Antigen-independent IFN-γ production by human naïve CD4 T cells activated by IL-12 plus IL-18

Effects of Heat-Killed Lacticaseibacillus paracasei MCC1849 on Immune Parameters in Healthy Adults-A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Study

Previous clinical studies have shown that heat-killed Lacticaseibacillus paracasei MCC1849 suppresses subjective symptoms among healthy adults. However, the mechanism underlying this beneficial effect remains unclear. This clinical study aimed to investigate the effects of MCC1849 on immune functions in humans. In this randomized, double-blind, placebo-controlled, parallel-group study, 100 healthy adults were randomly divided into MCC1849 or placebo groups. Participants ingested test powder with 5 × 1010 MCC1849 cells or placebo powder for 4 weeks. Immune functions were evaluated using expression levels of CD86 and HLA-DR on dendritic cells (DCs), neutrophils, and natural killer cells. The expression levels of interferon (IFN)-α, -β, and -γ in peripheral blood mononuclear cells incubated with Cpg2216 in vitro were quantified. Efficacy analysis was performed on participants in the per-protocol set (placebo group; n = 47, MCC1849 group; n = 49). The expression level of CD86 on pDCs and the gene expression levels of IFN-α, -β, and -γ upon TLR9 agonist stimulation were significantly higher in the MCC1849 group at 4 weeks. No side effects were observed. This is the first report to show the positive effects of MCC1849 on human immune cells. These findings reveal one possible mechanism of how MCC1849 suppresses subjective symptoms.

Long-chain polyphosphates inhibit type I interferon signaling and augment LPS-induced cytokine secretion in human leukocytes

Inorganic polyphosphates are evolutionarily conserved bioactive phosphate polymers found as various chain lengths in all living organisms. In mammals, polyphosphates play a vital role in the regulation of cellular metabolism, coagulation, and inflammation. Long-chain polyphosphates are found along with endotoxins in pathogenic gram-negative bacteria and can participate in bacterial virulence. We aimed to investigate whether exogenously administered polyphosphates modulate human leukocyte function in vitro by treating the cells with 3 different chain lengths of polyphosphates (P14, P100, and P700). The long-chain polyphosphates, P700, had a remarkable capacity to downregulate type I interferon signaling dose dependently in THP1-Dual cells while only a slight elevation could be observed in the NF-κB pathway with the highest dose of P700. P700 treatment decreased lipopolysaccharide-induced IFNβ transcription and secretion, reduced STAT1 phosphorylation, and downregulated subsequent interferon-stimulated gene expression in primary human peripheral blood mononuclear cells. P700 also augmented lipopolysaccharide-induced secretion of IL-1α, IL-1β, IL-4, IL-5, IL-10, and IFNγ. Furthermore, P700 has previously been reported to increase the phosphorylation of several intracellular signaling mediators, such as AKT, mTOR, ERK, p38, GSK3α/β, HSP27, and JNK pathway components, which was supported by our findings. Taken together, these observations demonstrate the extensive modulatory effects P700 has on cytokine signaling and the inhibitory effects specifically targeted to type I interferon signaling in human leukocytes.

Synergistic Effect of Ginsenoside Rh2 Combines with Ionizing Radiation on CT26/luc Colon Carcinoma Cells and Tumor-Bearing Animal Model

BACKGROUND

The local tumor control rate of colon cancer by radiotherapy is unsatisfactory due to recurrence and radioresistance. Ginsenoside Rh2 (Rh2), a panoxadiol saponin, possesses various antitumor effects.

METHODS

CT26/luc murine colon carcinoma cells and a CT26/luc tumor-bearing animal model were used to investigate the therapeutic efficacy of Rh2 combined with ionizing radiation and the underlying mechanisms.

RESULTS

Rh2 caused cell cycle arrest at the G1 phase in CT26/luc cells; however, when combined with ionizing radiation, the cells were arrested at the G2/M phase. Rh2 was found to suppress the activity of NF-κB induced by radiation by inhibiting the MAPK pathway, consequently affecting the expression of effector proteins. In an in vivo study, the combination treatment significantly increased tumor growth delay time and overall survival. Furthermore, the combination treatment significantly reduced NF-κB and NF-κB-related effector proteins, along with PD-1 receptor expression. Additionally, Rh2 administration led to increased levels of interleukin-12, -18, and interferon-γ in the mice's sera. Importantly, biochemical analysis revealed no toxicities associated with Rh2 alone or combined with radiation.

CONCLUSIONS

The combination of Rh2 with radiation may have potential as an alternative to improve the therapeutic efficacy of colorectal cancer.

