Translational potential of the interleukin-6/interleukin-10 ratio for immune monitoring after radiofrequency ablation

Abstract

The interleukin (IL)-6/IL-10 ratio emerges as an important biomarker which is utilized for monitoring systemic immune balance after radiofrequency ablation in liver malignant tumors. Although, a study has proved that it has independent prognostic significance for early immune disorder, this review puts forward the view that the ratio reflects a deeper mutual action between pro-inflammatory thermal injury and compensatory immunosuppression. We hold the viewpoint that the translational potential exists in the establishment of standardized 24-hour thresholds and the integration of them into a multidimensional “immune-inflammatory risk score“ together with tumor burden variables. In addition, this ratio can give guidance to individual adjuvant immunotherapies, for example IL-6 receptor antagonists, thus to reduce recurrence. Even though multicenter verification is essential, the IL-6/IL-10 ratio provides a clear pathway for the immunosurveillance-driven model in post-radiofrequency ablation management, thus shifting attention from non-special inflammation signs to accurate immunomodulation.

Key Words: Interleukin-6/interleukin-10 ratio; Radiofrequency ablation; Hepatic malignancies; Immune dysregulation; Risk stratification; Prognosis

Core Tip: The interleukin (IL)-6/IL-10 ratio stands for an important biological marker of immune abnormality after radio frequency ablation. It independently predicts bad results and thus gives a new direction for postoperative immune observation and risk classification in liver cancer patients.

INTRODUCTION

The primary liver cancer yet is a main reason which causes cancer-related death in the whole world[1,2]. In all the treatments that can be used at present, radiofrequency ablation (RFA) is a kind of important micro-traumatic choice for early-stage hepatocellular carcinoma (HCC), it can bring small wound and fast body recovery after operation[3-5]. Even so, the recurrence which happens after RFA still remains a key worry and may have connection with the unbalance of immunity inside the microenvironment of tumor (TME)[6,7]. In current time, real-time apparatuses to objectively evaluate post-procedure immune condition have absence. Clinical doctors usually rely on postponed and non-specific markers such as C-reactive protein and white blood cell number, which are not capable of distinguishing useful anti-tumor body immunity from harmful overmuch inflammation. Therefore, early identification of patients who have high risk of immune disorder, and the utilization of individual-based treatment measures, still are important unmet requirements in the management after RFA.

RFA not only causes coagulative necrosis of tumor cells via thermal damage but also greatly remolds the cytokine network through arousing partial and whole-body immune reactions, in part via the release of damage-associated molecular patterns[7]. The liver, which is an organ that has special immune-adjusting characteristics, keeps a carefully adjusted balance between pro-inflammation and anti-inflammation signals inside its TME[8]. A recent prospective investigation by Pang et al[9], which was published in the World Journal of Hepatology, has shown that among patients who have malignant liver tumors, levels of the pro-inflammation cytokine interleukin-6 (IL-6) have a rapid and obvious rise after RFA, whereas the rise of the anti-inflammation cytokine IL-10 is relatively smaller and comes later. This unbalance thus caused a continuously raised IL-6/IL-10 ratio, which may reflect the emergence and continuance of an immune-disordered condition.

Dynamic alterations in the IL-6/IL-10 ratio not only mirror the intensity of the acute inflammatory response to thermal injury but may also be closely linked to changes in immune surveillance, postoperative recovery, and long-term recurrence risk. Therefore, systematic evaluation of post-RFA IL-6/IL-10 ratio patterns and their clinical relevance is valuable for improving understanding of RFA-related immunomodulatory mechanisms, identifying high-risk patients at an early stage, and guiding the development of adjuvant immunoregulatory approaches.

MECHANISMS OF IL-6 AND IL-10 IN MALIGNANT TUMORS

IL-6 is a pleiotropic cytokine produced by multiple cell types in both the innate and adaptive immune systems. It plays a central role in immune regulation, inflammatory processes, and metabolic homeostasis[10]. By contrast, IL-10 is a major anti-inflammatory cytokine. Together, these cytokines form a functional axis, referred to as the IL-6/IL-10 axis, that jointly regulates immune equilibrium[11,12].

