COVID-19 related neurological manifestations in Parkinson's disease: has ferroptosis been a suspect?

A rising number of patient cases point to a probable link between SARS-CoV-2 infection and Parkinson's disease (PD), yet the mechanisms by which SARS-CoV-2 affects the brain and generates neuropsychiatric symptoms in COVID-19 patients remain unknown. Ferroptosis, a distinct iron-dependent non-apoptotic type of cell death characterized by lipid peroxidation and glutathione depletion, a key factor in neurological disorders. Ferroptosis may have a pathogenic role in COVID-19, according to recent findings, however its potential contributions to COVID-19-related PD have not yet been investigated. This review covers potential paths for SARS-CoV-2 infection of the brain. Among these putative processes, ferroptosis may contribute to the etiology of COVID-19-associated PD, potentially providing therapeutic methods.

The Regulation and Double-Edged Roles of the Deubiquitinase OTUD5.

OTUD5 (OTU Deubiquitinase 5) is a functional cysteine protease with deubiquitinase activity and is a member of the ovarian tumor protease (OTU) family. OTUD5 is involved in the deubiquitination of many key proteins in various cellular signaling pathways and plays an important role in maintaining normal human development and physiological functions. Its dysfunction can affect physiological processes, such as immunity and DNA damage repair, and it can even lead to tumors, inflammatory diseases and genetic disorders. Therefore, the regulation of OTUD5 activity and expression has become a hot topic of research. A comprehensive understanding of the regulatory mechanisms of OTUD5 and its use as a therapeutic target for diseases is of great value. Herein, we review the physiological processes and molecular mechanisms of OTUD5 regulation, outline the specific regulatory processes of OTUD5 activity and expression, and link OTUD5 to diseases from the perspective of studies on signaling pathways, molecular interactions, DNA damage repair and immune regulation, thus providing a theoretical basis for future studies.

Deubiquitylase OTUD3 Mediates Endoplasmic Reticulum Stress through Regulating Fortilin Stability to Restrain Dopaminergic Neurons Apoptosis.

OTU domain-containing protein 3 (OTUD3) knockout mice exhibited loss of nigral dopaminergic neurons and Parkinsonian symptoms. However, the underlying mechanisms are largely unknown. In this study, we observed that the inositol-requiring enzyme 1α (IRE1α)-induced endoplasmic reticulum (ER) stress was involved in this process. We found that the ER thickness and the expression of protein disulphide isomerase (PDI) were increased, and the apoptosis level was elevated in the dopaminergic neurons of OTUD3 knockout mice. These phenomena were ameliorated by ER stress inhibitor tauroursodeoxycholic acid (TUDCA) treatment. The ratio of p-IRE1α/IRE1α, and the expression of X-box binding protein 1-spliced (XBP1s) were remarkably increased after OTUD3 knockdown, which was inhibited by IRE1α inhibitor STF-083010 treatment. Moreover, OTUD3 regulated the ubiquitination level of Fortilin through binding with the OTU domain. OTUD3 knockdown resulted in a decrease in the interaction ability of IRE1α with Fortilin and finally enhanced the activity of IRE1α. Taken together, we revealed that OTUD3 knockout-induced injury of dopaminergic neurons might be caused by activating IRE1α signaling in ER stress. These findings demonstrated that OTUD3 played a critical role in dopaminergic neuron neurodegeneration, which provided new evidence for the multiple and tissue-dependent functions of OTUD3.

Association between mixed dietary B vitamin intake and insulin resistance in US middle-aged and older adults without diabetes: The Bayesian kernel machine regression approach.