Molecular Profiling of Inflammatory Mediators in Human Respiratory Syncytial Virus and Human Bocavirus Infection

Infections due to human respiratory syncytial virus (HRSV) and human bocavirus (HBoV) can mediate the release of several pro-inflammatory cytokines such as IL-6, IL-8, and TNF-α, which are usually associated with disease severity in children. In this study, the change in the expression profile of cytokines and chemokines were determined during HRSV, HBoV, and HRSV coinfection with HBoV in 75 nasopharyngeal aspirates (NPAs) samples, positive real-time reverse transcriptase PCR Assay (rRT-PCR) for HRSV (n = 36), HBoV (n = 23) infection alone or HRSV coinfection with HBoV (n = 16). The samples were collected from hospitalized children. qPCR-based detection revealed that the levels of IL-6, IL-8, IL-10, IL-13, IL-33, and G-CSF were significantly (p < 0.05) greater in patients than in controls. IL-4, IL-17, GM-CSF, and CCL-5 were significantly elevated in children with HRSV coinfection with HBoV than in other groups (p < 0.05). TNF-α, IL-6, IL-8, IL-10, IL-13, and IL-33 in children with HRSV were significantly increased in severe infections compared to mild infections. Whereas, IL-10, IL-13, and IL-33 were significantly increased in severe infection in compared a mild infection in children with HBoV. Further large-scale investigations involving isolates are needed to enhance our knowledge of the association between viral infections and cytokine expression patterns during the different stages of HRSV and HBoV infection.

Immunomodulation of Natural Killer Cell Function by Ribavirin Involves TYK-2 Activation and Subsequent Increased IFN-γ Secretion in the Context of In Vitro Hepatitis E Virus Infection

Hepatitis E virus (HEV) is a major cause of acute hepatitis globally. Chronic and fulminant courses are observed especially in immunocompromised transplant recipients since administration of ribavirin (RBV) does not always lead to a sustained virologic response. By in vitro stimulation of NK cells through hepatoma cell lines inoculated with a full-length HEV and treatment with RBV, we analyzed the viral replication and cell response to further elucidate the mechanism of action of RBV on immune cells, especially NK cells, in the context of HEV infection. Co-culture of HEV-infected hepatoma cells with PBMCs and treatment with RBV both resulted in a decrease in viral replication, which in combination showed an additive effect. An analysis of NK cell functions after stimulation revealed evidence of reduced cytotoxicity by decreased TRAIL and CD107a degranulation. Simultaneously, IFN-ɣ production was significantly increased through the IL-12R pathway. Although there was no direct effect on the IL-12R subunits, downstream events starting with TYK-2 and subsequently pSTAT4 were upregulated. In conclusion, we showed that RBV has an immunomodulatory effect on the IL-12R pathway of NK cells via TYK-2. This subsequently leads to an enhanced IFN-ɣ response and thus, to an additive antiviral effect in the context of an in vitro HEV infection.

Soluble factors from TLR4- or TCR-activated cells contribute to stability of the resting phenotype and increase the expression of CXCR4 of human memory CD4 T cells

It has been proposed that cytokines can induce activation of resting T cells in an antigen-independent manner. However, experimental conditions have included the use of fetal serum and nanogram concentrations of added cytokines. To evaluate the effect of cytokines and chemokines generated by activated immune cells on the phenotypic profile of human memory CD4 T cells, the cells were cultured in FBS-free conditions in the presence of IL-15 and 5% of hAB serum and incubated with conditioned medium (CM) obtained from PBMC activated through the TCR using anti-CD3/CD28/CD2 antibodies (TCR-CM) or through TLR4 using bacterial LPS (TLR4-CM). Cytokines and chemokines present in the CMs were evaluated by ProcartaPlex immunoassay. Cell viability, proliferation, and surface markers were determined by flow cytometry on day 2, 5, and 8 of culture. Cell viability was maintained by TLR4-CM plus IL-15 for 8 days but decreased in the presence of the TCR-CM plus IL-15. In combination with IL-15, the TLR4-CM, but not the TCR-CM, maintained the expression of CD3 and CD4 stable. Both conditions stabilized the expression of CD45RO and CCR5. Thus, the TLR4-CM better supported the viability and stability of the memory phenotype. None of the CMs induced proliferation or expression of activation markers; however, they induced an increased expression of CXCR4. This study indicates that resting memory CD4 T cells are not activated by, but may be sensitive to soluble factors produced by antigen or PAMP-stimulated cells, which may contribute to their homeostasis and favor the CXCR4 expression.

Mitochondrial reactive oxygen is critical for IL-12/IL-18-induced IFN-γ production by CD4+ T cells and is regulated by Fas/FasL signaling

