Phenotypic and Genotypic Assays to Evaluate Coagulase-Negative Staphylococci Biofilm Production in Bloodstream Infections.

Coagulase-negative staphylococci (CoNS) are commensal on human body surfaces and, for years, they were not considered a cause of bloodstream infection and were often regarded as contamination. However, the involvement of CoNS in nosocomial infection is increasingly being recognized. The insertion of cannulas and intravascular catheters represents the primary source of CoNS entry into the bloodstream, causing bacteremia and sepsis. They owe their pathogenic role to their ability to produce biofilms on surfaces, such as medical devices. In this study, we evaluate the adhesive capacity of CoNS isolated from blood cultures by comparing a spectrophotometric phenotypic assay with genotypic analysis based on the evidence of the ica operon. We retrospectively reviewed the database of CoNS isolated from blood cultures from January to December 2021 that were considered responsible for 361 bloodstream infections. Eighty-nine CoNS were selected among these. Our data show that Staphylococcus epidermidis was the predominant species isolated, expressing greater adhesive capacities, especially those with the complete operon. Knowledge of the adhesive capabilities of a microorganism responsible for sepsis can be useful in implementing appropriate corrective and preventive measures, since conventional antibiotic therapy cannot effectively eradicate biofilms.

Clinical Trials of Cellular Therapies in Solid Tumors.

In the past years cancer treatments have drastically changed, mainly due to the development of immune checkpoint inhibitors capable of immune modulation in vivo, thus providing major clinical benefit in a number of malignancies. Simultaneously, considerable technical refinements have opened new prospects for the development of immune cell-based medicinal products and unprecedented success with chimeric antigen receptor (CAR)-T cells targeting B-cell hematologic malignancies has been obtained. However, T cell therapies introduced and performed in the field of solid tumors have produced so far only limited responses in selected patient populations. This standstill is attributable to the difficulty in identifying target antigens which are homogeneously expressed by all tumor cells while absent from normal tissues, and the limited T cell persistence and proliferation in a hostile tumor microenvironment that favors immune escape. Replicating the results observed in hematology is a major scientific challenge in solid tumors, and ongoing translational and clinical research is focused on obtaining insight into the mechanisms of tumor recognition and evasion, and how to improve the efficacy of cellular therapies, also combining them with immune checkpoint inhibitors or other agents targeting either the cancer cell or the tumor environment. This paper provides an overview of current adaptive T cell therapy approaches in solid tumors, the research performed to increase their efficacy and safety, and results from ongoing clinical trials.

Mycobacterium chimaera Identification Using MALDI-TOF MS Technology: A Practical Approach for the Clinical Microbiology Laboratories.

Mycobacterium chimaera (MC) is an environmental, slowly growing, non-tuberculous mycobacterium (NTM) belonging to Mycobacterium avium complex (MAC), which recently has been linked to severe cardiovascular infections following open heart and vascular surgery. The majority of the diagnostic laboratory tests used in routine are not able to distinguish MC from M. intracellulare (MI), because of the great genetic similarity existing between these two species. The Genotype Mycobacterium NTM-DR™ represents a valid method to differentiate between these species, but it is expensive, requiring also specialized personnel. Recently, MALDI-TOF MS has been proposed to identify relevant NTM. However, a software implementation is required to distinguish between MC and MI, presenting the two microorganisms' overlapping spectra. The present study evaluates the feasibility of applying a MALDI-TOF logarithmic-based analysis in the routine of a clinical microbiology laboratory, and proposes an easy-to-use template spreadsheet to make the results quickly interpretable. The protocol was previously validated through the identification of 87 strains of MC/MI collected from clinical and environmental samples, and it was identified using the GenoType Mycobacterium NTM-DR™ and/or WGS. The proposed protocol provides accurate identification for the isolates tested; moreover, it is less expensive and more rapid than sequencing methods and can be implemented with minimum effort.

A comprehensive report of long-term stability data for a range ATMPs: A need to develop guidelines for safe and harmonized stability studies.

BACKGROUND AIMS: Advanced therapy medicinal products (ATMPs) are novel drugs based on genes, cells or tissues developed to treat many different diseases. Stability studies of each new ATMP need to be performed to define its shelf life and guarantee efficacy and safety upon infusion, and these are presently based on guidelines originally drafted for standard pharmaceutical drugs, which have properties and are stored in conditions quite different from cell products. The aim of this report is to provide evidence-based information for stability studies on ATMPs that will facilitate the interlaboratory harmonization of practices in this area. METHODS: We have collected and analyzed the results of stability studies on 19 different cell-based experimental ATMPs, produced by five authorized cell factories forming the Lombardy "Plagencell network" for use in 36 approved phase I/II clinical trials; most were cryopreserved and stored in liquid nitrogen vapors for 1 to 13 years. RESULTS: The cell attributes collected in stability studies included cell viability, immunophenotype and potency assays, in particular immunosuppression, cytotoxicity, cytokine release and proliferation/differentiation capacity. Microbiological attributes including sterility, endotoxin levels and mycoplasma contamination were also analyzed. All drug products (DPs), cryopreserved in various excipients containing 10% DMSO and in different primary containers, were very stable long term at <-150°C and did not show any tendency for diminished viability or efficacy for up to 13.5 years. CONCLUSIONS: Our data indicate that new guidelines for stability studies, specific for ATMPs and based on risk analyses, should be drafted to harmonize practices, significantly reduce the costs of stability studies without diminishing safety. Some specific suggestions are presented in the discussion.

