Research progress on chemical modifications of tyrosine residues in peptides and proteins.

The chemical modifications (CMs) of protein is an important technique in chemical biology, protein-based therapy, and material science. In recent years, there has been rapid advances in the development of CMs of peptides and proteins, providing new approaches for peptide and protein functionalization, as well as drug discovery. In this review, we highlight the methods for chemically modifying tyrosine (Tyr) residues in different regions, offering a comprehensive exposition of the research content related to Tyr modification. This review summarizes and provides an outlook on Tyr residue modification, aiming to offer readers assistance in the site-selective modification of macromolecules and to facilitate application research in this field.

A fluorogenic nitric oxide donor induced by yellow LED light for cells proliferation inhibition and imaging.

Nitric oxide (NO), as a vital cellular signalling molecule in physiological processes, has been found to play an important role in various biological functions. In this study, we rationally designed three NO donors by tethering nitrobenzene derivatives to three fluorescent chromophores. NX-NO was found to release NO and exhibit a high fluorescence turn-on signal ratio upon exposure to LED yellow light. Additionally, it had excellent photo-stability and good inhibitory activity against cancer cell proliferation, and was successfully applied to cell imaging. Moreover, we detected the release of NO and fluorescence response in the blood of a mouse, suggesting its potential therapeutic application in living organisms.

Research Progress on Cognitive Frailty in Older Adults with Chronic Kidney Disease.

BACKGROUND: As the medical challenges posed by the ageing population become increasingly severe, the proportion of older people among patients with chronic kidney disease (CKD) is increasing every year. SUMMARY: The prevalence of frailty in patients with CKD is significantly higher than that in the general population, and older patients are also a high-risk group for frailty and cognitive impairment. Cognitive frailty, as an important subtype of frailty, is a syndrome characterised by cognitive dysfunction caused by physiological factors, excluding Alzheimer's disease and other types of dementia. It is characterised by the coexistence of physical frailty and cognitive impairment. Previous studies have mainly focused on cognitive impairment, and there is limited research on cognitive frailty, particularly in older patients with CKD. KEY MESSAGES: This article provides a comprehensive review of the concept, epidemiology, screening methods, prevention, and treatment measures and possible pathogenesis of cognitive frailty in patients with CKD.

Analysis of m6A-regulated genes and subtype classification in lupus nephritis.

BACKGROUND: Lupus nephritis (LN) is the most common and severe clinical manifestation of systemic lupus erythematosus (SLE). N6-methyladenosine (m6A) is a reversible RNA modification and has been implicated in various biological processes. However, the roles of m6A regulators in LN are not fully demonstrated. METHODS: We downloaded the kidney tissue transcriptome dataset of LN patients and normal controls from the GEO database and extracted the expression levels of m6A regulators. We constructed and compared Random Forest (RF) and Support Vector Machine (SVM) models, and subsequently selected featured genes to develop nomogram models. The m6A subtypes were identified based on significantly differentially expressed m6A regulators, and the m6A gene subtypes were identified based on m6A-associated differential genes, and the two m6A modification patterns were comprehensively evaluated. RESULTS: We obtained the GSE32591 and GSE112943 datasets from the GEO database, including 78 LN samples and 36 normal control samples. We extracted the expression levels of 20 m6A regulators. By RF analysis we identified 7 characteristic m6A regulators and constructed nomogramh models with these 7 genes. We identified two m6A subtypes based on these seven important m6A regulators, and the immune cell infiltration levels of the two subtype clusters were significantly different. We identified two more m6A gene subtypes based on m6A-associated DEGs. We calculated the m6A scores using the principal component analysis (PCA) algorithm and found that the m6A scores of m6A cluster A and gene cluster A were lower than those of m6A cluster B and gene cluster B. In addition, we found that the levels of inflammatory factors were also significantly different between m6A clusters and gene clusters. CONCLUSION: This study confirms that m6A regulators are involved in the LN process through different modes of action and provide new diagnostic and therapeutic targets for LN.

