Return of the tetracyclines: omadacycline, a novel aminomethylcycline antimicrobial.

Omadacycline is a novel aminomethylcycline antimicrobial agent that is available in both oral and intravenous formulations. The distinguishing structural characteristics of omadacycline from other tetracyclines allow for its continued antimicrobial activity in the presence of traditional tetracycline resistance mechanisms (efflux pumps and ribosomal protection proteins). Omadacycline has been found to have potent activity against antibiotic-resistant pathogens including methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, extended spectrum beta-lactamase-producing Escherichia coli and multidrug-resistant Streptococcus pneumoniae. Currently available data indicate that omadacycline is generally well tolerated with the most common adverse effects being gastrointestinal symptoms. Omadacycline seems to be a promising new agent for the treatment of community-acquired bacterial pneumonia and acute bacterial skin and skin structure infections. Studies for the treatment of cystitis in adult females are currently underway, and future results of these studies will further help delineate the antibacterial role of omadacycline.

In Vitro Induction of Human Regulatory T Cells Using Conditions of Low Tryptophan Plus Kynurenines.

Thymic regulatory T cells (tTregs) and induced regulatory T cells (iTregs) suppress murine acute graft-versus-host disease (GVHD). Previously, we demonstrated that the plasmacytoid dendritic cell indoleamine 2,3-dioxygenase (IDO) fosters the in vitro development of human iTregs via tryptophan depletion and kynurenine (Kyn) metabolites. We now show that stimulation of naïve CD4+ T cells in low tryptophan (low Trp) plus Kyn supports human iTreg generation. In vitro, low Trp + Kyn iTregs and tTregs potently suppress T effector cell proliferation equivalently but are phenotypically distinct. Compared with tTregs or T effector cells, bioenergetics profiling reveals that low Trp + Kyn iTregs have increased basal glycolysis and oxidative phosphorylation and use glutaminolysis as an energy source. Low Trp + Kyn iTreg viability was reliant on interleukin (IL)-2 in vitro. Although in vivo IL-2 administration increased low Trp + Kyn iTreg persistence on adoptive transfer into immunodeficient mice given peripheral blood mononuclear cells to induce GVHD, IL-2-supported iTregs did not improve recipient survival. We conclude that low Trp + Kyn create suppressive iTregs that have high metabolic needs that will need to be addressed before clinical translation.

The Knife's Edge of Tolerance: Inducing Stable Multilineage Mixed Chimerism but With a Significant Risk of CMV Reactivation and Disease in Rhesus Macaques.

Although stable mixed-hematopoietic chimerism induces robust immune tolerance to solid organ allografts in mice, the translation of this strategy to large animal models and to patients has been challenging. We have previously shown that in MHC-matched nonhuman primates (NHPs), a busulfan plus combined belatacept and anti-CD154-based regimen could induce long-lived myeloid chimerism, but without T cell chimerism. In that setting, donor chimerism was eventually rejected, and tolerance to skin allografts was not achieved. Here, we describe an adaptation of this strategy, with the addition of low-dose total body irradiation to our conditioning regimen. This strategy has successfully induced multilineage hematopoietic chimerism in MHC-matched transplants that was stable for as long as 24 months posttransplant, the entire length of analysis. High-level T cell chimerism was achieved and associated with significant donor-specific prolongation of skin graft acceptance. However, we also observed significant infectious toxicities, prominently including cytomegalovirus (CMV) reactivation and end-organ disease in the setting of functional defects in anti-CMV T cell immunity. These results underscore the significant benefits that multilineage chimerism-induction approaches may represent to transplant patients as well as the inherent risks, and they emphasize the precision with which a clinically successful regimen will need to be formulated and then validated in NHP models.

Superiority of rapamycin over tacrolimus in preserving nonhuman primate Treg half-life and phenotype after adoptive transfer.

Many critical issues remain concerning how best to deploy adoptive regulatory T cell (Treg) immunotherapy to the clinic. These include a determination of their pharmacokinetic characteristics, their optimal dose, their phenotypic stability and the best therapies with which to pair Tregs. By performing a CFSE-labeled autologous Treg pulse experiment, we determined that the accessible peripheral blood Treg pool in rhesus macaques is quite large (75 ± 11 × 10(6) Tregs/kg). Pharmacokinetic analysis revealed that Tregs have two phases of elimination: an α phase, with a T1/2 in the peripheral blood of 32.4 ± 11.3 h and a ß phase with a T1/2 of 120.4 ± 19.7 h. In addition to their short initial half-life, Tregs underwent rapid phenotypic shifts after infusion, with significant loss of both CD25 and FoxP3 by day +6. While tacrolimus stabilized CD25 expression, it did not improve T1/2 , nor mitigate the loss of FoxP3. In contrast, rapamycin significantly stabilized both CD25 and FoxP3, and supported an increased half-life, with an α phase of 67.7 ± 6.9 h and a ß phase of 252.1 ± 54.9 h. These results suggest that rapamycin may be a necessary addition to Treg immunotherapy, and that tacrolimus may be deleterious to Treg integrity posttransfer.

