Reliability of automated synovial fluid cell counting with Mindray BC-6800 body fluid mode.

INTRODUCTION: The enumeration and differentiation of nuclear elements in synovial fluid is a cornerstone for diagnosis and follow-up of many orthopedic and rheumatologic diseases. In this study, we evaluated the analytical performance of Mindray BC-6800 BF mode (BC-6800-BF) for synovial fluid analysis. METHODS: Overall, 78 synovial fluids were collected and analyzed with both BC-6800-BF and light microscopy. The study also entailed the assessment of limit of blank (LoB), limit of detection (LoD), limit of quantification (LoQ), carryover and linearity. RESULTS: The LoB for the parameters total cells and white blood cells was 6 × 106 cells/L, and the LoD and LoQ were instead 15 and 16 × 106 cells/L, respectively. Linearity was excellent and carryover was negligible. The agreement between BC-6800-BF and light microscopy was satisfactory for all samples pretreated with hyaluronidase, displaying a bias between -5.9% and 8.2%. CONCLUSIONS: The use of BC-6800-BF for synovial fluid analysis enables rapid and accurate assessment, especially for total cell and polymorphonuclear counts. The use of BC-6800-BF may therefore allow the replacement of optical analysis, especially in samples pretreated with hyaluronidase, thus allowing its routine use for the screening of synovial specimens.

Density heterogeneity and fluid-blood levels in patients aged over 55 with lobar hematoma.

BACKGROUND: Density heterogeneity and fluid-blood levels (FBLs) are frequently seen on acute CT scans of deep brain hemorrhage. Our aim was to analyze the density heterogeneity and FBLs seen on acute/subacute CT in patients aged>55 with lobar haemorrhage (LH), and to study the relationship of these brain abnormalities with other parameters, including cerebral amyloid angiopathy (CAA)-related abnormalities. METHODS: This was an observational study and retrospective analysis of early CT scans (<7 days) in patients aged>55 years with acute lobar hemorrhage who, between 2012 and 2015, were entered into our stroke database. A total of 37 LH episodes (without trauma, abnormal coagulation/platelet counts, vascular malformation, tumor or vasculitis) in 35 patients were analyzed. Other studied parameters were gender, age, history of hypertension, blood pressure on admission, prior antiplatelet treatment, aPTT, PTT, platelet count, hematocrit, timing of first CT, LH volume, involved lobe, cortical superficial siderosis, microbleeds, chronic LH and CAA (classic and modified Boston) criteria. CAA-related abnormalities seen on MRI were also scored. RESULTS: Overall, in 26 LH episodes (70%), CT was performed within 24h. Density heterogeneity and FBLs were seen in 19 (51%) and 9 (24%) LH episodes, respectively. Also, according to classic and modified Boston criteria, 18 (51%) and 24 (69%) patients, respectively, fulfilled criteria for probable/definite CAA. As for the presence of FBLs, a statistically significant association was found with both the presence of probable/definite CAA according to modified Boston criteria (P=0.033) and the presence of superficial siderosis (P=0.019). CONCLUSION: Density heterogeneity and, to a lesser degree, FBLs are frequently seen in patients aged>55 with LH. FBLs may also be associated with CAA-related hemorrhage.

Dose-finding/phase II trial: bevacizumab, immunotherapy, and chemotherapy (BIC) in metastatic renal cell cancer (mRCC). Antitumor effects and variations of circulating T regulatory cells (Treg).

