Whole blood assessment of antigen specific cellular immune response by real time quantitative PCR: a versatile monitoring and discovery tool

Functional Verification of Transcription Factor comp54181_c0 in Monascus purpureus

Monacolin K is a valuable secondary metabolite produced after a period of fermentation by Monascus purpureus; however, our current understanding of the regulatory mechanisms of its synthesis remains incomplete. This study conducted functional analysis on the key transcription factor, comp54181_c0, that is involved in the synthesis of monacolin K in Monascus. Mutant strains with either knockout or overexpression of comp54181_c0 were constructed using CRISPR/Cas9. A comparison between the knockout and overexpression strains revealed changes in fungal morphology and growth, with a significant increase in the production of Monascus pigments and monacolin K when comp54181_c0 was absent. Real-time fluorescence quantitative PCR analysis revealed that comp54181_c0 significantly influenced the transcription of key genes related to monacolin K biosynthesis in Monascus. In conclusion, our study elucidates the crucial role of comp54181_c0 in Monascus, enriches our understanding of fungal secondary metabolite development and regulation, and provides a foundation for the development and regulation of Monascus and monacolin K production.

Antigen Recognition and Immune Response to Acute and Chronic Hepatitis B Virus Infection

The antigen recognition and immune response to acute and chronic hepatitis B virus (HBV) infections are the result of both the innate and adaptive immune response. The innate immune response comprises Dendritic Cells (DCs), which served as professional antigen-presenting cells and a bridge between innate and adaptive immunity, Kupffer cells and inflammatory monocytes for the continuous inflammation of hepatocyte, neutrophils for hepatic tissue damage due to acute inflammation, type I interferons (IFN), which induce an antiviral state on infected cells, directs natural killer (NK) cells to kill virally infected cells, reduces the population of infected cells, and promotes the effective maturation and site recruitment of adaptive immunity through the production of pro-inflammatory cytokines and chemokines. Through stimulating B cells, T-helper, and cytotoxic T cells, the adaptive immune system also protects against hepatitis B infection. During HBV infection, a network of cell types that can either play protective or harmful functions creates the anti-viral adaptive immune response. These many elements, such as ‎Cluster of differentiation four (CD4) T cells (traditionally known as helper T cells), are potent cytokine producers and necessary for the effective maturation of effector cytotoxic cluster of differentiation eight (CD8) T cells and B cell antibody production. By cytolytic and non-cytolytic processes, CD8 T cells are able to eliminate HBV-infected hepatocytes and directly detect virus-infected cells, and circulating CD4+ CD25+ regulatory T cells for the modulation of immune system. In order to avoid reinfection, B cells can produce antibodies that destroy free viral particles. Moreover, by presenting HBV antigens to helper T cells, B cells may also influence how well these cells operate.

Overexpression of Monacolin K Biosynthesis Genes in the Monascus purpureus Azaphilone Polyketide Pathway

Monascus purpureus is an important food and drug microbial resource through the production of a variety of secondary metabolites, including monacolin K, a well-recognized cholesterol-lowering agent. However, the high production costs and naturally low contents of monacolin K have restricted its large-scale production. Thus, in this study we sought to improve the production of monacolin K in M. purpureus through overexpression of four genes ( mokC, mokD, mokE, and mokI). Four overexpression strains were successfully constructed by protoplast electric shock conversion, which resulted in a 234.3%, 220.8%, 89.5%, and 10% increase in the yield of monacolin K, respectively. The overexpression strains showed clear changes to the mycelium surface with obvious folds and the spores with depressions, whereas the pBC5 mycelium had a fuller structure with a flatter surface. Further investigation of these strains can provide the theoretical basis and technical support for the development of functional Monascus varieties.

Bioreactor-engineered cancer tissue-like structures mimic phenotypes, gene expression profiles and drug resistance patterns observed "in vivo"

