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Regulatory B cells (Bregs) play a prominent role in various disease settings. While progress has been hindered by the lack of a specific Breg marker, new findings highlight their role modulating the alloimmune response and promoting allograft survival.Herein, we focus on the recent advances in Breg biology and their role in transplantation. We review studies showing that T-cell immunoglobulin and mucin domain 1 (TIM-1) is an inclusive and functional Breg marker in mice that may have human relevance. We highlight the utility of the B cell interleukin-10/tumor necrosis factor-alpha (IL-10/TNFα) ratio in identifying underlying immunological reactivity and predicting clinical outcomes in kidney transplantation. This may identify patients requiring more immunosuppression and provide insight into potential therapeutic approaches that can modulate the Breg: B effector cell (Beff) balance.Emerging data support Bregs as potent modulators of immune responses in humans. Their ability to promote allograft survival must await development of approaches to expand Bregs in vitro/in vivo . The low IL-10/TNFα ratio reflecting decreased Breg/Beff balance, predicts acute rejection (AR) and poorer outcomes in renal transplantation. It remains to be determined whether this paradigm can be extended to other allografts and whether therapy aiming to correct the relative deficiency of Bregs will improve outcomes.

Many bacterial pathogens, including Staphylococcus aureus, require inosine 5'-monophosphate dehydrogenase (IMPDH) for infection, making this enzyme a promising new target for antibiotics. Although potent selective inhibitors of bacterial IMPDHs have been reported, relatively few have displayed antibacterial activity. Here we use structure-informed design to obtain inhibitors of S. aureus IMPDH (SaIMPDH) that have potent antibacterial activity (minimal inhibitory concentrations less than 2 μM) and low cytotoxicity in mammalian cells. The physicochemical properties of the most active compounds were within typical Lipinski/Veber space, suggesting that polarity is not a general requirement for achieving antibacterial activity. Five compounds failed to display activity in mouse models of septicemia and abscess infection. Inhibitor-resistant S. aureus strains readily emerged in vitro. Resistance resulted from substitutions in the cofactor/inhibitor binding site of SaIMPDH, confirming on-target antibacterial activity. These mutations decreased the binding of all inhibitors tested, but also decreased catalytic activity. Nonetheless, the resistant strains had comparable virulence to wild-type bacteria. Surprisingly, strains expressing catalytically inactive SaIMPDH displayed only a mild virulence defect. Collectively these observations question the vulnerability of the enzymatic activity of SaIMPDH as a target for the treatment of S. aureus infections, suggesting other functions of this protein may be responsible for its role in infection.

Borderline rejection (BL) in renal transplantation is associated with decreased allograft survival, yet many patients with BL maintain stable graft function. Identifying patients with early BL at-risk for shortened allograft survival would allow for timely targeted therapeutic intervention aimed at improving outcomes. 851/1187 patients transplanted between 2013-18 underwent early biopsy (0-4mos). 217/851 (25%) had BL and were compared to 387/851 without significant inflammation (NI). Serial surveillance and for-cause biopsies and seven-year follow-up were used to evaluate histological and clinical progression. To identify high-risk patients, we examined clinical/histological parameters using regression and non-linear dimensionality reduction (tSNE), and a biomarker based on peripheral blood transitional-1 B cell (T1B) IL-10/TNFα ratio. Compared to NI, early BL was associated with increased progression to late acute rejection (AR; 5-12mos), premature interstitial fibrosis and tubular atrophy (IFTA) and decreased seven-year graft survival. However, decreased graft survival was limited to BL patients who progressed to late AR or IFTA, and was not influenced by treatment. Although tSNE clustered patients into groups based on clinical factors, the ability of these factors to risk stratify BL patients was modest. In contrast, a low T1B IL-10/TNFα ratio at 3 months identified BL patients at high-risk for progression to AR (ROC AUC 0.87) and poor 7yr-graft survival (52% vs. 92%, p=0.003), while BL patients with a high ratio had similar graft survival to patients with NI (91%, p=NS). Thus, progressive early allograft inflammation manifest as BL that progresses to late AR in the first post-transplant year represents a high-risk clinical state for poor allograft outcomes. Such high-risk status can be predicted by the T1B IL-10/TNFα ratio before irreversible scarring sets in, thus allowing timely risk stratification.

