Upregulation of PD-1 expression on circulating CD8+ but not CD4+ T cells is associated with tuberculosis infection in health care workers.

BACKGROUND: Health care workers (HCWs) are at risk for occupationally acquired Mycobacterium tuberculosis infection and tuberculosis (TB) disease due to repeated exposure to workplace tubercle bacilli. To determine whether continual mycobacterial stimulation correlates with increased expression of inhibitory T cell receptors, here we compared PD-1 receptor expression on surfaces of circulating T cells between naïve (uninfected) HCWs and HCWs with latent TB infection (LTBI). RESULT: Data collected from 133 medical workers who met study selection criteria were included in the final analysis. QuantiFERON-TB Gold In-​Tube (QFT-GIT) testing yielded positive results for 32 HCWs, for an overall LTBI rate of 24.1%. Multivariate analysis identified HCW length of service > 15 years as an independent risk factor for a positive QFT-GIT result. In addition, comparisons of blood T cell subgroup profiles between QFT- and QFT+ groups indicated QFT+ subjects possessed greater proportions of mature (TM), transitional memory (TTM) and effector memory (TEM) CD4+ T cell subgroups and lower proportions of naïve T cells (TN). Moreover, the QFT+ group percentage of CD8+ T cells with detectable surface PD-1 was significantly higher than the corresponding percentage for the QFT- group. Meanwhile, no statistical intergroup difference was observed in percentages of CD4+ T cells with detectible surface PD-1. CONCLUSIONS: Our data demonstrated that upregulated PD-1 expression on circulating CD8+, but not CD4+ T cells, was associated with latent TB infection of HCWs. As compared to other hospitals, occupational TB infection risk in our hospital was substantially mitigated by implementation of multitiered infection control measures.

Clinical characteristics and laboratory indicator analysis of 67 COVID-19 pneumonia patients in Suzhou, China.

BACKGROUND: Sudden exacerbations and respiratory failure are major causes of death in patients with severe coronavirus disease 2019(COVID-19) pneumonia, but indicators for the prediction and treatment of severe patients are still lacking. METHODS: A retrospective analysis of 67 collected cases was conducted and included approximately 67 patients with COVID-19 pneumonia who were admitted to the Suzhou Fifth People's Hospital from January 1, 2020 to February 8, 2020. The epidemiological, clinical and imaging characteristics as well as laboratory data of the 67 patients were analyzed. RESULTS: The study found that fibrinogen (FIB) was increased in 45 (65.2%) patients, and when FIB reached a critical value of 4.805 g/L, the sensitivity and specificity、DA, helping to distinguish general and severe cases, were 100 and 14%、92.9%, respectively, which were significantly better than those for lymphocyte count and myoglobin. Chest CT images indicated that the cumulative number of lung lobes with lesions in severe patients was significantly higher than that in general patients (P < 0.05), and the cumulative number of lung lobes with lesions was negatively correlated with lymphocyte count and positively correlated with myoglobin and FIB. Our study also found that there was no obvious effect of hormone therapy in patients with severe COVID-19. CONCLUSIONS: Based on the retrospective analysis, FIB was found to be increased in severe patients and was better than lymphocyte count and myoglobin in distinguishing general and severe patients. The study also suggested that hormone treatment has no significant effect on COVID-19.

Clinical metagenomic sequencing for diagnosis of pulmonary tuberculosis.

