Impact of Cryopreservation on Viability, Phenotype, and Functionality of Porcine PBMC

Acquisition of different transcriptional shear mRNA and biological function of porcine interleukin 18 binding protein in PRRSV infection

Interleukin-18 binding protein (IL-18BP), a natural regulator molecule of the pro-inflammatory cytokine interleukin-18 (IL-18), plays an important role in regulating the expression of the cellular immunity factor interferon-γ (IFN-γ). In a previous RNA-seq analysis of porcine alveolar macrophages (PAM) infected with the TIM and TJ strains of porcine reproductive and respiratory syndrome virus (PRRSV), we unexpectedly found that the mRNA expression of porcine interleukin 18-binding protein (pIL-18BP) in PAM cells infected with the TJM strain was significantly higher than that infected with the TJ strain. Studies have shown that human interleukin-18 binding protein (hIL-18bp) plays an important role in regulating cellular immunity in the course of the disease. However, there is a research gap on pIL-18BP. At the same time, PRRSV infection in pigs triggers weak cellular immune response problems. To explore the expression and the role of pIL-18BP in the cellular immune response induced by PRRSV, we strived to acquire the pIL-18BP gene from PAM or peripheral blood mononuclear cell (PBMC) with RT-PCR and sequencing. Furthermore, pIL-18BP and pIL-18 were both expressed prokaryotically and eukaryotically. The colocalization and interaction based on recombinant pIL-18BP and pIL-18 on cells were confirmed in vitro. Finally, the expression of pIL-18BP, pIL-18, and pIFN-γ was explored in pigs with different PRRSV infection states to interpret the biological function of pIL-18BP in vivo. The results showed there were five shear mutants of pIL-18BP. The mutant with the longest coding region was selected for subsequent functional validation. First, it was demonstrated that TJM-induced pIL-18BP mRNA expression was higher than that of TJ. A direct interaction between pIL-18BP and pIL-18 was confirmed through fluorescence colocalization, bimolecular fluorescent complimentary (BIFC), and co-immunoprecipitation (CO-IP). pIL-18BP also can regulate pIFN-γ mRNA expression. Finally, the expression of pIL-18BP, pIL-18, and pIFN-γ was explored in different PRRSV infection states. Surprisingly, both mRNA and protein expression of pIL-18 were suppressed. These findings fill the gap in understanding the roles played by pIL-18BP in PRRSV infection and provide a foundation for further research.IMPORTANCEPRRSV-infected pigs elicit a weak cellular immune response and the mechanisms of cellular immune regulation induced by PRRSV have not yet been fully elucidated. In this study, we investigated the role of pIL-18BP in PRRSV-induced immune response referring to the regulation of human IL-18BP to human interferon-gamma (hIFN-γ). This is expected to be used as a method to enhance the cellular immune response induced by the PRRSV vaccine. Here, we mined five transcripts of the pIL-18BP gene and demonstrated that it interacts with pIL-18 and regulates pIFN-γ mRNA expression. Surprisingly, we also found that both mRNA and protein expression of pIL-18 were suppressed under different PRRSV strains of infection status. These results have led to a renewed understanding of the roles of pIL-18BP and pIL-18 in cellular immunity induced by PRRSV infection, which has important implications for the prevention and control of PRRS.

Comparison of the Single Cell Immune Landscape between Subjects with High Mycobacterium tuberculosis Bacillary Loads during Active Pulmonary Tuberculosis and Household Members with Latent Tuberculosis Infection

It is unclear how the immune system controls the transition from latent tuberculosis (TB) infection (LTBI) to active pulmonary infection (PTB). Here, we applied mass spectrometry cytometry time-of-flight (CyTOF) analysis of peripheral blood mononuclear cells to compare the immunological landscapes in patients with high tuberculous bacillary load PTB infections and LTBI. A total of 32 subjects (PTB [n = 12], LTBI [n = 17], healthy volunteers [n = 3]) were included. Participants with active PTBs were phlebotomized before administering antituberculosis treatment, whereas participants with LTBI progressed to PTB at the time of household screening. In the present study, CyTOF analysis identified significantly higher percentages of mucosal-associated invariant natural killer T (MAIT NKT) cells in subjects with LTBI than in those with active PTB and healthy controls. Moreover, 6 of 17 (35%) subjects with LTBI progressed to active PTB (LTBI progression) and had higher proportions of MAIT NKT cells and early NKT cells than those without progression (LTBI non-progression). Subjects with LTBI progression also showed a tendency toward low B cell levels relative to other subject groups. In conclusion, MAIT NKT cells were substantially more prevalent in subjects with LTBI, particularly those with progression to active PTB.

Fresh or frozen grafts for allogeneic stem cell transplantation: conceptual considerations and a survey on the practice during the COVID-19 pandemic from the EBMT Infectious Diseases Working Party (IDWP) and Cellular Therapy & Immunobiology Working Party (CTIWP)

The COVID-19 pandemic has had a significant impact on medical practices, including the delivery of allogeneic hematopoietic cell transplantation (HCT). In response, transplant centers have made changes to their procedures, including an increased use of cryopreservation for allogeneic haematopoietic progenitor cell (HPC) grafts. The use of cryopreserved grafts for allogeneic HCT has been reviewed and analysed in terms of potential benefits and drawbacks based on existing data on impact on cell subsets, hematological recovery, and clinical outcomes of approximately 2000 patients from different studies. A survey of European Society for Blood and Marrow Transplantation centers was also conducted to assess changes in practice during the pandemic and any unnecessary burdens on HPC donors. Before the pandemic, only 7.4% of transplant centers were routinely cryopreserving HPC products, but this percentage increased to 90% during the pandemic. The results of this review and survey suggest that cryopreservation of HPC grafts is a viable option for allogeneic HCT in certain situations, but further research is needed to determine long-term effects and ethical discussions are required to balance the needs of donors and patients when using frozen allografts.