Human mesenchymal stromal cells do not express ACE2 and TMPRSS2 and are not permissive to SARS-CoV-2 infection.

Anti-inflammatory and immune-modulatory therapies have been proposed for the treatment of COVID-19 and its most serious complications. Among others, the use of mesenchymal stromal cells (MSCs) is under investigation given their well-documented anti-inflammatory and immunomodulatory properties. However, some critical issues regarding the possibility that MSCs could be infected by the virus have been raised. Angiotensin-converting enzyme 2 (ACE2) and type II transmembrane serine protease (TMPRSS2) are the main host cell factors for the severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2), entry, but so far it is unclear if human MSCs do or do not express these two proteins. To elucidate these important aspects, we evaluated if human MSCs from both fetal and adult tissues constitutively express ACE2 and TMPRSS2 and, most importantly, if they can be infected by SARS-CoV-2. We evaluated human MSCs derived from amnios, cord blood, cord tissue, adipose tissue, and bone marrow. ACE2 and TMPRSS2 were expressed by the SARS-CoV-2-permissive human pulmonary Calu-3 cell line but not by all the MSCs tested. MSCs were then exposed to SARS-CoV-2 wild strain without evidence of cytopathic effect. Moreover, we also excluded that the MSCs could be infected without showing lytic effects since their conditioned medium after SARS-CoV-2 exposure did not contain viral particles. Our data, demonstrating that MSCs derived from different human tissues are not permissive to SARS-CoV-2 infection, support the safety of MSCs as potential therapy for COVID-19.

Harnessing T Cells to Control Infections After Allogeneic Hematopoietic Stem Cell Transplantation.

Dramatic progress in the outcome of allogeneic hematopoietic stem cell transplantation (allo-HSCT) from alternative sources in pediatric patients has been registered over the past decade, providing a chance to cure children and adolescents in need of a transplant. Despite these advances, transplant-related mortality due to infectious complications remains a major problem, principally reflecting the inability of the depressed host immune system to limit infection replication and dissemination. In addition, development of multiple infections, a common occurrence after high-risk allo-HSCT, has important implications for overall survival. Prophylactic and preemptive pharmacotherapy is limited by toxicity and, to some extent, by lack of efficacy in breakthrough infections. T-cell reconstitution is a key requirement for effective infection control after HSCT. Consequently, T-cell immunotherapeutic strategies to boost pathogen-specific immunity may complement or represent an alternative to drug treatments. Pioneering proof of principle studies demonstrated that the administration of donor-derived T cells directed to human herpesviruses, on the basis of viral DNA monitoring, could effectively restore specific immunity and confer protection against viral infections. Since then, the field has evolved with implementation of techniques able to hasten production, allow for selection of specific cell subsets, and target multiple pathogens. This review provides a brief overview of current cellular therapeutic strategies to prevent or treat pathogen-related complications after HSCT, research carried out to increase efficacy and safety, including T-cell production for treatment of infections in patients with virus-naïve donors, results from clinical trials, and future developments to widen adoptive T-cell therapy access in the HSCT setting.

Management of PTLD After Hematopoietic Stem Cell Transplantation: Immunological Perspectives.

Post-transplant lymphoproliferative disorders (PTLDs) are life-threatening complications of iatrogenic immune impairment after allogeneic hematopoietic stem cell transplantation (HSCT). In the pediatric setting, the majority of PTLDs are related to the Epstein-Barr virus (EBV) infection, and present as B-cell lymphoproliferations. Although considered rare events, PTLDs have been increasingly observed with the widening application of HSCT from alternative sources, including cord blood and HLA-haploidentical stem cell grafts, and the use of novel agents for the prevention and treatment of rejection and graft-vs.-host disease. The higher frequency initially paralleled a poor outcome, due to limited therapeutic options, and scarcity of controlled trials in a rare disease context. In the last 2 decades, insight into the relationship between EBV and the immune system, and advances in early diagnosis, monitoring and treatment have changed the approach to the management of PTLDs after HSCT, and significantly ameliorated the prognosis. In this review, we summarize literature on the impact of combined viro-immunologic assessment on PTLD management, describe the various strategies for PTLD prevention and preemptive/curative treatment, and discuss the potential of novel immune-based therapies in the containment of this malignant complication.