IP-10 can be measured in dried plasma spots in patients with chronic hepatitis C infection

Changes in serum interferon-γ-inducible protein-10 levels and liver stiffness among chronic hepatitis C Egyptian patients in response to directly acting antiviral agents

BACKGROUND

Interferon-γ inducible protein-10 (IP-10) is chemokine biomarker of liver inflammation, elevated in patients with chronic hepatitis C infection.

AIMS

Investigating if changes in serum IP-10 levels in response to directly acting antiviral agents (DAAs) treatment for chronic HCV patients are paralleled by changes in liver stiffness measurements (LSM), and assessing role of using serum IP-10 as a noninvasive accurate method to predict changes in hepatic necro-inflammation and fibrosis.

MATERIAL AND METHODS

A prospective observational study included 92 Egyptian chronic HCV patients, who received treatment with sofosbuvir with daclatasvir regimen. Patients were classified into two groups; group I (53 patients) with non to mild significant liver fibrosis (F0-F1), and group II (39 patients) with significant to advanced liver fibrosis (F2-F4). Fibroscan and serum IP-10 were assessed pretreatment and 3 months after end of treatment.

RESULTS

All patients achieved SVR. Both IP-10 and LSM showed significant decline after treatment in both groups. No significant correlation was found between changes in LSM and IP-10. IP-10 detected liver cirrhosis at cut off level of 17.8 pg/ml, with 75% sensitivity and 73.86% specificity, with area under the curve = 0.66, however, IP-10 had no statistical significance in detecting advanced fibrosis.

CONCLUSION

IP-10 might be of significance as a noninvasive predictor of liver cirrhosis. IP-10 significant decline post-DAAs treatment in chronic HCV genotype IV infected patients reflects significant improvement in fibrosis stage and hepatic necro-inflammation in response to treatment. No significant correlation was detected in the changes of both IP-10 and LSM.

Solutions for hematocrit bias in dried blood spot hormone analysis

Over the last years, dried blood spot (DBS) sampling has gained significant interest due to development of analytical techniques combined with DBS, the simplicity and low cost of the method. Despite its wide use, DBS sampling can lead to inaccurate results due to the impact of the hematocrit (Hct) on the analysis. Some analytes have shown to be hardly impacted by Hct values. However, in other cases, a significant impact of Hct is observed, which requires the use of alternative approaches to circumvent this issue. This review describes the possible impact of Hct-related bias in DBS sampling in the context of hormone analysis and discusses the different methodologies that can be used to overcome this bias to ensure accurate results.

Determination of anti-HCV and quantification of HCV-RNA and IP-10 from dried blood spots sent by regular mail

BACKGROUND

With the introduction of direct acting antivirals, treatment of hepatitis C virus (HCV) in hard-to-reach populations is now feasible. Therefore, new cost-effective and reliable test methods are needed. Determination of HCV antibodies and HCV-RNA from dried blood spots samples could represent one such method. Here we examined whether anti-HCV could be detected-and HCV-RNA quantified-from dried blood spots, sent by regular mail. We also investigated, if IP-10 determined from dried blood spots correlated with fibrosis progression appraised by transient elastography.

METHOD

Forty chronic HCV infected patients were consecutively enrolled. At baseline and after six months, dried blood spots were prepared from blood collected by venous puncture, dried for 4-6 hours, then stored in gas-impermeable plastic bags with a desiccator, before being sent by regular mail. At each visit, approximately six months apart, paired venous samples was obtained and analyzed for anti-HCV, HCV-RNA and IP-10.

RESULTS

Anti-HCV was found in 66/67 of the dried blood spots. Sixty-six paired samples were available for HCV-RNA analysis. A statistically significant correlation was found between log HCV-RNA concentrations in plasma, and log HCV-RNA obtained from (P < 0.0001, Pearson's R 0.6788, R2 0.4607). HCV-RNA, derived from DBS samples, was lower than the corresponding plasma concentration, reflected by a Bland-Altman bias of 3 with SD of bias ± 0.6472. We found no correlation between IP-10 and fibrosis progression.

CONCLUSIONS

We identified anti-HCV in 66/67samples, and quantified IP-10 and HCV-RNA from dried blood spots, dried at room temperature and sent by regular mail. HCV-RNA concentrations from the dried blood spots were lower than corresponding plasma values; a probable result of heparin coated test tubes. We found no correlation between IP-10 and fibrosis progression. Overall, dried blood spots could be a cost-effective and easy-to-use alternative to standard tests for the diagnosis of HCV infections.