OBJECTIVES: The aim of this study is to investigate the clinical usefulness of metagenomic Next-generation sequencing (mNGS) on bronchoalveolar lavage fluid (BALF) samples to discriminate pulmonary tuberculosis (PTB) from Non-TB community-acquired pneumonia (CAP) in PTB suspects. METHODS: We investigate the performance of mNGS on BALF samples from 110 PTB suspects, in comparison with conventional microbiological testing (solid media culture, acid-fast bacilli staining (AFS), Xpert) of BALF or sputum samples and final clinical diagnosis. RESULTS: We finally clinically diagnosed 48 cases of pulmonary tuberculosis patients and 62 cases of non-tuberculosis patients. Comparing to the final clinical diagnosis, mNGS produced a sensitivity of 47.92%, which was similar to that of Xpert (45.83%) and culture (46.81%), but much higher than that of AFS (29.17%) for TB diagnosis in BALF samples. Apart from detecting Mycobacterium tuberculosis, mNGS also identified mixed infections in PTB patients, including 3 fungal cases and 1 bacteria case. Meanwhile, mNGS efficiently identified 14 of 22 (63.63%) cases of non-tuberculous mycobacteria (NTM), 7 cases of fungi, 1 case of viral infection, and other common bacterial pathogens in Non-PTB group. Finally, mNGS identified 67.23% infection cases within 3 days, while the conventional methods identified 49.58% infection cases for over 90 days. CONCLUSION: Our data show that mNGS of BALF represents a potentially effective tool for the rapid diagnosis of PTB suspects.

Clinical evaluation of potential usefulness of serum lactate dehydrogenase (LDH) in 2019 novel coronavirus (COVID-19) pneumonia.

BACKGROUND: There was much evidence suggesting that the serum lactate dehydrogenase (LDH) levels reflect the extent of various pathophysiological processes. However, the current information about dynamic change of LDH in COVID-19 pneumonia has not been well investigated. METHODS: Study was performed in 87 cases confirmed by COVID-19 infection. The serum LDH levels were determined at diagnosis and follow-up visits. The evaluation of clinical response to therapy was based on chest CT scan. We selected the value of LDH around the data of chest CT scan (- 1 ~ + 1 day). RESULTS: At diagnosis, significant differences in LDH levels were found between non-severe and severe group (P < 0.05). It was demonstrated that increase or decrease of LDH was indicative of radiographic progress or improvement (P < 0.05). The time to LDH normalization (5.67 ± 0.55, days) was positively correlated with the time to radiographic absorption (5.57 ± 0.65 days, r = 0.53, P < 0.05). Applying the cut-off value of the increase in LDH has good specificity to predict disease progression. CONCLUSIONS: Serum LDH was validated for its potential usefulness as markers for evaluating clinical severity and monitoring treatment response in COVID-19 pneumonia.

Discrepant Clinical Significance of CD28+CD8- and CD4+CD25high Regulatory T Cells During the Progression of Hepatitis B Virus Infection.

Accumulating evidence demonstrates that CD8+CD28- regulatory T cells increase in chronic viral infection as well as tumorigenesis. However, it is still not clear about their characteristics in hepatitis B virus (HBV) infection. In addition, it is not understood whether this regulatory immune subset is distinct from CD4+CD25high regulatory T cells in the aspect of impact on or relationship to the progression of HBV infection. Hence, we investigated their dynamics and compared their correlations with clinical parameters in the chronic and advanced phases of HBV infection. The data showed that compared with healthy controls, the frequencies of CD28+CD8- and CD4+CD25high T cells increased in both chronic and advanced phases, while there is no significant difference between the two case groups. Interestingly, we found that in chronic phase, the frequency of CD8+CD28- subset was negatively correlated with the levels of alanine aminotransaminase (ALT) and aspartate aminotransferase (AST), respectively, and did not present association with HBV DNA load, whereas that of CD4+CD25high T cells was positively correlated with HBV DNA load and the levels of ALT and AST, respectively. Amazingly, in advanced phase, the frequency of CD4+CD25high T cells was negatively correlated with HBV DNA load and the levels of ALT, respectively, while there is no significant correlation between the frequency of CD8+CD28- subset and those clinical parameters. Thereby, our findings demonstrated that CD28+CD8- and CD4+CD25high regulatory T cells might exert distinct effect on modulating antiviral immune responses and mitigate immunomediated liver damage in different phases of HBV infection, which represent potential prognostic markers and therapeutic targets for HBV-infected patients based on further exploration of detailed mechanism.

