H2M3wt-restricted, Listeria monocytogenes-immune CD8 T cells respond to multiple formylated peptides and to a variety of gram-positive and gram- negative bacteria

A subset of H2M3wt-restricted, Listeria monocytogenes (LM)-immune CD8 effectors recognize antigen-presenting cells (APC) preincubated with heat-killed LM. The responsible product, which we have previously designated heat-killed Listeria-associated antigen (HAA), is extremely hydrophobic and resistant to proteolytic degradation. Despite the protease resistance of HAA, we now report that HAA-immune clones are uniformly responsive to fMIGWII, a formylated oligopeptide derived from the recently described LM product, lemA. While fMIGWII was by far the most potent peptide tested, over half our clones also responded to the LM-derived peptide fMIVII and cross-reactive responses to two other unrelated formylated peptides at concentrations of <1 microM were frequently observed. One of these peptides (fBlaZ) did not share any amino acid in common with fMIGWII except N-formyl methionine at position 1. Unformylated variants of the same peptides were inactive. HAA-immune CD8 cells also responded in an H2M3wt-restricted manner to APC pretreated with heat-killed or live preparations of other gram- positive and gram-negative bacteria such as Streptococcus pyogenes (SP) and Proteus vulgaris (PV). Unlike fMIGWII which is water soluble and protease sensitive, the native antigens extracted from SP and PV, like HAA, were very hydrophobic and proteinase K resistant, presumably reflecting in each case the association of cross-reactive polypeptides with bacterial lipid or phospholipid. Thus, HAA/lemA-immune, H2M3wt- restricted effectors can respond to a variety of formylated peptides and bacterial antigens in vitro. Similar cross-reactions in vivo might have physiologically significant implications.      

Prior chemotherapy and allograft CD34+ dose impact donor engraftment following nonmyeloablative allogeneic stem cell transplantation in patients with solid tumors

Significant engraftment variability occurs among patients following nonmyeloablative hematopoietic cell transplantation. We analyzed the impact of multiple factors on donor myeloid and T-cell engraftment in 36 patients with metastatic tumors undergoing cyclophosphamide/fludarabine-based conditioning. Higher CD34(+) doses facilitated donor myeloid engraftment, while prior chemotherapy exposure facilitated both donor myeloid and T-cell engraftment. At day 30, median donor T-cell and myeloid chimerism was 98% and 76%, respectively, in those patients with prior chemotherapy versus 88% (P =.008) and 26% (P <.0001) in chemotherapy-naive patients. Donor myeloid chimerism at day 45 was predicted by prior chemotherapy exposure and the log(10) of the CD34(+) dose (adjusted coefficient of determination [R(2)] =.47; P <.0001), while chemotherapy alone impacted donor T-cell engraftment. Patients with prior chemotherapy were more likely to develop acute grades II to IV graft-versus-host disease (GVHD; 8/18) compared with chemotherapy-naive patients (2/18; P =.031). Thus, tailoring the intensity of nonmyeloablative conditioning based on prior chemotherapy exposure is an important consideration in trial design.     

Regression and Random Forest Machine Learning Have Limited Performance in Predicting Bowel Preparation in Veteran Population

Digestive Diseases and Sciences - Inadequate bowel preparation undermines the quality of colonoscopy, but patients likely to be affected are difficult to identify beforehand. This study aimed to...     

Using Health Systems Engineering Approaches to Prepare for Tailoring of Implementation Interventions