Regulatory B cells (Bregs) ameliorate autoimmune disease and prevent allograft rejection. Conversely, they hinder effective clearance of pathogens and malignancies. Breg activity is mainly attributed to IL-10 expression, but also utilizes additional regulatory mechanisms such as TGF-β, FasL, IL-35, and TIGIT. Although Bregs are present in various subsets defined by phenotypic markers (including canonical B cell subsets), our understanding of Bregs has been limited by the lack of a broadly inclusive and specific phenotypic or transcriptional marker. TIM-1, a broad marker for Bregs first identified in transplant models, plays a major role in Breg maintenance and induction. Here, we expand on the role of TIM-1+ Bregs in immune tolerance and propose TIM-1 as a unifying marker for Bregs that utilize various inhibitory mechanisms in addition to IL-10. Further, this review provides an in-depth assessment of our understanding of Bregs in transplantation as elucidated in murine models and clinical studies. These studies highlight the major contribution of Bregs in preventing allograft rejection, and their ability to serve as highly predictive biomarkers for clinical transplant outcomes.

Prior experience of pathogen-associated stimuli reduces morbidity and mortality to newly encountered infections through innate immune training, which can be enhanced by childhood vaccination. Fibroblastic reticular cells (FRCs) are stromal cells in lymphoid organs that support lymphocyte localization and survival and modulate adaptive immune responses. IL-17 signaling is important for FRC metabolism and proliferation during inflammatory responses. Here, we show that FRC-intrinsic IL-17 signaling was required for protective antibody-mediated immunity to the gut bacterial pathogen Citrobacter rodentium. We asked whether prior activation of FRC through nonspecific inflammatory “training” of the gut would alter subsequent immune response to C. rodentium . Inflammatory training increased the number of activated FRC in mesenteric LN (MLN) and enhanced the antibody response to C. rodentium in an IL-17–dependent manner. FRC demonstrated cardinal features of innate immune training, including increased epigenetic markers of activation and increased metabolic response to infection. Enhanced responses were still evident 6 weeks after training. The kinetics of bacterial infection were not changed by inflammatory training, but colon inflammation was paradoxically reduced. Mechanistically, IL-10 production by activated B cells was required for colon protective effects of inflammatory training. Enhancing tissue protective B cell responses thus led to increased production of antibody and IL-10, allowing clearance of infection with reduced tissue inflammation. These data identify a new mode of immune training through FRC to modulate future adaptive responses and better preserve host health.

Many bacterial pathogens, including Staphylococcus aureus, require inosine 5’-monophosphate dehydrogenase (IMPDH) for infection, making this enzyme a promising new target for antibiotics. Although potent selective inhibitors of bacterial IMPDHs have been reported, relatively few have displayed antibacterial activity. Here we use structure-informed design to obtain inhibitors of S. aureus IMPDH (SaIMPDH) that have potent antibacterial activity (minimal inhibitory concentrations less than 2 μM) and low cytotoxicity in mammalian cells. The physicochemical properties of the most active compounds were within typical Lipinski/Veber space, suggesting that polarity is not a general requirement for achieving antibacterial activity. Five compounds failed to display activity in mouse models of septicemia and abscess infection. Inhibitor-resistant S. aureus strains readily emerged in vitro. Resistance resulted from substitutions in the cofactor/inhibitor binding site of SaIMPDH, confirming on-target antibacterial activity. These mutations decreased the binding of all inhibitors tested, but also decreased catalytic activity. Nonetheless, the resistant strains had comparable virulence to wild-type bacteria. Surprisingly, strains expressing catalytically inactive SaIMPDH displayed only a mild virulence defect. Collectively these observations question the vulnerability of the enzymatic activity of SaIMPDH as a target for the treatment of S. aureus infections, suggesting other functions of this protein may be responsible for its role in infection.