Anticancer compound screening on 2D cell cultures poorly predicts "in vivo" performance, while conventional 3D culture systems are usually characterized by limited cell proliferation, failing to produce tissue-like-structures (TLS) suitable for drug testing. We addressed engineering of TLS by culturing cancer cells in porous scaffolds under perfusion flow. Colorectal cancer (CRC) HT-29 cells were cultured in 2D, on collagen sponges in static conditions or in perfused bioreactors, or injected subcutaneously in immunodeficient mice. Perfused 3D (p3D) cultures resulted in significantly higher (p < 0.0001) cell proliferation than static 3D (s3D) cultures and yielded more homogeneous TLS, with morphology and phenotypes similar to xenografts. Transcriptome analysis revealed a high correlation between xenografts and p3D cultures, particularly for gene clusters regulating apoptotic processes and response to hypoxia. Treatment with 5-Fluorouracil (5-FU), a frequently used but often clinically ineffective chemotherapy drug, induced apoptosis, down-regulation of anti-apoptotic genes (BCL-2, TRAF1, and c-FLIP) and decreased cell numbers in 2D, but only "nucleolar stress" in p3D and xenografts. Conversely, BCL-2 inhibitor ABT-199 induced cytotoxic effects in p3D but not in 2D cultures. Our findings advocate the importance of perfusion flow in 3D cultures of tumor cells to efficiently mimic functional features observed "in vivo" and to test anticancer compounds.

Development of a one-step probe based molecular assay for rapid immunodiagnosis of infection with M. tuberculosis using dried blood spots

Background

Antigen specific release of IP-10 is the most promising alternative marker to IFN-γ for infection with M. tuberculosis. Compared to Interferon-γ release assays (IGRA), IP-10 is released in high levels enabling novel approaches such as field friendly dried blood spots (DBS) and molecular detection.

Aim

To develop a robust IP-10 based molecular assay for the diagnosis of infection with M. tubercuolsis from whole blood and DBS.

Method

We developed a one-step probe based multiplex RT-qPCR assay for detecting IP-10 and IFN-γ mRNA expression from whole blood and DBS samples. The assay was validated and applied for the diagnosis of M. tuberculosis infection in DBS samples from 43 patients with confirmed TB, 13 patients with latent TB and 96 presumed uninfected controls. In parallel, IP-10 and INF-γ levels were measured in Quantiferon (QFT-TB) plasma supernatants.

Results

IP-10 mRNA upregulation was detectable at 4 hours after stimulation (6 fold upregulation) peaking at 8 hours (108 fold upregulation). IFN-γ expression occurred in concert but levels were lower (peak 6.7 fold upregulation). IP-10 gene expression level was significantly higher in patients with tuberculosis (median 31.2, IQR 10.7–67.0) and persons with latent tuberculosis infection (LTBI) (41.2, IQR 9.8–64.9) compared to healthy controls (1.6, IQR 1.1–2.4; p<0.0001). The IP-10 mRNA and protein based tests had comparable diagnostic accuracy to QFT-TB, sensitivity (85% and 88% vs 85%) and specificity (96% and 96% vs 97%, p = ns.).

Conclusion

We developed a rapid, robust and accurate molecular immunodiagnostic test for M. tuberculosis infection. By combining DBS based sample acquisition, mail or currier based sample transport with centralized molecular detection, this immunodiagnostic test concept can reduce the local technological requirements everywhere and make it possible to offer highly accurate immunodiagnostic tests in low resource settings.

Considerations for accurate gene expression measurement by reverse transcription quantitative PCR when analysing clinical samples

Reverse transcription quantitative PCR is an established, simple and effective method for RNA measurement. However, technical standardisation challenges combined with frequent insufficient experimental detail render replication of many published findings challenging. Consequently, without adequate consideration of experimental standardisation, such findings may be sufficient for a given publication but cannot be translated to wider clinical application. This article builds on earlier standardisation work and the MIQE guidelines, discussing processes that need consideration for accurate, reproducible analysis when dealing with patient samples. By applying considerations common to the science of measurement (metrology), one can maximise the impact of gene expression studies, increasing the likelihood of their translation to clinical tools.

CCR5 plays important roles in hepatitis B infection

In humans, hepatitis B virus (HBV) is the most prevalent and the main infectious agent that leads to liver disease. Previous investigations identified that long-term HBV-infected patients are unable to eradicate HBV completely from hepatocytes. The main mechanisms responsible for long-term forms of the infections are yet to be clarified. However, researchers believe that the differences in genetic and immunological parameters in the patients in comparison to subjects who successfully clear HBV infections may be the causes for long-term infection. Previous studies demonstrated that chemokines play important roles in the regulation of immune cell migration and activation, which is crucial for a comprehensive immune response against HBV. RANTES, MIP-1α, and MIP-1β are important CC chemokines which act through CC chemokines receptor 5 (CCR5). This receptor is expressed on several effector immune cells including NK cells, T lymphocytes, and macrophages, and plays a crucial role in the regulation of activation and migration of the immune cells during immune responses against viruses, including HBV. Therefore, alterations in its expression or functions could be associated with attenuated immune responses against HBV. In addition, previous studies identified that a 32 base pair deletion (Δ32) in exon 1, as well as three polymorphisms in the promoter region of the CCR5 gene results in downregulation of the molecule. Previous studies revealed that CCR5 expression was altered in hepatitis B but the role of the CCR5 Δ32 mutation and CCR5 promoter polymorphisms in this disease is controversial. This review addresses the recent information regarding the status of CCR5 expression on immune cells and the association of CCR5 promoter polymorphisms with HBV-infected patients.