BACKGROUND AND OBJECTIVES: In daily life, the intake of dietary nutrients is mixed. However, evidence for the association between mixed dietary B vitamin intake and insulin resistance is limited. In this study, we estimated the joint effect of intake of various dietary B vitamins on insulin resistance. METHODS AND STUDY DESIGN: This cross-sectional study used data from the National Health and Nutrition Examination Survey 2011-2018. We included 1,628 middle-aged and 1,058 older adults without diabetes. Multivariable logistic regression and Bayesian kernel machine regression models were constructed. RESULTS: In the multivariable logistic regression, when all B vitamins were included in the model, the ORs (95% CIs) of insulin resistance were 3.06 (1.00-9.37) and 0.42 (0.19- 0.93) for the highest quartile of vitamin B-1 and B-12 intake in the middle-aged group when the lowest quartile was the reference. In the older group, no significant association was observed. In the Bayesian kernel machine regression analysis, a negative trend was noted between mixed B vitamin intake and insulin resistance in both examined groups. The univariate exposure-response function indicated that vitamin B-12 intake was negatively associated with insulin resistance in the middle-aged group, and that vitamin B-6 and dietary folate equivalent intakes were negatively associated with insulin resistance in older group. The bivariate exposure-response function indicated a potential interaction effect between dietary intake of vitamin B-12 and those of vitamin B-1, B-2, niacin, and dietary folate equivalent on insulin resistance in older people. CONCLUSIONS: Our results suggest that mixed dietary B vitamin intake tends to decrease the OR of insulin resistance both in middle-aged and older people.

Ghrelin Bridges DMV Neuropathology and GI Dysfunction in the Early Stages of Parkinson's Disease.

Ghrelin contributes to the communication between the brain and gastrointestinal (GI) tract. Both decreased ghrelin levels and functional GI disorders are early events in Parkinson's disease (PD) patients and animal models. However, the reason is not clear. Here it is found that choline acetyltransferase (ChAT)-positive neurons in the dorsal motor nucleus of the vagus nerve (DMV), are lost in PD transgenic mice. In response to the selective damaging of DMV neurons with mu p75-SAP, a rapid reduction both in plasma total and active ghrelin levels is observed. While by contrast, chemogenetic activation of DMV cholinergic neurons can increase the plasma ghrelin levels. Impairment of cholinergic neurons is accompanied by GI disorders, including decreased stool wet weight, stool dry weight, small intestine advancing rate, and gastric emptying rate, while exogenous ghrelin treatment can partially ameliorate GI dysfunction of A53T α-synuclein transgenic mice. Using pseudorabies virus retrograde trace method, the existence of a direct pathway from the stomach fundus to the DMV is shown. Taken together, the findings suggest that the reduction in plasma ghrelin levels in the early stages of PD may be the result of the lesion of cholinergic neurons in the DMV, thus linking neurodegeneration and GI dysfunction in PD.

Deubiquitylase OTUD3 prevents Parkinson's disease through stabilizing iron regulatory protein 2.

Iron deposits are neuropathological hallmark of Parkinson's disease (PD). Iron regulatory protein 2 (IRP2) is a key factor in regulating brain iron homeostasis. Although two ubiquitin ligases that promote IRP2 degradation have been identified, the deubiquitylase for stabilization of IRP2 in PD remains undefined. Here, we report OTUD3 (OTU domain-containing protein 3) functions as a deubiquitylase for IRP2, interacts with IRP2 in the cytoplasm, de-polyubiquitylates, and stabilizes IRP2 protein in an iron-independent manner. Depletion of OTUD3 results in a disorder of iron metabolism. OTUD3 knockout mice display nigral iron accumulation, motor deficits, and nigrostriatal dopaminergic neurodegeneration, which resembles the pathology of PD. Consistently, decreased levels of OTUD3 are detected in transgenic PD mice expressing A53T mutant of human α-synuclein. Five single nucleotide polymorphism mutations of OTUD3 are present in cases of sporadic PD or controls, although no significant associations of OTUD3 SNPs with sporadic PD are detected. Taken together, these findings demonstrate that OTUD3 is a bona fide deubiquitylase for IRP2 and plays a critical role in the nigral iron deposits in PD.

Biogenic volatile organic compound emission patterns and secondary pollutant formation potentials of dominant greening trees in Chengdu, southwest China.

