A flow cytometric method for determination of the interferon receptor IFNAR2 subunit in peripheral blood leukocyte subsets

HIV infection does not alter interferon α/β receptor 2 expression on mucosal immune cells

The innate immune response induced by type I interferons (IFNs) plays a critical role in the establishment of HIV infection. IFNs are induced early in HIV infection and trigger an antiviral defense program by signaling through the IFNα/β receptor (IFNAR), which consists of two subunits, IFNAR1 and IFNAR2. Changes in IFNAR expression in HIV target cells, as well as other immune cells, could therefore have important consequences for initial HIV spread. It was previously reported that IFNAR2 expression is increased in peripheral blood CD4+ CXCR4+ T cells of HIV+ patients compared to HIV uninfected controls, suggesting that HIV infection may alter the IFN responsiveness of target cells. However, the earliest immune cells affected by HIV in vivo reside in the gut-associated lymphoid tissue (GALT). To date, it remains unknown if IFNAR expression is altered in GALT immune cells in the context of HIV infection and exposure to IFNs, including the 12 IFNα subtypes. Here, we analyzed the expression of surface bound and soluble IFNAR2 on Lamina propria mononuclear cells (LPMCs) isolated from the GALT of HIV- individuals and in plasma samples of HIV+ patients. IFNAR2 expression varied between different T cells, B cells and natural killer cells, but was not altered following HIV infection. Furthermore, expression of the soluble IFNAR2a isoform was not changed in HIV+ patients compared to healthy donors, nor in LPMCs after HIV-1 infection ex vivo. Even though the 12 human IFNα subtypes trigger different biological responses and vary in their affinity to both receptor subunits, stimulation of LPMCs with different recombinant IFNα subtypes did not result in any significant changes in IFNAR2 surface expression. Our data suggests that potential changes in the IFN responsiveness of mucosal immune cells during HIV infection are unlikely dictated by changes in IFNAR2 expression.

Type I interferon as a biomarker in autoimmunity and viral infection: a leukocyte subset-specific analysis unveils hidden diagnostic options

Interferon alpha and its surrogates, including IP-10 and SIGLEC1, paralleled changes of disease activity in systemic lupus erythematosus (SLE). However, the whole blood interferon signature (WBIFNS)-the current standard for type I IFN assessment in SLE-does not correlate with SLE disease activity in individual patients over time. The underlying causes for this apparent contradiction have not been convincingly demonstrated. Using a multicenter dataset of gene expression data from leukocyte subsets in SLE, we identify distinctive subset-specific contributions to the WBIFNS. In a subsequent analysis, the effects of type I interferon on cellular blood composition in patients with SLE and hepatitis B were also studied over time. We found that type I interferon mediates significant alterations in whole blood composition, including a neutropenia and relative lymphocytosis. Given different effects of type 1 interferon on different leukocyte subsets, these shifts confound measurement of a type 1 interferon signature in whole blood. To minimize and overcome these limitations of the WBIFNS, we suggest to measure IFN-induced transcripts or proteins in a specific leukocyte subset to improve clinical impact of interferon biomarkers.

KEY MESSAGES

Myeloid cells contribute more to the WBIFNS in SLE than their lymphocytic counterpart. Very similar leukocyte subsets reveal distinctive IFN signatures. IFN alpha mixes up composition of blood and leads to a preferential neutropenia, yielding relative lymphocytosis.

Brief Report: Increased Expression of the Type I Interferon Receptor on CD4+ T Lymphocytes in HIV-1-Infected Individuals

BACKGROUND

Type I interferons (IFN1s; eg, interferon-alpha and interferon-beta) are potent cytokines that inhibit the replication of human immunodeficiency virus-1 (HIV-1) and other viruses. The antiviral and immunoregulatory activities of IFN1 are mediated through ligand-receptor interactions with the IFN1 receptor complex (IFNAR). Variation in the cell-surface density of IFNAR could play a role in HIV-1 pathogenesis.

METHODS

In this cross-sectional study of fresh whole blood, we used flow cytometry to evaluate the expression of IFNAR2 on lymphocyte subsets from HIV-1-infected (n = 33) and HIV-1-uninfected (n = 22) individuals.

RESULTS

In comparison with healthy blood bank donors, we observed that the HIV-1-infected individuals, particularly those having advanced to disease, exhibited the increased expression of IFNAR2 on CD4 T cells (relative fluorescence intensity 6.9 vs. 9.0; P = 0.027). The CD4:CD4 T-cell IFNAR2 expression-level ratio provides an internally standardized measure of this alteration. The observed increased expression of IFNAR2 was largely restricted to CD4 T cells that expressed the chemokine receptor CXCR4 and lacked the expression of CCR5.

CONCLUSIONS

HIV-1-infected individuals exhibit an increased expression of the IFN1 receptor on CD4 T cells. The level of IFNAR2 expression seems to increase with disease progression. These findings provide insight for the immunologic alterations associated with HIV-1 infection and possibly new therapeutic approaches.