Monitoring antigen-specific T cell responses using real-time PCR

Flow cytometry-, ELISA-, and ELISpot-based in vitro assays have played important roles in assessing the frequencies and functional competence of antigen-specific T cells in the setting of infectious disease and cancer. Such methods have helped in the development of antigen-specific vaccines for human disease prevention/treatment and have also served as a foundation for the monitoring of patients' immune responsiveness based on antigen-induced T cell expression of effector molecules (such as cytokines, chemokines, or proteins associated with cytolysis) as a consequence of therapeutic intervention. The following method outlines a protocol employing quantitative real-time PCR (qRT-PCR) with SYBR(®) green technology to examine antigen-specific CD8(+) T cell responses based on their rapid up-regulation of IFN-γ mRNA transcription following in vitro stimulation with peptide (antigen)-loaded, autologous peripheral blood mononuclear cells (PBMCs). The advantages of the current qRT-PCR approach over protein-based detection methods include the sensitivity to distinguish resident CD8(+) T cell responses against multiple antigens without the need to artificially pre-expand T cell numbers ex vivo, as is commonly required for the latter in vitro assay systems. Following qRT-PCR setup and run, the level of human IFN-γ transcript is normalized to CD8 transcript expression level, with data reported as the relative fold change in this index versus a patient-matched PBMC sample stimulated with a negative control peptide (e.g., HIV NEF).

Furin mRNA expression in peripheral blood correlates with chronic hepatitis B virus infection

AIM

  The mechanisms underlying development of chronic hepatitis B virus (HBV) infection are related to immune tolerance, but are as yet incompletely understood. Furin has been found to be essential for maintenance of peripheral immune tolerance mediated by regulatory T cells (Treg). Such effect of furin on chronic HBV infection was investigated in this study.

METHODS

  Peripheral blood from 40 individuals with self-limited HBV infection, 40 patients with asymptomatic persistent HBV infection and 40 patients with chronic hepatitis B (CHB) was collected and mRNA expression levels of furin, transforming growth factor (TGF)-β1 and the Treg-function-related forkhead transcription factor FoxP3 were detected using quantitative real-time polymerase chain reaction. CD4(+) CD25(+) FoxP3(+) Treg were detected using flow cytometry.

RESULTS

  Furin mRNA expression in peripheral blood was significantly higher in patients with persistent HBV infection than in individuals with self-limited infection (P < 0.01), and was much higher in CHB patients than in those with asymptomatic persistent infection (P < 0.01). Furthermore, furin mRNA was relatively higher in patients with positive hepatitis B e antigen and higher levels of serum HBV DNA (>10 000 copies/mL). In patients with CHB, furin mRNA expression was found to correlate with TGF-β1 mRNA and FoxP3 mRNA expression using Spearman's rank correlation coefficient test. It was 5.7-times higher in CD4(+) CD25(+) T cells than in CD4(+) CD25(-) T cells and correlated with the frequency of Treg (P < 0.05).

CONCLUSION

  Furin mRNA expression in peripheral blood correlates with chronic HBV infection and liver damage, and seems to participate in immune inhibitory and anti-inflammatory mechanisms in HBV infection, mediated by TGF-β1 and/or Treg.

A whole blood monokine-based reporter assay provides a sensitive and robust measurement of the antigen-specific T cell response

BACKGROUND

The ability to measure T-cell responses to antigens is proving critical in the field of vaccine development and for understanding immunity to pathogens, allergens and self-antigens. Although a variety of technologies exist for this purpose IFNγ-ELISpot assays are widely used because of their sensitivity and simplicity. However, ELISpots cannot be performed on whole blood, and require relatively large volumes of blood to yield sufficient numbers of peripheral blood mononuclear cells. To address these deficiencies, we describe an assay that measures antigen-specific T cell responses through changes in monokine gene transcription. The biological amplification of the IFNγ signal generated by this assay provides sensitivity comparable to ELISpot, but with the advantage that responses can be quantified using small volumes of whole blood.