A great number of researches have pointed out IL-6 and IL-10 are very important inflammation biomarkers, they have obvious rise in many kinds of malignant tumors which include breast cancer, lung cancer and colorectal cancer[13-15]. As the main controlling factor of the acute stage response, IL-6 has close connection with the pathogenesis of chronic inflammation[16]. It is secreted by many different kinds of sources, among which include immune cells, parenchymal cells, stromal cells, and also the tumor cells themselves. Besides the activation of T and B lymphocytes, IL-6 carries out direct stimulation of tumor cell proliferation[17]. From the mechanism perspective, IL-6 initiates many intracellular signaling pathways, for example Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3), mitogen-activated protein kinase, and nuclear factor kappa B, hence it promotes tumorigenesis, angiogenesis, and distant metastasis[18]. These signal pathways cause abnormal cell proliferation, metabolic reprogramming, increased oxidative stress, and epithelial-mesenchymal transition, and at the same time they inhibit programmed cell death and cell cycle arrest[19]. In clinical practice, the rising peripheral IL-6 concentrations act as strong indicators for diagnosis and prognosis prediction in digestive system malignant tumors, such as HCC and colorectal cancer[20,21]. Therefore, therapeutic strategies that target the IL-6/IL-6R complex or its downstream effectors have shown obvious clinical potential[22].

IL-10 is a multi-function cytokine that mainly recognized for its anti-inflammation characteristics and its function in immune evasion[23]. In gastrointestinal cancers, the expression of IL-10 has been obviously upregulated[24-26]. It brings immunosuppressive effects through the inhibition of cytolytic activity of T cells and natural killer cells, therefore, it facilitates the progress of tumor[27]. After IL-10 has bound to its receptor, it causes the activation of the JAK/STAT3 and phosphatidylinositol 3-kinase/protein kinase B signaling pathways[28]. It is worth pointing out that IL-10 shows a dose-dependent duality: Although high-dose IL-10 can bring out immunostimulatory functions through promoting interferon-gamma secretion from tumor-infiltrating T cells[29], its immunosuppressive function usually holds a dominant position inside the TME. Although on theory IL-10 can restrict the tumor-causing chronic inflammation in the early period of disease through ending inflammation responses, its rising level in advanced stages has strong connection with poor clinical outcomes[30,31]. Preclinical researches have studied the potential of IL-10 to orchestrate anti-tumor immune responses when it is combined with other treatment methods[32]. Emerging evidence puts forward that in special situations, IL-10 may support the survival and cytotoxicity of CD8+ T cells, although this possible effect is frequently covered by its overall immunosuppression character in the TME[33]. With respect to HCC, the conclusive evidence which can prove that IL-10 has a protective effect still cannot be obtained. The current common view holds that IL-10 promotes HCC development via immune evasion, therefore it particularly appears as a dominant tumor-promoting factor in the late period of disease.

To make the summary, both IL-6 and IL-10 have key functions in the starting and development of malignant tumors, therefore they exert obvious pathological effects on hepatic malignant diseases. Previous researches have systematically reported on their expression profiles, regulatory mechanisms, and clinical significance in hepatic carcinoma, and the main results are collected in Table 1[34-50]. Therefore, the tissue expression levels and serum concentrations of IL-6 and IL-10 have the potential value that can be used for tumor diagnosis and prognosis evaluation. Furthermore, the immune balance which is kept by these two cytokines therefore may hold an important function in reducing the risk of oncogenesis. The relationship that explains the concrete functions and adjustment routes of IL-6 and IL-10 in malignant tumors is placed in Figure 1.

Figure 1 Roles of interleukin-6 and interleukin-10 in malignant tumors. CAF: Cancer-associated fibroblasts; EMT: Epithelial-mesenchymal transition; IL-6: Interleukin-6; IL-10: Interleukin-10; MDSC: Myeloid-derived suppressor cells; TAM: Tumor-associated macrophages; Tregs: Regulatory T cells.

