Heparin and EDTA as anticoagulant differentially affect cytokine mRNA level of cultured porcine blood cells

Porcine Peripheral Blood Mononuclear Cells (PBMCs): Methods of Isolation, Cryopreservation, and Translational Applications in Human Studies

Porcine peripheral blood mononuclear cells (pPBMCs) are increasingly recognized as a valuable model in biomedical and translational research, particularly in contexts directly related to human health and disease. Their immunological features, such as the presence of CD4+CD8+ double-positive T cells and cytokine expression patterns, exhibit a notable degree of similarity to human immune cells, making them an attractive tool for studying human-relevant immune responses. This review outlines current methodologies for isolating and cryopreserving pPBMCs, with a focus on maintaining high cell viability and functionality. Key technical considerations, including the optimal use of gradient media, appropriate anticoagulants, and standardized freezing/thawing protocols, are discussed in detail. Furthermore, the article highlights the applications of pPBMCs in various research contexts, including vaccine development, inflammation studies, infection models, and xenotransplantation. A comparative perspective is provided to identify similarities and differences between porcine and human PBMCs, supporting the validity of swine as a translational model. Evidence from pPBMC-based studies has shown predictive value for human outcomes, reinforcing their role as a surrogate system for preclinical investigations. Given their anatomical, physiological, and immunogenetic similarities to humans, porcine PBMCs represent a valuable bridge between basic science and clinical application, playing an increasingly important role in translational medicine.

Long-term monocyte activation after coronary artery bypass grafting: An exploratory prospective observational study

Major surgery such as coronary artery bypass grafting (CABG) is associated with an increased post-operative risk of atherosclerotic cardiovascular events. Cells of the innate immune system can adopt a long-lasting pro-inflammatory and atherogenic phenotype after brief exposure to exogenous or endogenous inflammatory stimuli, a process called "trained immunity". We hypothesized that the surgery-induced inflammation leads to sustained alterations in monocyte function, which promote the subsequent occurrence of cardiovascular events. Blood from 13 patients undergoing elective CABG was obtained before, 3-7 days (median 4) after, and 6-8 weeks (median 6) weeks after surgery. At 3-7 days postoperatively, circulating C-reactive protein (CRP) concentration, leukocyte counts and ex vivo Peripheral Blood Mononuclear Cell (PBMC) IL-6, TNFα and IL-1Ra production after stimulation (with various inflammatory stimuli) were significantly increased. Simultaneously, there was a reduction in monocyte HLA-DR expression. 6-8 weeks after CABG there was an ongoing systemic pro-inflammatory state with higher CRP concentrations, increased stimulated ex vivo PBMC IL-6 production, changes in monocytes subsets, and a higher expression of CCR2 on monocytes compared to baseline. In conclusion, CABG induces a persistent systemic inflammatory reaction with a sustained activated monocyte phenotype. This might contribute to the increased atherosclerotic cardiovascular event risk observed in cardiac surgery patients.

Rules of thumb to obtain, isolate, and preserve porcine peripheral blood mononuclear cells

One of the most used biospecimens in immunology are peripheral blood mononuclear cells (PBMC). PBMC are particularly useful when evaluating immunity through responses of circulating B- and T-cells, during an infection, or after a vaccination. While several reviews and research papers have been published aiming to point out critical steps when sampling, isolating, and cryopreserving human PBMC -or even analyzing any parameter before sampling that could impair the immune assays' outcomes-, there are almost no publications in swine research dealing with these topics. As it has been demonstrated, several factors, such as stress, circadian rhythmicity, or the anticoagulant used have serious negative impact, not only on the separation performance of PBMC, but also on the ulterior immune assays. The present review aims to discuss studies carried out in humans that could shed some light for swine research. When possible, publications in pigs are also discussed. The main goal of the review is to encourage swine researchers to standardize protocols to obtain, manage and preserve porcine PBMC, as well as to minimize, or at least to consider, the bias that some parameters might induce in their studies before, during and after isolating PBMC.

