Infectious Complications Predict Premature CD8+ T-cell Senescence in CD40 Ligand-Deficient Patients.

PURPOSE: CD40 ligand (CD40L)-deficient patients display increased susceptibilities to infections that can be mitigated with effective prophylactic strategies including immunoglobulin G (IgG) replacement and prophylactic antibiotics. CD8+ T-cell senescence has been described in CD40L deficiency, but it is unclear if this is an intrinsic feature of the disease or secondary to infectious exposures. To address this question, we assessed CD8+ T-cell senescence and its relationship to clinical histories, including prophylaxis adherence and infections, in CD40L-deficient patients. METHODS: Peripheral CD8+ T-cells from seven CD40L-deficient patients and healthy controls (HCs) were assessed for senescent features using T-cell receptor excision circle (TREC) analysis, flow cytometry, cytometry by time of flight (CyTOF) and in vitro functional determinations including CMV-specific proliferation and cytokine release assays. RESULTS: Three patients (5, 28, and 34 years old) who were poorly adherent to immunoglobulin G replacement and Pneumocystis jirovecii pneumonia (PJP) prophylaxis and/or experienced multiple childhood pneumonias (patient group 1) had an expansion of effector memory CD8+ T-cells with the senescent phenotype when compared to HCs. Such changes were not observed in the patient group 2 (four patients, 16, 22, 24, and 33 years old) who were life-long adherents to prophylaxis and experienced few infectious complications. CyTOF analysis of CD8+ T-cells from the 5-year-old patient and older adult HCs showed similar expression patterns of senescence-associated molecules. CONCLUSIONS: Our findings support that recurrent infections and non-adherence to prophylaxis promote early CD8+ T-cell senescence in CD40L deficiency. Premature senescence may increase malignant susceptibilities and further exacerbate infectious risk in CD40L-deficient patients.

Early Human B Cell Response to Ebola Virus in Four U.S. Survivors of Infection.

The human B cell response to natural filovirus infections early after recovery is poorly understood. Previous serologic studies suggest that some Ebola virus survivors exhibit delayed antibody responses with low magnitude and quality. Here, we sought to study the population of individual memory B cells induced early in convalescence. We isolated monoclonal antibodies (MAbs) from memory B cells from four survivors treated for Ebola virus disease (EVD) 1 or 3 months after discharge from the hospital. At the early time points postrecovery, the frequency of Ebola-specific B cells was low and dominated by clones that were cross-reactive with both Ebola glycoprotein (GP) and with the secreted GP (sGP) form. Of 25 MAbs isolated from four donors, only one exhibited neutralization activity. This neutralizing MAb, designated MAb EBOV237, recognizes an epitope in the glycan cap of the surface glycoprotein. In vivo murine lethal challenge studies showed that EBOV237 conferred protection when given prophylactically at a level similar to that of the ZMapp component MAb 13C6. The results suggest that the human B cell response to EVD 1 to 3 months postdischarge is characterized by a paucity of broad or potent neutralizing clones. However, the neutralizing epitope in the glycan cap recognized by EBOV237 may play a role in the early human antibody response to EVD and should be considered in rational design strategies for new Ebola virus vaccine candidates.IMPORTANCE The pathogenesis of Ebola virus disease (EVD) in humans is complex, and the mechanisms contributing to immunity are poorly understood. In particular, it appears that the quality and magnitude of the human B cell response early after recovery from EVD may be reduced compared to most viral infections. Here, we isolated human monoclonal antibodies from B cells of four survivors of EVD at 1 or 3 months after hospital discharge. Ebola-specific memory B cells early in convalescence were low in frequency, and the antibodies they encoded demonstrated poor neutralizing potencies. One neutralizing antibody that protected mice from lethal infection, EBOV237, was identified in the panel of 25 human antibodies isolated. Recognition of the glycan cap epitope recognized by EBOV237 suggests that this antigenic site should be considered in vaccine design and treatment strategies for EVD.

Serum Procalcitonin Level Is Associated with Positive Blood Cultures, In-hospital Mortality, and Septic Shock in Emergency Department Sepsis Patients.

This study examines the accuracy of initial and subsequent serum procalcitonin (PCT) levels in predicting positive blood cultures, in-hospital mortality, and development of septic shock in emergency department (ED) patients with severe sepsis. This study includes all patients who presented to our ED with an admission diagnosis of severe sepsis over a period of nine months. The median initial PCT was 0.58 ng/mL, interquartile range (IQR) 0.16-5.39. The median subsequent serum PCT was 2.1 ng/mL, with an IQR of 0.3-11.1. The PCT trend over the initial three hours increased in 67% of the study population. Blood cultures were positive in 38% of the cohort. The median maximum PCT in those with a negative blood culture was 1.06 ng/mL compared to 4.19 ng/mL in those with a positive blood culture (p=0.0116). Serum PCT levels >2.0 ng/mL display significant correlation with positive blood cultures, in-hospital mortality, and development of septic shock and as such may serve as a biomarker for more serious infections.