The aim of this study was to explore the efficacy and toxicities of a combined regimen of bevacizumab plus immunotherapy and chemotherapy (BIC) and the circulating T regulatory cells (Treg) in metastatic renal cell cancer (mRCC). Nephrectomized mRCC patients were enrolled into a multicenter single-arm dose-finding study with five escalated dose levels of chemotherapy with intravenous gemcitabine and 5-fluorouracil associated with fixed intravenous doses of bevacizumab, subcutaneous low doses of interleukin-2, and interferon-α-2a. An expanded cohort (phase II study) was treated at the recommended dose for additional safety and efficacy information according to minimax Simon two-stage design. Blood samples for Treg were collected and evaluated by fluorescence-activated cell sorting (FACS) analysis on cycle 1. Fifty-one patients were entered to receive one of five dose levels. Median age was 58 years (male 67 %, pretreated 49 %): 15 patients were low risk according to Memorial Sloan-Kettering Cancer Center (MSKCC) criteria, while 27 and nine were respectively intermediate- and high-risk patients. More frequent grade 3 and 4 toxicities included nonfebrile neutropenia, thrombocytopenia, and fever. Among patients evaluable for response (49), 29.5 % had partial response and 37 % stable disease. Overall median time to progression and median overall survival were 8.8 and 22.67 months, respectively. We observed a rapid increase in the percentage of Treg after immunotherapy and a reduction after bevacizumab only in patient who obtained a partial response or stable disease. The BIC was feasible, well tolerated, and shown interesting activity. Further studies are needed to explore if Treg could have a role in clinical response in mRCC treated with bevacizumab.

Adaptive immune contexture at the tumour site and downmodulation of circulating myeloid-derived suppressor cells in the response of solitary fibrous tumour patients to anti-angiogenic therapy.

BACKGROUND: Host immunity is emerging as a key player in the prognosis and response to treatment of cancer patients. However, the impact of the immune system and its modulation by therapies are unknown in rare soft tissue sarcomas such as solitary fibrous tumours (SFTs), whose management in the advanced forms includes anti-angiogenic therapy. Here, we studied the in situ and systemic immune status of advanced SFT patients and the effects of sunitinib malate (SM) in association with the clinical efficacy. METHODS: Immune contexture of SFTs was assessed by immunohistochemistry in lesions from untreated or SM-treated patients. Frequency of circulating myeloid-derived suppressor cells (MDSCs), regulatory T cells (Tregs) and T-cell functions was assessed ex vivo in SFT patients prior and during anti-angiogenic therapy. Patients with long-term tumour control were included to correlate immune profiles and clinical responses. RESULTS: Anti-angiogenic naïve SFT lesions were heavily infiltrated by CD163(+)CD14(+)CD68(-) and CD163(+)CD14(-)CD68(-) myeloid cells but devoid of T cells. Conversely, post-SM tumours acquired a new subset of CD68(+)CD14(+) myeloid cells and displayed traits of an on-going adaptive immunity, strongly enriched in activated CD8(+) and CD4(+) T cells. These changes at the tumour site paralleled the alleviation of systemic immunosuppression and the drop in the frequency of circulating monocytic MDSCs (mMDSCs) and granulocytic MDSCs (gMDSCs). Rebound in the number of mMDSCs, but not of gMDSCs occurred at disease progression, and a reduced percentages of mMDSCs, comparable to those found in healthy donors (HDs), endured only in the SM-responsive patients. CONCLUSIONS: The immune contexture of SFT patients is heavily involved in anti-angiogenic therapy and it could be exploited to achieve more durable disease control through immune-based combination strategies.

Risk assessment of venous thrombosis in families with known hereditary thrombophilia: the MARseilles-NImes prediction model.

BACKGROUND: Although predicting the risk of venous thrombosis (VT) in an individual from a family with inherited thrombophilia is of major importance, it is often not feasible. OBJECTIVES: To develop a simple risk assessment model that improves prediction of the risk of VT for individuals of families with inherited thrombophilia. PATIENTS/METHODS: 1201 relatives from 430 families with inherited thrombophilia (deficiencies of antithrombin, protein C or protein S, and the factor V Leiden and F2 20210A mutations) were recruited at the referral center for thrombophilia in Marseilles, France, from 1986 to 2008. One hundred and twenty-two individuals had a personal history of VT. Sixteen preselected clinical and laboratory variables were used to derive the VT risk score. RESULTS: The scores based on the 16 variables and on the five most strongly associated variables performed similarly (areas under receiver operating characteristic curves of 0.85 and 0.83, respectively). For the five-variable score, named the MARNI score, derived from family history score of VT, von Willebrand factor antigen levels, age, severity of thrombophilia, and FGG rs2066865, the risk of VT ranged from 0.2% for individuals with a score of 0 (n = 186) to > 70% for individuals with a score of ≥ 7 (n = 27). The model was validated with an internal bootstrap method. CONCLUSIONS: With the use of a simple scoring system, assessment of the risk of VT in subjects from families with inherited thrombophilia can be greatly improved. External validation is now needed to replicate these findings.