Serum metabolomics study of narcolepsy type 1 based on ultra-performance liquid chromatography-tandem mass spectrometry.

Narcolepsy is a chronic and underrecognized sleep disorder characterized by excessive daytime sleepiness and cataplexy. Furthermore, narcolepsy type 1 (NT1) has serious negative impacts on an individual's health, society, and the economy. Currently, many sleep centers lack the means to measure orexin levels in the cerebrospinal fluid. We aimed to analyze the characteristics of metabolite changes in patients with NT1, measured by ultra-performance liquid chromatography-tandem mass spectrometry. A principal component analysis (PCA), an orthogonal partial least square discriminant analysis (OPLS-DA), t tests, and volcano plots were used to construct a model of abnormal metabolic pathways in narcolepsy. We identified molecular changes in serum specimens from narcolepsy patients and compared them with control groups, including dehydroepiandrosterone, epinephrine, N-methyl-D-aspartic acid, and other metabolites, based on an OPLS-loading plot analysis. Nine metabolites yielded an area under the receiver operating curve > 0.75. Meanwhile, seven abnormal metabolic pathways were correlated with differential metabolites, such as metabolic pathways; neuroactive ligand‒receptor interaction; and glycine, serine, and threonine metabolism. To our knowledge, this is the first study to reveal the characteristic metabolite changes in sera from NT1 patients for the selection of potential blood biomarkers and the elucidation of NT1 pathogenesis.

Impaired CBS-H2S signaling axis contributes to MPTP-induced neurodegeneration in a mouse model of Parkinson's disease.

Hydrogen sulfide (H2S), a novel neuromodulator, is linked to the pathogenesis of several neurodegenerative disorders. Exogenous application of H2S exerts neuroprotection via anti-inflammation and anti-oxidative stress in animal and cellular models of Parkinson's disease (PD). However, the role of endogenous H2S and the contribution of its various synthases in PD remain unclear. In the present study, we found a decline of plasma and striatal sulfide level in 1-methy-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced PD mouse model. Interestingly, among the three H2S generating enzymes, only cystathionine ß-synthase (CBS) expression was largely reduced in the striatum of MPTP-treated mice. The in vitro study confirmed a significant decrease of CBS expression in 1-methyl-4-phenylpyridinium (MPP+)-stimulated astrocytes and microglia, but not in neurons or SH-SY5Y dopaminergic cells. Striatal CBS overexpression, elicited by stereotaxic delivery with Cbs gene using recombinant adeno-associated-virus (rAAV-Cbs), successfully enhanced the sulfide level in the striatum and partially rescued the MPTP-induced dopaminergic neurotoxicity in the midbrain. Specifically, striatal CBS overexpression alleviated the motor deficits and dopaminergic neuron losses in the nigro-striatal pathway, with a concomitant inhibition of glial activation in MPTP-treated mice. Furthermore, compared to rAAV-Vector, rAAV-Cbs injection reduced the aberrant accumulation of nitric oxide and 3-nitrotyrosine (an indicator of protein nitration) in the striatum of MPTP-treated mice. Notably, it also attenuated the increase of nitrated α-synuclein level in MPTP mice. The in vitro study demonstrated that lentivirus-mediated CBS overexpression elevated the sulfide generation in glial cells. Moreover, glial CBS overexpression offered protection to midbrain dopaminergic neurons through repressing nitric oxide overproduction in both glial and neuronal cells induced by MPP+. Taken together, our data suggest that impaired CBS-H2S axis may contribute to the pathogenesis of PD, and that modulation of this axis may become a novel therapeutic approach for PD.

Cell-based vs enzyme-linked immunosorbent assay for detection of anti-Tribbles homolog 2 autoantibodies in Chinese patients with narcolepsy.