Interferon signaling patterns in peripheral blood lymphocytes may predict clinical outcome after high-dose interferon therapy in melanoma patients

Background

High-dose Interferon (HDI) therapy produces a clinical response and achieves relapse-free survival in 20-33% of patients with operable high risk or metastatic melanoma. However, patients may develop significant side effects frequently necessitating dose reduction or discontinuation of therapy. We recently showed that peripheral blood lymphocytes (PBL) from some melanoma patients have impaired interferon (IFN) signaling which could be restored with high concentrations of IFN. This exploratory study evaluated IFN signaling in PBL of melanoma patients to assess whether the restoration of PBL IFN signaling may predict a beneficial effect for HDI in melanoma patients.

Methods

PBL from 14 melanoma patients harvested on Day 0 and Day 29 of neoadjuvant HDI induction therapy were analyzed using phosflow to assess their interferon signaling patterns through IFN-α induced phosphorylation of STAT1-Y701.

Results

Patients who had a clinical response to HDI showed a lower PBL interferon signaling capacity than non-responders at baseline (Day 0). Additionally, clinical responders and patients with good long-term outcome showed a significant increase in their PBL interferon signaling from Day 0 to Day 29 compared to clinical non-responders and patients that developed metastatic disease. The differences in STAT1 activation from pre- to post- HDI treatment could distinguish between patients who were inclined to have a favorable or unfavorable outcome.

Conclusion

While the sample size is small, these results suggest that interferon signaling patterns in PBL correlate with clinical responses and may predict clinical outcome after HDI in patients with melanoma. A larger confirmatory study is warranted, which may yield a novel approach to select patients for HDI therapy.

Alteration of interferon-α/β receptors in chronic hepatitis B patients

BACKGROUND

The present study determined type I interferon (IFN) receptor (interferon-α/β receptor (IFNAR)) and its predicable role in interferon-α2b treatment in chronic hepatitis B (CHB) patients.

METHODS

Expression of IFN-α/βR-1 and IFN-α/βR-2 in peripheral blood mononuclear cells and in liver tissue was measured by flow cytometry, immunofluorescence, immunohistochemistry and RT-PCR.

RESULTS

IFN-α/βR-1 and IFN-α/βR-2 in monocytes and lymphocytes increased in CHB patients. Expression of IFNAR-1 and IFNAR-2 in liver had positive correlation with HBV-DNA in liver tissue. Expression of IFN-α/βR in lymphocytes and monocytes increased in the first month, but then decreased during the subsequent interferon-α2b treatment, patients who had higher levels of IFN-α/βR-2 in monocytes prior to therapy showed better viral response than those with lower levels.

CONCLUSIONS

Expression of IFN-α/βR-2 in monocytes can be used as a predictable parameter to evaluate the effect of IFN-α treatment in CHB patients.

Induction of type 1 interferon receptor by zinc in U937 cells

This study aims to determine whether zinc enhances interferon (IFN)-alpha activity in U937 cells. Type 1 IFN2 receptor (IFNAR2) protein in U937 cells was measured by flow cytometry. After 24h of exposure to zinc chloride or polaprezinc (a chelate of zinc and L-carnosine) at concentrations ranging from 50 to 200 microM, histograms showing anti-IFNAR2 antibody-positive cells shifted to a higher FITC intensity. Zinc chloride and polaprezinc increased IFNAR2 mRNA levels approximately 30% and 40%, respectively, compared to the control. L-carnosine alone did not alter IFNAR2 mRNA or protein levels. Cellular levels of 2'-5' oligoadenylate synthetases (OAS) were markedly increased by IFN-alpha, and the increase was significantly accelerated by polaprezinc. However, polaprezinc alone did not increase 2'-5'OAS levels. The finding suggests that zinc, especially polaprezinc, enhances the expression of INFAR2 in U937 cells, thereby inducing production of the anti-viral protein 2'-5'OAS.

Increased interferon alpha receptor 2 mRNA levels is associated with renal cell carcinoma metastasis

Background

Interferon-α (IFN-α) is one of the central agents in immunotherapy for renal cell carcinoma (RCC) and binds to the IFN-α receptor (IFNAR). We investigated the role of IFNAR in RCC.

Methods

We quantified IFNAR mRNA expression in paired tumor and non-tumor samples from the surgical specimens of 103 consecutive patients with RCC using a real-time reverse transcription polymerase chain reaction (RT-PCR), and IFNAR2 protein using Western blotting.

Results

The absolute level of IFNAR1 and IFNAR2 mRNAs in tumor and non-tumor tissues did not correlate with the malignant and metastatic profiles. The relative yields of the PCR product from the tumor tissue to that from the corresponding non-tumor tissue (T/N) for the expression of IFNAR mRNAs were calculated. While the T/N ratio of IFNAR1 did not correlate with any factor, a high T/N ratio of IFNAR2 correlated with poor differentiation (P < 0.05), local invasion (P < 0.001), and metastasis (P < 0.0001). By multivariate analysis, a high T/N ratio of IFNAR2 predicted a shortened overall survival in all cases (P < 0.05) and a shorter disease-free survival in those without metastasis (M0; 68 cases, P < 0.05). Impressively, patients with a poorer response to IFN-α treatment had a higher IFNAR2 T/N ratio than those who had a good response (P < 0.05). IFNAR2c protein expression was higher in the primary tumors in patients with metastases (M1; 35 cases) compared to those without ( P < 0.0001).