Risk assessment of venous thrombosis in families with known hereditary thrombophilia: the MARseilles-NImes prediction model.

BACKGROUND: Although predicting the risk of venous thrombosis (VT) in an individual from a family with inherited thrombophilia is of major importance, it is often not feasible. OBJECTIVES: To develop a simple risk assessment model that improves prediction of the risk of VT for individuals of families with inherited thrombophilia. PATIENTS/METHODS: 1201 relatives from 430 families with inherited thrombophilia (deficiencies of antithrombin, protein C or protein S, and the factor V Leiden and F2 20210A mutations) were recruited at the referral center for thrombophilia in Marseilles, France, from 1986 to 2008. One hundred and twenty-two individuals had a personal history of VT. Sixteen preselected clinical and laboratory variables were used to derive the VT risk score. RESULTS: The scores based on the 16 variables and on the five most strongly associated variables performed similarly (areas under receiver operating characteristic curves of 0.85 and 0.83, respectively). For the five-variable score, named the MARNI score, derived from family history score of VT, von Willebrand factor antigen levels, age, severity of thrombophilia, and FGG rs2066865, the risk of VT ranged from 0.2% for individuals with a score of 0 (n = 186) to > 70% for individuals with a score of ≥ 7 (n = 27). The model was validated with an internal bootstrap method. CONCLUSIONS: With the use of a simple scoring system, assessment of the risk of VT in subjects from families with inherited thrombophilia can be greatly improved. External validation is now needed to replicate these findings.

[ICU patients and days of intensive care: A mathematical model optimizing the consequences of ICU unit function, intensive care and continual monitoring on incurred supplementary costs]. / Patient de réanimation, journées de réanimation ? Modélisation d'un fonctionnement optimisé des unités de réanimation, de soins intensifs et de surveillance continue et conséquences sur les suppléments tarifaires induits.

INTRODUCTION: "Critical Care Units" are intended to admit patients with multiple organ failure. The severity of patients admitted is variable. The aim of the study was to estimate the number of days that an optimum care organization could release, and therefore the additional admissions that would have been allowed. Estimates of earnings related to the various supplements were carried out jointly. METHODS: Reporting days associated or not with a resuscitation care during the year 2011 in an ICU of a university hospital (16 beds), optimized patient flow simulation, and computation of medical act inducing financial supplements. RESULTS: Six hundred and fifty-seven patients (SAPS II from 0 to 110, 41% ventilated more than 48hours, mortality=26%) were admitted representing 5095days (occupancy rate=87%). Two hundred and twenty-two patients (34%) did not trigger supplement for resuscitation care for 415days in the unit. Four hundred and thirty-five patients have triggered this supplement representing 4680days, including 3035days with resuscitation care and 1645 (35% of days valued resuscitation, 32% of total days) without any. The entire year 2011 has generated earnings of 3,980,192€. Optimization of management would have allowed the admission of additional 235 to 295 patients and potential additional earnings from 524,735€ to 1,063,804€, depending on the occupancy rate chosen (80% or real 2011s) and the severity of discharged patients. CONCLUSION: Optimization of the patients flow between "Critical Care", Intensive Care and Continuous Monitoring Units would increase the number of patients admitted in "Critical Care" Units without any financial loss related to supplements.

Do female translocations influence the ovarian response pattern to controlled ovarian stimulation in preimplantation genetic diagnosis?