Integral to the urban ecosystem, greening trees provide many ecological benefits, but the active biogenic volatile organic compounds (BVOCs) they release contribute to the production of ozone and secondary organic aerosols, which harm ambient air quality. It is, therefore, necessary to understand the BVOC emission characteristics of dominant greening tree species and their relative contribution to secondary pollutants in various urban contexts. Consequently, this study utilized a dynamic enclosure system to collect BVOC samples of seven dominant greening tree species in urban Chengdu, Southwest China. Gas chromatography/mass spectrometry was used to analyze the BVOC components and standardized BVOC emission rates of each tree species were then calculated to assess their relative potential to form secondary pollutants. We found obvious differences in the composition of BVOCs emitted by each species. Ficus virens displayed a high isoprene emission rate at 31.472 µgC/(gdw (g dry weight)•hr), while Cinnamomum camphora emitted high volumes of D-Limonene at 93.574 µgC/(gdw•hr). In terms of the BVOC emission rates by leaf area, C. camphora had the highest emission rate of total BVOCs at 13,782.59 µgC/(m2•hr), followed by Cedrus deodara with 5466.86 µgC/(m2•hr). Ginkgo biloba and Osmanthus fragrans mainly emitted oxygenated VOCs with lower overall emission rates. The high BVOC emitters like F. virens, C. camphora, and Magnolia grandiflora have high potential for significantly contributing to environmental secondary pollutants, so should be cautiously considered for future planting. This study provides important implications for improving urban greening efforts for subtropical Chinese urban contexts, like Chengdu.

Rethinking IRPs/IRE system in neurodegenerative disorders: Looking beyond iron metabolism.

Iron regulatory proteins (IRPs) and iron regulatory element (IRE) systems are well known in the progression of neurodegenerative disorders by regulating iron related proteins. IRPs are also regulated by iron homeostasis. However, an increasing number of studies have suggested a close relationship between the IRPs/IRE system and non-iron-related neurodegenerative disorders. In this paper, we reviewed that the IRPs/IRE system is not only controlled by iron ions, but also regulated by such factors as post-translational modification, oxygen, nitric oxide (NO), heme, interleukin-1 (IL-1), and metal ions. In addition, by regulating the transcription of non-iron related proteins, the IRPs/IRE system functioned in oxidative metabolism, cell cycle regulation, abnormal proteins aggregation, and neuroinflammation. Finally, by emphasizing the multiple regulations of IRPs/IRE system and its potential relationship with non-iron metabolic neurodegenerative disorders, we provided new strategies for disease treatment targeting IRPs/IRE system.

Liver injury in COVID-19: Holds ferritinophagy-mediated ferroptosis accountable.

Even in patients without a history of liver disease, liver injury caused by coronavirus disease 2019 (COVID-19) is gradually becoming more common. However, the precise pathophysiological mechanisms behind COVID-19's liver pathogenicity are still not fully understood. We hypothesize that inflammation may become worse by cytokine storms caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Elevated ferritin levels can initiate ferritinophagy mediated by nuclear receptor coactivator 4 (NCOA4), which leads to iron elevation, and ferroptosis. In COVID-19 patients, ferroptosis can be restricted to reduce disease severity and liver damage by targeting NCOA4-mediated ferritinophagy. To confirm the role of ferritinophagy-mediated ferroptosis in SARS-CoV-2 infection, further research is required.

Early low-dose ghrelin intervention via miniosmotic pumps could protect against the progressive dopaminergic neuron loss in Parkinson's disease mice.

Ghrelin has been identified as a multifunctional peptide that has a potential application for treating Parkinson's disease (PD). The objective of this study was to assess the effects of subcutaneous administration of low-dose ghrelin via miniosmotic pumps on PD progression. The decreased levels of total and active ghrelin in plasma were rescued by ghrelin administration in PD mice. Interestingly, ghrelin did not affect weight gain in wild-type mice but improved weight loss in PD mice. We observed the attenuation of dopaminergic neuron loss in substantia nigra and a low level of dopamine content in the striatum in PD mice with ghrelin treatment. Ghrelin administration could improve the microenvironment of dopaminergic neurons by inhibiting microglial proliferation and proinflammatory cytokine expression and could enhance cell survival by upregulating Bcl-2/Bax ratio and superoxide dismutase1 protein level in the substantia nigra of PD mice. Subcutaneous administration of low-dose ghrelin could prevent the onset of the progression of PD and also provide a possible method for ghrelin application to cure PD.

NCOA4-Mediated Ferritinophagy: A Vicious Culprit in COVID-19 Pathogenesis?