High-throughput measurement of double strand break global repair phenotype in peripheral blood mononuclear cells after long-term cryopreservation

Peripheral blood mononuclear cells (PBMCs) are a useful model for biochemical assays, particularly for etiological studies. We describe here a method for measuring DNA repair capacity (DRC) in archival cryogenically preserved PBMCs. To model DRC, we measured γ-H2AX repair kinetics in thawed PBMCs after irradiation with 3 Gy gamma rays. Time-dependent fluorescently labeled γ-H2AX levels were measured at five time points from 1 to 20 h, yielding an estimate of global DRC repair kinetics as well as a measure of unrepaired double strand breaks at 20 h. While γ-H2AX levels are traditionally measured by either microscopy or flow-cytometry, we developed a protocol for imaging flow cytometry (IFC) that combines the detailed information of microscopy with the statistical power of flow methods. The visual imaging component of the IFC allows for monitoring aspects such as cellular health and apoptosis as well as fluorescence localization of the γ-H2AX signal, which ensures the power and significance of this technique. Application of a machine-learning based image classification improved flow cytometry fluorescent measurements by identifying apoptotic cells unable to undergo DNA repair. We present here DRC repair parameters from 18 frozen archival PBMCs and 28 fresh blood samples collected from a demographically diverse cohort of women measured in a high-throughput IFC format. This thaw method and assay can be used alone or in conjunction with other assays to measure etiological phenotypes in cryogenic biobanks of PBMCs.

A semi high-throughput whole blood-based flow cytometry assay to detect and monitor Bordetella pertussis-specific Th1, Th2 and Th17 responses

Introduction

The characterization of B. pertussis (Bp) antigen-specific CD4⁺ T cell cytokine responses should be included in the evaluation of immunogenicity of pertussis vaccines but is often hindered by the lack of standardized robust assays.

Methods

To overcome this limitation, we developed a two-step assay comprising a short-term stimulation of fresh whole blood with Bp antigens and cryopreservation of the stimulated cells, followed later on by batch-wise intracellular cytokine analysis by flow cytometry. Blood samples collected from recently acellular (aP) vaccine boosted subjects with a whole-cell- or aP-primed background was incubated for 24 hrs with Pertussis toxin, Filamentous hemagglutinin or a Bp lysate (400µl per stimulation). Antigen-specific IFN-γ-, IL-4/IL-5/IL-13-, IL-17A/IL-17F- and/or IL-22-producing CD4⁺ T cells were quantified by flow cytometry to reveal Th1, Th2, and Th17-type responses, respectively. The frequencies of IFN-γ-producing CD8⁺ T cells were also analyzed.

Results

We demonstrate high reproducibility of the Bp-specific whole blood intracellular staining assay. The results obtained after cryopreservation of the stimulated and fixed cells were very well correlated to those obtained without cryopreservation, an approach used in our previously published assay. Optimization resulted in high sensitivity thanks to very low non-specific backgrounds, with reliable detection of Bp antigen-specific Th1, Th2 and Th17-type CD4⁺ T cells, in the lowest range frequency of 0.01-0.03%. Bp antigen-specific IFN-γ⁺ CD8⁺ T lymphocytes were also detected. This test is easy to perform, analyse and interpret with the establishment of strict criteria defining Bp antigen responses.

Discussion

Thus, this assay appears as a promising test for evaluation of Bp antigen-specific CD4⁺ T cells induced by current and next generation pertussis vaccines.

The FlagT4G Vaccine Confers a Strong and Regulated Immunity and Early Virological Protection against Classical Swine Fever

Control of classical swine fever virus (CSFV) in endemic countries relies on vaccination, mostly using vaccines that do not allow for differentiation of vaccinated from infected animals (DIVA). FlagT4G vaccine is a novel candidate that confers robust immunity and shows DIVA capabilities. The present study assessed the immune response elicited by FlagT4G and its capacity to protect pigs for a short time after vaccination. Five days after a single dose of FlagT4G vaccine, animals were challenged with a highly virulent CSFV strain. A strong, but regulated, interferon-α response was found after vaccination. Vaccinated animals showed clinical and virological protection against the challenge, in the absence of antibody response at 5 days post-vaccination. Upon challenge, a rapid rise in the titers of CSFV neutralizing antibodies and an increase in the IFN-γ producing cells were noticed in all vaccinated-challenged pigs. Meanwhile, unvaccinated pigs showed severe clinical signs and high viral replication, being euthanized before the end of the trial. These animals were unable to generate neutralizing antibodies and IFN-γ responses after the CSFV challenge. The results from the present study assert the fast and efficient protection by FlagT4G, a highly promising tool for CSFV control worldwide.