BACKGROUND: Ovarian response in female translocation carriers is not well understood. We aimed to evaluate the impact of chromosomal autosomal balanced translocations on the ovarian response to controlled ovarian stimulation (COS) in female carriers undergoing IVF and PGD. METHODS: In a retrospective study, we included all female translocation carriers who underwent PGD at our centre. We compared these patients to female patients from couples with male translocation carriers who underwent PGD. RESULTS: Results from 79 cycles of PGD from 33 female translocation carriers were compared with 116 cycles from 55 male translocation carriers. No difference was observed for patient characteristics: female age, anti-Müllerian hormone or antral follicle count. No difference in COS parameters was observed for the total dose of recombinant FSH, the number of retrieved oocytes and embryos on Day 3, for unaffected and transferred embryos. For the two groups, pregnancy rate was similar per cycle (12.7 versus 20.7%, P = 0.208). Multivariate analysis demonstrated that female translocation carriers had a significantly higher estradiol level on the day of hCG administration (+540 pg/ml, P = 0.05). CONCLUSIONS: This paper is the largest to report ovarian response of female translocation carriers. This study showed that the ovarian response to COS was not impaired by balanced translocation status, suggesting that female chromosomal structural abnormalities did not influence the results of COS in PGD. Thus, female carriers of balanced translocations could be considered normal responders and standard doses of gonadotrophins used for ovarian stimulation.

Clinical predictors of dual aspirin and clopidogrel poor responsiveness in stable cardiovascular patients from the ADRIE study.

BACKGROUND: Poor response to both aspirin and clopidogrel (dual poor responsiveness [DPR]) is a major risk factor for recurrent ischemic events. OBJECTIVES: The aim of this study was to identify factors associated with DPR, defined with specific tests, and derive a predictive clinical score. METHODS: We studied 771 consecutive stable cardiovascular patients treated with aspirin (n = 223), clopidogrel (n = 111), or both drugs (n = 37). Aspirin responsiveness was evaluated by serum thromboxane (Tx)B2 assay, and clopidogrel responsiveness by calculating the platelet reactivity index (PRI) on the basis of the phosphorylation status of the vasodilator phosphoprotein. The analysis was focused on patients treated with both drugs, and on independent predictors of DPR. RESULTS: Among patients on dual therapy, there was no relevant correlation between TxB2 levels and PRI values (r = 0.11). Sixty-seven patients (15.4%) had DPR. Diabetes [odds ratio (OR) 1.89, 95% confidence interval (CI) 1.06-3.39], high body weight (> 86 kg vs. < 77 kg, OR 4.74, 95% CI 2.49-9.73), low aspirin dose (75-81 mg vs. ≥ 160 mg, OR 0.12, 95% CI 0.09-0.93) and high C-reactive protein (CRP) level (> 1.6 mg L⁻¹ vs. < 0.6 mg L⁻¹, OR 3.66, 95% CI 1.74-8.72) were independently associated with DPR, via increased TxB(2) levels, increased PRI, or both. These associations with TxB2 and PRI were reproduced across the whole population. With use of a factor-weighed score (c-index = 0.74), the predicted prevalence of DPR was 57% in the highest strata of the score as compared with < 4% for the lowest strata. CONCLUSIONS: Diabetes, body weight, the aspirin dose and CRP levels are readily available independent predictors of DPR, and some are potential targets for reducing its prevalence.

Myotonic dystrophy type 1 and PGD: ovarian stimulation response and correlation analysis between ovarian reserve and genotype.

This study aimed at evaluating parameters and results of ovarian stimulation for myotonic dystrophy type 1 (DM1) female patients undergoing preimplantation genetic diagnosis (PGD) and to assess an eventual association between genotype and ovarian reserve. A retrospective study involved all 17 DM1 patients treated in the study centre's PGD programme. The control group consisted of 22 patients treated for X-linked disorders in the same period. Comparative analysis of ovarian stimulation parameters and results was performed with bivariate and multivariate analysis. Then, among DM1 patients, a correlation between genotype (number of CTG repeats) and ovarian reserve, assessed by antral follicle count, was investigated. Comparative study showed no difference concerning the number of oocytes, embryos and pregnancy rate between the two groups. Multivariate analysis demonstrated that DM1 patients needed a significantly higher dose of gonadotrophins (+544IU, P<0.001) than X-linked disorders patients and suggests a decreased ovarian sensitivity. However, with higher dose of gonadotrophins, PGD for DM1 offers good reproductive outcomes with a clinical pregnancy rate of 35.7%. Genotype was not correlated to ovarian reserve and appeared not to be helpful for the choice of the dose of gonadotrophins.