B cells can be polarized to express various cytokines. The roles of IFNγ and IL-10, expressed respectively by B effector 1 (Be1) and Bregs, have been established in pathogen clearance, tumor growth, autoimmunity and allograft rejection. However, the

Over the past three decades, improved immunosuppression has significantly reduced T cell-mediated acute rejection rates, but long-term graft survival rates have seen only marginal improvement. The cause of late graft loss has been under intense investigation, and chronic antibody-mediated rejection (AMR) has been identified as one of the leading causes, thus providing a strong rationale for basic science investigation into donor-specific B cells and antibodies in transplantation and ways to mitigate their pathogenicity. In 2018, the American Society of Transplantation launched a community-wide online discussion of Outstanding Questions in Transplantation, and the topic of B cell biology and donor-specific antibody prevention emerged as a major area of interest to the community, leading to a highly engaged dialogue, with comments from basic and translational scientists as well as physicians (http://community.myast.org/communities/community-home/digestviewer). We have summarized this discussion from a bedside to bench perspective and have organized this review into outstanding questions within the paradigm that AMR is a leading cause of graft loss in the clinic, and points of view that challenge aspects of this paradigm. We also highlight opportunities for basic and translational scientists to contribute to the resolution of these questions, mapping important future directions for the transplant research field.

Post-transplant donor specific antibody (DSA) is associated with poor renal allograft outcomes. However, variable timing of DSA assessment and inclusion of patients who undergo desensitization treatments have hindered our understanding of its consequences and limited its predictive value. Here we prospectively studied non-desensitized patients to determine factors associated with poor four-year outcomes in patients who developed post-transplant DSA. Using serial monitoring, 67 of 294 patients were found to develop DSA by one year. Compared to patients who do not develop DSA, those with DSA exhibit an increased incidence of both clinical and subclinical T-cell-mediated rejection (TCMR). The combination of TCMR plus DSA led to an almost three-fold increase in graft loss compared to either DSA or TCMR alone. Moreover, DSA was associated with higher Banff grade TCMR and chronic changes at one year. Antibody-mediated rejection was uncommon and always associated with TCMR. Amongst factors independently associated with DSA plus TCMR; non-adherence is potentially modifiable. Non-adherence, measured as intra-patient variability of calcineurin trough levels during the first post-transplant year, further risk-stratified patients with DSA plus TCMR such that about 75% of these patients had impending graft loss by four years, whereas adherent patients with DSA plus TCMR had outcomes comparable to other patient groups. Thus, early post-transplant DSA, especially in non-adherent patients, is associated with increased incidence of TCMR and represents a high-risk group of patients who might benefit from targeted therapeutic interventions.

B cells shape the alloimmune response through polarized subsets. These cells inhibit or promote immune responses by expressing suppressive or proinflammatory cytokines. Their summed activity dictates the influence of B cells on the alloimmune response. We review the evidence for regulatory B cells and effector B cells in mice and humans, discuss current limitations in their phenotypic identification, and discuss regulatory B cells as a signature for clinical renal allograft tolerance and predictive markers for allograft outcomes. We discuss the effects of therapeutic agents on regulatory B cells and potential approaches to augment their numbers as a therapeutic tool.

Early immunological biomarkers that predict rejection and chronic allograft loss are needed to inform preemptive therapy and improve long-term outcomes. Here, we prospectively examined the ratio of interleukin-10 (IL-10) to tumor necrosis factor-α (TNFα) produced by transitional-1 B cells (T1B) 3 months after transplantation as a predictive biomarker for clinical and subclinical renal allograft rejection and subsequent clinical course. In both Training (n = 162) and Internal Validation (n = 82) Sets, the T1B IL-10/TNFα ratio 3 months after transplantation predicted both clinical and subclinical rejection anytime in the first year. The biomarker also predicted subsequent late rejection with a lead time averaging 8 months. Among biomarker high-risk patients, 60% had early rejection, of which 48% recurred later in the first posttransplant year. Among high-risk patients without early rejection, 74% developed rejection later in the first year. In contrast, only 5% of low-risk patients had early and 5% late rejection. The biomarker also predicted rejection in an External Validation Set (n = 95) and in key patient subgroups, confirming generalizability. Biomarker high-risk patients exhibited progressively worse renal function and decreased 5-year graft survival compared to low-risk patients. Treatment of B cells with anti-TNFα in vitro augmented the IL-10/TNFα ratio, restored regulatory activity, and inhibited plasmablast differentiation. To conclude, the T1B IL-10/TNFα ratio was validated as a strong predictive biomarker of renal allograft outcomes and provides a rationale for preemptive therapeutic intervention with TNF blockade.