STUDY OBJECTIVES: Narcolepsy type 1 is attributed to a deficiency in cerebrospinal fluid orexin and is considered linked to autoimmunity. The levels of anti-Tribbles homolog 2 (TRIB2) autoantibodies are elevated in the sera of some patients with narcolepsy with cataplexy. Additionally, injecting mice with serum immunoglobulin from patients with narcolepsy with positive anti-TRIB2 antibodies can induce hypothalamic neuron loss and alterations in sleep patterns. Consequently, we hypothesized the existence of a potential association between anti-TRIB2 antibodies and narcolepsy. To test this possibility, we used cell-based assays (CBAs) and enzyme-linked immunosorbent assays (ELISAs) to detect the presence of anti-TRIB2 antibodies in Chinese patients with narcolepsy. METHODS: We included 68 patients with narcolepsy type 1, 39 patients with other central disorders of hypersomnolence, and 43 healthy controls. A CBA and a conventional ELISA were used to detect anti-TRIB2 antibody levels in patients' sera. RESULTS: CBA was used to detect serum anti-TRIB2 antibodies in Chinese patients with narcolepsy, and the results were negative. However, when the ELISA was used, only 2 patients with narcolepsy type 1 had TRIB2 antibody titers higher than the mean titer plus 2 standard deviations of the healthy controls. CONCLUSIONS: In our study, ELISA identified TRIB2 autoantibodies in sera of patients with narcolepsy where CBA failed to demonstrate them. Contrary to our hypothesis, this intriguing finding deserves further research to elucidate the potential association between TRIB2 and narcolepsy type 1. Exploring the implications of TRIB2 autoantibodies in narcolepsy and disparate outcomes between ELISA and CBA could provide crucial insights. CITATION: Zhong X, Yuan Y, Zhan Q, et al. Cell-based vs enzyme-linked immunosorbent assay for detection of anti-Tribbles homolog 2 autoantibodies in Chinese patients with narcolepsy. J Clin Sleep Med. 2024;20(6):941-946.

Injectable Thermosensitive Gel CH-BPNs-NBP for Effective Periodontitis Treatment through ROS-Scavenging and Jaw Vascular Unit Protection.

Periodontitis, a prevalent inflammatory condition in the oral cavity, is closely associated with oxidative stress-induced tissue damage mediated by excessive reactive oxygen species (ROS) production. The jaw vascular unit (JVU), encompassing both vascular and lymphatic vessels, plays a crucial role in maintaining tissue fluid homeostasis and contributes to the pathological process in inflammatory diseases of the jaw. This study presents a novel approach for treating periodontitis through the development of an injectable thermosensitive gel (CH-BPNs-NBP). The gel formulation incorporates black phosphorus nanosheets (BPNs), which are notable for their ROS-scavenging properties, and dl-3-n-butylphthalide (NBP), a vasodilator that promotes lymphatic vessel function within the JVU. These results demonstrate that the designed thermosensitive gel serve as a controlled release system, delivering BPNs and NBP to the site of inflammation. CH-BPNs-NBP not only protects macrophages and human lymphatic endothelial cells from ROS attack but also promotes M2 polarization and lymphatic function. In in vivo studies, this work observes a significant reduction in inflammation and tissue damage, accompanied by a notable promotion of alveolar bone regeneration. This research introduces a promising therapeutic strategy for periodontitis, leveraging the unique properties of BPNs and NBP within an injectable thermosensitive gel.

The microbiome types of colorectal tissue are potentially associated with the prognosis of patients with colorectal cancer.

As the second leading cause of cancer worldwide, colorectal cancer (CRC) is associated with a poor prognosis. Although recent studies have explored prognostic markers in patients with CRC, whether tissue microbes carry prognostic information remains unknown. Here, by assessing the colorectal tissue microbes of 533 CRC patients, we found that Proteobacteria (43.5%), Firmicutes (25.3%), and Actinobacteria (23.0%) dominated the colorectal tissue microbiota, which was different from the gut microbiota. Moreover, two clear clusters were obtained by clustering based on the tissue microbes across all samples. By comparison, the relative abundances of Proteobacteria and Bacteroidetes in cluster 1 were significantly higher than those in cluster 2; while compared with cluster 1, Firmicutes and Actinobacteria were more abundant in cluster 2. In addition, the Firmicutes/Bacteroidetes ratios in cluster 1 were significantly lower than those in cluster 2. Further, compared with cluster 2, patients in cluster 1 had relatively poor survival (Log-rank test, p = 0.0067). By correlating tissue microbes with patient survival, we found that the relative abundance of dominant phyla, including Proteobacteria, Firmicutes, and Bacteroidetes, was significantly associated with survival in CRC patients. Besides, the co-occurrence network of tissue microbes at the phylum level of cluster 2 was more complicated than that of cluster 1. Lastly, we detected some pathogenic bacteria enriched in cluster 1 that promote the development of CRC, thus leading to poor survival. In contrast, cluster 2 showed significant increases in the abundance of some probiotics and genera that resist cancer development. Altogether, this study provides the first evidence that the tissue microbiome of CRC patients carries prognostic information and can help design approaches for clinically evaluating the survival of CRC patients.