Prothrombin G20210A carriers the genetic mutation and a history of venous thrombosis contributes to thrombin generation independently of factor II plasma levels.

SUMMARY BACKGROUND: The prothrombin (PT) G20210A gene mutation is a common risk factor for venous thrombosis (VT), which is mainly mediated through an increase in factor II (FII) plasma levels. High FII plasma levels may act through an increase in endogenous thrombin potential (ETP) a key step in hemostasis and thrombosis. While FII may be the main contributor to ETP in PT G20210A carriers, the knowledge of other environmental or genetic factors influencing ETP may help to better identify those at risk of VT. AIMS: ETP was determined in 472 non-carriers of PT G20210A (PT-) and in 325 unrelated carriers of PT G20210A (PT+) with (symptomatic n = 158) or without (asymptomatic, n = 167) a history of VT. All PT+ were heterozygous and free of other thrombophilic defects. RESULTS: ETP was higher in asymptomatic PT+ than in PT- (2038 +/- 371 vs. 1616 +/- 267 nmol L(-1) min; P < 0.0001). ETP was significantly higher in symptomatic PT+ than in controls PT+ (2129 +/- 430 vs. 2038 +/- 371 nmol L(-1) min; P = 0.01). Multivariate analyses evidenced the importance of FII and fibrinogen plasma levels in determining ETP. DISCUSSION: After taking these variables into account, a personal history of VT remained associated with ETP in PT+ carriers. Moreover, PTG20210A still contributes to ETP after consideration of FII levels. CONCLUSION: In conclusion, the increase in ETP observed in carriers is not entirely explained by higher FII or fibrinogen plasma levels but also by the history of VT.

Inhibition of serine-peptidase activity enhances the generation of a survivin-derived HLA-A2-presented CTL epitope in colon-carcinoma cells.

Cytotoxic T lymphocytes eliminate tumor cells expressing antigenic peptides in the context of MHC-I molecules. Peptides are generated during protein degradation by the proteasome and resulting products, surviving cytosolic amino-peptidases activity, may be presented by MHC-I molecules. The MHC-I processing pathway is altered in a large number of malignancies and modulation of antigen generation is one strategy employed by cells to evade immune control. In this study we analyzed the generation and presentation of a survivin-derived CTL epitope in HLA-A2-positive colon-carcinoma cells. Although all cell lines expressed the anti-apoptotic protein survivin, some tumors were poorly recognized by ELTLGEFLKL (ELT)-specific CTL cultures. The expression of MHC-I or TAP molecules was similar in all cell lines suggesting that tumors not recognized by CTLs may present defects in the generation of the ELT-epitope which could be due either to lack of generation or to subsequent degradation of the epitope. The cells were analyzed for the expression and the activity of extra-proteasomal peptidases. A significant overexpression and higher activity of TPPII was observed in colon-carcinoma cells which are not killed by ELT-specific CTLs, suggesting a possible role of TPPII in the degradation of the ELT-epitope. To confirm the role of TPPII in the degradation of the ELT-peptide, we showed that treatment of colon-carcinoma cells with a TPPII inhibitor resulted in a dose-dependent increased sensitivity to ELT-specific CTLs. These results suggest that TPPII is involved in degradation of the ELT-peptide, and its overexpression may contribute to the immune escape of colon-carcinoma cells.