Renal transplantation using belatacept without maintenance steroids or calcineurin inhibitors.

Kidney transplantation remains limited by toxicities of calcineurin inhibitors (CNIs) and steroids. Belatacept is a less toxic CNI alternative, but existing regimens rely on steroids and have higher rejection rates. Experimentally, donor bone marrow and sirolimus promote belatacept's efficacy. To investigate a belatacept-based regimen without CNIs or steroids, we transplanted recipients of live donor kidneys using alemtuzumab induction, monthly belatacept and daily sirolimus. Patients were randomized 1:1 to receive unfractionated donor bone marrow. After 1 year, patients were allowed to wean from sirolimus. Patients were followed clinically and with surveillance biopsies. Twenty patients were transplanted, all successfully. Mean creatinine (estimated GFR) was 1.10 ± 0.07 mg/dL (89 ± 3.56 mL/min) and 1.13 ± 0.07 mg/dL (and 88 ± 3.48 mL/min) at 12 and 36 months, respectively. Excellent results were achieved irrespective of bone marrow infusion. Ten patients elected oral immunosuppressant weaning, seven of whom were maintained rejection-free on monotherapy belatacept. Those failing to wean were successfully maintained on belatacept-based regimens supplemented by oral immunosuppression. Seven patients declined immunosuppressant weaning and three patients were denied weaning for associated medical conditions; all remained rejection-free. Belatacept and sirolimus effectively prevent kidney allograft rejection without CNIs or steroids when used following alemtuzumab induction. Selected, immunologically low-risk patients can be maintained solely on once monthly intravenous belatacept.

Antidepressants for mothers: what are psychiatrists prescribing?

BACKGROUND AND AIMS: Depressive illness in the perinatal period is common and can be associated with detrimental effects to both mother and child. The evolving evidence base on the safety of antidepressants in pregnancy and breastfeeding can make prescribing decisions challenging. This study aimed to investigate current prescribing practices and attitudes of hospital psychiatrists towards depression in pregnant and breastfeeding mothers. METHODS AND RESULTS: This qualitative survey was conducted by way of e-mail survey to 95 psychiatrists, of all grades and specialities, based within The Royal Edinburgh Hospital. A majority of psychiatrists are choosing and avoiding antidepressants in accordance with the National Institute for Health and Clinical Excellence guidelines. A minority of respondents are selecting classes of antidepressants, which raises concern about the safety of such prescribing decisions. The majority of psychiatrists expressed a lack of confidence when prescribing and expressed a wish for further training in this area. CONCLUSION: This study indicates a degree of uncertainty amongst psychiatrists of all grades when prescribing to these special groups. We would recommend increased training in this area to all psychiatrists and an increased emphasis placed upon incorporating perinatal psychiatry within the postgraduate psychiatric curriculum.

Evidence for kidney rejection after combined bone marrow and renal transplantation despite ongoing whole-blood chimerism in rhesus macaques.

Although there is evidence linking hematopoietic chimerism induction and solid organ transplant tolerance, the mechanistic requirements for chimerism-induced tolerance are not clearly elucidated. To address this, we used an MHC-defined primate model to determine the impact of impermanent, T cell-poor, mixed-chimerism on renal allograft survival. We compared two cohorts: one receiving a bone marrow and renal transplant ("BMT/renal") and one receiving only a renal transplant. Both cohorts received maintenance immunosuppression with CD28/CD40-directed costimulation blockade and sirolimus. As previously demonstrated, this transplant strategy consistently induced compartmentalized donor chimerism, (significant whole-blood chimerism, lacking T cell chimerism). This chimerism was not sufficient to prolong renal allograft acceptance: the BMT/renal mean survival time (MST, 76 days) was not significantly different than the renal transplant alone MST (85 days, p = 0.46), with histopathology documenting T cell mediated rejection. Flow cytometric analysis revealed significant enrichment for CD28-/CD95+ CD4+ and CD8+ Tem cells in the rejected kidney, suggesting a link between CD28-negative Tem and costimulation blockade-resistant rejection. These results suggest that in some settings, transient T cell-poor chimerism is not sufficient to induce tolerance to a concurrently placed renal allograft and that the presence of this chimerism per se is not an independent biomarker to identify tolerance.

