Role of human interleukin-17 producing T cells (Th17) and regulatory (Foxp3+) T cells in graft versus host disease (GvHD)

Allogeneic stem cell transplantation (AHSCT) remains the only curative option for a number of patients with haematological malignancies. The interplay between a number of T cell subsets including Th1, Th2, Th17 and regulatory-T cells (Treg) has been linked to the establishment of graft-versus-leukaemia (GvL) as well as its deleterious counterpart graft-versus-host-disease (GvHD). A recent study defined a subset of memory antigen-specific CD8+T cells, with the ability to efflux cytotoxic drugs through the (ABC)-superfamily multidrug efflux complex. I hypothesized that a subset of CD4+T cells, capable of drug efflux through the MDR pump also exists. I confirmed the existence of CD4+T cells with "stem-like" properties, capable of rapidly effluxing Rhodamine123 as well as cytotoxic drugs such as daunorubicin. I confirmed that the effluxing properties of these cells are through ABCB1 and ABCC1 transporters. Similar to their CD8 counterpart, the rhodamine-effluxing subset of CD4+T cells had a memory phenotype and was enriched within the CD161+T cell compartment. Lastly, using CMV and Flu as model antigens, I showed that viral-specific memory CD4+T cells are enriched within the rhodamine-effluxing CD4+CD161+T cell population. Once I characterized these cells, I hypothesized that, through effluxing corticosteroids and other immunosuppressant drugs,CD161+CD4+ T cells may also play a role in acute GvHD. CD161+CD4+ T cells are precursors of Th17 cells. I demonstrated that, whereas Tregs are prone to apoptosis when exposed to corticosteroids, CD4+CD161+Th17 cells rapidly efflux and survive exposure to corticosteroids and other immunosuppressive drugs in vitro. Inhibition of the ABCB1 and ABCC1 with inhibitors such as vinblastine induced apoptosis of this CD4+CD161+Th17 steroid-refractory T cell subset. I observed that patients with steroid-refractory GvHD had significantly higher frequencies of CD161+CD4+ T cells compared to patients with no or steroid-responsive GvHD. I also enumerated CD161+CD4+ T cells and Foxp3+T cells in the stem cell graft and donor lymphocytes and found an association between higher CD4+CD161+ and lower Foxp3+T cells frequencies and the risk of GvHD post-transplant. These data advance our understanding of potential mechanisms of steroid-refractory GvHD and have important implications for the development of novel therapeutic approaches for the treatment of this challenging group of patients

Membrane bioreactor treating kraft evaporative condensate at a high temperature under different operational conditions and turpentine shockloads

This study was initiated to assess the feasibility of biological treatment and reuse of kraft pulp mill evaporator condensate, using a high temperature MBR operated at a short solids retention time (SRT) and low hydraulic retention time (HRT). In addition, the mechanisms responsible for the fouling of the membrane were examined. The decline in the biomass concentration associated with short SRT operation affected membrane fouling. Furthermore, the impact of short-term turpentine shock loads on the overall removal kinetics of the contaminants of concern present in the evaporator condensate was investigated. To obtain as much data as possible within a short time frame, a lab scale system consisting of two bench scale high temperature MBRs was operated at different operational SRTs and FIRTs. The SRT conditions selected were 15 and 10 days. The associated HRTs set at either 12, 10, or 8 hours. Other operating parameters were selected according to recommendations from a membrane manufacturing company and from a previous study (Berube, 2000). Methanol, monoterpenes, and organic compounds represented by total organic carbon (TOC) were identified as the primary contaminants of concern contained in the evaporator condensate. Methanol and monoterpenes are of concern primarily because they are hazardous air pollutants (HAP) and/ or foul odorous compounds. They contribute 60 to 75% of the biochemical oxidation demand (BOD) in the evaporator condensate (Hough et al, 1977). The results of the study indicated that the biological removal of the contaminants of concern using a high temperature MBR operated at a short SRT (as short as 10 days) and a low HRT (as low as 10 hours) was feasible. However, when the HRT was decreased from 10 to 8 hours (organic load increased), the mixed microbial culture responsible for the removal of methanol was inhibited. The potential toxic contaminants present in the evaporator condensate exhibited an immediate influence on the biotic removal kinetics and removal efficiencies of methanol. For monoterpenes and TOC, the significant decline in the values of overall removal kinetics and efficiencies, when HRT was lowered to 8 hours, was due to the short contact time imposed. Investigation of the membrane performance indicated that the reduction in the permeate flux with time and the resulting cleaning intervals were a function of the operational SRTs and HRTs. Membrane fouling was found to be a function of the mixed liquor volatile suspended solids (MLVSS) concentration in the MBR and the operational transmembrane pressure (TMP). Membrane fouling was mainly controlled by pore plugging resistance (R[sub pp]) rather than concentration polarization (R[sub cp]) and membrane resistances (R[sub m]). R[sub pp] composed from 60 to 80% of the total foulant resistance. Turpentine shock loads exerted a significant impact on the overall removal kinetics of the main contaminants of concern in evaporator condensate. Overall removal rates decreased significantly as the spiked monoterpenes accumulated in the MBRs. The overall removal rates decreased more significantly when the spiking concentrations of monoterpenes were increased from 300 to 1500 mg/L.Applied Science, Faculty ofCivil Engineering, Department ofGraduat