Protocol for the assessment of human T cell activation by real-time metabolic flux analysis

The elevation of glycolysis in autoreactive T cells is a key target for the prevention and treatment of T cell-related autoimmune diseases, such as type 1 diabetes (T1D). Here, we describe a simple and efficient protocol for isolating human peripheral blood mononuclear cells (PBMCs) and T cells, and the subsequent assessment of T cell glycolysis using Seahorse analyzer. This protocol is useful to analyze different subsets of T cells and applicable to different autoimmune disease models (i.e., T1D, multiple sclerosis). For complete details on the use and execution of this profile, please refer to Kong et al. (2021).

The Overt and Hidden Use of Animal-Derived Products in Alternative Methods for Skin Sensitisation: A Systematic Review

In vitro methods that can replace animal testing in the identification of skin sensitisers are now a reality. However, as cell culture and related techniques usually rely on animal-derived products, these methods may be failing to address the complete replacement of animals in safety assessment. The objective of this study was to identify the animal-derived products that are used as part of in vitro methods for skin sensitisation testing. Thus, a systematic review of 156 articles featuring 83 different in vitro methods was carried out and, from this review, the use of several animal-derived products from different species was identified, with the use of fetal bovine serum being cited in most of the methods (78%). The use of sera from other animals, monoclonal antibodies and animal proteins were also variously mentioned. While non-animal alternatives are available and methods free of animal-derived products are emerging, most of the current methods reported used at least one animal-derived product, which raises ethical and technical concerns. Therefore, to deliver technically and ethically better in vitro methods for the safety assessment of chemicals, more effort should be made to replace products of animal origin in existing methods and to avoid their use in the development of new method protocols.

Detection of circulating extracellular mRNAs by modified small-RNA-sequencing analysis

Extracellular mRNAs (ex-mRNAs) potentially supersede extracellular miRNAs (ex-miRNAs) and other RNA classes as biomarkers. We performed conventional small-RNA-sequencing (sRNA-seq) and sRNA-seq with T4 polynucleotide kinase (PNK) end-treatment of total exRNA isolated from serum and platelet-poor EDTA, ACD, and heparin plasma to study the effect on ex-mRNA capture. Compared to conventional sRNA-seq PNK-treatment increased the detection of informative ex-mRNAs reads up to 50-fold. The exRNA pool was dominated by hematopoietic cells and platelets, with additional contribution from the liver. About 60% of the 15- to 42-nt reads originated from the coding sequences, in a pattern reminiscent of ribosome-profiling. Blood sample type had a considerable influence on the exRNA profile. On average approximately 350 to 1,100 distinct ex-mRNA transcripts were detected depending on plasma type. In serum, additional transcripts from neutrophils and hematopoietic cells increased this number to near 2,300. EDTA and ACD plasma showed a destabilizing effect on ex mRNA and non-coding RNA ribonucleoprotein complexes compared to other plasma types. In a proof-of-concept study, we investigated differences between the exRNA profiles of patients with acute coronary syndrome (ACS) and healthy controls. The improved tissue resolution of ex mRNAs after PNK-treatment enabled us to detect a neutrophil-signature in ACS that escaped detection by ex miRNA analysis.

Characterization of the blastogenic response to LPS of bovine peripheral blood mononuclear cells

Mitogens are diverse compounds of plant and microbial origin, widely employed to test immunocompetence in animals. The blastogenic response of bovine Peripheral Blood Mononuclear Cells (PBMC) to lypopolysaccharides (LPS) has been investigated in our laboratories for a long time. In particular, a possible correlation between blastogenic response to LPS and disease resistance of periparturient dairy cows had been observed in previous studies. Most important, low responder cows presented a higher frequency of disease cases after calving, compared with high responder animals. Owing to the above, different aspects of the blastogenic response to LPS were investigated on PBMC of healthy Friesian cows, using a 72-hour Bromodeoxyuridin (BrDU) cell proliferation assay. Stimulation with LPS induced little if any replication of bovine PBMC over 72 hours despite consistent BrDU detection in all the PBMC samples under study. Poor replication of LPS-stimulated PBMC was confirmed by cell cycle and cell growth flow cytometry analyses. In particular, LPS stimulation gave rise to very low percentages of S phase cells, sometimes lower than in control, unstimulated cells, as opposed to Concanavalin A-stimulated PBMC. Magnetic separation and analysis of BrDU-treated bovine PBMC after exposure to LPS showed that both B and CD4 T cells are involved in the blastogenic response to LPS, in contrast with current data based on human and murine models. Finally, LPS caused an early, specific up-regulation of TNF-α and TLR4 genes in bovine PBMC, and significant correlations were shown between the expression of inflammatory cytokine and Indoleamine-pyrrole 2,3-dioxygenase (IDO1) genes. On the whole, our data indicate that differences in the blastogenic response to LPS could be partly accounted for by heterogenicity of responding cells (B and T lymphocytes), which might also have an impact on induction and regulation of inflammatory responses and endotoxin tolerance.