Coronavirus disease 2019 (COVID-19) is a global pandemic that has caused widespread loss of life. Notably, in this disease, severe inflammatory reactions characterized by cytokine storms are caused by severe acute respiratory syndrome coronavirus 2. The cytokine storms may promote hyper-ferritinemia which can further intensify the inflammation. Moreover, elevated ferritin levels trigger nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy, in which ferritin is degraded and iron is released. Excess iron released from ferritinophagy can promote ferroptosis and cellular damage. Therefore, we propose that NCOA4-mediated ferritinophagy can be targeted to limit the ferroptosis and prevent the multi-organ damage and severity in COVID-19 patients.

High Dietary Iron Supplement Induces the Nigrostriatal Dopaminergic Neurons Lesion in Transgenic Mice Expressing Mutant A53T Human Alpha-Synuclein.

Both alpha-synuclein aggregation and iron deposits are neuropathological hallmarks of Parkinson's disease (PD). We are particularly interested in whether iron could synergize with alpha-synuclein pathology in vivo, especially in the nigrostriatal system. In the present study, we reported transgenic mice with overexpressing human A53T alpha-synuclein, as well as WT mice with high dietary iron displayed hyperactive motor coordination and impaired colonic motility, compared with those with basal dietary iron. Only A53T mice, but not WT mice with high dietary iron exhibited nigral dopaminergic neuronal loss, lower levels of tyrosine hydroxylase (TH) in the substantia nigra (SN) and decreased dopamine contents in the striatum. Although there was no obvious elevation of iron contents in the SN in WT mice with high dietary iron, we observed iron contents in the SN were especially higher than the other brain regions in 12-month aged mice with either high or basal dietary iron. These results suggested high dietary iron supplement could induce nigral dopaminergic neurons lesion in A53T mice, which might be due to the vulnerability of SN to accumulate iron.

Control of body temperature and immune function in patients undergoing open surgery for gastric cancer.

The influence of mild perioperative hypothermia on the immune function and incidence of postoperative wound infections has been suggested, but the specific mechanism is unclear. This study aimed to analyze the body temperature, immune function, and wound infection rates in patients receiving open surgery for gastric cancer. Body temperature was controlled in each patient using one of four different methods: wrapping limbs, head and neck; insulated blankets; warming infusion fluids and insulated blankets; and warming fluids without insulated blankets. One hundred patients were randomly divided into four groups of 25 patients each, and every group received a different intraoperative treatment for maintaining normal body temperature. Nasopharyngeal and rectal temperatures, transforming growth factor beta (TGF-ß), interleukin 10 (IL-10) levels, and cluster of differentiation (CD)3+T and CD4+/CD25+ regulatory T cell (Treg) counts were measured before surgery and at 2 and 4 hours postoperatively. Patients were evaluated at one week after surgery for signs of infection. Intraoperative body temperature and measures of immune function varied significantly between the four groups, with the largest temperature changes observed in the group in which only the limbs were wrapped in cotton pads to control the body temperature. The lowest temperature change (i.e., close to normal temperature) and cytokine response after surgery were observed in the group in which infusion fluids and transfused blood (if needed) were heated to 37℃, peritoneal irrigation fluid was heated to 37℃, and an insulation blanket was heated to 39℃ and placed under the patient. No intergroup differences were found in the infection rates at one week after surgery. In conclusion, body temperature variation during surgery affects the immune function of patients, and maintaining body temperature close to normal results in the least variation of immune function.

Biometal Dyshomeostasis and Toxic Metal Accumulations in the Development of Alzheimer's Disease.

Biometal dyshomeostasis and toxic metal accumulation are common features in many neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease, and Huntington's disease. The neurotoxic effects of metal imbalance are generally associated with reduced enzymatic activities, elevated protein aggregation and oxidative stress in the central nervous system, in which a cascade of events lead to cell death and neurodegeneration. Although the links between biometal imbalance and neurodegenerative disorders remain elusive, a major class of endogenous proteins involved in metal transport has been receiving increasing attention over recent decades. The abnormal expression of these proteins has been linked to biometal imbalance and to the pathogenesis of AD. Here, we present a brief overview of the physiological roles of biometals including iron, zinc, copper, manganese, magnesium and calcium, and provide a detailed description of their transporters and their synergistic involvement in the development of AD. In addition, we also review the published data relating to neurotoxic metals in AD, including aluminum, lead, cadmium, and mercury.