Mitochondrial activation and the production of mitochondrial reactive oxygen species (mROS) are crucial for CD4⁺ T cell responses and have a role in naïve cell signaling after TCR activation. However, little is known about mROS role in TCR-independent signaling and in recall responses. Here, we found that mROS are required for IL-12 plus IL-18-driven production of IFN-γ, an essential cytokine for inflammatory and autoimmune disease development. Compared to TCR stimulation, which induced similar levels of mROS in naïve and memory-like cells, IL-12/IL-18 showed faster and augmented mROS production in memory-like cells. mROS inhibition significantly downregulated IFN-γ and CD44 expression, suggesting a direct mROS effect on memory-like T cell function. The mechanism that promotes IFN-γ production after IL-12/IL-18 challenge depended on the effect of mROS on optimal activation of downstream signaling pathways, leading to STAT4 and NF-κB activation. To relate our findings to IFN-γ-driven lupus-like disease, we used Fas-deficient memory-like CD4⁺ T cells from lpr mice. Importantly, we found significantly increased IFN-γ and mROS production in lpr compared with parental cells. Treatment of WT cells with FasL significantly reduced mROS production and the activation of signaling events leading to IFN-γ. Moreover, Fas deficiency was associated with increased mitochondrial levels of cytochrome C and caspase-3 compared with WT memory-like cells. mROS inhibition significantly reduced the population of disease-associated lpr CD44^hiCD62L^loCD4⁺ T cells and their IFN-γ production. Overall, these findings uncovered a previously unidentified role of Fas/FasL interaction in regulating mROS production by memory-like T cells. This apoptosis-independent Fas activity might contribute to the accumulation of CD44^hiCD62L^loCD4⁺ T cells that produce increased IFN-γ levels in lpr mice. Overall, our findings pinpoint mROS as central regulators of TCR-independent signaling, and support mROS pharmacological targeting to control aberrant immune responses in autoimmune-like disease.

Interferon-Gamma (IFNg) +874A/T Polymorphism Does Not Significantly Affect the Severity of Periodontitis

OBJECTIVES

Interferon-gamma (IFNg) is an immune-regulatory cytokine with a role in host responses to periodontitis. Genetic factors have been reported to modify the corresponding protein expression. The objective of this study was to evaluate the association and role of IFNg polymorphisms, such as IFNg +874 A/T, and the susceptibility to periodontitis.

MATERIALS AND METHODS

A total of 100 unrelated subjects were included in the present study. Genomic deoxyribonucleic acid (DNA) was obtained from peripheral blood of 43 patients with mild periodontitis and 57 patients with severe periodontitis. The determined clinical parameters of periodontitis included probing depth, clinical attachment loss, and papilla bleeding index. The oral hygiene indicators were also assessed. The level of IFNg was determined from the gingival crevicular fluid by enzyme-linked immunosorbent assay technique. The IFNg +874 A/T polymorphisms were analyzed from peripheral blood by the method of restriction fragment length polymorphism-polymerase chain reaction.

STATISTICAL ANALYSIS

Statistical analysis of the results was conducted using chi-squared testing for categorical data. Independent t-tests and Mann-Whitney U tests were used for numeric data. Kruskal-Wallis testing was used to compare genotypes concerning for IFNg +874 A/T polymorphism. A p-value < 0.05 was assumed for statistical significance.

RESULTS

Analysis of the IFNg +874 A/T polymorphism showed no significant differences with the level of IFNg. No significant differences were observed either in IFNg +874 A/T polymorphism between the subjects with mild periodontitis and those with severe periodontitis (p > 0.05). The subjects with severe periodontitis showed marginally but not significantly higher levels of IFNg compared with subjects with mild periodontitis (p > 0.05).

CONCLUSION

The polymorphism of IFNg +874 A/T was not associated with the level of IFNg nor with the risk of periodontitis in this study.

Association of Blastocystis ST6 with higher protease activity among symptomatic subjects

BACKGROUND

Blastocystis sp. is an anaerobic intestinal protozoan parasite of humans and a wide range of animals worldwide. In the current study the correlation between the cysteine protease activity of clinical samples of Blastocystis sp. ST1-3 and 6 with the levels of pro-inflammatory cytokines was evaluated.

METHODS

Stool samples were collected from subjects with or without clinical symptoms. All samples were cultivated in DMEM medium. The bacteria were eliminated or reduced in Blastocystis sp. positive samples subtypes 1-3 and 6 by a variety of antibiotics and consecutive sub-cultures. To prepare parasite lysate, 1 × 105 Blastocystis sp. from each isolate were harvested and lysed using freeze-thaw. Protease activity of each isolate was measured and the gene expression of pro-inflammatory biomarkers in HT-29 cell line sensed by isolates was investigated using quantitative Real-time PCR.

RESULTS

Protease activity assay showed inter- and intra-subtype variations among subtypes regarding the presence of symptoms, while the protease activity of symptomatic isolates was higher than asymptomatic isolates. The highest and lowest levels of protease activity were seen in ST6 and ST2, respectively. However, patterns of the expression of pro-inflammatory biomarkers in HT-29 cell line was different regarding the presence of symptoms and time points. There was no significant correlation between protease activity of different subtypes with the expression levels of pro-inflammatory biomarkers.

CONCLUSIONS

Our study indicated a higher protease activity among isolates from symptomatic compared to asymptomatic subjects, suggesting functional role for proteases in clinical symptoms due to Blastocystis sp. The lack of correlation between the levels of expression of pro-inflammatory biomarkers with subtypes regarding the presence of clinical symptoms proposes the importance of host-related factors in presentation of clinical symptoms.

