute stroke. METHODS: A total of 76 cases were recruited for the study and out of which 44 were available for the analysis after six months. Patients were divided into three groups according to severity of depression: Group A (without depression), Group B (mild-to-moderate depression), and Group C (severe depression) on the basis of Patient Health Questionnaire-9 (PHQ-9) scale scores. All patients were assessed for depression by PHQ-9, and for quality of life by Stroke Specific Quality of Life (SSQOL) scale. Neuroplasticity was assessed by measuring levels of serum brain-derived neurotrophic factor. RESULTS: Quality of life was observed to be significantly affected by depression (P ≤ 0.05). The most commonly affected characteristics were energy, family roles, mobility, self-care, social roles, upper extremity function, and work productivity. Serum BDNF levels were also affected significantly by depression (P ≤ 0.05). CONCLUSION: PSD is a serious complication, affecting quality of life and neuroplasticity (BDNF) in patients. Decreased neuroplasticity further may affect functional improvement.

Diabetes mellitus type 2 impedes functional recovery, neuroplasticity and quality of life after stroke.

OBJECTIVES: The recovery after stroke depends on the resolution of brain edema and neuroplasticity. The comorbidities associated with stroke such as type 2 diabetes mellitus (T2DM) may increase the chances of unfavorable outcome and delay the recovery from stroke and needs further investigation. SUBJECTS AND METHODS: The study dealt with 208 patients. The neurological status of the patients was assessed by Glasgow Coma Scale and the severity of stroke was assessed by the National Institute of Health Stroke Scale. Patients were divided into two groups: T2DM in group 1 and without T2DM in group 2. We assessed functional improvement by Functional Independence Measure (FIM) Scale, quality of life by Stroke Specific Quality of Life (SSQOL) Scale, and serum levels of brain-derived neurotrophic factor (BDNF) for assessing neuroplasticity. RESULTS: We observed lower levels of BDNF in diabetic stroke patients. There was significant improvement in FIM scale scores and SSQOL scale scores in non-diabetic stroke patients after 6 months (P < 0.05). The relative risk (RR) of poor functional recovery (FIM) in the diabetic group was 1.34 [95% confidence interval (CI) 1.0-1.8] and the odds ratio (OR) was 1.8 (95% CI 1.03-3.12). Diabetes is an independent risk factor for poor BDNF recovery (serum BDNF < mean value, i.e. 10.07 ± 3.8 ng/mL) (RR 2.40; 95% CI: 1.36-4.21 and OR 1.6; 95% CI: 1.15-2.13] and poor quality of life (RR 1.56; 95% CI: 1.13-2.16 and OR 2.83; 95% CI: 1.14-7.0). CONCLUSION: Diabetes is not only a risk factor for stroke occurrence but also delayed recovery after stroke.

Immunochemical Characterization of Setaria cervi Microfilarial Antigens Using Novel Antibodies.

BACKGROUND: Filariasis affects millions of people in tropical and subtropical regions of the world and is caused by nematode roundworm. In order to develop a vaccine and specific diagnostic tests, it is important to characterize different stages of the filarial worms. Microfilariae (Mf) stage of the roundworm is found in host's blood or lymph vessels and can be important not only for developing better immunodiagnostics but also for understanding immune recognition and its relevance to immunepathogenesis and protective immunity. OBJECTIVE: The present study aimed to immunocharacterize Mf and adult worm antigens that could be helpful in future diagnostic tests. METHODS: Four different immune sera against Setaria cervi intact live, intact live with adjuvant, intact glutaraldehyde fixed with adjuvant and total somatic Mf were prepared and used for the immunocharacterization of Mf antigens. RESULTS: Our study results suggest that compared to fixed intact Mf, live intact Mf are more immunogenic, as the immune sera generated against intact live Mf showed high ELISA reactivity with Setaria cervi Mf and adult worm antigens. All the four immune sera IgG fractions had surface specificity as determined through considerable ELISA reactivity with S. cervi intact Mf. When tested under native conditions (immunoelectrophoresis and crossed immunoelectrophoresis), all the four immune rabbit sera were able to detect antigens of S. cervi Mf and adult stages. CONCLUSION: These results can be useful in detailed understanding of the complex nature of the Mf and adult antigens, which are prerequisites in the development of vaccine and more specific diagnostic tests.

A high methionine, low folate and vitamin B6/B12 containing diet can be associated with memory loss by epigenetic silencing of netrin-1.

Memory-epigenetics which is the loss of memory due to epigenetic modifications can be due to the silencing of genes involved in cognitive functions and this is the basis of the current study. We hypothesize that a diet containing high methionine and low vitamins can lead to memory impairment by increasing global DNA methylation and therefore, silencing the netrin-1 gene, which encodes the glycoprotein involved in neurogenesis, axonal guidance and maintenance of the synaptic plasticity. Wild type (C57BL/6J) mice were fed with a diet containing excess methionine (1.2%), low-folate (0.08 mg/kg), vitamin B6 (0.01 mg/kg), and B12 (10.4 mg/kg) for 6 weeks. Mice were examined weekly for the long-term memory function, using a passive avoidance test, which determined loss of fear-motivated long-term memory starting from the fourth week of diet. Similarly, an increase in brain %5-methyl cytosine was observed starting from the 4th week of diet in mice. Mice fed with a high methionine, low folate and vitamins containing diet showed a decrease in netrin-1 protein expression and an increase in netrin-1 gene promotor methylation, as determined by methylation-sensitive restriction enzyme-polymerase chain reaction analysis. The increase in methylation of netrin-1 gene was validated by high-resolution melting and sequencing analysis. Furthermore, the association of netrin-1 with memory was established by administering netrin that considerably restored long-term fear motivated memory. Taken together, these results suggest that a diet rich in methionine and lacking in folate and vitamin B6/B12 can induce defects in learning and memory. Furthermore, the data indicates that decrease in netrin-1 expression due to hyper-methylation of its gene can be associated with memory loss. The animal procedures were approved by the Institutional Animal Care and Use Committee, University of Louisville, USA (No. A3586-01) on February 2, 2018.