Effect of age on chronic inflammation and responsiveness to bacterial and viral challenges

To identify reliable biomarkers of age-related changes in chronic inflammation and responsiveness to bacterial and viral challenges, we evaluated endogenous and ex vivo stimulated levels of 18 inflammatory markers, using whole blood collected in EDTA and sodium heparin tubes from 41 healthy volunteers, i.e., 11 men + 10 women aged 20–35 and 10 men + 10 women aged 50–77. These studies revealed significant differences in the levels of inflammatory markers when blood was collected in EDTA versus sodium heparin and age related differences in these biomarkers were confirmed with blood collected in EDTA from 120 healthy volunteers in 3 age categories, ie, 20 men + 20 women, aged 20–35, 36–49 and 50–77. Studies with unstimulated blood samples, to measure levels of chronic inflammation, revealed a significant increase with age in IL-12p70, CRP and PGE₂, consistent with the concept of “inflammaging”, and a decrease in G-CSF in both men and women. Interestingly, in response to E. coli stimulation, PGE₂ levels were markedly reduced in the 50–77 year old cohort while they were increased following Herpes Simplex virus-1 (HSV-1) stimulation, along with IL-8. In addition, unlike E. coli, HSV-1 potently stimulated IFNα production, but levels were dramatically reduced in the older cohort, consistent with a reduced ability to generate an anti-viral response. We also found platelets and CD8⁺ T cells were reduced with age while CD4⁺ T cells were significantly increased, resulting in a substantially higher CD4/CD8 ratio in the older cohort. Surprisingly, however, we found that the older cohort exhibited more T cell proliferation and IFNγ production in response to anti-CD3+anti-CD28 stimulation. Importantly, there was considerable person-to-person variation in these inflammatory markers in all age groups, making possible comparisons between a person’s “inflammage” and chronological age. These assays should help to identify individuals at high risk of autoimmune disorders and cancer.

Dynamics of cytokine gene expression in peripheral blood mononuclear cells of indigenous and exotic breeds of pigs in India

To incorporate immune competence traits in swine breeding programs, association between immune responsiveness and susceptibility to specific infectious diseases must be established. In order to understand the differences in immune competence between indigenous (Zovawk) and exotic (Large White Yorkshire: LWY) pigs reared in India, we carried out a time course expression analysis of immune-regulating key cytokine genes (interleukin (IL)-2, interferon (IFN)-γ, IL-4 and IL-10) in the phytohemagglutinin-P stimulated peripheral blood mononuclear cells (PBMCs). The IL-2 transcript levels in PBMCs increased several thousand-fold when compared to unstimulated cells in both the breeds, albeit the response in that of Zovawk was remarkably higher. Higher and earlier IFN-γ and IL-4 expression levels in Zovawk pigs suggest that both T_H 1 and T_H 2 immune responsiveness of this indigenous breed affords better preparedness for danger signals. Moreover, the low expression levels of IL-10 depict a regulated adaptive immune responsiveness. Remarkable difference between the two breeds of the pigs is evident showing a clear advantage of the Zovawk over LWY in terms of a shorter lag period of adaptive immune response. These findings provide a lead for understanding the genetic differences with respect to immune competence levels of indigenous pigs compared to exotic counterparts.