Table 1 Studies on the roles and clinical significance of interleukin-6 and interleukin-10 in hepatic malignancies.

Ref.	Parameter	Research type	Test set	Key findings
Paul et al[34]	IL-6	Retrospective study	229 patients	High IL-6 levels can independently predict adverse pathological features of liver cancer and increase the risk of recurrence after transplantation
Hu et al[35]		Retrospective study	101 patients	High serum IL-6 concentration before radiotherapy is an independent predictor of poor prognosis after radiotherapy in patients with HCC
Shao et al[36]		Prospective study	128 patients	In patients with advanced HCC, elevated pre-treatment plasma IL-6 levels (> 4.28 pg/mL) are an independent prognostic indicator for poor overall survival after sorafenib treatment
Myojin et al[37]		Prospective study	64 patients	Plasma IL-6 level is a novel circulating biomarker for poor prognosis in patients with advanced HCC receiving atezolizumab/bevacizumab combination immunotherapy, and its high level is significantly associated with poorer treatment response and shorter progression-free survival and overall survival
Dalbeni et al[38]		Retrospective study	93 patients	Elevated IL-6 levels are significantly associated with advanced disease stage (BCLC stage C) of HCC and represent a potential novel biomarker for sarcopenia in cirrhotic patients with HCC
Song et al[39]		Basic study	-	IL-6 enhances the anti-apoptotic, proliferative and migratory capabilities of liver cancer cells by activating the Janus kinase 2/STAT3 signaling pathway to upregulate the expression of its receptor IL-6R, thereby promoting liver cancer progression
Zhu et al[40]		Basic study	-	IL-6 released by hepatic stellate cells enhances the glycolytic and migratory capabilities of liver cancer cells by activating the Janus kinase 1/von willebrand factor/TGF-β1 axis
Xu et al[41]		Basic study	-	IL-6 upregulates the expression of the pro-apoptotic protein prostate apoptosis response protein-4 by activating the STAT3 signaling pathway, thereby stimulating the proliferation and migration of liver cancer cells and reducing their drug sensitivity to sorafenib, thus promoting liver cancer progression
Srivastava et al[42]		Basic study	-	In HCC, TGF-β can attenuate the IL-6-induced proliferation of cancer cells by downregulating the IL-6 receptor, inhibiting its downstream STAT-3/p65 signaling pathway, and altering the epigenetic profile of histone modifications
Mei et al[43]	IL-10	Meta analysis	8182 participants	IL-10 gene is associated with HCC risk in an ethnicity-specific manner (significant in non-Asian populations)
Chen et al[44]		Mendelian randomization	-	IL-10 levels have a negative causal association with liver cancer risk, exerting a protective effect
Lin et al[45]		Basic study	-	liver-directed adeno-associated virus vector-IL-10 delivery can overcome local immunosuppression and enhance CD8+T cell-mediated anti-tumor immunity, thereby effectively inhibiting the growth of HCC
Ouyang et al[46]		Basic study	160 patients	In HCC, dendritic cells in the tumor microenvironment activate B cells to produce IL-10, which in turn inhibits the immune function of cytotoxic T cells, thereby promoting tumor immune escape
Chamseddine et al[47]		Prospective study	767 patients	In patients with HCC, elevated serum IL-10 levels are a marker of poor prognosis and significantly associated with shorter overall survival
El-Emshaty et al[48]		Cross-sectional study	51 patients	Serum IL-10 levels are significantly elevated during the progression from chronic liver disease to HCC, which may promote the development of HCC by inhibiting the body’s immune surveillance
Sharafeldin et al[49]		Prospective study	100 patients	IL-10 levels are significantly elevated in the serum of patients with HCV-related HCC, which can serve as a novel biomarker reflecting the degree of tumor inflammation, and its combined application with alpha-fetoprotein improves the diagnostic performance of HCC
Yang et al[50]		Retrospective study	110 patients	In patients with HCV-related HCC, plasma IL-10 levels are significantly elevated. On one hand, it may limit liver damage through anti-inflammatory effects, but on the other hand, its immunosuppressive function promotes tumor immune escape and progression

HCC: Hepatocellular carcinoma; IL-6: Interleukin-6; IL-10: Interleukin-10; STAT3: Signal transducer and activator of transcription 3; TGF-β: Transforming growth factor beta.