Bystander CD4+ T cells: crossroads between innate and adaptive immunity

T cells are the central mediators of both humoral and cellular adaptive immune responses. Highly specific receptor-mediated clonal selection and expansion of T cells assure antigen-specific immunity. In addition, encounters with cognate antigens generate immunological memory, the capacity for long-term, antigen-specific immunity against previously encountered pathogens. However, T-cell receptor (TCR)-independent activation, termed “bystander activation”, has also been found. Bystander-activated T cells can respond rapidly and secrete effector cytokines even in the absence of antigen stimulation. Recent studies have rehighlighted the importance of antigen-independent bystander activation of CD4⁺ T cells in infection clearance and autoimmune pathogenesis, suggesting the existence of a distinct innate-like immunological function performed by conventional T cells. In this review, we discuss the inflammatory mediators that activate bystander CD4⁺ T cells and the potential physiological roles of these cells during infection, autoimmunity, and cancer.

Immune cells that become activated in the absence of antigen stimulation could be harnessed in the fight against infection, autoimmunity, and cancer. Je-Min Choi and colleagues from Hanyang University in Seoul, South Korea, review how the immune system can deploy helper T cells through an unusual process called bystander activation. Most T cells become activated only after receptors on their surface bind to specific cognate antigen. In contrast, bystander T cells are activated non-specifically in response to cytokines and other pro-inflammatory mediators. Studies have shown that this cell population has a variety of protective and pathogenic functions, for example, guarding against multiple sclerosis, aggravating the symptoms of parasitic infections and promoting antitumor immunity. A better understanding of these immune cells could lead to new therapeutic options for these diseases.

MAP3K2 augments Th1 cell differentiation via IL-18 to promote T cell-mediated colitis

T cell-mediated immunity in the intestine is stringently controlled to ensure proper immunity against pathogenic microbes and to prevent autoimmunity, a known cause of inflammatory bowel disease. However, precisely how T cells regulate intestine immunity remains to be fully understood. In this study, we found that mitogen-activated protein kinase kinase kinase 2 (MAP3K2) is required for the CD4⁺ T cell-mediated inflammation in the intestine. Using a T cell transfer colitis model, we found that MAP3K2-deficient naïve CD4 T cells had a dramatically reduced ability to induce colitis compared to wild type T cells. In addition, significantly fewer IFN-γ- but more IL-17A-producing CD4⁺ T cells in the intestines of mice receiving MAP3K2-deficient T cells than in those from mice receiving wild type T cells was observed. Interestingly, under well-defined in vitro differentiation conditions, MAP3K2-deficient naïve T cells were not impaired in their ability to differentiate into Th1, Th17 and Treg. Furthermore, the MAP3K2-regulated colitis severity was mediated by Th1 but not Th17 cells in the intestine. At the molecular level, we showed that MAP3K2-mediated Th1 cell differentiation in the intestine was regulated by IL-18 and required specific JNK activation. Together, our study reveals a novel regulatory role of MAP3K2 in intestinal T cell immunity via the IL-18-MAP3K2-JNK axis and may provide a novel target for intervention in T cell-mediated colitis.

Inhibitory effects of glycopyrronium, formoterol, and budesonide on coronavirus HCoV-229E replication and cytokine production by primary cultures of human nasal and tracheal epithelial cells

BACKGROUND

Coronavirus 229E (HCoV-229E), one of the causes of the common cold, exacerbates chronic obstructive pulmonary disease (COPD) and bronchial asthma. Long-acting muscarinic antagonists and β₂-agonists and inhaled corticosteroids inhibit the exacerbation of COPD and bronchial asthma caused by infection with viruses, including HCoV-229E. However, the effects of these drugs on HCoV-229E replication and infection-induced inflammation in the human airway are unknown.

METHODS

Primary human nasal (HNE) and tracheal (HTE) epithelial cell cultures were infected with HCoV-229E.

RESULTS

Pretreatment of HNE and HTE cells with glycopyrronium or formoterol decreased viral RNA levels and/or titers, the expression of the HCoV-229E receptor CD13, the number and fluorescence intensity of acidic endosomes where HCoV-229E RNA enters the cytoplasm, and the infection-induced production of cytokines, including IL-6, IL-8, and IFN-β. Treatment of the cells with the CD13 inhibitor 2'2'-dipyridyl decreased viral titers. Pretreatment of the cells with a combination of three drugs (glycopyrronium, formoterol, and budesonide) exerted additive inhibitory effects on viral titers and cytokine production. Pretreatment of HNE cells with glycopyrronium or formoterol reduced the susceptibility to infection, and pretreatment with the three drugs inhibited activation of nuclear factor-kappa B p50 and p65 proteins. Pretreatment with formoterol increased cAMP levels and treatment with cAMP decreased viral titers, CD13 expression, and the fluorescence intensity of acidic endosomes.

CONCLUSIONS

These findings suggest that glycopyrronium, formoterol, and a combination of glycopyrronium, formoterol, and budesonide inhibit HCoV-229E replication partly by inhibiting receptor expression and/or endosomal function and that these drugs modulate infection-induced inflammation in the airway.

Mesangial Cells Exhibit Features of Antigen-Presenting Cells and Activate CD4+ T Cell Responses

Background

Mesangial cells play a prominent role in the development of inflammatory diseases and autoimmune disorders of the kidney. Mesangial cells perform the essential functions of helping to ensure that the glomerular structure is stable and regulating capillary flow, and activated mesangial cells acquire proinflammatory activities. We investigated whether activated mesangial cells display immune properties and control the development of T cell immunity.