Regulatory T cells exhibit decreased proliferation but enhanced suppression after pulsing with sirolimus.

Although regulatory T cells (Tregs) suppress allo-immunity, difficulties in their large-scale production and in maintaining their suppressive function after expansion have thus far limited their clinical applicability. Here we have used our nonhuman primate model to demonstrate that significant ex vivo Treg expansion with potent suppressive capacity can be achieved and that Treg suppressive capacity can be further enhanced by their exposure to a short pulse of sirolimus. Both unpulsed and sirolimus-pulsed Tregs (SPTs) are capable of inhibiting proliferation of multiple T cell subpopulations, including CD4(+) and CD8(+) T cells, as well as antigen-experienced CD28(+) CD95(+) memory and CD28(-) CD95(+) effector subpopulations. We further show that Tregs can be combined in vitro with CTLA4-Ig (belatacept) to lead to enhanced inhibition of allo-proliferation. SPTs undergo less proliferation in a mixed lymphocyte reaction (MLR) when compared with unpulsed Tregs, suggesting that Treg-mediated suppression may be inversely related to their proliferative capacity. SPTs also display increased expression of CD25 and CTLA4, implicating signaling through these molecules in their enhanced function. Our results suggest that the creation of SPTs may provide a novel avenue to enhance Treg-based suppression of allo-immunity, in a manner amenable to large-scale ex vivo expansion and combinatorial therapy with novel, costimulation blockade-based immunosuppression strategies.

Nonhuman primate transplant models finally evolve: detailed immunogenetic analysis creates new models and strengthens the old.

Nonhuman primate (NHP) models play a critical role in the translation of novel therapies for transplantation to the clinic. However, although MHC disparity significantly affects the outcome of transplantation, until recently, experiments using NHP models were performed without the ability to rigorously control the degree of MHC disparity in transplant cohorts. In this review, we discuss several key technical breakthroughs in the field, which have finally enabled detailed immunogenetic data to be incorporated into NHP transplantation studies. These advances have created a new gold-standard for NHP transplantation research, which incorporates detailed information regarding the degree of relatedness and the degree of MHC haplotype disparity between transplant pairs and the precise MHC alleles that both donors and recipients express. The adoption of this new standard promises to increase the rigor of NHP transplantation studies and to ensure that these experiments are optimally translatable to patient care.

Immunogenetic Management Software: a new tool for visualization and analysis of complex immunogenetic datasets.

Here we describe the Immunogenetic Management Software (IMS) system, a novel web-based application that permits multiplexed analysis of complex immunogenetic traits that are necessary for the accurate planning and execution of experiments involving large animal models, including nonhuman primates. IMS is capable of housing complex pedigree relationships, microsatellite-based MHC typing data, as well as MHC pyrosequencing expression analysis of class I alleles. It includes a novel, automated MHC haplotype naming algorithm and has accomplished an innovative visualization protocol that allows users to view multiple familial and MHC haplotype relationships through a single, interactive graphical interface. Detailed DNA and RNA-based data can also be queried and analyzed in a highly accessible fashion, and flexible search capabilities allow experimental choices to be made based on multiple, individualized and expandable immunogenetic factors. This web application is implemented in Java, MySQL, Tomcat, and Apache, with supported browsers including Internet Explorer and Firefox on Windows and Safari on Mac OS. The software is freely available for distribution to noncommercial users by contacting Leslie.kean@emory.edu. A demonstration site for the software is available at http://typing.emory.edu/typing_demo , user name: imsdemo7@gmail.com and password: imsdemo.

CD40 blockade combines with CTLA4Ig and sirolimus to produce mixed chimerism in an MHC-defined rhesus macaque transplant model.

In murine models, T-cell costimulation blockade of the CD28:B7 and CD154:CD40 pathways synergistically promotes immune tolerance after transplantation. While CD28 blockade has been successfully translated to the clinic, translation of blockade of the CD154:CD40 pathway has been less successful, in large part due to thromboembolic complications associated with anti-CD154 antibodies. Translation of CD40 blockade has also been slow, in part due to the fact that synergy between CD40 blockade and CD28 blockade had not yet been demonstrated in either primate models or humans. Here we show that a novel, nondepleting CD40 monoclonal antibody, 3A8, can combine with combined CTLA4Ig and sirolimus in a well-established primate bone marrow chimerism-induction model. Prolonged engraftment required the presence of all three agents during maintenance therapy, and resulted in graft acceptance for the duration of immunosuppressive treatment, with rejection resulting upon immunosuppression withdrawal. Flow cytometric analysis revealed that upregulation of CD95 expression on both CD4+ and CD8+ T cells correlated with rejection, suggesting that CD95 may be a robust biomarker of graft loss. These results are the first to demonstrate prolonged chimerism in primates treated with CD28/mTOR blockade and nondepletional CD40 blockade, and support further investigation of combined costimulation blockade targeting the CD28 and CD40 pathways.