In addition to their role in humoral immunity, B cells can exhibit regulatory activity. Such B cells have been termed regulatory B cells (Bregs). Bregs have been shown to inhibit inflammatory immune responses in a variety of autoimmune, alloimmune, and infectious settings. Breg activity is frequently IL-10-dependent, although a number of other mechanisms have been identified. However, our understanding of Bregs has been hampered by their rarity, lack of a specific phenotypic marker, and poor insight into their induction and maintenance. A variety of B-cell subsets enriched for IL-10

In addition to their role in humoral immunity, B cells can exhibit regulatory activity. Such B cells have been termed regulatory B cells (Bregs). Bregs have been shown to inhibit inflammatory immune responses in a variety of autoimmune, alloimmune, and infectious settings. Breg activity is frequently IL-10-dependent, although a number of other mechanisms have been identified. However, our understanding of Bregs has been hampered by their rarity, lack of a specific phenotypic marker, and poor insight into their induction and maintenance. A variety of B-cell subsets enriched for IL-10+ Bregs have been identified in multiple murine disease models that can adoptively transfer Breg activity. However, most of these B-cell subsets actually contain only a minority of all IL-10+ B cells. In contrast, TIM-1 identifies over 70% of IL-10-producing B cells, irrespective of other markers. Thus, TIM-1 can be considered a broad marker for IL-10-expressing Bregs. Moreover, TIM-1 signaling plays a direct role in both the maintenance and induction of Bregs under physiological conditions, in response to both TIM-1 ligation and to apoptotic cells. TIM-1 expression has also been reported on IL-10+ human B cells. Together, these findings suggest that TIM-1 may represent a novel therapeutic target for modulating the immune response and provide insight into the signals involved in the generation and induction of Bregs. Here, we provide the methods to analyze and purify the murine TIM-1+ B-cell subset for further in vitro and in vivo experiments. We also provide methods for in vitro analysis and in vivo tracking of Bregs using IL-10-reporter mice.

We perform all-electron, pure-sampling quantum Monte Carlo (QMC) calculations on ethylene and bifuran molecules. The orbitals used for importance sampling with a single Slater determinant are gener...

The impact of PD-1 immune checkpoint therapy prompts exploration of other strategies to downregulate PD-1 for cancer therapy. We previously showed that the serine/threonine kinase, glycogen synthase kinase, GSK-3α/β, is a central regulator of PD-1 transcription in CD8+ T cells. Here, we show that the use of small-molecule inhibitors of GSK-3α/β (GSK-3i) to reduce pcdc1 (PD-1) transcription and expression was as effective as anti–PD-1 and PD-L1–blocking antibodies in the control of B16 melanoma, or EL4 lymphoma, in primary tumor and metastatic settings. Furthermore, the conditional genetic deletion of GSK-3α/β reduced PD-1 expression on CD8+ T cells and limited B16 pulmonary metastasis to the same degree as PD-1 gene deficiency. In each model, GSK-3i inhibited PD-1 expression on tumor-infiltrating lymphocytes, while increasing Tbx21 (T-bet) transcription, and the expression of CD107a+ (LAMP1) and granzyme B (GZMB) on CD8+ T cells. Finally, the adoptive transfer of T cells treated ex vivo with a GSK-3 inhibitor delayed the onset of EL4 lymphoma growth to a similar extent as anti–PD-1 pretreatment. Overall, our findings show how GSK-3 inhibitors that downregulate PD-1 expression can enhance CD8+ T-cell function in cancer therapy to a similar degree as PD-1–blocking antibodies. Significance: These findings show how GSK-3 inhibitors that downregulate PD-1 expression can enhance CD8+ T-cell function in cancer therapy to a similar degree as PD-1 blocking antibodies, offering a next-generation approach in the design of immunotherapeutic approaches for cancer management. Cancer Res; 78(3); 706–17. ©2017 AACR.