Interferon-Gamma Release Assay is Not Appropriate for the Diagnosis of Active Tuberculosis in High-Burden Tuberculosis Settings: A Retrospective Multicenter Investigation.

BACKGROUND: Interferon-gamma release assay (IGRA) has been used in latent tuberculosis (TB) infection and TB diagnosis, but the results from different high TB-endemic countries are different. The aim of this study was to investigate the value of IGRA in the diagnosis of active pulmonary TB (PTB) in China. METHODS: We conducted a large-scale retrospective multicenter investigation to further evaluate the role of IGRA in the diagnosis of active PTB in high TB-epidemic populations and the factors affecting the performance of the assay. All patients who underwent valid T-SPOT.TB assays from December 2012 to November 2015 in six large-scale specialized TB hospitals in China and met the study criteria were retrospectively evaluated. Patients were divided into three groups: Group 1, sputum culture-positive PTB patients, confirmed by positive Mycobacterium tuberculosis sputum culture; Group 2, sputum culture-negative PTB patients; and Group 3, non-TB respiratory diseases. The medical records of all patients were collected. Chi-square tests and Fisher's exact test were used to compare categorical data. Multivariable logistic analyses were performed to evaluate the relationship between the results of T-SPOT in TB patients and other factors. RESULTS: A total of 3082 patients for whom complete information was available were included in the investigation, including 905 sputum culture-positive PTB cases, 914 sputum culture-negative PTB cases, and 1263 non-TB respiratory disease cases. The positive rate of T-SPOT.TB was 93.3% in the culture-positive PTB group and 86.1% in the culture-negative PTB group. In the non-PTB group, the positive rate of T-SPOT.TB was 43.6%. The positive rate of T-SPOT.TB in the culture-positive PTB group was significantly higher than that in the culture-negative PTB group (χ2 = 25.118, P < 0.01), which in turn was significantly higher than that in the non-TB group (χ2 = 566.116, P < 0.01). The overall results were as follows: sensitivity, 89.7%; specificity, 56.37%; positive predictive value, 74.75%; negative predictive value, 79.11%; and accuracy, 76.02%. CONCLUSIONS: High false-positive rates of T-SPOT.TB assays in the non-TB group limit the usefulness as a single test to diagnose active TB in China. We highly recommend that IGRAs not be used for the diagnosis of active TB in high-burden TB settings.

Risk factors of latent tuberculosis infection and immune function in health care workers in Suzhou, China.

BACKGROUND: The Chinese government has pay attention about tuberculosis infection among medical staff in infectious disease hospitals, but the effects have not yet been reported. This study will explore latent infection and immune function in the medical staff and systematically analyze the associated influencing factors. METHODS: Ninety-four medical staffs were enrolled and 20 medical staffs were defined as low risk group and others were high risk group. We used IFN-γ release assay and flow cytometry to analyze the latent TB infection status and immune function. Logistic regression analyses were performed to identify the independent risk factors of latent TB infection. RESULTS: This study explored and compared the infection status of medical workers and found that the rate of positive TB-IGRA results was higher among high risk group than in low risk group. Working environment, occupational history and work type were risk factors for TB infection in hospital. This study also found that high risk group had higher IFN-γ expression and a lower ratio of CD4+ to CD8+ T cells and further analysis found that this immune disorder is associated with wards and occupations. CONCLUSIONS: This study through rigorous sample collection and analysis found the risk factors of latent tuberculosis infection in health care workers. This finding may provide a theoretical basis to be used by the countries with a high TB burden to further improve their strategies for the prevention of TB infections in hospitals and may give an indication for improving the personal health of medical staff in infectious disease hospitals.

More significance of TB-IGRA except for the diagnose of tuberculosis.