An MHC-defined primate model reveals significant rejection of bone marrow after mixed chimerism induction despite full MHC matching.

In murine models, mixed hematopoietic chimerism induction leads to robust immune tolerance. However, translation to primates and to patients has been difficult. In this study, we used a novel MHC-defined rhesus macaque model to examine the impact of MHC matching on the stability of costimulation blockade-/sirolimus-mediated chimerism, and to probe possible mechanisms of bone marrow rejection after nonmyeloablative transplant. Using busulfan-based pretransplant preparation and maintenance immunosuppression with sirolimus, as well as CD28 and CD154 blockade, all recipients demonstrated donor engraftment after transplant. However, the mixed chimerism that resulted was compartmentalized, with recipients demonstrating significantly higher whole blood chimerism compared to T cell chimerism. Thus, the vast majority of T cells presenting posttransplant were recipient-rather than donor-derived. Surprisingly, even in MHC-matched transplants, rejection of donor hematopoiesis predominated after immunosuppression withdrawal. Weaning of immunosuppression was associated with a surge of antigen-experienced T cells, and transplant rejection was associated with the acquisition of donor-directed T cell alloreactivity. These results suggest that a reservoir of alloreactive cells was present despite prior costimulation blockade and sirolimus, and that the post-immunosuppression lymphocytic rebound may have lead to a phenotypic shift in these recipient T cells towards an activated, antigen-experienced phenotype, and ultimately, to transplant rejection.

Resources for genetic management and genomics research on non-human primates at the National Primate Research Centers (NPRCs).

The National Primate Research Centers (NPRCs) established Working Groups (WGs) for developing resources and mechanisms to facilitate collaborations among non-human primate (NHP) researchers. Here we report the progress of the Genome Banking and the Genetics and Genomics WGs in developing resources to advance the exchange, analysis and comparison of NHP genetic and genomic data across the NPRCs. The Genome Banking WG has established a National NHP DNA bank comprising 1250 DNA samples from unrelated animals and family trios from the 10 NHP species housed within the NPRC system. The Genetics and Genomics WG is developing SNP arrays that will provide a uniform, highly informative, efficient and low-cost method for rhesus and long-tailed macaque genotyping across the eight NPRCs. This WG is also establishing a Biomedical Informatics Research Network-based portal for shared bioinformatics resources including vital statistics, genotype and population data and information on the National NHP DNA bank.

Expanded nonhuman primate tregs exhibit a unique gene expression signature and potently downregulate alloimmune responses.

We have established two complementary strategies for purifying naturally occurring regulatory T cells (Tregs) from rhesus macaques in quantities that would be sufficient for use as an in vivo cellular therapeutic. The first strategy identified Tregs based on their being CD4+/CD25(bright). The second incorporated CD127, and purified Tregs based on their expression of CD4 and CD25 and their low expression of CD127. Using these purification strategies, we were able to purify as many as 1x10(6) Tregs from 120 cc of peripheral blood. Cultures of these cells with anti-CD3, anti-CD28 and IL-2 over 21 days yielded as much as a 450-fold expansion, ultimately producing as many as 4.7x10(8) Tregs. Expanded Treg cultures potently inhibited alloimmune proliferation as measured by a carboxyfluorescein succinimidyl ester- mixed lymphocyte reaction (CFSE-MLR) assay even at a 1:100 ratio with responder T cells. Furthermore, both responder-specific and third-party Tregs downregulated alloproliferation similarly. Both freshly isolated and cultured Tregs had gene expression signatures distinguishable from concurrently isolated bulk CD4+ T-cell populations, as measured by singleplex reverse transcriptase-polymerase chain reaction (RT-PCR) and gene array. Moreover, an overlapping yet distinct gene expression signature seen in freshly isolated compared to expanded Tregs identifies a subset of Treg genes likely to be functionally significant.

NK cells rapidly reject allogeneic bone marrow in the spleen through a perforin- and Ly49D-dependent, but NKG2D-independent mechanism.