Analytical Aspects of the Implementation of Biomarkers in Clinical Transplantation

In response to the urgent need for new reliable biomarkers to complement the guidance of the immunosuppressive therapy, a huge number of biomarker candidates to be implemented in clinical practice have been introduced to the transplant community. This includes a diverse range of molecules with very different molecular weights, chemical and physical properties, ex vivo stabilities, in vivo kinetic behaviors, and levels of similarity to other molecules, etc. In addition, a large body of different analytical techniques and assay protocols can be used to measure biomarkers. Sometimes, a complex software-based data evaluation is a prerequisite for appropriate interpretation of the results and for their reporting. Although some analytical procedures are of great value for research purposes, they may be too complex for implementation in a clinical setting. Whereas the proof of "fitness for purpose" is appropriate for validation of biomarker assays used in exploratory drug development studies, a higher level of analytical validation must be achieved and eventually advanced analytical performance might be necessary before diagnostic application in transplantation medicine. A high level of consistency of results between laboratories and between methods (if applicable) should be obtained and maintained to make biomarkers effective instruments in support of therapeutic decisions. This overview focuses on preanalytical and analytical aspects to be considered for the implementation of new biomarkers for adjusting immunosuppression in a clinical setting and highlights critical points to be addressed on the way to make them suitable as diagnostic tools. These include but are not limited to appropriate method validation, standardization, education, automation, and commercialization.

Cytokine-like Activity of Liver Type Fatty Acid Binding Protein (L-FABP) Inducing Inflammatory Cytokine Interleukin-6

It has been reported that fatty acid binding proteins (FABPs) do not act only as intracellular mediators of lipid responses but also have extracellular functions. This study aimed to investigate whether extracellular liver type (L)-FABP has a biological activity and to determined serum L-FABP levels in patients with end-stage renal disease (ESRD). We isolated L-FABP complementary deoxyribonucleic acid (cDNA) from the Huh7 human hepatocarcinoma cell line and expressed the recombinant L-FABP protein in Escherichia coli. A549 lung carcinoma and THP-1 monocytic cells were stimulated with the human recombinant L-FABP. Human whole blood cells were also treated with the human recombinant L-FABP or interleukin (IL)-1α. IL-6 levels were measured in cell culture supernatants using IL-6 enzyme-linked immunosorbent assay (ELISA). Human recombinant L-FABP induced IL-6 in a dose-dependent manner in A549, THP-1 cells, and whole blood cells. The blood samples of healthy volunteers and patients with ESRD were taken after an overnight fast. The serum levels of L-FABP in healthy volunteers and ESRD patients were quantified with L-FABP ELISA. The values of L-FABP in patients with ESRD were significantly lower than those in the control group. Our results demonstrated the biological activity of L-FABP in human cells suggesting L-FABP can be a mediator of inflammation.

Genome-wide Long Non-coding RNA Analysis Identified Circulating LncRNAs as Novel Non-invasive Diagnostic Biomarkers for Gynecological Disease

Increasing evidence indicates that long non-coding RNAs (lncRNAs) play important roles in human diseases. This study aimed to investigate the tissue and serum lncRNAs that are differentially expressed between patients with endometriosis, a gynecological disease, to evaluate the potential of these lncRNAs as non-invasive markers for the disease. The differentially expressed lncRNAs as competing endogenous RNAs (ceRNAs) were also analyzed to predict their functions in disease development. Genome-wide profiling of lncRNA expression patterns revealed that many lncRNAs were abnormally expressed between sera and tissuesof the patient samples. A set of aberrant differentially expressed lncRNAs were further validated in a validation cohort of 110 serum and 24 tissue samples. Functional analysis predicted that differentially expressed lncRNAs may participate in disease development through crosstalk between the ceRNAs of miRNAs and may be involved in a range of cellular pathways including steroid or hormone responses. We also found a unique set of lncRNAs that were associated with disease severity and progression, and their diagnostic values were also investigated. Our study demonstrated that lncRNAs could potentially serve as non-invasive biomarkers for the diagnosis of endometriosis and as important regulators in the progression of this disease.