B cells give rise to polarized subsets, including B effector 1 (Be1) cells and regulatory B cells, which can promote or inhibit immune responses through expression of IFN-γ and IL-10, respectively. Such subsets likely explain why B cell depletion can either ameliorate or exacerbate inflammatory diseases; however, these cells remain poorly understood because of the absence of specific markers. Although T cell Ig and mucin domain-containing molecule (TIM)-1 broadly identifies IL-10+ regulatory B cells, no similar markers for Be1 cells have been described. We now show that TIM-4 is expressed by a subset of B cells distinct from those expressing TIM-1. Although TIM-1+ B cells are enriched for IL-10, TIM-4+ B cells are enriched for IFN-γ. TIM-1+ B cells enhanced the growth of B16-F10 melanoma. In contrast, TIM-4+ B cells decreased B16-F10 metastasis and s.c. tumor growth, and this was IFN-γ dependent. TIM-1+ B cells prolonged islet allograft survival in B-deficient mice, whereas TIM-4+ B cells accelerated rejection in an IFN-γ–dependent manner. Moreover, TIM-4+ B cells promoted proinflammatory Th differentiation in vivo, increasing IFN-γ while decreasing IL-4, IL-10, and Foxp3 expression by CD4+ T cells—effects that are opposite from those of TIM-1+ B cells. Importantly, a monoclonal anti–TIM-4 Ab promoted allograft tolerance, and this was dependent on B cell expression of TIM-4. Anti–TIM-4 downregulated T-bet and IFN-γ expression by TIM-4+ B cells and indirectly increased IL-10 expression by TIM-1+ B cells. Thus, TIM-4+ B cells are enriched for IFN-γ–producing proinflammatory Be1 cells that enhance immune responsiveness and can be specifically targeted with anti–TIM-4.

Human transitional B cells express relatively high IL-10 and low TNF-α levels, which correlate with B regulatory activity in vitro. Herein, we aim to further define B regulatory phenotype and determine whether B regulatory activity can serve as a prognostic marker for renal allograft dysfunction (graft loss or 2-fold fall in estimated glomerular filtration rate). Transitional B cells can be divided into T1 and T2 subsets based on surface phenotype. T1 cells express a significantly higher ratio of IL-10 to TNF-α than T2 cells or other B subsets. When analyzed in 45 kidney transplant recipients at the time of late for-cause biopsy, the T1/T2 ratio was independently associated with allograft dysfunction over the next 5 years. Next, the T1/T2 ratio was examined in an independent set of 97 clinically stable kidney transplant recipients 2 years after transplant. Again, the T1/T2 ratio was strongly and independently associated with allograft dysfunction over the ensuing 5 years. In these clinically quiescent patients, a low T1/T2 ratio identified a 41-patient subgroup in which 35% developed allograft dysfunction, with 25% losing their allografts. However, none of the 56 patients with a high ratio developed graft dysfunction. In both the initial study and validation groups, the T1/T2 ratio was a much stronger predictor of graft dysfunction than donor-specific antibodies or the estimated glomerular filtration rate. Thus, the T1/T2 ratio, a relative measure of expressing an anti-inflammatory cytokine profile, is a novel prognostic marker that might inform individualized immunosuppression.

Previous observations suggest periodic freshwater patches separating from the Block Island Sound (BIS) estuarine plume. In this study, the dynamics of the separation process is investigated through a series of numerical experiments using the Regional Ocean Modeling System (ROMS). In addition, we explore the seasonal variability of the freshwater patches and their response to river discharge and ambient current. The model results indicate that episodic freshwater patches are triggered by small changes in tidal currents over the spring-neap tidal cycle. The spring-neap variation in tidal currents causes significant, monthly fluctuations in turbulent mixing and vertical stratification in BIS, modulating the freshwater discharge thereby generating episodic freshwater patches that move both downstream along the southern shore of Long Island and toward Rhode Island Sound (RIS). The realistically configured model shows that the freshwater patches experience strong seasonal variability. They are largest in spring when the river discharge peaks, and smallest in summer due to the weak river discharge and a robust upstream ambient current from RIS. According to the analysis of the freshwater transport out of BIS, we conclude that such detachment occurs at tidal mixing fronts.

IL-10+ regulatory B cells (Bregs) inhibit immune responses in various settings. While Bregs appear to inhibit inflammatory cytokine expression by CD4+ T cells and innate immune cells, their reported impact on CD8+ T cells is contradictory. Moreover, it remains unclear which effects of Bregs are direct versus indirect. Finally, the subanatomical localization of Breg suppressive function and the nature of their intercellular interactions remain unknown. Using novel tamoxifen-inducible B cell-specific IL-10 knockout mice, we found that Bregs inhibit CD8+ T cell proliferation and inhibit inflammatory cytokine expression by both CD4+ and CD8+ T cells. Sort-purified Bregs from IL-10-reporter mice were adoptively transferred into wild-type hosts and examined by live-cell imaging. Bregs localized to the T:B border, specifically entered the T cell zone, and made more frequent and longer contacts with both CD4+ and CD8+ T cells than did non-Bregs. These Breg:T cell interactions were antigen-specific and reduced subsequent T:DC contacts. Thus, Bregs inhibit T cells through direct cognate interactions that subsequently reduce DC:T cell interactions.