Methods

Flow cytometry analysis was used to study the expression of antigen-presenting cell surface markers and costimulatory molecules in mesangial cells. CD4+ T cell activation induced by mesangial cells was detected in terms of T cell proliferation and cytokine production.

Results

IFN-γ-treated mesangial cells express membrane proteins involved in antigen presentation and T cell activation, including MHC-II, ICAM-1, CD40, and CD80. This finding suggests that activated mesangial cells can take up and present antigenic peptides to initiate CD4+ T cell responses and thus act as nonprofessional antigen-presenting cells. Polarization of naïve CD4+ T cells (Th0 cells) towards the Th1 phenotype was induced by coculture with activated mesangial cells, and the resulting Th1 cells showed increased mRNA and protein expression of inflammation-associated genes.

Conclusion

Mesangial cells can present antigen and modulate CD4+ T lymphocyte proliferation and differentiation. Interactions between mesangial cells and T cells are essential for sustaining the inflammatory response in a variety of glomerulonephritides. Therefore, mesangial cells might participate in immune function in the kidney.

Pathogenic function of bystander-activated memory-like CD4+ T cells in autoimmune encephalomyelitis

T cells generate antigen-specific immune responses to their cognate antigen as a hallmark of adaptive immunity. Despite the importance of antigen-specific T cells, here we show that antigen non-related, bystander memory-like CD4⁺ T cells also significantly contribute to autoimmune pathogenesis. Transcriptome analysis demonstrates that interleukin (IL)-1β- and IL-23-prime T cells that express pathogenic T_Η17 signature genes such as RORγt, CCR6, and granulocyte macrophage colony-stimulating factor (GM-CSF). Importantly, when co-transferred with myelin-specific 2D2 TCR-transgenic naive T cells, unrelated OT-II TCR-transgenic memory-like T_H17 cells infiltrate the spinal cord and produce IL-17A, interferon (IFN)-γ, and GM-CSF, increasing the susceptibility of the recipients to experimental autoimmune encephalomyelitis in an IL-1 receptor-dependent manner. In humans, IL-1R1^high memory CD4⁺ T cells are major producers of IL-17A and IFN-γ in response to IL-1β and IL-23. Collectively, our findings reveal the innate-like pathogenic function of antigen non-related memory CD4⁺ T cells, which contributes to the development of autoimmune diseases.

T cells express specific T cell receptors (TCR) to recognise antigens and initiate adaptive immune responses. Here the authors show, in a mouse model of autoimmune encephalomyelitis, that memory-like CD4 T cells expressing unrelated TCR can also infiltrate the spinal cord and contribute to autoimmunity.

Rapamycin as an Adjunctive Therapy for NLRC4 Associated Macrophage Activation Syndrome

Gain of function (GOF) mutations affecting the inflammasome component NLRC4 are known to cause early-onset macrophage activation syndrome (MAS) and neonatal enterocolitis. Here we report a patient with a NLRC4 GOF mutation presenting with neonatal MAS efficiently treated with a combination of anakinra and rapamycin. Through in vitro studies, we show that rapamycin reduces both IL-1β and IL-18 secretion by the patient's phagocytic cells. The reduction of cytokine secretion is associated with a reduction of caspase-1 activation regardless of the pathogen- or danger-associated molecular patterns triggering the activation of the inflammasome. This study suggests that patients with inherited auto-inflammatory disorders could benefit from an adjunctive therapy with rapamycin.

A Mechanistic Computational Model Reveals That Plasticity of CD4+ T Cell Differentiation Is a Function of Cytokine Composition and Dosage

CD4⁺ T cells provide cell-mediated immunity in response to various antigens. During an immune response, naïve CD4⁺ T cells differentiate into specialized effector T helper (Th1, Th2, and Th17) cells and induced regulatory (iTreg) cells based on a cytokine milieu. In recent studies, complex phenotypes resembling more than one classical T cell lineage have been experimentally observed. Herein, we sought to characterize the capacity of T cell differentiation in response to the complex extracellular environment. We constructed a comprehensive mechanistic (logical) computational model of the signal transduction that regulates T cell differentiation. The model's dynamics were characterized and analyzed under 511 different environmental conditions. Under these conditions, the model predicted the classical as well as the novel complex (mixed) T cell phenotypes that can co-express transcription factors (TFs) related to multiple differentiated T cell lineages. Analyses of the model suggest that the lineage decision is regulated by both compositions and dosage of signals that constitute the extracellular environment. In this regard, we first characterized the specific patterns of extracellular environments that result in novel T cell phenotypes. Next, we predicted the inputs that can regulate the transition between the canonical and complex T cell phenotypes in a dose-dependent manner. Finally, we predicted the optimal levels of inputs that can simultaneously maximize the activity of multiple lineage-specifying TFs and that can drive a phenotype toward one of the co-expressed TFs. In conclusion, our study provides new insights into the plasticity of CD4⁺ T cell differentiation, and also acts as a tool to design testable hypotheses for the generation of complex T cell phenotypes by various input combinations and dosages.