Extended Microbiological Characterization of Göttingen Minipigs in the Context of Xenotransplantation: Detection and Vertical Transmission of Hepatitis E Virus

Xenotransplantation has been proposed as a solution to the shortage of suitable human donors. Pigs are currently favoured as donor animals for xenotransplantation of cells, including islet cells, or organs. To reduce the xenotransplantation-associated risk of infection of the recipient the pig donor should be carefully characterised. Göttingen minipigs from Ellegaard are often used for biomedical research and are regularly tested by their vendor for the presence of numerous bacteria, fungi, viruses and parasites. However, screening for some pathogens transmittable to humans had not been performed.The presence of microorganisms was examined in Göttingen Minipigs by PCR methods. Since zoonotic transmission of porcine hepatitis E virus HEV to humans has been demonstrated, extended search for HEV was considered as a priority. RNA from sera, islet and other cells from 40 minipigs were examined for HEV using different real-time reverse transcription (RT)-PCRs, among them two newly established. In addition, sera were examined by Western blot analysis using two recombinant capsid proteins of HEV as antigens. HEV RNA was not detected in pigs older than one year including gilts, but it was detected in the sera of three of ten animals younger than 1 year. Furthermore, HEV was also detected in the sera of three sows six days after delivery and their offspring, indicating vertical transmission of the virus. PCR amplicons were cloned, sequenced and the viruses were found to belong to the HEV genotype (gt) 3/4. Anti-HEV immunoglobulins G were detected in one sow and maternal antibodies in her six day old piglet. Since Göttingen minipigs were negative for many xenotransplantation-relevant microorganisms, they can now be classified as safe. HEV may be eliminated from the Ellegaard herd by selection of negative animals and/or by treatment of the animals.

Influence of pre-analytical variables on VEGF gene expression and circulating protein concentrations

BACKGROUND

The extended role of vascular endothelial growth factor (VEGF) in human pathophysiology led us to evaluate pre-analytical parameters possibly influencing its levels in peripheral blood and tissues. The effects on VEGF protein levels and mRNA expression were measured after storage delay (blood and tissue), use of different types of anticoagulants (blood), and after different numbers of freeze-thaw cycles (blood).

METHODS

Blood from healthy donors was sampled simultaneously in ethylene diamine tetraacetic acid (EDTA), acid citrate dextrose (ACD-A), hirudin, and serum separation tubes. For each anticoagulant, VEGF was measured by enzyme-linked immunosorbent assay (ELISA) with different conditions of delay at 4°C before centrifugation (2 h, 4 h, or 48 h) and of different numbers of freeze-thaw cycles (1, 2, and 10). The transcripts coding for the VEGF165 isoform were quantified in peripheral blood mononuclear cells by RT-PCR. Muscle biopsy samples were frozen with delays of 15, 30, or 60 min after surgery. VEGF expression was quantified on immunofluorescence stained slides.

RESULTS

The period of storage and the number of freeze-thaw cycles correlated with an increase in the levels of circulating VEGF (for each anticoagulant but not for serum) and its expression in PBMCs. VEGF expression measured from muscle biopsy sections was higher with freezing delays, with a peak at 30 and 60 min as compared to 15 min.

CONCLUSIONS

The most reliable conditions for measuring both circulating VEGF and its gene expression are to reduce time between blood collection and centrifugation, and to avoid multiple freeze-thaw cycles. Serum collection tubes with no additive and no separator were less sensitive to the pre-analytical variations analyzed in this study. Freezing delay had a significant influence on VEGF protein expression in tissue samples.

Multiplexed measurements of immunomodulator levels in peripheral blood of healthy subjects: Effects of analytical variables based on anticoagulants, age, and gender

Multiplex microbead immunoassay (MMIA) is a powerful technology for a wide range of biomedical and clinical applications. It is important to study the normal concentration ranges of immunomodulators under different sample preparation conditions and age groups of subjects in order to more precisely determine their reference values for use in assessing alterations of their levels in disease. The aim of this study was to determine the plasma concentrations of immunomodulators (cytokines, chemokines, and growth factors) in the peripheral blood from healthy subjects by the use of a large multiplex panel, and to determine the effects of different anticoagulants, age, and gender on the immunomodulator levels. In addition, the assay precision for these biomarker analytes was determined. Plasma samples from 107 healthy subjects, aged 18 to 85 years, were collected in three different anticoagulants (sodium citrate, EDTA, Heparin); corresponding serum samples were also obtained. Multiplex microbead immunoassays were performed for measuring a total of 23 analytes including chemokines, cytokines, and growth factors (IL-1β, IL-1ra, IL-2, IL-6, IL-7, IL-8, IL-12 p70, IL-17, IFN-γ, IP-10, MCP-1, PDGF-BB, RANTES, TNF-α, IL-1a, IL-16, HGF, MIG, TNF-β, PDGF-ABBB, EGF, Flt-3 Ligand, VEGF). For these analytes, our results showed that the anticoagulant affected the concentration measurements and the coefficients of variation. However, the relative levels of the analytes (profiles) of samples collected in a particular anticoagulant are consistent. The analytes IL-1β, IL-7, Flt-3 Ligand, and IL-12p70 show the largest variation (up to fourfold) between the age groups. In addition, no statistically significant differences in the level of the analytes were found between the sexes.