Opposite immune functions of GM-CSF administered as vaccine adjuvant in cancer patients.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) has been and is still widely used as an adjuvant in clinical trials of vaccination with autologous tumor cells, peptides and/or dendritic cells in a variety of human neoplasms. This cytokine was administered either as product of gene-transduced tumor cells or as recombinant protein together with the vaccine given subcutaneously or intradermally. Results of these trials were heterogeneous in terms of induction of vaccine-specific immune response and of clinical response. Though in some of these studies GM-CSF appeared to help in generating an immune response, in others no effect or even a suppressive effect was reported. Here, we review the literature dealing with the immune adjuvant activity of GM-CSF both in animal models and clinical trials. As a consequence of such analysis, we conclude that GM-CSF may increase the vaccine-induced immune response when administered repeatedly at relatively low doses (range 40-80 microg for 1-5 days) whereas an opposite effect was often reported at dosages of 100-500 microg. The potential mechanisms of the GM-CSF-mediated immune suppression are discussed at the light of studies describing the activation and expansion of myeloid suppressor cells by endogenous tumor-derived or exogenous GM-CSF.

Pre-formed articulating knee spacer in two-stage revision for the infected total knee arthroplasty.

We performed a prospective study to assess safety and effectiveness of a pre-formed articulating spacer made of gentamicin-impregnated acrylic cement in the management of infected total knee arthroplasty. Twenty-one consecutive patients with unilateral deep infection were treated by two-stage revision in two centres. Two patients were excluded, and 19 patients remained available for assessment. The mean implantation time of the spacer was 12 weeks. The rehabilitation programme between stages consisted in early range of motion exercises and partial weight bearing. Mean follow-up after removal of the spacer and insertion of the final prosthesis was 24 (range, 12-43) months. No patient had recurrence of infection at the latest follow-up. The mean Knee Society functional score during spacer management was rated 75 points and was rated 84 points at the latest follow-up. No device-related complication was observed.

Photosensitizing properties of 6-methoxy-2-naphthylacetic acid, the major metabolite of the phototoxic non-steroidal anti-inflammatory and analgesic drug nabumetone.

The photobiological properties of 6-methoxy-2-naphthylacetic acid (6-MNAA) were studied using a variety of in vitro phototoxicity assays: photohemolysis, photoperoxidation of linoleic acid, photosensitized degradation of histidine and thymine and the Candida phototoxicity test. 6-MNAA was phototoxic in vitro. 6-MNAA reduced nitro blue tetrazolium (NBT) when irradiated with lambda > or = 300 nm in deoxygenated aqueous buffer solution (pH 7.4). NBT can be reduced by reaction with the excited state of 6-MNAA subject to interference with molecular oxygen. The photohemolysis rate was inhibited by the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO), sodium azide (NaN3) and reduced glutathione (GSH). Photoperoxidation of linoleic acid and photosensitized degradation of histidine and thymine were significantly inhibited by sodium azide and reduced glutathione. 6-MNAA was phototoxic to C. albicans, C. lipolytica and C. tropicalis. A mechanism involving singlet oxygen, radicals, and electron transfer reactions is suggested for the observed phototoxicity.

Levocloperastine in the treatment of chronic nonproductive cough: comparative efficacy versus standard antitussive agents.

The medical and social impact of cough is substantial. Current antitussive agents at effective doses have adverse events such as drowsiness, nausea and constipation that limit their use. There is also recent evidence that standard antitussive agents, such as codeine, may not reduce cough during upper respiratory infections. Therefore, there is a need for more effective and better-tolerated agents. The efficacy of levocloperastine, a novel antitussive, which acts both centrally on the cough center and on peripheral receptors in the tracheobronchial tree in treating chronic cough, was compared with that of other standard antitussive agents (codeine, levodropropizine and DL-cloperastine) in six open clinical trials. The studies enrolled patients of all ages with cough associated with various respiratory disorders including bronchitis, asthma, pneumonia and chronic obstructive pulmonary disease. Levocloperastine significantly improved cough symptoms (intensity and frequency of cough) in all trials, and improvements were observed after the first day of treatment. In children, levocloperastine reduced nighttime awakenings and irritability, and in adults it was effective in treating cough induced by angiotensin-converting enzyme inhibitors. When compared with other antitussive agents, levocloperastine had improved or comparable efficacy, with a more rapid onset of action. Importantly, no evidence of central adverse events was recorded with levocloperastine, whereas drowsiness was reported by a significant number of patients receiving codeine. Levocloperastine is an effective antitussive agent for the treatment of cough in patients of all ages. It has a more rapid onset of action than standard agents with an improved tolerability profile.