Tuberculin skin test reaction is related to memory, but not naive CD4+ T cell responses to mycobacterial stimuli in BCG-vaccinated young adults

Bacillus Calmette-Guérin (BCG) is the only vaccine available against tuberculosis and the tuberculin skin test (TST) is the most widely used method to detect BCG take. However, subjects may remain TST-negative, even after several BCG administrations. To investigate some of the potential reasons underlying this inability of developing tuberculin sensitivity in response to BCG we compared the effect of different mycobacterial stimuli in the groups differently responding to tuberculin. TST was performed on 71 healthy adults aged 25-30 years, who had received BCG in their childhood, and considered TST-positive at ≥10 mm. Dendritic cells (DCs) were incubated with PPD, live BCG or rBCGhIL-18, producing human IL-18. The latter strain was used to investigate whether the production of IL-18 could overcome some of the immune read-out limitations in the TST-negative subjects. CD86, CD80, CD40, and DC-specific intracellular adhesion molecule-3 grabbing nonintegrin (DC-SIGN) expression was analysed by flow cytometry and IL-10, IL-23 and IP-10 secretion in culture supernatants by ELISA. In DCs-T cell co-cultures with naive and memory CD4⁺ T cells, the IFN-γ and IL-10 levels were determined by ELISA. We found no difference in IL-10 and IFN-γ production by naive T cells between the TST-negative and TST-positive subjects. However, IFN-γ was produced in significantly higher amounts by memory T cells incubated with PPD, BCG or rBCGhIL-18-pulsed DCs in TST-positive than in TST-negative subjects, whereas the numbers of the IFN-γ-producing T cells were similar in both groups. This difference may be partially due to a decreased CD40 and enhanced reduction in DC-SIGN expression by DCs of TST-negative versus TST-positive subjects. A strong effect of IL-18 expression by rBCGhIL-18 on IL-23 production by the DC was seen in both groups, which likely was the reason for the increased IFN-γ production by naïve T cells upon incubation with mycobacteria-pulsed DC, regardless of the TST status.

Inhibition of Myeloid Differentiation Factor 88 Reduces Human and Mouse T-Cell Interleukin-17 and IFNγ Production and Ameliorates Experimental Autoimmune Encephalomyelitis Induced in Mice

Myeloid differentiation factor 88 (MyD88) recruits signaling proteins to the intracellular domain of receptors belonging to the toll-like/interleukin-1 (IL-1) receptor superfamily. Mice lacking MyD88 are highly susceptible to infectious diseases, but tend to resist experimentally induced autoimmune diseases such as experimental autoimmune encephalomyelitis (EAE) and manifest diminished allograft rejection. We reasoned that inhibition of MyD88 should influence the cytokine profile of responding T cells by blocking costimulatory molecule expression by antigen-presenting cells (APCs) and by inhibiting T-cell responses to IL-18. We now report that inhibition of MyD88 in human APCs led to decreased IFNγ and IL-17 production and a shift to IL-4 production by responding T cells in a mixed lymphocyte reaction. Direct inhibition of Myd88 in mouse and human T cells also reduced their production of IFNγ in response to IL-12/IL-18 stimulation. Finally, systemic MyD88 antagonism significantly reduced the clinical manifestations of EAE in mice. Thus, MyD88 appears to be a key factor in determining T cell phenotype and represents a potential target for therapeutic intervention.

Interferon-α curbs production of interleukin-22 by human peripheral blood mononuclear cells exposed to live Borrelia burgdorferi

Cytokine networks initiated by means of innate immunity are regarded as a major determinant of host defence in response to acute infection by bacteria including Borrelia burgdorferi. Herein, we demonstrate that interferon (IFN)-α, either endogenously produced after exposure of cells to toll-like receptor-9-activating CpG oligonucleotides or provided as recombinant cytokine, weakens activation of the anti-bacterial interleukin (IL)-1/IL-22 axis in human peripheral blood mononuclear cells exposed to viable B. burgdorferi. As IFN-α has been related to pathological dissemination of the spirochaete, data suggest an immunoregulatory role of type I IFN in this context that is able to significantly modify cytokine profiles thereby possibly determining early course of B. burgdorferi infection.