OBJECTIVE: Tuberculosis (TB)-interferon gamma release assay (IGRA) test has the characteristics of short time, high specificity, and high sensitivity, but it lacks the correlation research between TB-IGRA test results and body's immune cells, disease progression and prognosis, which is explored in this study. DESIGN: A retrospective study was carried out on positive TB-IGRA patients who were infected with TB and diagnosed at our hospital from January 2014 to June 2015. The TB-IGRA, routine blood test, T-cell subgroup data were collected for statistical analysis. RESULTS: TB-IGRA results were in positive proportion to the lymphocytes, CD4+ T cells and CD4+ CD28+ T cells, whereas negative to the Treg cells. Patient with unilateral pulmonary lesion had higher TB-IGRA than those with bilateral pulmonary lesions. After the stimulation of TB-specific antigen, the proportion of CD4+ IFN-γ+ and CD8+ IFN-γ+ T Tcells were both increased and the CD4+ IFN-γ+ T had positive correlation with the value of TB-IGRA. CONCLUSIONS: IFN-γ was tested with TB-IGRA in patients with TB by the specific TB T cells and correlated with the lymphocytes, while the lymphocytes also closely related to the host's anti-TB immunity and disease outcome. Hence the result of TB-IGRA could reflect the specific anti-TB immunity ability of the host, disease progression and prognosis. This study further expands the application scope of TB-IGRA technology in the diagnosis of TB and lays a foundation for clinical practice to understand the immunity state of the patients with TB and the application of auxiliary clinical immunity regulators.

New attempt in tuberculosis treatment: autologous cytokine-induced killer after chemotherapy treatment failure in a case of multi-drug resistant tuberculosis (MTB).

A 32-year-old woman was diagnosed as pulmonary tuberculosis 15 years ago and recurred several times due to long-term nonstandard treatment. Drug sensitivity test indicated that multidrug-resistant tuberculosis had emerged and we determined relevant therapeutic schedule according to this result. However, it didn't show any amelioration of the disease after 3-month chemotherapy. We formulated 3-course CIK immunotherapy based on patient's condition. After 3 courses of immunotherapy, we found obvious amelioration of the patient's condition. And there was no recurrence during the follow-up in the past 3 years. Therefore, we considered that the CIK immunotherapy is an effective method for tuberculosis treatment and recurrence prevention. (Sarcoidosis Vasc Diffuse Lung Dis 2017; 34: 97-99).

Clinical Significance of Dynamics of Programmed Death Ligand-1 Expression on Circulating CD14+ Monocytes and CD19+ B Cells with the Progression of Hepatitis B Virus Infection.

Programmed death-1 (PD-1) expression has been revealed to be upregulated on T cells and contributes to T cell exhaustion in patients with hepatitis B virus (HBV) infection. In this study, we investigated the dynamic expression of programmed death ligand-1 (PD-L1), the ligand of PD-1, on circulating CD14+ monocytes and CD19+ B cells of HBV-infected patients at the stages of chronic HBV (CHB) infection, liver cirrhosis (LC), and hepatocellular carcinoma (HCC), respectively. The results showed that compared with healthy controls, the levels of PD-L1 expression on CD14+ and CD19+ populations were both upregulated in CHB, LC, and HCC groups. Although there was no significant difference of PD-L1 expression on CD14+ population among three disease groups, further analysis demonstrated that the frequency of CD14+PD-L1+ population was negatively correlated with HBV DNA load, the levels of alanine aminotransaminase (ALT), and the levels of aspartate aminotransferase (AST), respectively, at CHB stage, while it did not present significant correlation with such parameters at LC stage and was only positively correlated with HBV DNA load at HCC stage. Similarly, the levels of PD-L1 expression on CD19+ population also did not present much difference among three disease groups. Intriguingly, the frequencies of CD19+PD-L1+ population at CHB and LCC stages were both positively correlated with the levels of ALT and AST, but they were not significantly correlated with HBV DNA load. Thereby, the current study elucidated the dynamics of PD-L1 expression on monocytes and B cells, along with the dynamic regulation of PD-1 on T cells, which had a close relationship during the progression of HBV infection. Collectively, our findings demonstrated that in the course of HBV infection development, PD-L1 expression on CD14+ monocytes and CD19+ B cells varied and significantly correlated with clinical parameters, which could be utilized as a potential clinical indicator.