Vaccination of patients with solid tumours.

The molecular characterisation of human tumour antigens recognised by T cells has provided new impetus for immunisation of patients bearing tumours expressing well-defined antigens. After evaluating the immunogenicity of the new, molecularly characterised antigens in vitro, several clinical studies were conducted to assess the in vivo immunogenicity and the clinical efficacy of vaccines including these antigens. The findings generated by trials based on the administration of peptides or DNA-encoding antigens are discussed to highlight the limits of this therapeutic approach; however, this approach has resulted in some complete and durable regressions, although still in a unsatisfactory small number of cases (5-25%). The recent use of dendritic cells loaded ex vivo with tumour antigens suggests that a high frequency of tumour-specific immune responses can be achieved. Possible means of overcoming the clinical limits and improving the outcome of previous studies are also discussed.

An unsuspected autoregulatory pathway involving apocytochrome TorC and sensor TorS in Escherichia coli.

Trimethylamine N-oxide (TMAO) respiration is carried out mainly by the Tor system in Escherichia coli. This system is encoded by the torCAD operon and comprises a periplasmic TMAO reductase (TorA) and a c-type cytochrome (TorC), which shuttles electrons to TorA. Expression of the tor operon is positively controlled by the TorS/TorR phosphorelay system in response to TMAO availability and negatively regulated by apocytochrome TorC. Interaction studies showed that, when immature, TorC can no longer bind TorA efficiently but can bind the periplasmic detector region of sensor TorS. ApoTorC negative autoregulation and TMAO induction are thus mediated by the same sensor protein. As apocytochromes related to TorC could not down-regulate the tor operon, we concluded that this negative control is highly specific. Moreover, the N-terminal half of apoTorC played no role in this control but the immature C-terminal domain of TorC strongly down-regulated the tor operon and interacted with the TorS detector region. This sophisticated autoregulatory pathway thus involves the C-terminal domain of apoTorC and allows optimal TorC biogenesis by preventing from saturation the c-type cytochrome maturation machinery.

Tumor necrosis factor-alpha induces coordinated changes in major histocompatibility class I presentation pathway, resulting in increased stability of class I complexes at the cell surface.

It is demonstrated that similar to interferon gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha) induces coordinated changes at different steps of the major histocompatibility complex (MHC) class I processing and presentation pathway in nonprofessional antigen-presenting cells (APCs). TNF-alpha up-regulates the expression of 3 catalytic immunoproteasome subunits--LMP2, LMP7, and MECL-1--the immunomodulatory proteasome activator PA28 alpha, the TAP1/TAP2 heterodimer, and the total pool of MHC class I heavy chain. It was also found that in TNF-alpha--treated cells, MHC class I molecules reconstitute more rapidly and have an increased average half-life at the cell surface. Biochemical changes induced by TNF-alpha in the MHC class I pathway were translated into increased sensitivity of TNF-alpha--treated targets to lysis by CD8(+) cytotoxic T cells, demonstrating improved presentation of at least certain endogenously processed MHC class I--restricted peptide epitopes. Significantly, it was demonstrated that the effects of TNF-alpha observed in this experimental system were not mediated through the induction of IFN-gamma. It appears to be likely that TNF-alpha--mediated effects on MHC class I processing and presentation do not involve any intermediate messengers. Collectively, these data demonstrate the existence of yet another biologic activity exerted by TNF-alpha, namely its capacity to act as a coordinated multi-step modulator of the MHC class I pathway of antigen processing and presentation. These results suggest that TNF-alpha may be useful when a concerted up-regulation of the MHC class I presentation machinery is required but cannot be achieved by IFN-gamma. (Blood. 2001;98:1108-1115)