Combined Expression of IFN-γ, IL-17, and IL-4 mRNA by Recall PBMCs Moderately Discriminates Active Tuberculosis from Latent Mycobacterium tuberculosis Infection in Patients with Miscellaneous Inflammatory Underlying Conditions

Expression profile of KIR3DS1/KIR3DL1 receptors in association with immunological responses in TB, HIV and HIV/TB infected patients

Several studies investigated KIR3DS1 and KIR3DL1 in the context of various infections. However, none of the studies were performed on KIR3DS1/L1 in association with IFN-ɣ/IL-10 in TB, HIV-1, and their confections. We aimed to evaluate KIR3DS1/KIR3DL1 expression in association with IFNɣ/IL-10 in HIV-1 and TB mono-infections and HIV-1/TB confection and compared with uninfected controls using RTq PCR. We also performed correlation analysis between KIR3DS1, KIR3DL1, IFN-ɣ and IL-10 in the respective cohorts. The overall expression of KIR3DS1 was found to be downregulated in all groups, whereas in HIV-1 and HIV-1/TB, the frequency of KIR3DS1⁽⁺⁾ expression was significantly (p < 0.05) associated with undetected HIV-1 viral load. However, expression of KIR3DL1 was found to be significantly (p < 0.05) upregulated in HIV-1 only. In addition, IFNɣ expression was significantly (p < 0.05) decreased in TB, whereas in HIV-1/TB, IFNɣ expression was significantly (p < 0.05) increased. In contrast, IL-10 expression was significantly (p < 0.05) increased in HIV-1 and HIV-1/TB but not in TB. Also, we found significant positive correlation (p < 0.05, r = 0.61) between KIR3DL1 and IFNɣ expression in TB and negative correlation (p < 0.05, r = - 0.62) between KIR3DS1 and IL-10 in HIV-1/TB. In conclusion, we suggest that expression of KIR3DS1/L1 is associated with IFNɣ/IL-10 responses and it is involved in modulating disease severity in HIV-1 and TB infections.

Diagnostic Performance of a Novel CXCL10 mRNA Release Assay for Mycobacterium tuberculosis Infection

One-fourth of the world’s population has been infected with Mycobacterium tuberculosis (M.tb). Although interferon-gamma release assays (IGRAs) have been shown to be valid methods for identifying M.tb infection and auxiliary methods for diagnosis of active tuberculosis (TB), lower sensitivity and higher indeterminate rate were often detected among immunosuppressed patients. IP-10 was an alternative biomarker due to the higher expression level after M.tb antigen stimulation, but whether CXCL10 mRNA (the gene that transcribes for the IP-10 protein) can be used as a target for M.tb infection diagnosis was limited. Therefore, we aimed to evaluate the performance of a novel M.tb-specific CXCL10 mRNA release assay in diagnosis of M.tb infection. Suspected TB patients and healthy controls were prospectively recruited between March 2018 and November 2019 from three hospitals in China. CXCL10 mRNA release assay and traditional interferon-gamma release assay (T-SPOT.TB) were simultaneously performed on peripheral blood. Of the 1,479 participants enrolled in the study, 352 patients with definite TB and 153 healthy controls were analyzed. CXCL10 mRNA release assay provided a sensitivity of 93.9% (95% CI = 90.8–96.2%) and a specificity of 98.0% (95% CI = 94.3–99.6%) in the diagnosis of M.tb infection, respectively, while T-SPOT.TB gave a sensitivity of 94.5% (95% CI = 91.5–96.6%) and a specificity of 100% (95% CI = 97.6–100.0%) in the diagnosis of M.tb infection, respectively. The diagnostic performance of CXCL10 mRNA release assay was consistent with T-SPOT.TB, with a total coincidence rate of 95.0% (95% CI = 93.0–96.9%) and a Cohen’s kappa value of 0.89 (0.84–0.93, p < 0.001). However, among TB patients with HIV co-infection (n = 14), CXCL10 mRNA release assay presented significantly higher positive rate [92.9% (66.1–99.8%) vs. 61.5% (31.6–86.1%), p = 0.029] than those of T-SPOT.TB. These results suggested that M.tb-specific CXCL10 mRNA was a novel and useful target in the diagnosis of M.tb infection.