An open-label, randomized and multi-center clinical trial to evaluate the efficacy of Silibinin in preventing drug-induced liver injury.

UNLABELLED: To assess the clinical efficacy and safety of Silibinin in preventing drug-induced liver injury (DILI) in the general population (high-risk patients with non-drug induced liver injury). METHOD: A prospective, multi-center, randomized, open-label and controlled trial was conducted with 568 patients undergoing primary treatment of pulmonary tuberculosis. The study included 277 patients in experimental group and 291 patients in control group. The patients in the two group were treated with conventional 2HREZ (S)/4HR for tuberculosis (TB), and additional Silibinin capsules (oral administration of 70 mg/time, 3 times/day for 8 weeks in experimental group. Outcomes of liver function, interruption of anti-TB treatment and therapeutic results, as well as adverse reactions were observed and analyzed. RESULTS: At 2, 4 and 8 weeks of treatment, the incidences of liver injury in experimental group were 3.97%, 1.44% and 2.17%, respectively; the incidences in control group were 4.12%, 4.12% and 2.41%, respectively. Statistical analysis showed that there was no difference in the incidence between the two groups at each treatment period (P>0.05). At 8 weeks, the numbers of patients diagnosed of DILI were 18 (7.22%) and 27 (9.28%) in experimental and control groups, respectively (P>0.05). 34.30% and 27.49% of the patients in experimental and control groups had transient abnormal liver function or symptoms, respectively; similar percentages (3.25% and 6.19%) of the patients in two groups have liver function injury and symptoms, and were suspended for anti-TB treatment (P>0.05). The incidence of anorexia and nausea symptoms was lower in experimental group than in control group, and the differences were significant at 4 and 8 weeks (P<0.05). 8 weeks after the treatment, 98.30% of the sputum smear culture were negative in experimental group, which was significantly higher (P<0.01) than that in control group (92.98%). CONCLUSION: Preventive hepatoprotective therapy in the general population may reduce drug discontinuation rate, improve patient's compliance and outcomes of anti-TB treatment.

A cross-sectional and follow-up study of leukopenia in tuberculosis patients: prevalence, risk factors and impact of anti-tuberculosis treatment.

BACKGROUND: To investigate the prevalence of and risk factors for leukopenia in tuberculosis patients and the impact of anti-tuberculosis regimens on the occurrence of leukopenia in newly treated tuberculosis patients. METHODS: A total of 1,904 tuberculosis patients were included in the study. A cross-sectional survey of the prevalence of leukopenia was initially conducted, and then factors influencing leukopenia were identified using Logistic regression analysis. Non-treatment factors influencing peripheral blood leukocyte counts were analyzed using univariate COX proportional hazards models. Covariate analysis was used to assess the independent effect of different anti-tuberculosis regimens on peripheral blood leukocyte counts. RESULTS: Being female, advanced age and longer duration of previous anti-tuberculosis treatment (>6 month) were risk factors for leukopenia in tuberculosis patients, while secondary pulmonary tuberculosis, higher body mass index (BMI: 24-27.9 kg/m(2)), and higher degree of education (senior high school or above) were protective factors. Gender, vegetable consumption, drinking, pulmonary infection, other chronic diseases, and use of antibiotics were significantly associated with the development of leukopenia in patients on anti-tuberculosis treatment. In tuberculosis patients treated with anti-tuberculosis regimens not containing antibiotics, peripheral blood leukocyte levels gradually declined with the prolongation of treatment duration. In tuberculosis patients treated with anti-tuberculosis regimens containing antibiotics, peripheral blood leukocyte levels showed a declining trend. CONCLUSIONS: Female patients, patients at advanced age and recurrent tuberculosis patients having longer previous anti-tuberculosis treatment are high-risk populations for leukopenia. Attention should be paid to the influence of vegetable consumption and drinking, co-morbidities and use of antibiotics during anti-tuberculosis treatment.