Liberal versus restrictive fluid management in abdominal surgery: a meta-analysis.

PURPOSE: This study compared perioperative restrictive fluid therapy to liberal (conventional) fluid therapy in patients undergoing major abdominal surgery and investigated the rate of post-operative morbidity (complication rates), recovery (time to flatus), and the length of hospital stay. METHODS: The Medline, PubMed, Cochrane, and EMBASE databases were searched until June 18, 2015. Randomized controlled trials, two-arm prospective studies, and retrospective studies were included in our analyses. A sensitivity analysis, publication bias assessment, and quality assessment were performed. RESULTS: The effects of the two therapies were similar in the subgroup analysis of patients who underwent hepato-gastroenterological surgery (P = 0.287). However, in a subgroup of patients who underwent vascular abdominal surgery, the restricted fluid treatment regimen was associated with a lower risk of complications in comparison with the conventional regimen (pooled OR = 0.12, 95 % CI 0.03-0.47, P = 0.002). There was no difference between the two regimens with respect to the incidence of cardiopulmonary complications (P = 0.733). However, the patients who received the restricted fluid treatment regimen had a shorter time to flatus (P = 0.031) and a shorter hospital stay (P = 0.033) than the patients who received the conventional regimen. CONCLUSIONS: Restrictive fluid therapy and liberal conventional therapy were associated with similar rates of overall and cardiopulmonary complications; however, restrictive fluid therapy was associated with a more rapid recovery and a shorter length of hospital stay.

Establishment of lymphatic filarial specific IgG4 indirect ELISA detection method.

OBJECTIVE: To establish the lymphatic filarial specific IgG4 indirect ELISA detection method and develop the kits. METHODS: ELISA and the developed specific IgG4 reagent was used to explore the best way for detecting filarial specific IgG4. Combined with the production process of commercialized enzyme immunoassay kit to develop economical lymphatic filarial specific IgG4 test kit, and to explore the value of the kit in the laboratory. RESULTS: We determined the most optimal detective antigen was Malay adult filarial antigen and the optimal concentration of coating antigen was 1.0 µg/ml. The appropriate serum dilution was 1:20 to 40 and the work titers of specific IgG4 agents was 1:800. We determined the optimal reaction time for substrates and developed a reproducible and stable detection kit with sensitive and specificity, which was easy to operate. CONCLUSION: We successfully established the lymphatic filarial specific IgG4 indirect ELISA detection method and developed the kits with good reproducibility and stable result, which should be widely applied.

Construction and identification of Complex DNA vaccine of hepatitis B and Toxoplasma gondii.

OBJECTIVE: To construct and identify multi-gene recombinant expression vector pcDNA3-HBsAg-p30-ROP2. METHOD: Primers were designed according to the gene sequences of restriction enzyme cutting site of recombinant pcDNA3-p30-ROP2 and hepatitis B surface antigen (HBsAg). The target fragment of HBsAg was amplified and cloned to expression vector pcDNA3-p30-ROP2 by restriction enzyme digestion and ligation. The recombinant expression vector pcDNA3-HBsAg-p30-ROP2 was identified by PCR detection, followed by enzyme restriction and sequencing. RESULTS: The target fragment of HBsAg was successfully amplified, and the multi-gene eukaryotic expression vector pcDNA3-HBsAg-p30-ROP2 was established. PCR detection and restriction enzyme digestion showed that the length of the target fragment was consistent with the theoretical value. The recombinant expression vector contained the complete sequences of p30-ROP2 compound gene and HBsAg. CONCLUSION: Multi-gene recombinant expression vector pcDNA3-HBsAg-p30-ROP2 was successfully established. The constructed expression vector could be used to develop multi-gene nucleic acid vaccines.

[Cloning, expression, purification and identification of Toxoplasma gondii SAG2 gene in Escherichia coli].