Graft-versus-host disease (GVHD) is a major cause of morbidity and mortality in allogeneic hematopoietic stem cell transplantation (alloSCT). By static microscopy, cutaneous GVHD lesions contain a mix of T cells and myeloid cells. We used 2-photon intravital microscopy to investigate the dynamics of CD4+ and CD8+ T cells and donor dendritic cells (DCs) in cutaneous GVHD lesions in an MHC-matched, multiple minor histocompatibility antigen-mismatched (miHA) model. The majority of CD4 and CD8 cells were stationary, and few cells entered and stopped or were stopped and left the imaged volumes. CD8 cells made TCR:MHCI-dependent interactions with CD11c+ cells, as measured by the durations that CD8 cells contacted MHCI+ vs MHCI− DCs. The acute deletion of Langerin+CD103+ DCs, which were relatively rare, did not affect CD8 cell motility and DC contact times, indicating that Langerin−CD103− DCs provide stop signals to CD8 cells. CD4 cells, in contrast, had similar contact durations with MHCII+ and MHCII− DCs. However, CD4 motility rapidly increased after the infusion of an MHCII-blocking antibody, indicating that TCR signaling actively suppressed CD4 movements. Many CD4 cells still were stationary after anti-MHCII antibody infusion, suggesting CD4 cell heterogeneity within the lesion. These data support a model of local GVHD maintenance within target tissues.

The objective of this chapter is to introduce the reader to fixed-node quantum Monte Carlo methods for atoms and molecules. In the first instance we describe fixed-node diffusion Monte Carlo (FNDMC), followed by a discussion of a more versatile method, Pure-Sampling Quantum Monte Carlo (PSQMC). The former is designed to calculate the ground-state energy, formally without bias save for the fixed-node approximation, by sampling the local energy from a stochastically generated “mixed” electron distribution: ΨΦ0, where Ψ is an input trial function and Φ0 is the unknown, exact ground-state solution to the Schrodinger equation. In addition to the ground-state energy, the latter algorithm also calculates electronic properties, such as the electric moments, again formally without bias within the fixed-node approximation, by sampling estimators for those properties from a stochastically generated “pure-electron distribution,” Φ 0 2 . We illustrate pure-sampling with an application to the ground state of ethene. Derivations of expressions that rest at the foundations of FNDMC and PSQMC are given in the last section.

Observations reveal a near-surface circulation around the periphery of Rhode Island Sound (RIS) that occurs in summer stratified conditions and disappears in winter when weak solar insolation and wind stirring result in strong vertical mixing. According to a series of numerical simulations and theoretical analysis, we attribute the summer intensification of this “periphery current” to a circulation produced by seasonal bottom thermal fronts often observed from May to September. The strength of the thermal fronts is proportional to the surface solar radiation. Meanwhile, the simulations capture a continuous topographically rectified tidal residual current in RIS and a pair of opposite-sign headland eddies around Montauk Point in Block Island Sound (BIS). Our analysis suggests the importance of nonlinear vorticity advection and frictional torques in BIS. On the other hand, the vorticity balance shows the importance of velocity torque by contributing to the opposite headland gyres, while the effect by planetary vorticity stretching is negligible over BIS but important in RIS.

A numerical simulation using the Regional Ocean Modeling System (ROMS) indicates that there was significant interannual-to-interpentadal variability of along-shelf transport and water properties over the Middle Atlantic Bight (MAB) from 2004 to 2013. To examine the relative contribution from local atmospheric forcing versus remote oceanic open boundary forcing to such low-frequency variability, we implement a suite of process oriented numerical experiments. Results show that the interannual variability is dominated by remote forcing from the open boundaries of the region rather than by local atmospheric forcing. The penetration of the Labrador Current into the region contributes to a significant increase of along-shelf transport in the winters of 2009 and 2010. By contrast, the anti-cyclonic mesoscale eddies associated with the Gulf Stream decrease the background along-shelf jet and, in certain cases, even reverse the along-shelf transport. In addition, the along-shelf transport appears to possess an interpentadal variation, i.e., weaker during 2004–2008 but stronger during 2009–2013, which is found caused by the migration of the Gulf Stream.