Exploratory reference intervals on hematology and cellular immune system of multiparous Large White sows

There is significant lack of basic hematologic and immunological data in adult sows. Therefore, aim of this study was to provide respective reference intervals. 32 clinically healthy multiparous Large White sows aged 33.5 ± 9.6 months and all of them two months postpartum were included in this study. Mean erythrocyte count was 5.5 ± 0.7 × 10(6)/μl and total leukocyte count was 12.1 ± 2.1 × 10(3)/μl. Proportion of lymphocytes was 44.7 ± 10.2% and of neutrophils 41.6 ± 11.0%. The ratio of naïve T helper (Th) cells to memory Th cells was 1:3.1 and the ratio of Th cells to cytotoxic T cells (CTLs) was 1:4.2. Proportions of regulatory T cells, NK cells, and CD21(+) B cells were lower (3.1, 2.6, and 6.0%) than those of memory Th cells ranging from 8.8 to 27.5% depending on the activation status and CTLs with 37.3%. γδ T cells were found at comparably high numbers (19.1%). Flow cytometric measurement of intracellular cytokines in PBMCs revealed marginal levels for IL-1β, IL-2, IL-4, IL-6, IL-10, and IL-12p35, but remarkable levels for TNF-α and IFN-γ. Highest mRNA levels were found for IL-1, IL-10, and TNF-α, with TNF-α showing the least inter-individual variation.

Before you analyze a human specimen, think quality, variability, and bias

Personalized medicine requires capabilities to detect and measure health-associated biomarkers with increasingly specific and sensitive methods, putting analytical chemists at the front lines of translational research. Analytical scientists must be upstream in the experimental design process because the analysis of a biospecimen (tissue, blood, etc.) presents technical and experimental design complexities. (To listen to a podcast about this feature, please go to the Analytical Chemistry multimedia page at pubs.acs.org/page/ancham/audio/index.html.).

A direct immunoassay assessment of streptavidin- and N-hydroxysuccinimide-modified biochips in validation of serological TNFalpha responses in hemophagocytic lymphohistiocytosis

The authors report 2 biochip platforms on gold manufactured by either nanoscale biotinylated self-assembled architectures to streptavidin surface or proteins containing free NH(2) groups to N-hydroxysuccinimide (NHS)-activated surfaces and investigated the potential application of tumor necrosis factor-alpha (TNFalpha) serodiagnosis of hemophagocytic lymphohistiocytosis (HLH). Interactions of TNFalpha antigen and TNFalpha antibody on the biochips were optimized using an indirect immunofluorescence method. Variation coefficients were 1.87% to 4.56% on the streptavidin biochip and 5.03% to 8.64% on the NHS biochip. The correlation coefficients (r) in TNFalpha and TNFalpha antibody assays in HLH patients between the 2 biochip formats were 0.9623 and 0.9386 and the concordance frequencies were 92.2% and 96.1%, respectively. To detect plasma TNFalpha-receptor complexes (TNFR1 and R2) in HLH, a biochip assay strategy was developed. Plasma levels of TNFalpha, TNFalpha antibody, and TNFalpha-receptor complexes (TNFR1 and R2) were detected in plasmas from 42 HLH cases using streptavidin biochips. Frequencies of the biomarkers in the plasmas were 40.5% (17/42) for TNFalpha, 30.9% (13/42) for TNFalpha antibody, 28.6% (12/42) for TNFalpha-receptor 1 complex, and 26.1% (11/42) for TNFalpha-receptor 2 complex, respectively. The streptavidin biochip format was more sensitive than the NHS surface and was demonstrated to be a valuable tool to identify individual biomarker molecules and molecular complexes in sera and cell lysates and to track therapeutic progress of patients.