[Influence of iron ion on the growth of Trichomonas vaginalis in vitro].

OBJECTIVE: To study the influence of iron ion on the growth of Trichomonas vaginalis in vitro. METHODS: Quantitative pure incubation of T. vaginalis trophozoites with an initial density of 1 x l0(5)/ml was carried out at 37 degrees C in TYM (trypticase-yeast extract-maltose) medium (pH 6.0) with additional 100, 200, 300, and 400 micromol/L iron ion, respectively, and in TYM medium without additional iron ion as control The numbers of live and dead trichomonads were counted under an optical microscope after trypan blue staining, and the growth curve and survival rate of T. vaginalis were drawn to calculate the generation time of T. vaginalis. The minimal lethal concentration (MLC) of metronidazole was tested by serial dilution method when the trophozoites of T. vaginalis were incubated in TYM medium with 200 micromol/L iron ion and in control group without additional iron ion. RESULTS: The maximum densities of 2.9 x 10(6), 3.2 x 10(6), 3.1 x 10(6), and 2.8 x 10(6)/ml were obtained when the trophozoites were incubated for 40 h in TYM medium with 100, 200, 300, and 400 micromol/L iron ion, respectively, while the maximum density was achieved at 50 h in the control, which was 2.5 x l0(6)/ml. The generation time was (6.8 +/- 0.7) h in 400 micromol/L iron ion group, longer than those in the groups with 100-300 micromol/L iron ion, which were (4.8 +/- 0.3), (4.8 +/- 0.2), and (5.0 +/- 0.4) h, respectively (P < 0.05). While the generation times in 100-400 micromol/L groups were all shorter than that of the control [(10.2 +/- 3.1) h] (P < 0.05). MLC of metronidazole for T. vaginalis in TYM medium with 200 micromol/L iron ion was (23.44 +/- 11.56) microg/ml, significantly lower than that of the control [(31.25 +/- 15.44) microg/ml] (P < 0.05). CONCLUSION: In TYM medium with 100-400 micromol/L iron ion, T. vaginalis trophozoites reproduce faster, and the MLC of metronidazole to the parasites is lower.

[Cryopreservation of Trichomonas vaginalis and its influence factors].

Different concentrations of dimethylsulfoxide (DMSO) and glycerol, various densities of Trichomonas vaginalis trophozoites and duration of storage were used to study the effects on the cryopreservation of T. vaginalis at -78 degrees C. The optimal densities of trichomonads for cryopreservation were (1-2) x10(6)/ml. Glycerol and DMSO showed a high protective effect, with a maximum effect at a concentration of 10%, and the survival rates were 38.0% and 31.7%, respectively. There was no significant difference between them (P > 0.05). The results showed that the above optimized factors can provide a good protection in short-term (1-16 weeks) cryopreservation, and the trichomonads can be incubated to a logarithmic growth phase at 37 degrees C.

Potato Preload Mitigated Postprandial Glycemic Excursion in Healthy Subjects: An Acute Randomized Trial.