A single in vivo cocaine administration impairs 5-HT(1B) receptor-induced long-term depression in the nucleus accumbens.

The nucleus accumbens (NAc) is a crucial forebrain nucleus implicated in reward-based decision-making. While NAc neurons are richly innervated by serotonergic fibers, information on the functional role of serotonin 5-hydroxytryptamine (5-HT) in the NAc is still sparse. Here, we demonstrate that brief application of 5-HT or 5-HT1B receptor agonist CP 93129 induced a long-term depression (LTD) of glutamatergic transmission in NAc neurons. This LTD was presynaptically mediated and inducible by endogenous 5-HT. Remarkably, a single cocaine exposure impaired the induction of LTD by 5-HT or CP 93129. The inhibition was blocked when a selective dopamine D1 receptor antagonist SCH23390 was coadministered with cocaine. Cocaine treatment resulted in increased phosphorylation of presynaptic proteins, rabphilin 3A and synapsin 1, and significantly attenuated CP 93129-induced decrease in rabphilin 3A and synapsin 1 phosphorylation. Application of cAMP-dependent protein kinase inhibitor KT5720 caused a prominent synaptic depression in NAc neurons of mice with a history of cocaine exposure. Our results reveal a novel 5-HT1B receptor-mediated LTD in the NAc and suggest that cocaine exposure may result in elevated phosphorylation of presynaptic proteins involved in regulating glutamate release, which counteracts the presynaptic depressant effects of 5-HT1B receptors and thereby impairs the induction of LTD by 5-HT.

[Expression of PD-1/PD-L1 in peripheral blood mononuclear cells in lung cancer patients and its biological significance].

OBJECTIVE: To analyze the expression of co-stimulatory molecules PD-1/PD-L1 in peripheral blood mononuclear cells in lung cancer patients, and to explore its biological significance. METHODS: One hundred and thirty-three lung cancer patients, 25 lung infection patients and 23 healthy donors were enrolled in this study. 100 µl of whole blood from these subjects were collected. Multi-color immunofluorescence staining and flow cytometry were used to detect PD-1/PD-L1 expression. The results were statistically analyzed. RESULTS: The expression level of CD3⁺CD8⁺ T cells in the lung cancer patients was (38.83 ± 1.74)%, significantly lower than that in the control group [(43.25 ± 3.35)%, P < 0.05]. CD8⁺CD28⁺ T cell subset in the peripheral blood of lung cancer patients was (17.73 ± 1.21)% significantly lower than that of the healthy donors [(27.96 ± 2.72)%, P < 0.01]. The CD8⁺CD28⁻ T cell subset was (21.19 ± 1.92)% in the lung cancer patients, significantly higher than that of the healthy control group [(15.18 ± 2.93)%, P < 0.05]. The expression level of PD-1 on the surface of CD8⁺CD28⁺ T cells was (10.67 ± 1.12)% in the group of lung cancer patients, significantly higher than that of the control group [(5.32 ± 1.58)%, P < 0.01]. It was also found that the expression of PD-1 on CD8⁺CD28⁻ T cells was up-regulated in the group of lung cancer patients (7.46 ± 1.25)%, significantly higher than that of the healthy control group [(2.68+1.07)%, P < 0.01]. The expression level of PD-L1 on CD68⁺ cells in the lung cancer patients was (16.03 ± 2.06)%, significantly higher than that of the healthy control group [(9.32 ± 2.00)%, P < 0.05]. CONCLUSION: Up-regulation of PD-1/PD-L1 on peripheral blood cells in lung cancer patients negatively regulates the lymphocytes, inhibits the immune response for killing tumor cells, and promotes tumor development and immune escape.

[Development and evaluation of a quantitative double antibodies sandwich ELISA assay for rIFN-alpha1b].