Immunohistochemical analysis of the expression of cellular transcription NFκB (p65), AP-1 (c-Fos and c-Jun), and JAK/STAT in leprosy

Leprosy is a disease whose clinical spectrum depends on the cytokine patterns produced during the early stages of the immune response. The main objective of this study was to describe the activation pattern of cellular transcription factors and to correlate these factors with the clinical forms of leprosy. Skin samples were obtained from 16 patients with the tuberculoid (TT) form and 14 with the lepromatous (LL) form. The histologic sections were immunostained with anti-c-Fos and anti-c-Jun monoclonal antibodies for investigation of AP-1, anti-NFκB p65 for the study of NFκB, and anti-JAK2, STAT1, STAT3, and STAT4 for investigation of the JAK/STAT pathway. Cells expressing STAT1 were more frequent in the TT form than in LL lesions (P = .0096), in agreement with the protective immunity provided by IFN-γ. STAT4 was also more highly expressed in the TT form than in the LL form (P = .0098). This transcription factor is essential for the development of a Th1 response because it is associated with interleukin-12. NFκB (p65) and STAT4 expression in the TT form showed a strong and significant correlation (r = 0.7556 and P = .0007). A moderate and significant correlation was observed between JAK2 and STAT4 in the TT form (r = 0.6637 and P = .0051), with these factors responding to interleukin-12 in Th1 profiles. The results suggest that STAT1, JAK2, and NFκB, together with STAT4, contribute to the development of cell-mediated immunity, which is able to contain the proliferation of Mycobacterium leprae.

In utero arsenic exposure and fetal immune repertoire in a US pregnancy cohort

Arsenic has wide-ranging effects on human health and there is evidence that it alters the immune response by influencing CD4+/CD8+ T cell ratios, IL-2 cytokine levels, and the expression of immune-response genes. We investigated the impact of in utero environmental arsenic exposure on immune development and function in newborns participating in a pregnancy cohort in New Hampshire, U.S., where arsenic levels have exceeded the current EPA maximum contaminant level of 10 μg/L. Our results showed that maternal urinary arsenic concentrations were inversely related to absolute total CD45RA+ CD4+ cord blood CD69+ T cell counts (N=116, p=0.04) and positively associated with CD45RA+ CD69- CD294+ cell counts (p=0.01). In placental samples (N=70), higher in utero urinary arsenic concentrations were positively associated with the expression of IL1β (p=0.03). These data provide evidence that relatively low-level arsenic exposure in utero may alter the fetal immune system and lead to immune dysregulation.

Upregulation of IFN-γ and IL-12 is associated with a milder form of hantavirus hemorrhagic fever with renal syndrome

Hantavirus hemorrhagic fever with renal syndrome (HFRS) is a zoonotic disease characterized by acute onset, fever, malaise, and back pain. As the disease progresses, hemorrhagic disturbances and kidney dysfunctions predominate. The examination of tissue collected postmortem supports the premise that virus replication is not responsible for this pathology; therefore, it is widely believed that virus-induced immune responses lead to the clinical manifestations associated with HFRS. The overproduction of inflammatory cytokines is commonly reported in subjects with HFRS and has given rise to the hypothesis that a so-called "cytokine storm" may play a pivotal role in the pathogenesis of this disease. Currently, supportive care remains the only effective treatment for HFRS. Our data show that serum levels of interferon (IFN)-γ, interleukin (IL)-10, CCL2, and IL-12 are upregulated in HFRS cases when compared to healthy controls and the level of upregulation is dependent on the phase and severity of the disease. Furthermore, we observed an association between the mild form of the disease and elevated serum levels of IFN-γ and IL-12. Collectively, these observations suggest that the administration of exogenous IFN-γ and IL-12 may provide antiviral benefits for the treatment of HFRS and, thus, warrants further investigations.

IL-18, but not IL-12, induces production of IFN-γ in the immunosuppressive environment of HPV16 E7 transgenic hyperplastic skin

IFN-γ plays a central role in the defense against infections and cancer. More recently, however, IFN-γ has also been reported to have immunosuppressive effects in models of autoimmune disease, melanoma and premalignant skin disease. While IL-12 and IL-18 are critical inducers of IFN-γ during infection, the mechanisms that induce IFN-γ in an immunosuppressive context are unknown. Previously, we identified a key role for IFN-γ in mediating the suppression of antigen-specific immune responses in a transgenic mouse model of HPV-associated epidermal hyperplasia, driven by expression of the HPV16 E7 oncoprotein from a keratin 14 promoter (K14E7). We now demonstrate elevated production of IFN-γ, IL-18 and IL-12 by K14E7 transgenic compared to non-transgenic skin. IFN-γ in K14E7 transgenic skin was produced predominantly by CD8⁺ and CD4⁺ T cells, which were present in greater number in K14E7 transgenic skin. Production of IFN-γ in K14E7 skin required IL-18 but not IL-12. Our findings show that IL-18 contributes to inducing IFN-γ in an immunosuppressive cutaneous environment caused by viral oncogene-driven hyperplasia.

Pro-Inflammatory Signaling by IL-10 and IL-22: Bad Habit Stirred Up by Interferons?

Interleukin (IL)-10 and IL-22 are key members of the IL-10 cytokine family that share characteristic properties such as defined structural features, usage of IL-10R2 as one receptor chain, and activation of signal transducer and activator of transcription (STAT)-3 as dominant signaling mode. IL-10, formerly known as cytokine synthesis inhibitory factor, is key to deactivation of monocytes/macrophages and dendritic cells. Accordingly, pre-clinical studies document its anti-inflammatory capacity. However, the outcome of clinical trials assessing the therapeutic potential of IL-10 in prototypic inflammatory disorders has been disappointing. In contrast to IL-10, IL-22 acts primarily on non-leukocytic cells, in particular epithelial cells of intestine, skin, liver, and lung. STAT3-driven proliferation, anti-apoptosis, and anti-microbial tissue protection is regarded a principal function of IL-22 at host/environment interfaces. In this hypothesis article, hidden/underappreciated pro-inflammatory characteristics of IL-10 and IL-22 are outlined and related to cellular priming by type I interferon. It is tempting to speculate that an inherent inflammatory potential of IL-10 and IL-22 confines their usage in tissue protective therapy and beyond that determines in some patients efficacy of type I interferon treatment.