BackgroundImplementation of evidence-based practices often requires tailoring implementation strategies to local contextual factors, including available resources, expertise, and cultural norms. Using an exemplar case, we describe how health systems engineering methods can be used to understand system-level variation that must be accounted for prior to broad implementation.MethodsWithin the context of a single-center quality improvement activity, a multi-disciplinary stakeholder team used health systems engineering methods to describe how pre-endoscopy antithrombotic management was executed, and implemented a redesigned process to improve clinical care. The research team then conducted multiple stakeholder focus groups at four different health-care systems to describe and compare current processes for pre-endoscopy antithrombotic medication management. Detailed work flow maps for each health-care system were developed, analyzed, and integrated to develop an overarching current work flow map, identify key process steps, and describe areas of process variation.ResultsFive key process steps were identified across the four health systems: (1) place an endoscopy order, (2) screen for antithrombotic use, (3) coordinate medication management, (4) instruct the patient, and (5) confirm appropriate medication management before procedure. Across health systems, we found a high degree of variation in each step (e.g., who performed, use of technology, systematic vs. ad hoc process). This variation was influenced by two key system-level contextual factors: (1) degree of health system integration and (2) role and training level of available staff. These key steps, areas of variation, and contextual factors were integrated into an assessment tool designed to facilitate tailoring of a future implementation and dissemination strategy.ConclusionsTools from health systems engineering can be used to identify key work flow process steps, variations in how those steps are executed, and influential contextual factors. This process and the associated assessment tool may facilitate broader implementation tailoring.Electronic supplementary materialThe online version of this article (10.1007/s11606-020-06121-5) contains supplementary material, which is available to authorized users.KEY WORDS: implementation, dissemination, adaptation, quality improvement, health systems engineering     

Defects in mononuclear phagocytic system (MPS) function in autoimmune MRL-lpr/lpr mice

MRL-lpr/lpr mice develop an autoimmune disease similar to systemic lupus erythematosus. To determine whether mice of this strain develop defects in mononuclear phagocyte system (MPS) function similar to those observed in patients, the pattern of sequestration of labeled immune complexes was compared 90 min after infusion into MRL-lpr/lpr and into normal B6D2 mice. The amount of complexes persisting in the blood was increased, and the amount sequestered in the liver was significantly reduced in MRL-lpr/lpr mice in comparison to normal B6D2 controls. This defect was most evident in MRL-lpr/lpr mice of the ages of 25-26 weeks; mice of this age also demonstrated the greatest elevation of anti-DNA antibody levels. The role of the MRL strain background and of the lpr gene in determining this defect was investigated by analysis of MRL-+/-/+/- and of other lpr congenic strains (B6-lpr/lpr, AKR-lpr/lpr, and C3H-lpr/lpr). Both MRL-+/-/+/- and congenic lpr animals showed similar defects, although to a lesser degree than MRL-lpr/lpr mice. In contrast, MRL-lpr/lpr mice demonstrated normal clearance of heat-damaged red blood cells and heat-aggregated albumin. Thus MRL-lpr/lpr mice display a selective defect in MPS Fc receptor function and may provide a valuable model for elucidating the etiology and importance of MPS dysfunction in immune complex deposition disease.     

Recombinant lemA without adjuvant induces extensive expansion of H2-M3-restricted CD8 effectors, which can suppress primary listeriosis in mice.

Mice infected with Listeria monocytogenes (LM) produce large numbers of H2-M3-restricted CD8 T cells directed against the formylated peptides, f-MIGWII and f-MIVIL. To examine responsiveness to these epitopes in the absence of infection, we inoculated mice with recombinant lemA (r-lemA) containing f-MIGWII or r-vemA (a variant of r-lemA containing f-MIVIL in place of f-MIGWII) without adjuvant. To monitor responses, we measured peptide-specific cytoplasmic IFN-gamma production ex vivo by freshly harvested splenocytes at varying times post-inoculation. B6 mice inoculated with r-lemA produced substantial numbers of epitope-specific CD8 cells with peak levels on day 7 when there were 1.1 x 10(6) f-MIGWII-specific CD8 cells in the spleen (8.2% of total CD8 splenocytes). The r-vemA-treated animals accumulated 0.25 x 10(6) cells (1.8% of total CD8 cells) at this time point. Comparable responses were observed after rechallenge of immunized animals. Other elements in the lemA moiety distinct from the immunogenic peptide were required since mice did not respond to equimolar amounts of synthetic f-MIGWII or f-MIVIL alone. In comparative studies, B6 and C3H/HeJ mice responded to r-lemA much more vigorously than BALB/c animals. When r-lemA- or r-vemA-treated B6 animals were challenged i.v. with LM 7 days later, they suppressed splenic accumulation of bacteria much more effectively than controls. On the other hand, antigen-treated animals were not protected against infection 1 month later. Thus, responsive strains of mice respond vigorously to H2-M3-restricted epitopes, even in the absence of bacterial infection or adjuvant. The resulting effectors acutely enhance antimicrobial resistance but do not confer long-term memory protection.