Buoyant discharge of freshwater from Long Island Sound (LIS) forms a seasonal buoyant plume outside Block Island Sound (BIS) between the coast of Long Island and the denser shelf waters. The plume’s seasonal variability and its response to tides, winds, and surface heating are investigated through a series of process-oriented experiments using the Regional Ocean Modeling System (ROMS). Results show the importance of river discharge, wind directions, and surface heating in the seasonal variation of the BIS buoyant plume. In winter and spring, the plume is intermediate with a large surface offshore extension detached from the bottom. From winter to spring, the river discharge increases; meanwhile, upwelling-favorable winds keep dominating. They compete with the increase of surface heating and generate a broader buoyant plume in spring than in winter. In summer, the plume is bottom advected with most of its width in contact with the bottom and is featured with the steepest isopycnals and narrowest plume, which is driven by a combination of strong insolation, weak buoyant discharge from LIS, and feeble winds. In fall, although the river discharge is comparable to that in winter, the upwelling-favorable wind is relatively weaker, corresponding to a narrower intermediate plume.

TIM-1+ B cells are enriched for IL-10+ B regulatory cells (Bregs). However, TIM-1+ B cells are also enriched for IL-4+ B effector 2 cells (Be2). Tolerogenic α-TIM-1 (RMT1-10) prolongs islet allograft survival (GS) by expanding (IL-10+) Bregs. Interestingly, IL-4KO and IL-4Rα-KO mice are deficient in Bregs and are not responsive to αTIM-1. To establish the importance of IL-4R signaling, and the source of IL-4 for Breg induction, we made tamoxifen (TAM) inducible BALB/c hCD20Cre.ERT2+/− X IL-4Rαfl/fl (B-IL-4RαKO) and hCD20Cre.ERT2+/− X IL-4/13fl/fl mice (B-IL-4KO) to respectively delete IL-4Rα or IL-4/IL-13 in B cells. After TAM, αTIM-1 treatment of alloimmunized B-IL-4RαKO mice had ↓ TIM-1+ B cells (50%), Be2 (50%) and Bregs (40%) vs. IL-4Rαfl/fl littermate controls and a concomittant 33%↑ in IFNγ+ and 33% ↓ in IL-10+ CD4 T cells, and a 20%↑ in IFNγ+ CD8 T cells vs. controls. Finally, α–TIM-1 led to >100d GS in 75% of control mice, but failed to improve GS in B-IL-4RαKO mice (MST 20d, p=0.03). Similarly, TAM treated B-IL-4KO mice had a 3x ↓ in Be2 and Bregs vs. IL-4fl/fl controls, and a 6x drop in IL-4+ CD4 T cells. Importantly, B-IL-4KO mice rejected islets more rapidly (MST 20d) than controls (MST 31d, p=0.04), and α–TIM-1 failed to improve B-IL-4KO GS (MST 17d) vs. controls (MST >100d). In contrast, in Th2 dominant OVA-induced allergic airway disease (AAD), B-IL-4KO mice had 3x decrease in total lymphocyte infiltrate, 5x decrease CD4 T cells and 8x decrease eosinophils in BAL fluid vs. controls. CD4+ T cells from whole lung tissue produced 2x less IL-4 and 3x less IL-5 vs. controls. Hence, IL-4 production by B cells is important for both Breg induction and Th2 polarization and absence of B cell IL-4/IL-13 promotes allograft rejection yet reduces AAD.

Purpose of review Regulatory B cells (Bregs) are potent inhibitors of the immune system with the capacity to suppress autoimmune and alloimmune responses. Murine transplant models showing that Bregs can promote allograft tolerance are now supported by clinical data showing that patients who develop operational tolerance have higher frequency of Bregs. Breg function has been widely studied resulting in improved understanding of their biology and effector mechanisms. However, our overall understanding of Bregs remains poor due the lack of specific marker, limited knowledge of how and where they act in vivo, and whether different Breg subpopulations exhibit different functions. Recent findings In this review we detail murine and human phenotypic markers used to identify Bregs, their induction, maintenance, and mechanisms of immune suppression. We highlight recent advances in the field including their use as biomarkers to predict allograft rejection, in-vitro expansion of Bregs, and the effects of commonly used immunosuppressive drugs on their induction and frequency. Summary Clinical data continue to emerge in support of Bregs playing an important role in preventing transplant rejection. Hence, it is necessary for the transplant field to better comprehend the mechanisms of Breg induction and approaches to preserve or even enhance their activity to improve long-term transplant outcomes.