This study investigated the preload effect of the medium and high glycemic index (GI) potato, as well as the combination of partially hydrolyzed guar gum (HG) and potato, when ingested prior to a rice meal, on the iso-carbohydrate basis. In a randomized crossover trial, 17 healthy female subjects consumed (1) rice; (2) co-ingestion of highly cooked potato (HP), and rice (HP + R); (3) co-ingestion of minimally cooked potato (MP) and rice (MP + R); (4) preload HP prior to rice meal (PHP + R); (5) preload MP prior to rice meal (PMP + R); (6) co-ingestion of partially hydrolyzed guar gum (HG), HP and rice (HG + HP + R); (7) preload HG prior to co-ingestion of HP and rice (PHG + HP + R); (8) co-preload of HG and HP prior to rice (PHG + PHP + R); and (9) preload of HP prior to co-ingestion of HG and rice (PHP + HG + R). Postprandial glycemic response (GR) tests and subjective satiety tests were conducted for each test food. Cooked potato as a preload to a rice meal could significantly cut the acute postprandial glycemic excursion by around 1.0 mmol/L, irrespective of the GI of the preload. Co-preload of partial hydrolyzed guar gum and highly cooked potato (PHG + PHP + R) resulted in improved acute GR in terms of peak glucose value and glycemic excursion compared with either HG preload or HP preload. All the meals with preload showed comparable or improved self-reported satiety. Within an equicarbohydrate exchange framework, both high-GI and medium-GI potato preload decreased the postprandial glycemic excursion in young healthy female subjects. The combination of HG and HP as double preload resulted in better GR than both single HG or HP preload did.

shRNA targeting PLK1 inhibits the proliferation and invasion of nasopharyngeal carcinoma cells.

BACKGROUND: Polo-like kinase 1 (PLK1) is a serine/threonine protein kinase, which has been studied as a potential gene therapy target for many years. PLK1 is overexpressed in a variety of tumors, and its expression often negatively correlated with patient prognosis. However, the role of PLK1 in nasopharyngeal carcinoma (NPC) is rarely studied. METHODS: Two recombinant vector plasmids were transfected into CNE2 cell lines by liposome transfection, CNE2/PLK1 shRNA target PLK1 mRNA, as well as a non-targeting control plasmid, CNE2/NC shRNA. Meanwhile, non-transfected cells (CNE2) were also used as controls. Real-time quantitative PCR (qRT-PCR) and Western blotting were performed to detect the transfection effect. The effects of the downregulation of PLK1 on cell biological behavior was evaluated in vitro by using CCK8, Transwell, colony-forming and flow-cytometry assays. RESULTS: PLK1 mRNA and protein were significantly inhibited in CNE2/PLK1 shRNA cells. Compared to control groups, the CNE2/PLK1 shRNA cells showed slower cell growth and a significantly decreased cell-cloning rate. Both migration and invasion were significantly inhibited in experimental cells. The proportions of G2-phase and apoptotic cells within the experimental group were significantly increased. CONCLUSIONS: Our results indicate that specific interference of PLK1 gene expression can significantly inhibit the proliferation and invasion of NPC (CNE2) cells.

Organocatalytic peroxy-asymmetric allylic alkylation.

The peroxy-asymmetric allylic alkylation of hydroperoxyalkanes with Morita-Baylis-Hillman carbonates was catalysed by modified cinchona alkaloids (up to 93% ee), from which chiral alpha-methylene-beta-hydroxy esters could be efficiently derived.

Tumor necrosis factor-alpha is a potent endogenous mutagen that promotes cellular transformation.

Tumor necrosis factor-alpha (TNF-alpha) is an important inflammation cytokine without known direct effect on DNA. In this study, we found that TNF-alpha can cause DNA damages through reactive oxygen species. The mutagenic effect of TNF-alpha is comparable with that of ionizing radiation. TNF-alpha treatment in cultured cells resulted in increased gene mutations, gene amplification, micronuclei formation, and chromosomal instability. Antioxidants significantly reduced TNF-alpha-induced genetic damage. TNF-alpha also induced oxidative stress and nucleotide damages in mouse tissues in vivo. Moreover, TNF-alpha treatment alone led to increased malignant transformation of mouse embryo fibroblasts, which could be partially suppressed by antioxidants. As TNF-alpha is involved in chronic inflammatory diseases, such as chronic hepatitis, ulcerative colitis, and chronic skin ulcers, and these diseases predispose the patients to cancer development, our results suggest a novel pathway through which TNF-alpha promotes cancer development through induction of gene mutations, in addition to the previously reported mechanisms, in which nuclear factor-kappaB activation was implicated.