THE ROLE OF IL-6 AND IL-10 IN IMMUNE REGULATION FOLLOWING RFA FOR HEPATIC MALIGNANCIES

During the progression of HCC, IL-6 binds to its receptor and activates signaling pathways such as JAK/STAT, thereby promoting tumor growth and associating with poor prognosis[51]. It can stimulate inflammatory responses, for instance through activation of hepatic stellate cells, and contribute to the formation of an immunosuppressive TME, facilitating immune escape[51,52]. Previous studies suggest that activation of the IL-6/STAT3/HGF/c-MET pathway after RFA may accelerate distant tumor progression[52]. At the same time, IL-10 further strengthens tumor immune evasion by suppressing Th1 cell activity and promoting the expansion of regulatory T cells[53,54].

RFA eliminates tumor cells through thermal damage and simultaneously alters the local immune microenvironment. This process releases tumor-associated antigens and damage-associated molecular patterns, activates CD8+ T cells, and stimulates the secretion of pro-inflammatory cytokines such as IL-6, thereby enhancing anti-tumor immune responses[55-57]. However, the inflammatory milieu induced by RFA may also activate regulatory T cells and myeloid-derived suppressor cells. These cells secrete IL-10 to control excessive inflammation but may concurrently impair the host anti-tumor immune response[55,58]. Hence, both IL-6 and IL-10 are crucially participated in the initiation and development of liver malignant tumors. Through influencing the dynamic balance which exists among these cytokines, RFA forms the TME, and the result of treatment relies on the accurate regulation of pro-inflammatory and anti-inflammatory signals.

In summary, RFA exerts influence on IL-6 and IL-10 concentrations by way of direct tissue damage and immune system activation. IL-6 has the function of supporting acute inflammation and tissue repair, yet the persistent elevation of it may promote tumor recurrence through the pathway of STAT3 signaling. IL-10 holds back excessive inflammation but at the same time can cultivate an immunosuppression microenvironment. It is very important that, neither of these two cytokines is purely beneficial or purely harmful. The effects of them depend on the context, and are kept in a dynamic balancing state. Clinical results after RFA do not only depend on absolute concentrations of each single molecule but on their relative balance, this ratio can reflect the whole immune condition and therefore helps forecast recovery and prognosis. In the future, the strategies should put their emphasis on the integration of immunomodulatory therapies, therefore to refine this balance and increase the effectiveness of RFA.

HIGHLIGHTS AND CLINICAL IMPLICATIONS OF THE STUDY

The prospective analysis which is done by Pang et al[9] has established that the post-RFA IL-6/IL-10 ratio is an independent predictor of immune disorder in patients who have hepatic malignancies, therefore it gives a new biomarker for postoperative management. One important strong point of the research is that it puts cytokine ratio as an indicator of systemic immune balance. The result discovers that the continuous elevation after the operation – which is mainly caused by the obvious IL-6 surge – has independent connection with poor outcomes, indicating that RFA brings about a persistent immune unbalance, not a transient inflammation response. This observation strengthens the core function of immune regulation in recovery and prognosis, thus gives a quantitative foundation for early recognition of high-risk patients.

From a methodological perspective, the successive measurement work of cytokines in seven days has captured the dynamic change situations of this ratio. The multivariate model has properly incorporated both the IL-6/IL-10 ratio and liver function indicators, thus strengthening the validity of the conclusions. Importantly, the proposal which one single measurement at 24 hours after RFA may be enough thus markedly promotes the clinical practicality.