The immune system is comprised of several CD4(+) T regulatory (Treg) cell types, of which two, the Foxp3(+) Treg and T regulatory type 1 (Tr1) cells, have frequently been associated with transplant tolerance. However, whether and how these two Treg-cell types synergize to promote allograft tolerance remains unknown. We previously developed a mouse model of allogeneic transplantation in which a specific immunomodulatory treatment leads to transplant tolerance through both Foxp3(+) Treg and Tr1 cells. Here, we show that Foxp3(+) Treg cells exert their regulatory function within the allograft and initiate engraftment locally and in a non-antigen (Ag) specific manner. Whereas CD4(+) CD25(-) T cells, which contain Tr1 cells, act from the spleen and are key to the maintenance of long-term tolerance. Importantly, the role of Foxp3(+) Treg and Tr1 cells is not redundant once they are simultaneously expanded/induced in the same host. Moreover, our data show that long-term tolerance induced by Foxp3(+) Treg-cell transfer is sustained by splenic Tr1 cells and functionally moves from the allograft to the spleen.

Mutants of Bacillis subtilis that are temperature sensitive for RNA synthesis during sporulation were isolated after selection with a 32 P suicide agent. Whole-genome sequencing revealed that two of the mutants carried an identical lesion in the rsbU gene, which encodes a phosphatase that indirectly activates SigB, the stress-responsive RNA polymerase sigma factor. The mutation appeared to cause RsbU to be hyperactive, because the mutants were more resistant than the parent strain to ethanol stress. In support of this hypothesis, pseudorevertants that regained wild-type levels of sporulation at high temperature had secondary mutations that prevented expression of the mutant rsbU gene. The properties of these RsbU mutants support the idea that activation of SigB diminishes the bacterium's ability to sporulate. IMPORTANCE Most bacterial species encode multiple RNA polymerase promoter recognition subunits (sigma factors). Each sigma factor directs RNA polymerase to different sets of genes; each gene set typically encodes proteins important for responses to specific environmental conditions, such as changes in temperature, salt concentration, and nutrient availability. A selection for mutants of Bacillus subtilis that are temperature sensitive for RNA synthesis during sporulation unexpectedly yielded strains with a point mutation in rsbU , a gene that encodes a protein that normally activates sigma factor B (SigB) under conditions of salt stress. The mutation appears to cause RsbU, and therefore SigB, to be active inappropriately, thereby inhibiting, directly or indirectly, the ability of the cells to transcribe sporulation genes.

Strong surface winds of a hurricane locally cool the surface and warm the subsurface waters via turbulent mixing processes. While the surface cool anomalies generally decay in roughly a month, the warm subsurface anomalies can persist over a seasonal cycle. The authors examine questions related to the magnitude and cumulative footprint of subsurface warm anomalies forced by tropical cyclones during the combined global tropical cyclone seasons, making use of a global ocean model forced by tropical cyclones. Simulations of the 2004/05 tropical cyclone season are conducted with and without tropical cyclone wind forcing, blended with the daily Coordinated Ocean-Ice Reference Experiments (COREs) atmospheric state. Physical characteristics of cyclone-forced surface and subsurface anomalies are elucidated. In particular, the spatial extent and magnitude of tropical cyclone–forced subsurface warm anomalies over the course of an entire season are examined. This analysis permits the estimation of the contribution of cyclone-induced anomalies to the ocean heat content and sea surface temperature, aiding in understanding anomalous meridional heat transport. Globally, there is a maximum accumulated heat uptake 4.1 × 1021 J, with the greatest regional contributions in the North Atlantic (1.7 × 1021 J), west Pacific (1.5 × 1021 J), and east Pacific (1.7 × 1021 J). An export of heat from the subtropics to the tropics via rapid advective pathways is found, most notably in the west Pacific. These warm anomalies tend to remain in the equatorial band, with potential implications for the tropical climate system.