Evaluation of IP-10 in Quantiferon-Plus as biomarker for the diagnosis of latent tuberculosis infection

The QuantiFERON-TB Gold Plus (QFT-Plus) is a new test for latent tuberculosis infection (LTBI) diagnosis, in which has been added a new tube containing shorter peptides stimulating CD8 T-cells and CD4-stimulating-peptides. Measurement of alternative biomarkers to Interferon-γ (IFN-γ) in QFT-Plus may improve its sensitivity. Interferon-γ inducible protein 10 (IP-10), has been proposed as a tuberculosis (TB) biomarker. We aimed to evaluate the IP-10 accuracy in QFT-Plus for LTBI diagnosis. QFT-Plus was performed in 36 active TB, 31 LTBI and 16 healthy donors (HD). IP-10 was detected by ELISA. IP-10 is increased in TB1 and TB2 tubes in subjects with active TB and LTBI compared to HD. A ROC analysis comparing active TB and HD was performed and a cut-off of 1174 pg/mL for TB1 and 928.8 pg/mL for TB2 identified active TB with 86% sensitivity (Se) and 94% specificity (Sp). Moreover, increased IP-10 in response to TB1 was found in subjects with LTBI compared to those with active TB. A cut-off point of ≥16,108 pg/mL was chosen to maximize the test performance. However, the test predicted LTBI only with 58% Se and 61% Sp. These results suggest that IP-10 is an alternative biomarker to IFN-γ in the QFT-Plus format.

ELISA-based assay for IP-10 detection from filter paper samples

IP-10 is a small pro-inflammatory chemokine secreted primarily from monocytes and fibroblasts. Alterations in IP-10 levels have been associated with inflammatory conditions including viral and bacterial infections, immune dysfunction, and tumor development. IP-10 is increasingly recognized as a biomarker that predicts severity of various diseases and can be used in the immunodiagnostics of Mycobacterium tuberculosis and cytomegalovirus infection. Here, we describe an ELISA-based method to detect IP-10 from dried blood and plasma spot samples.

Hemato-critical issues in quantitative analysis of dried blood spots: challenges and solutions

Dried blood spot (DBS) sampling for quantitative determination of drugs in blood has entered the bioanalytical arena at a fast pace during the last decade, primarily owing to progress in analytical instrumentation. Despite the many advantages associated with this new sampling strategy, several issues remain, of which the hematocrit issue is undoubtedly the most widely discussed challenge, since strongly deviating hematocrit values may significantly impact DBS-based quantitation. In this review, an overview is given of the different aspects of the ‘hematocrit problem’ in quantitative DBS analysis. The different strategies that try to cope with this problem are discussed, along with their potential and limitations. Implementation of some of these strategies in practice may help to overcome this important hurdle in DBS assays, further allowing DBS to become an established part of routine quantitative bioanalysis.

Dried plasma spots in the diagnosis of tuberculosis: IP-10 release assay on filter paper

Interferon (IFN)-γ release assays (IGRAs) are probably the most accurate tests for the detection of latent Mycobacterium tuberculosis infection, but IGRAs are labour intensive and the transport of samples over longer distances is difficult. IFN-γ-induced protein (IP)-10 is expressed at 100-fold higher levels than IFN-γ, and IP-10 release assays have comparable performance to IGRAs. The aim of this study was to explore the diagnostic potential of a novel IP-10 release assay based on dried plasma spots (DPS). The presence of IP-10 and IFN-γ was determined in plasma and in DPS by ELISA. Diagnostic algorithms for plasma and DPS tests for IP-10 were developed on a training cohort comprising 60 tuberculosis (TB) patients and 59 healthy controls. Diagnostic accuracy was assessed in a validation cohort comprising 78 TB patients and 98 healthy controls. Plasma was measured in Spain and DPS samples were sent to Denmark using the conventional postal service for analysis. IP-10 was readily detectable in both plasma and DPS, and correlation was excellent (r(2) = 0.95). QuantiFERON-TB Gold In-Tube (QFT-TB) and IP-10 in DPS and plasma rendered comparable sensitivity (78%, 82% and 84%, respectively), specificity (100%, 97% and 97%, respectively) and indeterminate rates (p>0.55). The DPS-based IP-10 test has comparable diagnostic accuracy to the QFT-TB and samples can be sent via conventional mail over long distances for analysis without affecting the results.