Conclusion

IFNAR2 is associated with the progression of RCC.

Growth inhibitory effects of pegylated IFN alpha-2b on human liver cancer cells in vitro and in vivo

PURPOSE

We investigated the effects of pegylated IFN-alpha2b (PEG-IFN-alpha2b) on the growth of human liver cancer cells.

METHODS

The effect of PEG-IFN-alpha2b on the proliferation of 13 liver cancer cell lines was investigated in vitro. Chronological changes in growth and IFN-alpha receptor-2 (IFNAR-2) expression were monitored in hepatocellular carcinoma (HCC) cells (HAK-1B) cultured with PEG-IFN-alpha2b. After HAK-1B cells were transplanted into nude mice, various doses of PEG-IFN-alpha2b or IFN-alpha2b were administered, and tumor volume, weight, histology, and IFNAR-2 expression were examined.

RESULTS

PEG-IFN-alpha2b inhibited the growth of nine cell lines with apoptosis in a dose- and time-dependent manner. Continuous contact with PEG-IFN-alpha2b induced time-dependent growth inhibition and down-regulation of IFNAR-2 expression. PEG-IFN-alpha2b induced a dose-dependent decrease in tumor volume and weight, a significant increase of apoptotic cells, and a decrease in IFNAR-2 expression in the tumor. The clinical dose for chronic hepatitis C was also effective. The antitumor effect of PEG-IFN-alpha2b was significantly stronger than that of non-PEG-IFN-alpha2b in vivo.

CONCLUSIONS

Continuous contact with PEG-IFN-alpha2b induces strong antitumor effects and the down-regulation of IFNAR-2 in HCC cells. The data suggest potential clinical application of PEG-IFN-alpha2b for the prevention and treatment of HCC.

Functional expression of human type I interferon receptors in the mouse liver

We expressed human type I interferon (IFN) receptors (IFNAR) in mice and investigated their signaling. Using a hydrodynamics-based delivery method, vectors containing the genes for IFNAR1 and IFNAR2 were transferred into mice. Six hours after gene-transfer, mice were intravenously injected with human IFN-alpha at 10,000 IU. IFNAR1 and IFNAR2 were both expressed in the liver, but not spleen or lung. The receptors were coexpressed in single liver cells. One hour after IFN-alpha injection, the phosphorylation status of signal transducer and activator of transcription factor 1 (STAT1), a key molecule of IFN signaling, was determined. Phosphotyrosine-STAT1 (p-STAT1), localized to the nucleus of IFNAR-expressing cells, was increased in the livers of IFNAR gene-transferred mice but not in control vector-transferred animals. In conclusion, functional human IFNAR can be delivered to the mouse liver, resulting in an increase in p-STAT1 levels following human IFN-alpha stimulation.

A novel modification of a flow cytometric assay of phosphorylated STAT1 in whole blood lymphocytes for rapid detection of interferon-α signal in vivo

Phosphorylation of signal transducer and activator of transcription factor 1 (STAT1) is a key response in the type I interferon (IFN) signal cascade. We developed a novel flow cytometric assay for phosphotyrosine-STAT1 (p-STAT1) to rapidly monitor in vivo IFN signaling. Mouse blood stimulated with mouse IFN-alpha was hemolyzed with lysis buffer in place of lymphocyte purification, permeabilized with methanol, and stained with an Alexa Fluor 488-conjugated anti-p-STAT1 antibody. The cells were also stained with phycoerythrin (PE)-conjugated anti-CD45 antibody for eliminating debris (CD45-negative) from leukocytes (CD45-positive), and with PE covalently linked to cyanin 5-conjugated anti-Gr-1 antibody for separating lymphocytes (Gr-1-negative) and granulocytes (Gr-1-positive). When whole blood was treated with IFN-alpha, the Alexa Fluor 488 intensity of lymphocytes increased, reaching a peak within 1 h, and this increase was statistically significant at IFN-alpha concentrations of 100 U/mL and higher. When IFN-alpha was administered intravenously to mice, the Alexa Fluor 488 intensity of blood lymphocytes was increased, reaching a peak in 1 h and returning to baseline at 18 h, and this increase was dose-dependent, with statistically significant increases seen at doses of 1,000 U/body and higher. The kinetics and dose-responses of p-STAT1 levels in the spleen, lung, and liver were similar to those in blood lymphocytes. This new flow cytometric assay of p-STAT1 in peripheral blood leukocytes will be useful for examining IFN-alpha signaling and for monitoring tissue response to IFN-alpha in vivo.