However, several limitations are worthy of being thought over. The design of single center and the relatively small size of sample (n = 91) may have limitation on the generalizability. This very same-type research group, which is mainly made up of Child-Pugh A patients who have hepatitis B virus-connected early HCC, therefore puts limits on the extension of results to individuals who have worse liver function or other cause types. The brief 7-day follow observation and the employment of a combination endpoint concentrating on early inflammatory complication problems cannot set up a connection between this biomarkers and long-term results like recurrences or survivals, therefore this is a main gap for clinical transformation work. Even though a single 24-hour measurement is of practical use, it can neglect the dynamic change rules of individual cytokines, and it can be affected by perioperative interventions or sub-clinical infection.

FUTURE PERSPECTIVES: OPPORTUNITIES AND CHALLENGES

The complicated changes which occur in the immune microenvironment after operation have important influences on the postoperative recovery of patients and the development of their complications. The ratio of IL-6 to IL-10 reflects the balance that changes dynamically between the pro-inflammatory IL-6 and anti-inflammatory IL-10, and it acts as one key marker for systemic inflammatory response and compensatory anti-inflammatory response syndrome[59,60]. For making the IL-6/IL-10 ratio progress from one biomarker to one tool for clinical decision making, the research in future ought to put emphasis on a number of concrete and executable transformation paths.

Firstly, the standardized experiment testing flow charts and early-warning thresholds must be built up. Multicenter, large-scale verify studies are needed to confirm the dynamic changing path of the IL-6/IL-10 ratio in the first 24-48 hours after RFA. The special cut-off values for recognizing high-risk patients ought to be confirmed via receiver operating characteristic curve analysis, and their robustness ought to be evaluated in subgroups that have different liver function and tumor burden. The exploitation of fast, standardized detection kits suitable for point-of-care test or daily lab application is a precondition for clinic putting-into-use. Secondly, the prediction models that combine clinical and immunological information and the stratified management roads should be gotten to develop. Instead of only depending on this ratio, it must be put together with easy-to-get clinical parameters, such as preoperative albumin, aspartate aminotransferase, and tumor size and number, for building comprehensive score systems. For instance, an “immunity-inflammation risk score” can assist instantly postoperative stratification and be put into clinical decision supporting systems. According to the given risk grades, specially made monitoring time arrangements, anti-inflammation treatment measures, or earlier image checking follow-up plans can then be applied.

Thirdly, prospective intervention trials are needed to verify clinical utility. One crucial translational step lies in the confirming whether interventions directed by the IL-6/IL-10 ratio are able to promote the improvement of patient outcomes. Randomized controlled trials may evaluate whether patients who have continuously raised post-RFA ratios can get benefit from early, short-period directional anti-inflammation treatments, for example IL-6 receptor antagonists, with outcomes measured on the basis of complication rates, hospital stay duration, and long-term recurrence hazard. These research works can provide direct proof about this ratio’s usefulness in giving guidance to treatment.

Fourthly, the potential mutual effect that exists with current therapeutic method should be explored. In the present time of immunotherapy, the IL-6/IL-10 ratio can act as a biological marker for predicting the effect or poison of RFA that combines with immune checkpoint inhibitors. The analysis of ratio changes before and after combined treatment can assist in recognizing patients who have the highest possibility of obtaining benefit, hence guide the adjustment of immunotherapy treatment plans.

Through these approaches, the IL-6/IL-10 ratio possesses the potential to develop from a hopeful research indicator into a practical tool for guiding personalized management after RFA.

CONCLUSION

The IL-6/IL-10 ratio serves as an important biomarker for immune dysregulation after RFA, and it independently predicts adverse outcomes. This emphasizes that it has connection for the postoperative immunity observation and risk stratification. This ratio provides a novel direction for the personalization of immune regulation and the accurate management, thus, it has the potential to push the RFA therapy to the direction of a paradigm which is driven by immune monitoring.