Gout Due to Tacrolimus in a Liver Transplant Recipient.

Patients taking tacrolimus have an increased predisposition to hyperuricemia. Although literature has widely established the risk of gout in patients taking cyclosporine, the widespread use of tacrolimus in patients following liver transplantation necessitates further investigation into the potential connection between the drug's use and gout. Moreover, hyperuricemia in the context of liver transplants is associated with increased morbidities and mortalities. We describe a case of gout in a liver transplant patient taking the calcineurin inhibitor tacrolimus.

Analyzing the Efficacy and Cost-effectiveness of Anti-platelet Therapy in Unstable Angina/Non-ST Elevation Myocardial Infarction: A Decision Analysis.

Current pretreatment guidelines for coronary angiography in unstable angina (UA) and non-ST elevation myocardial infarction (NSTEMI) involve the use of dual antiplatelet therapy (DAPT: aspirin + adenosine diphosphate (ADP) P2Y12 inhibitor), whereas the use of triple antiplatelet therapy (TAPT: aspirin + ADP P2Y12 inhibitor + GpIIb/IIIa inhibitor) has limited data due to the increased bleeding risk. However, a study directly comparing the efficacy and cost-effectiveness of DAPT vs. TAPT has not been done. A decision analysis was constructed to determine the ideal pretreatment antiplatelet regimen for UA/NSTEMI patients. The parameters were calculated based on published randomized clinical trials. They consisted of probabilities based on a pretreatment strategy (DAPT, TAPT), interventions (percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG), medical management), and 30-day outcomes (no event, bleeding, vascular event, death). A 10,000 run Monte Carlo simulation provided two outputs: estimated life-years extended and costs for each treatment modality. Quality-adjusted life-years (QALYs) were taken into consideration using calculated coefficients from the literature. The cost/QALY ratio was $1,923/QALY for DAPT vs. $4,734/QALY for TAPT. The use of DAPT for pretreatment was favored (2.46 more cost-effective than TAPT). These results will aid clinicians in providing the most clinically sound and fiscally responsible care for UA/NSTEMI patients.

Inhibition of Cholera Toxin and Other AB Toxins by Polyphenolic Compounds.

Cholera toxin (CT) is an AB-type protein toxin that contains a catalytic A1 subunit, an A2 linker, and a cell-binding B homopentamer. The CT holotoxin is released into the extracellular environment, but CTA1 attacks a target within the cytosol of a host cell. We recently reported that grape extract confers substantial resistance to CT. Here, we used a cell culture system to identify twelve individual phenolic compounds from grape extract that inhibit CT. Additional studies determined the mechanism of inhibition for a subset of the compounds: two inhibited CT binding to the cell surface and even stripped CT from the plasma membrane of a target cell; two inhibited the enzymatic activity of CTA1; and four blocked cytosolic toxin activity without directly affecting the enzymatic function of CTA1. Individual polyphenolic compounds from grape extract could also generate cellular resistance to diphtheria toxin, exotoxin A, and ricin. We have thus identified individual toxin inhibitors from grape extract and some of their mechanisms of inhibition against CT.

Grape extracts inhibit multiple events in the cell biology of cholera intoxication.

Vibrio cholerae produces cholera toxin (CT), an AB5 protein toxin that is primarily responsible for the profuse watery diarrhea of cholera. CT is secreted into the extracellular milieu, but the toxin attacks its Gsα target within the cytosol of a host cell. Thus, CT must cross a cellular membrane barrier in order to function. This event only occurs after the toxin travels by retrograde vesicular transport from the cell surface to the endoplasmic reticulum (ER). The catalytic A1 polypeptide then dissociates from the rest of the toxin and assumes an unfolded conformation that facilitates its transfer to the cytosol by a process involving the quality control system of ER-associated degradation. Productive intoxication is blocked by alterations to the vesicular transport of CT and/or the ER-to-cytosol translocation of CTA1. Various plant compounds have been reported to inhibit the cytopathic activity of CT, so in this work we evaluated the potential anti-CT properties of grape extract. Two grape extracts currently sold as nutritional supplements inhibited CT and Escherichia coli heat-labile toxin activity against cultured cells and intestinal loops. CT intoxication was blocked even when the extracts were added an hour after the initial toxin exposure. A specific subset of host-toxin interactions involving both the catalytic CTA1 subunit and the cell-binding CTB pentamer were affected. The extracts blocked toxin binding to the cell surface, prevented unfolding of the isolated CTA1 subunit, inhibited CTA1 translocation to the cytosol, and disrupted the catalytic activity of CTA1. Grape extract could thus potentially serve as a novel therapeutic to prevent or possibly treat cholera.