Effects of downregulated expression of microRNA-187 in gastric cancer.

microRNAs (miRNAs) are involved in cancer development and progression, and have regulatory roles as tumor suppressors or oncogenes. Although aberrant expression of miR-187 has been observed in several types of cancer, its pathophysiological role and relevance to tumorigenesis in gastric cancer (GC) remains unknown. In the present study, the expression and biological role of miR-187 was investigated in 32 specimens of GC tissues and their adjacent non-tumorigenic controls, and the association between miR-187 expression and clinical features of GC were analyzed further. Kaplan-Meier survival curves determined the clinical significance of miR-187 expression in GC. Following transfection with miR-187 mimics, the biological functions of miR-187 were determined by cell proliferation and cell cycle assays. Moreover, following transfection with miR-187 mimics, the targets regulated by miR-187 were investigated using western blotting. Luciferase reporter assays confirmed whether miR-187 regulated MAD2 mitotic arrest deficient-like 2 (MAD2L2) and stomatin (EPB72)-like 2 (STOML2) expression. The data of the present study revealed that miR-187 was significantly downregulated in GC compared with adjacent non-tumorigenic counterparts. Furthermore, decreased expression of miR-187 correlated with cell differentiation (P<0.05), TNM staging (P<0.05) and poor prognosis in GC patients. Functional studies indicated that miR-187 overexpression evidently inhibited MGC-803 cell proliferation in vitro and altered the cell cycle by arresting cells in the G0/G1 phase. In addition, the luciferase assay and western blotting revealed that MAD2L2 and STOML2 were targeted by miR-187. In conclusion, it is suggested that miR-187 functions as a tumor suppressor in GC, and is important in the development and progression of GC. Moreover, miR-187 may be a potential biomarker and therapeutic target in GC.

Impact of cell fusion in myeloma marrow microenvironment on tumor progression.

BACKGROUND: Mesenchymal stem cells (MSCs) represent a subset of non-hematopoietic adult stem cells, which can also fuse with other cells spontaneously in bone marrow and capable of adopting the phenotype of other cells. The fusion of somatic cells with stem cells can reprogram somatic cells to a pluripotent state. Our research on the fusion of bone marrow mesenchymal stem cells(BM-MSCs) and MM cells demonstrate that the fused cells can exhibit stemness and cancer cell-like characteristics. RESULTS: We successfully produced a hybrid cells that acquired larger size and multinucleation, in which partial chromatin condensation, a visible nucleolus, and one or more round or oval nucleus. Experiments results showed that the stemness markers highly expressed in these fused cells and there were much more chromosomes in fused cells than those in parental cells as well as exhibited increased resistance to drug treatment. CONCLUSIONS: Our results suggest that cell fusion between BM-MSCs and MM cells could contribute it genomic heterogeneity and play a role on disease progression. METHODS: We fused human BM-MSCs with MM cells lines RPMI 8226 or XG1 in vitro by polyethylene glycol (PEG), and the hybrid cells were sorted by sedimentation assays. The growth, migration, cell cycle, chromosome and drug sensitive of hybrids were assessed by cell counting, cell colony formation, transwell assays, cytogenetic assay and flow cytometry (FCM). The proteins and genes related to stemness and cytokines were tested by western blot and/or real-time quantitative RT-PCR.

[The reperfusion injury model improvement and the tolerance time investigation of rabbit spinal cord ischemia under normothermia].