Exaggerated myocardial oxLDL amount and LOX-1 receptor over-expression associated with coronary microvessel inflammation in unstable angina

The pathophysiological relationship between coronary atherosclerosis and coronary microvessels remains undefined and the specific causative role of oxidatively modified low density lipoprotein (oxLDL) in human atherosclerosis is debated. The purposes of this study are to investigate whether coronary microvessels are involved in coronary atherosclerosis and whether increased myocardial oxLDL amount can be associated with coronary microvessel inflammation. A combination of immunohistochemical, RT-PCR and real-time PCR studies performed on myocardial biopsy specimens from patients with mitral stenosis (control hearts, CHs) and from unstable and stable angina patients (UAP and SAP), demonstrated that myocardial oxLDL was associated with a chronic low-grade inflammation in SAP and with a severe high grade inflammation in UAP. oxLDL amount was notably higher in UAP than in SAP and in UAP the high grade of inflammation was correlated with the increased amount of oxLDL in endothelial cells and macrophages. The exaggerated amount of oxLDL in UAP and the interaction of oxLDL with lectin-like oxLDL (LOX-1) receptor are amplified by the activation of transcriptional factor octamere 1 (OCT-1) with consequent activation of a series of inflammatory endothelial feed-back mechanisms resulting in LOX-1 gene over-expression, endothelial inflammation as well as uncontrolled nuclear factor kappa B (NFkB) activation. Moreover, in UAP genes for signal transducer and activator transcriptional factor 1α (STAT1α), angiotensin converting enzyme (ACE) and numerous pro-inflammatory cytokines were over-expressed. The present results may have clinical relevance because they show that coronary atherosclerosis is a disease not confined to the large arteries but involving the whole coronary tree. In UAP the exaggerated amount of myocardial oxLDL is associated with widespread high grade microvessel inflammation.

STAT4 regulates antiviral gamma interferon responses and recurrent disease during herpes simplex virus 2 infection

STAT4 is an important transcription factor that contributes to the incidence and severity of different autoimmune diseases and is implicated in the antiviral immune responses in mice. In this study, we evaluated the role of STAT4 in human and murine herpes simplex virus 2 (HSV-2) infections. We show that STAT4 regulates antiviral gamma interferon (IFN-γ) responses and disease severity during chronic HSV-2 infections in humans and vaccine-induced IFN-γ-mediated protection against HSV-2 infection in mice. In a cohort of 228 HSV-2-infected individuals, representing both patients with recurrent disease and asymptomatic HSV-2 carriers, we found that genetic variations in the STAT4 gene were associated with asymptomatic HSV-2 infection, as well as with increased in vitro secretion of IFN-γ in response to the virus. Mice that lacked STAT4 had impaired HSV-2-specific IFN-γ production and delayed-type hypersensitivity responses following vaccination, which led to impaired viral clearance in the genital tract of vaccinated animals after a genital HSV-2 challenge. We conclude that STAT4 plays an important role in IFN-γ-mediated HSV-2-specific immunity, affecting the severity of genital HSV-2 infection.

Global transcriptional response to ISCOM-Matrix adjuvant at the site of administration and in the draining lymph node early after intramuscular injection in pigs

ISCOM vaccines induce a balanced Th1/Th2 response, long-lasting antibody responses and cytotoxic T lymphocytes. The mode of action for the adjuvant component, the ISCOM-Matrix, is known to some extent but questions remain regarding its mechanism of action. The Affymetrix GeneChip® Porcine Genome Array was applied to study the global transcriptional response to ISCOM-Matrix in pigs at the injection site and in the draining lymph node 24h after i.m. injection. Gene enrichment analysis revealed inflammation, innate immunity and antigen processing to be central in the ISCOM-Matrix response. At the injection site, 594 genes were differentially expressed, including up-regulation of the cytokines osteopontin (SPP1), IL-10 and IL-18 and the chemokines CCL2, CCL19 and CXCL16. Of the 362 genes differentially expressed in the lymph node, IL-1β and CXCL11 were up-regulated whereas IL18, CCL15 and CXCL12 were down-regulated. ISCOM-Matrix also modulated genes for pattern recognition receptors at the injection site (TLR2, TLR4, MRC1, PTX3, LGALS3) and in the lymph node (TLR4, RIG-I, MDA5, OAS1, EIF2AK2, LGALS3). A high proportion of up-regulated interferon-regulated genes indicated an interferon response. Thus, several genes, genetic pathways and biological processes were identified that are likely to shape the early immune response elicited by ISCOM-based vaccines.