OBJECTIVE: To construct a recombinant plasmid containing surface antigen 2(SAG2) gene of Toxoplasma gondii and express it in Escherichia coli. METHODS: The truncated SAG2 gene was amplified from the genomic DNA of T. gondii RH strain and cloned into plasmid pGEX-4T. Then the recombinant pGEX-4T-SAG2 was induced by IPTG and expressed in E. richia col BL21. The expressed proteins were analyzed by SDS-PAGE and purified, and the immunogenicity of the product was analyzed by Western blotting. RESULTS: The amplified SAG2 gene was about 561 bp, which was accorded to the expectation. The recombinant plasmid was constructed successfully by digested with double restriction enzyme and confirmed with DNA sequencing. SDS-PAGE and Western blotting showed the molecular weight of SAG2 fusion protein was about 47 ku, and the protein could be identified by GST-tag antibody. CONCLUSION: The truncated SAG2 gene of T. gondii has been successfully cloned and expressed in E. coli BL21 cells, and the recombinant protein has immunogenicity.

[Extraction Method of Malaria Parasite DNA from Preserved Positive Blood Smears].

OBJECTIVE: To develop a method for DNA extraction from malaria parasites on preserved blood smears, to provide basis for research on malaria genetic traceability. METHODS: The improved DNA extraction kit (QIAamp DNA Mini Kit) was used to extract plasmodium DNA from 41 giemsa-stained blood smears, and the extraction was compared with that using the Chelex-100 and Na(2)HPO(4) methods. Nested PCR was used to amplify small subunit ribosomal RNA to identify Plasmodium parasite. The PCR products underwent sequencing and sequence alignment, to analyze the difference in PCR positive rates between blood smears prepared in the 1980s and in recent 10 years, between blood smears with and without deoil/decoloration, and between blood smears with different qualities. RESULTS: The total PCR positive rate for the improved kit method was 70.7% (29/41). The PCR positive rate for blood smears prepared in the 1980s and in recent 10 years was 78.6% (11/14) and 66.7% (18/27) respectively, with no significant difference (W=0.63, P>0.05). The PCR positive rate for blood smears with and with- out deoil/decoloration was 62.5% (15/24) and 82.4% (14/17) respectively, also with no significant difference (χ(2)= 1.89, P>0.05). However, the PCR positive rate was significantly higher in blood smears with high quality [93.3% (28/30)] than those with low quality [9.1%(1/1l)](=27.59, P<0.01). Sequence alignment showed that the PCR products were consistent with the target DNA fragments. However, DNA extracted using the Chelex-100 and Na(2)HPO(4) methods showed negative PCR results. CONCLUSIONS: DNA extracted from blood smears prepared in the 1980s using the improved Kit (QIAamp DNA Mini Kit) shows a high PCR positive rate. Besides, blood smear staining and use of oil for microscopic examination do not affect DNA extraction.

Unexpected improvements of spatial learning and memory abilities in chronic rotenone intoxicated mice.

The liposoluble insecticide rotenone is commonly used as a mitochondrial complex I inhibitor to replicate Parkinson's disease (PD) pathological features. However, there was no assessment of the spatial learning and memory abilities in chronic rotenone-induced PD models. In the present study, by rotarod test and Thioflavine T staining, we first noted the impairment of motor coordination in rotenone-treated group for 3 months, as well as alpha-synuclein inclusions in the nigral dopaminergic neurons in C57BL/6 mice with intragastrical delivery of rotenone (5 mg/Kg) for 3 months rather than 1 month. We then evaluated spatial learning and memory abilities by Morris water maze task in this model. The results showed escape latency reduced in rotenone-intoxicated mice for 3 months, indicating an improvement of learning ability. However, it was delayed slightly but not significantly in rotenone-intoxicated mice for 1 month. Similarly, we demonstrated that spatial memory ability was enhanced in 3-month-treatment group, but impaired in 1-month-treatment group. There were no proliferating cell nuclear antigen and doublecortin positive cells in the hippocampus by double immunofluorescent staining, indicating the absence of hippocampal neurogenesis in rotenone-intoxicated mice. These results suggest that spatial learning and memory abilities are disturbed in chronic rotenone-intoxicated PD model.