We have used a sensitive and specific in vivo killing assay to monitor the kinetics, anatomic location and mechanisms controlling NK-mediated rejection of Balb/c bone marrow by C57BL/6 natural killer (NK) cells. We find that NK killing of fully allogeneic bone marrow is a rapid, highly efficient process, leading to substantial rejection of transplanted marrow within 6 h of transplant and elimination of 85% of the transplanted cells within 2 days. NK-mediated rejection occurred predominantly in the spleen, with sparing of rejection in the bone marrow and lymph nodes. Rejection was dependent on Perforin gene function, but was independent of interferon-gamma. Finally, rejection of Balb/c bone marrow by B6 NK cells required signaling through the Ly49D receptor, but occurred despite blockade of NKG2D, which distinguishes these results from previous studies using semiallogeneic transplant pairs. These results identify NK cells as highly active mediators of bone marrow rejection, and suggest that inhibiting NK function early during transplantation may increase the efficiency of engraftment and allow successful engraftment of limiting doses of donor bone marrow.

Pregnancy outcome in Factor XI deficiency: incidence of miscarriage, antenatal and postnatal haemorrhage in 33 women with Factor XI deficiency.

Pregnancy complications in women with Factor XI deficiency were assessed in this retrospective analysis. All nonnulliparous women registered with Factor XI deficiency in the East Midlands region were included. Each woman was classified into 'bleeder' or 'nonbleeder'. Rates of antenatal and postnatal bleeding and miscarriage rate were recorded. A total of 33 women had 105 pregnancies. Pregnancy and delivery was uneventful in 70% of the cases. Postpartum haemorrhage (PPH) appears increased in women with a 'bleeding' phenotype with a highly significant difference between 'bleeders' and 'nonbleeders' (relative risk [RR] 7.2; CI 1.99-25.9). Miscarriage rate appeared unchanged. We conclude that PPH is increased in a subgroup with a bleeding phenotype. Larger studies are needed to define the underlying factors.

Induction of chimerism in rhesus macaques through stem cell transplant and costimulation blockade-based immunosuppression.

A strategy for producing high-level hematopoietic chimerism after non-myeloablative conditioning has been established in the rhesus macaque. This strategy relies on hematopoietic stem cell transplantation after induction with a non-myeloablative dose of busulfan and blockade of the IL2-receptor in the setting of mTOR inhibition with sirolimus and combined CD28/CD154 costimulation blockade. Hematopoietic stem cells derived from bone marrow and leukopheresis products both were found to be successful in inducing high-level chimerism. Mean peripheral blood peak donor chimerism was 81% with a median chimerism duration of 145 days. Additional immune modulation strategies, such as pre-transplant CD8 depletion, donor-specific transfusion, recipient thymectomy or peritransplant deoxyspergualin treatment did not improve the level or durability of chimerism. Recipient immunologic assessment suggested that chimerism occurred amidst donor-specific down-regulation of alloreactive T cells, and the reappearance of vigorous T-mediated alloreactivity accompanied rejection of the transplants. Furthermore, viral reactivation constituted a significant transplant-related toxicity and may have negatively impacted the ability to achieve indefinite survival of transplanted stem cells. Nevertheless, this chimerism-induction regimen induced amongst the longest-lived stem cell chimerism reported to date for non-human primates and thus represents a platform upon which to evaluate emerging tolerance-induction strategies.

Evaluation of the sensitivity of a rapid polymerase chain reaction for detection of group B streptococcus.

The objective of this study was to compare detection of group B streptococcal (GBS) carriage using 'real-time' polymerase chain reaction (PCR) and microbiological standard culture. The study design was a test accuracy study comparing a novel molecular technique against the standard microbiological cultural technique in normal pregnant women. The setting and population consisted of 143 pregnant women with pre-labour rupture of the membranes, recruited from two large teaching hospitals in the UK. The study examined the efficacy of a polymerase chain reaction (PCR) assay for screening pregnant women who presented with term rupture of the membranes. Low vaginal specimens were obtained from the women. The specimens were tested for GBS by conventional culture and with a GBS-specific real-time PCR assay. The main outcome measure was the sensitivity and specificity of the PCR assay with 95% confidence intervals (CI) compared with the standard culture. The length of time to obtain a result was also reported for both methods. Among the 143 women, the results of the culture were positive (at least one colony) for GBS in 20 women (14%). The PCR assay detected GBS carriage in 10 women (7%). As compared with the culture method, the sensitivity and specificity of the PCR assay were 45% and 99%, respectively. The positive and negative predictive values of the PCR assay were 90% and 92%, respectively. The length of time required to obtain results for the majority of women (94%) was <2.5 h for the PCR assay and at least 24 h for culture. While a rapid result (within 3 h) of carriage of GBS can be obtained by the PCR assay, at present, it cannot replace conventional culture without further optimisation of the DNA extraction method. The sensitivity may further be improved by testing both low vaginal and rectal specimens.