Mycobacterium tuberculosis Immune Response in Patients With Immune-Mediated Inflammatory Disease

Subjects with immune-mediated inflammatory diseases (IMID), such as rheumatoid arthritis (RA), have an intrinsic higher probability to develop active-tuberculosis (TB) compared to the general population. The risk ranges from 2.0 to 8.9 in RA patients not receiving therapies. According to the WHO, the RA prevalence varies between 0.3% and 1% and is more common in women and in developed countries. Therefore, the identification and treatment of TB infection (TBI) in this fragile population is important to propose the TB preventive therapy. We aimed to study the M. tuberculosis (Mtb) specific T-cell response to find immune biomarkers of Mtb burden or Mtb clearance in patients with different TB status and different risk to develop active-TB disease. We enrolled TBI subjects as example of Mtb-containment, the active-TB as example of a replicating Mtb status, and the TBI-IMID as fragile population. To study the Mtb-specific response in a condition of possible Mtb sterilization, we longitudinally enrolled TBI subjects and active-TB patients before and after TB therapy. Peripheral blood mononuclear cells were stimulated overnight with Mtb peptides contained in TB1- and TB2-tubes of the Quantiferon-Plus kit. Then, we characterized by cytometry the Mtb-specific CD4 and CD8 T cells. In TBI-IMID, the TB therapy did not affect the ability of CD4 T cells to produce interferon-γ, tumor necrosis factor-α, and interleukin-2, their functional status, and their phenotype. The TB therapy determined a contraction of the triple functional CD4 T cells of the TBI subjects and active-TB patients. The CD45RA- CD27+ T cells stood out as a main subset of the Mtb-specific response in all groups. Before the TB-preventive therapy, the TBI subjects had higher proportion of Mtb-specific CD45RA-CD27+CD4+ T cells and the active-TB subjects had higher proportion of Mtb-specific CD45RA-CD27-CD4+ T cells compared to other groups. The TBI-IMID patients showed a phenotype similar to TBI, suggesting that the type of IMID and the IMID therapy did not affect the activation status of Mtb-specific CD4 T cells. Future studies on a larger and better-stratified TBI-IMID population will help to understand the change of the Mtb-specific immune response over time and to identify possible immune biomarkers of Mtb-containment or active replication.

An IFN-γ and TNF-α dual release fluorospot assay for diagnosing active tuberculosis

OBJECTIVES

Currently available interferon (IFN)-γ-release assays (IGRA) cannot discriminate active tuberculosis (TB) from latent TB infection (LTBI), and so have limited clinical utility for diagnosing active TB. Since numbers of tumour necrosis factor (TNF)-α-producing T cells are highly correlated with active TB, we hypothesized that detecting IFN-γ- and/or TNF-α-producing T cells would overcome this limitation of IGRA. This study evaluated the diagnostic performances of the IFN-γ and TNF-α dual release fluorospot assay for active TB.

METHODS

Adult patients with suspected TB including recent TB exposers were prospectively enrolled over a 28-month period. In addition to the conventional IGRA test (i.e. QuantiFERON-In-Tube), a fluorospot assay for detecting IFN-γ- and TNF-α-producing T cells was performed. The final diagnoses were classified by clinical category. Patients with confirmed or probable TB were regarded as active TB, and patients with not active TB were further classified as having not active TB with and without LTBI, based on the QuantiFERON-In-Tube results.

RESULTS

A total of 153 patients including 45 with active TB and 108 with not active TB (38 LTBI vs. 70 not LTBI) were finally analysed. The sensitivity and specificity of the QuantiFERON-In-Tube assay for active TB were 84% (95% confidence interval (CI), 70-93) and 70% (95% CI 61-79), respectively. The IFN-γ/TNF-α dual release assay by fluorospot had substantially higher diagnostic specificity (94%) for diagnosing active TB than the IFN-γ single release assay (72%, p < 0.001), without compromising sensitivity (84% vs. 89%, p 0.79).

CONCLUSIONS

The fluorospot-based IFN-γ/TNF-α dual release assay appears to be a simple and useful test for diagnosing active TB.

Combined IFN-γ and TNF-α release assay for differentiating active tuberculosis from latent tuberculosis infection

OBJECTIVES

The IFN-γ-release assay (IGRA) cannot differentiate active tuberculosis (TB) from latent TB infection (LTBI). We hypothesized that the TNF-α-release assay (TARA) combined with IGRA might discriminate active TB from not active TB without LTBI.

METHODS

Adult patients with suspected TB, and with unrelated diseases such as herpes zoster as controls, were enrolled in an intermediate TB-burden country. Patients with confirmed or probable TB were regarded as active TB, and patients with not active TB were further classified as those having not active TB with and without LTBI based on IGRA results. The IGRA and TARA by using ELISPOT assays were performed on peripheral mononuclear cells.

RESULTS

Thirty six patients with active TB and 53 patients including 18 not active TB with LTBI and 35 not active TB without LTBI were finally included. The sensitivity and specificity of the IGRA for those patients found to have active TB were 94% (CI, 80-99) and 66% (CI 52-78), respectively. Combining the IGRA and the TARA substantially increased the specificity for active TB (93%, CI, 82-98; P = 0.001) compared with the IGRA only, without compromising sensitivity (89%, CI, 73-96; P = 0.67).

CONCLUSIONS

Combining the IGRA and TARA appears to be useful for diagnosing active TB.