Leukemia-induced phenotypic and functional defects in natural killer cells predict failure to achieve remission in acute myeloid leukemia

The majority of patients with acute myeloid leukemia will relapse, and older patients often fail to achieve remission with induction chemotherapy. We explored the possibility that leukemic suppression of innate immunity might contribute to treatment failure. Natural killer cell phenotype and function was measured in 32 consecutive acute myeloid leukemia patients at presentation, including 12 achieving complete remission. Compared to 15 healthy age-matched controls, natural killer cells from acute myeloid leukemia patients were abnormal at presentation, with downregulation of the activating receptor NKp46 (P=0.007) and upregulation of the inhibitory receptor NKG2A (P=0.04). Natural killer cells from acute myeloid leukemia patients had impaired effector function against autologous blasts and K562 targets, with significantly reduced CD107a degranulation, TNF-alpha and IFN-gamma production. Failure to achieve remission was associated with NKG2A overexpression and reduced TNF-alpha production. These phenotypic and functional abnormalities were partially restored in the 12 patients achieving remission. In vitro co-incubation of acute myeloid leukemia blasts with natural killer cells from healthy donors induced significant impairment in natural killer cell TNF-alpha and IFN-gamma production (P=0.02 and P=0.01, respectively) against K562 targets and a trend to reduced CD107a degranulation (P=0.07). Under transwell conditions, the inhibitory effect of AML blasts on NK cytotoxicity and effector function was still present, and this inhibitory effect was primarily mediated by IL-10. These results suggest that acute myeloid leukemia blasts induce long-lasting changes in natural killer cells, impairing their effector function and reducing the competence of the innate immune system, favoring leukemia survival

The Outcome of BNT162b2, ChAdOx1-Sand mRNA-1273 Vaccines and Two Boosters: A Prospective Longitudinal Real-World Study

To date, the effectiveness of COVID-19 vaccines and booster doses has yet to be evaluated in longitudinal head-to-head studies. This single-center longitudinal study assessed the effectiveness of ChAdOx1 nCoV-19, BNT162b2, and mRNA-1273 vaccines and assessed two BNT162b2 boosters in 1550 participants, of whom 26% had comorbidities. In addition, the SARS-CoV-2 antibody dynamics was monitored. A group of 1500 unvaccinated subjects was included as the controls. The study’s endpoint was the development of virologically-proven COVID-19 cases after vaccine completion, while the secondary endpoint was hospitalizations due to severe COVID-19. Overall, 23 (4.6%), 16 (3%), and 18 (3.8%) participants vaccinated with ChAdOx1 nCoV-19, BNT162b2, and mRNA-1273, respectively, developed COVID-19 after vaccine completion, with an effectiveness of 89%, 92%, and 90%. Ten COVID-19 cases were reported in participants with comorbidities, three of whom were hospitalized. No hospitalizations occurred after boosters. SARS-CoV-2 antibody levels peaked 2–4 weeks after the second vaccine dose but declined after a mean of 28.50 ± 3.48 weeks. Booster doses significantly enhanced antibody responses. Antibody titers ≤ 154 U/mL were associated with a higher risk of COVID-19 emergence. Thus, COVID-19 vaccines effectively reduced COVID-19 and prevented severe disease. The vaccine-induced SARS-CoV-2 antibody responses declined after 28–32 weeks. Booster doses induced significant maintained responses. SARS-CoV-2 antibody levels may help determine the timing and need for vaccine booster doses