OBJECTIVE: This study is designed to improve the rabbit model of ischemic- reperfusion injury and determine the safe clamping duration relevant to the spinal cord tolerance to ischemia at normothermia. METHODS: 50 New Zealand white rabbits were assigned randomly to 5 groups (Group C20, C25, C30, C40 and C60, 10 rabbits in each group) according to different clamping durations, ranging from 20 min to 60 min. The rabbits were endotracheally intubated for ventilation, and their left ear arteries were catheterized for monitoring the mean artery pressure. The spinal cord ischemia was induced by infrarenal aorta occlusion. A catheter was inserted into the aorta distal clamped site for monitoring the distal artery pressure. The neurological functional status of animal was assessed with the Tarlov scale system (0 or 1 meaning the rabbit paraplegia), at the moment of revival, 6 h, 24 h, and 48 h after the reperfusion. After last scoring, the lumbar segments of spinal cord (L4-L6) were removed for pathological examination, and the normal motor neurons of anterior horn were counted. RESULTS: Forty-eight hours after the infusion, the severe neurological impairments were not detected in the rabbits whose aorta were only clamped for 20 min (Group C20). However, the rabbits in Group CSO became totally paraplegic, and the rabbits in Group C25 C30 or C40 developed the paraplegia at 30% , 80% or 90% respectively. The median number of normal motor neuron was 12. 5, 10 or 2 respectively in Group C20, C25 or C30, and 0 median number resulted in Group C40 and C60. CONCLUSION: The rabbit model of ischemic-reperfusion injury is successfully improved, of which the safe clamping duration without spinal cord injury is not more than 20 min at normothermia.

IL-21 is required for CD4 memory formation in response to viral infection.

IL-21 has been shown to play an important role in the CD8 T cell response during acute and chronic viral infections. However, the role of IL-21 signaling in the CD4 T cell response to viral infection remains incompletely defined. In a model of infection with vaccinia virus, we show that intrinsic IL-21 signaling on CD4 T cells was critical for the formation of memory CD4 T cells in vivo. We further reveal that IL-21 promoted CD4 T cell survival in a mechanism dependent on activation of the STAT1 and STAT3 signaling pathways. In addition, the activation of Akt is also required for IL-21-dependent survival of CD4 T cells in vivo. These results identify a critical role for intrinsic IL-21 signaling in CD4 T cell survival and memory formation in response to viral infection in vivo and may provide insights into the design of effective vaccine strategies.

GYY4137, an H2S Slow-Releasing Donor, Prevents Nitrative Stress and α-Synuclein Nitration in an MPTP Mouse Model of Parkinson's Disease.

The neuromodulator hydrogen sulfide (H2S) was shown to exert neuroprotection in different models of Parkinson's disease (PD) via its anti-inflammatory and anti-apoptotic properties. In this study, we evaluated the effect of an H2S slow-releasing compound GYY4137 (GYY) on a mouse PD model induced by acute injection with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). GYY was intraperitoneally (i.p.) injected once daily into male C57BL/6J mice 3 days before and 2 weeks after MPTP (14 mg/kg, four times at 2-h intervals, i.p.) administration. Saline was given as a control. Behavioral tests (rotarod, balance beam, and grid walking) showed that 50 mg/kg GYY significantly ameliorated MPTP-caused motor impairments. At lower doses (12.5 and 25 mg/kg) GYY exhibited a less obvious effect. Consistent with this, immunohistochemistry and western blot analysis demonstrated that 50 mg/kg GYY attenuated the loss of tyrosine hydroxylase (TH) positive neurons in the substantia nigra and the decrease of TH expression in the striatum of MPTP-treated mice. Moreover, at this regimen GYY relieved the nitrative stress, as indicated by the decreases in nitric oxide (NO) generation and neuronal NO synthase (nNOS) upregulation elicited by MPTP in the striatum. The suppression of GYY on nNOS expression was verified in vitro, and the results further revealed that Akt activation may participate in the inhibition by GYY on nNOS upregulation. More important, GYY reduced the nitrated modification of α-synuclein, a PD-related protein, in MPTP-induced mice. Overall, our findings suggest that GYY attenuated dopaminergic neuron degeneration and reduced α-synuclein nitration in the midbrain, thus exerting neuroprotection in MPTP-induced mouse model of PD.