OBJECTIVE: To develop a double antibody sandwich ELISA assay for quantitative determination of recombinant human interferon alpha1b. METHODS: Mouse monoclonal antibodies with different binding site on rIFN-alpha1b were screened to select optimized candidates as coating and HRP-labeled index antibodies respectively. And a double antibodies sandwich ELISA was assembled; the reliable lower detection limit, specificity, accuracy and reproducibility were evaluated and validated. RESULTS: The quantitative sandwich ELISA had a reliable lower detection limit of 10 ng/ml, with a liner detection range 10-100 ng/ml (R2 = 0.992), variation coefficient inter-plates is less than 10%. CONCLUSION: The developed sandwich ELISA was a sensitive and specific, accuracy and reproducibility method for quantitative determination of recombinant human interferon alpha1b in final product.

Cocaine withdrawal impairs metabotropic glutamate receptor-dependent long-term depression in the nucleus accumbens.

Neuroadaptation in the nucleus accumbens (NAc), a central component of the mesolimbic dopamine (DA) system, has been implicated in the development of cocaine-induced psychomotor sensitization and relapse to cocaine seeking. However, little is known about the cellular and synaptic mechanisms underlying such adaptation. Using a mouse model of behavioral sensitization, we show that animals withdrawn from repeated cocaine exposure have a selective deficit in the ability to elicit metabotropic glutamate receptor (mGluR)-dependent long-term depression (LTD) in the shell of the NAc in response to bath application of the group I mGluR agonist (S)-3,5-dihydroxyphenylglycine (DHPG). Experiments conducted in the presence of the selective mGluR1 antagonists 7-(hydroxyimino)cyclopropachromen-carboxylate ethyl ester and (S)-(+)-α-amino-4-carboxy-2-methylbenzeneacetic acid, or the mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine, demonstrated that the impaired DHPG-LTD is likely attributable to a loss of mGluR5 function. Quantitative real-time reverse transcriptase-PCR and Western blot analysis revealed significant downregulation of mGluR5, but not mGluR1, mRNA and protein levels in the NAc shell. The inhibitory effect of repeated cocaine exposure on DHPG-LTD was selectively prevented when cocaine was coadministered with the selective D(1)-like DA receptor antagonist (R)-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine. Furthermore, the levels of brain-derived neurotrophic factor (BDNF) protein in the NAc shell increased progressively after cocaine withdrawal, and the impairment of DHPG-LTD in the NAc shell was not found in slices from BDNF-knock-out mice after cocaine withdrawal. These results suggest that withdrawal from repeated cocaine exposure may result in increased BDNF levels in the NAc shell, which leads to a selective downregulation of mGluR5 and thereby impairs the induction of mGluR-dependent LTD.

Repeated cocaine administration decreases 5-HT(2A) receptor-mediated serotonergic enhancement of synaptic activity in rat medial prefrontal cortex.

Neural adaptations in the medial prefrontal cortex (mPFC) are thought to be crucial in the development and maintenance of addictive behaviors. The mPFC receives a dense serotonergic (5-hydroxytryptamine, 5-HT) innervation from raphe nuclei and 5-HT exerts complex actions on mPFC pyramidal neurons. The present study, using a rat model of behavioral sensitization to cocaine, was designed to determine whether repeated cocaine exposure in vivo is capable of altering 5-HT-induced regulation of glutamatergic transmission in the mPFC. In layer V pyramidal neurons of the mPFC, application of 5-HT, through activation of 5-HT(2A) receptors, induced a massive enhancement of spontaneous excitatory postsynaptic currents (sEPSCs). Repeated cocaine administration for 5 days resulted in an attenuation in the ability of 5-HT to enhance sEPSCs. This effect was prevented when cocaine was co-administered with the selective 5-HT(2A) receptor antagonist ketanserin and was mimicked by repeated 5-HT(2A) receptor agonist (-)4-iodo-2,5-dimethoxyphenylisopropylamine administration. Repeated cocaine administration is not associated with any changes in the levels of 5-HT(2A) receptors or regulator of GTP-binding protein signaling 4. These results suggest that cocaine-induced inhibition of 5-HT(2A) receptor-mediated enhancement of glutamatergic transmission in the mPFC may be caused, at least in part, by the impairment of coupling of 5-HT(2A) receptors with GTP-binding proteins during cocaine withdrawal. These alterations in 5-HT(2A) receptor responsiveness in the mPFC may be relevant to the development of behavioral sensitization and withdrawal effects following repeated cocaine administration.