METHODS

Whole blood or peripheral blood mononuclear cells (PBMCs) from healthy controls and immunosuppressed recipients of solid organ transplants were incubated with peptide pools covering viral and control antigens or mitogen for 20 hours. Total RNA was extracted and reverse transcribed before amplification in a TaqMan qPCR reaction using primers and probes specific for MIG (CXCL9), IP-10 (CXCL10) and HPRT. The induction of MIG and IP-10 in response to stimuli was analysed and the results were compared with those obtained by ELISpot.

RESULTS

Antigen-specific T cell responses can be measured through the induction of MIG or IP-10 gene expression in PBMCs or whole blood with results comparable to those achieved in ELISpot assays. The biological amplification generated by IFNγ-R signaling allows responses to be detected in as little as 25 uL of whole blood and enables the assay to retain sensitivity despite storage of samples for up to 48 hours prior to processing.

CONCLUSIONS

A monokine-based reporter assay provides a sensitive measure of antigen-specific T cell activation. Assays can be performed on small volumes of whole blood and remain accurate despite delays in processing. This assay may be a useful tool for studying T cell responses, particularly when samples are limited in quantity or when storage or transportation are required before processing.

Fibroblast growth factor 2 and platelet-derived growth factor, but not platelet lysate, induce proliferation-dependent, functional class II major histocompatibility complex antigen in human mesenchymal stem cells

OBJECTIVE

To document the specificity and the mechanism of induction of a novel class II major histocompatibility complex (MHC) antigen by mitogenic growth factors in human mesenchymal stem cells (MSCs) expanded in vitro for translational applications.

METHODS

Expression of class II MHC molecules was measured in human MSCs and differentiated cells expanded in the presence of fibroblast growth factor 2 (FGF-2), platelet-derived growth factor BB (PDGF-BB), human platelet lysate, or interferon-γ (IFNγ). The roles of cell proliferation and growth factor-induced signaling pathways were investigated as well as the class II MHC assembly machinery and functional capacity.

RESULTS

FGF-2 and, to a lesser extent, PDGF-BB induced in adult human MSCs the expression of HLA-DR (normally induced by inflammatory cytokines), which was able to stimulate CD4+ T cells via superantigen binding. In contrast to IFNγ, FGF induced HLA-DR expression only in human MSCs proliferating under its mitogenic effect and not in mouse MSCs or in differentiated human cells. Although it induced cell proliferation, human platelet lysate did not cause HLA-DR expression in human MSCs. HLA-DR expression occurred following FGF-specific binding to its receptor(s), mainly FGF receptor 1, without inducing IFNγ or tumor necrosis factor α expression. Both MAPK/ERK-1/2 and phosphatidylinositol 3-kinase/Akt controlled cell proliferation and HLA-DR expression, but only MAPK/ERK-1/2 controlled the induction of the class II MHC transcription activator protein CIITA, the major determinant of HLA-DR transcription.

CONCLUSION

The induction of functional HLA-DR in proliferating progenitor MSCs is a property of human MSCs that have been expanded with mitogenic growth factors. This has potential biologic significance in the regulation and/or protection of progenitor cell subpopulations under sustained mitogenic proliferation and needs to be taken into account when expanding MSCs for use in in vivo applications.

In vitro end points for the assessment of cellular immune response-modulating drugs

BACKGROUND

The concept of immunotoxicology and the development of a battery of immune-function assays to screen potential immunotoxic compounds have been increasingly used in the past. Immunotoxic outcome generally seems appropriate to evaluate the risk in drug development. Improving this approach is possible, by using methods now available, to study the effect of a chemical compound on the immune system.

OBJECTIVE

The goal of this review is to provide an overview of the current and recent methodologies for testing the immunological effect and immunotoxic risks in drug candidates.

METHODS

The methodological details here discussed include a synthetic description of the immunocompetent cells in cell-mediated immunity and the choice of the most appropriate assay (bioassays, immunoassays, molecular biology techniques, flow cytometry).

CONCLUSION

This review offers an assessment of in vitro models to study the toxic impact of (bio)pharmaceuticals on cellular immune system and aid drug scientists in understanding the significance and the methods to approach immunotoxicology.