Identification of Biomarkers of Response to IFNg during Endotoxin Tolerance: Application to Septic Shock

Abstract

The rapid development in septic patients of features of marked immunosuppression associated with increased risk of nosocomial infections and mortality represents the rational for the initiation of immune targeted treatments in sepsis. However, as there is no clinical sign of immune dysfunctions, the current challenge is to develop biomarkers that will help clinicians identify the patients that would benefit from immunotherapy and monitor its efficacy. Using an in vitro model of endotoxin tolerance (ET), a pivotal feature of sepsis-induced immunosuppression in monocytes, we identified using gene expression profiling by microarray a panel of transcripts associated with the development of ET which expression was restored after immunostimulation with interferon-gamma (IFN-γ). These results were confirmed by qRT-PCR. Importantly, this short-list of markers was further evaluated in patients. Of these transcripts, six (TNFAIP6, FCN1, CXCL10, GBP1, CXCL5 and PID1) were differentially expressed in septic patients’ blood compared to healthy blood upon ex vivo LPS stimulation and were restored by IFN-γ. In this study, by combining a microarray approach in an in vitro model and a validation in clinical samples, we identified a panel of six new transcripts that could be used for the identification of septic patients eligible for IFNg therapy. Along with the previously identified markers TNFa, IL10 and HLA-DRA, the potential value of these markers should now be evaluated in a larger cohort of patients. Upon favorable results, they could serve as stratification tools prior to immunostimulatory treatment and to monitor drug efficacy.

LTR-retrotransposon transcriptome modulation in response to endotoxin-induced stress in PBMCs

“…As observed for TNF-α and IL10 genes, HERV/MaLR elements exhibit a dichotomy of tolerisable versus non tolerisable phenotypes, although some elements were found to be down-regulated in both conditions. As illustrated by 121601901-HERV0116uL and 081146702-MALR1129uL loci, HERV/MaLR tolerisation was surprisingly reversible upon IFN-γ addition, as previously described for TNF-α [ 51 , 52 ]. Again, this demonstrates that HERVs/MaLRs and genes share similar regulation control following stimulation inducing inflammation or anergy in PBMCs.…”

“…Conversely, 08114670-MALR1129uL is at a distance of more than 100 kb from the closest gene. Interestingly, as known for TNF-α [ 51 ], the tolerisable HERV phenotype was reversed by IFN-γ (Fig. 4a and b , column c).…”

Immunotherapy of Sepsis: Blind Alley or Call for Personalized Assessment?

“…Prerequisite for effective administration of immunotherapy is therefore the evaluation of immune system status and the degree of immunocompetence of individual patient. The example of such practice is French study on IFN-c administration in sepsis preceded with biomarkers detection for identification of appropriate candidates for the treatment (Allantaz-Frager et al 2013). The publication by Deutschman and Tracey suggest that severe sepsis and ''persistent critical illness'' are not immunopathologies ''per se'' but represent a failure of homeostasis caused by dysfunction of the neuroendocrine and immune system.…”

The role and regulation of inhibitor of Kappa B Kinase in the impaired monocyte response.

“…These findings are in keeping with previous in-vitro studies. 47 In addition, these positive effects by IFN-γ have been shown in-vivo with numerous clinical studies. 91 We have shown that IFN-γ also increases the expression of PD-L1 on the surface of monocytes.…”

“…Furthermore, bench to bedside studies of monocyte impairment reveal dysregulated gene expression patterns, including genes such as S100A8/9, TNFAIP6 and IRAK-M (as well as TNF-α, IL-10 and HLA-DR) which have been suggested to "monitor efficacy" of IFN-γ therapy [46][47][48] .…”