Insulin stimulates postsynaptic density-95 protein translation via the phosphoinositide 3-kinase-Akt-mammalian target of rapamycin signaling pathway.

Insulin receptors are highly enriched at neuronal synapses, but whose function remains unclear. Here we present evidence that brief incubations of rat hippocampal slices with insulin resulted in an increased protein expression of dendritic scaffolding protein postsynaptic density-95 (PSD-95) in area CA1. This insulin-induced increase in the PSD-95 protein expression was inhibited by the tyrosine kinase inhibitor, AG1024, phosphatidylinositol 3-kinase (PI3K) inhibitors, LY294002 and wortmannin, translational inhibitors, anisomycin and rapamycin, but not by LY303511 (an inactive analogue of LY294002), and transcriptional inhibitor, actinomycin D, suggesting that insulin regulates the translation of PSD-95 by activating the receptor tyrosine kinase-PI3K-mammalian target of rapamycin (mTOR) signaling pathway. A similar insulin-induced increase in the PSD-95 protein expression was detected after stimulation of the synaptic fractions isolated from the hippocampal neurons. Furthermore, insulin treatment did not affect the PSD-95 mRNA levels. In agreement, insulin rapidly induced the phosphorylation of 3-phosphoinositide-dependent protein kinase-1 (PDK1), protein kinase B (Akt), and mTOR, effects that were prevented by the AG1024 and LY294002. We also show that insulin stimulated the phosphorylation of 4E-binding protein 1 (4E-BP1) and p70S6 kinase (p70S6K) in a mTOR-dependent manner. Finally, we demonstrate the constitutive expression of PSD-95 mRNA in the synaptic fractions isolated from hippocampal neurons. Taken together, these findings suggest that activation of the PI3K-Akt-mTOR signaling pathway is essential for the insulin-induced up-regulation of local PSD-95 protein synthesis in neuronal dendrites and indicate a new molecular mechanism that may contribute to the modulation of synaptic function by insulin in hippocampal area CA1.

Rap1-induced p38 mitogen-activated protein kinase activation facilitates AMPA receptor trafficking via the GDI.Rab5 complex. Potential role in (S)-3,5-dihydroxyphenylglycene-induced long term depression.

Recent evidence has emphasized the importance of p38 mitogen-activated protein kinase (MAPK) in the induction of metabotropic glutamate receptor (mGluR)-dependent long term depression (LTD) at hippocampal CA3-CA1 synapses. However, the cascade responsible of mGluR to activate p38 MAPK and the signaling pathway immediately downstream from it to induce synaptic depression is poorly understood. Here, we show that transient activation of group I mGluR with the selective agonist (S)-3,5-dihydroxyphenylglycine (DHPG) activates p38 MAPK through G protein betagamma-subunit, small GTPase Rap1, and MAPK kinase 3/6 (MKK3/6), thus resulting in mGluR5-dependent LTD. Furthermore, our data clearly show that an accelerating AMPA receptor endocytosis by stimulating the formation of guanyl nucleotide dissociation inhibitor-Rab5 complex is a potential downstream processing of p38 MAPK activation to mediate DHPG-LTD. These results suggest an important role for Rap1-MKK3/6-p38 MAPK pathway in the induction of mGluR-dependent LTD by directly coupling to receptor trafficking machineries to facilitate the loss of synaptic AMPA receptors.