T-helper 1 and 2 cell densities, and mesenteric cytokine levels, are prognostic markers in colorectal cancer

Background

Colorectal cancer (CRC) is the third leading cause of cancer worldwide and is the second leading cause of death in the US (1). Various players drive the initiation and progression of CRC, including genetic, epigenetic, environmental, lifestyle, and microbial factors (2-4). Immune cells contribute and determine the outcomes of CRC. Several studies reported the roles of T-cell subsets (CD4⁺ T cells, CD8⁺ cells, FOXP3⁺ cells, CD45R0⁺ cells, and others) in the pathogenesis of CRC, the prediction of CRC clinical outcome, and therapeutic efficacy, especially in the tumor microenvironment (TME) (5-8). The level of CD8⁺ tumor-infiltrating lymphocytes (TILs) in the TME and invasive area have prognostic significance for cancer outcomes and patient survival (9). Patients with high CD8⁺ TILs in nonmetastatic CRC had better survival than those with low CD8⁺ TILs (9). Transcriptomic analysis of sorted CD3⁺CD8⁺ TILs in CRC patients at early and late stages of CRC revealed that genes that mediate cell cycle, mitosis, DNA repair, T-cell chemotaxis, interferon (IFN)-signaling, T-cell activation, cytokine secretion, chemokine signaling and antigen presentation are downregulated in late stage, while the genes mediate chromatin silencing, Wnt-signaling, and apoptotic process were upregulated (10). Saleh and colleagues reported the gene signatures of CD8⁺ TILs linked to worse outcome in CRC (10). The baseline levels of CD8⁺ TILs and the CD8⁺/T regulatory cell ratio in patients with metastatic CRC can predict the outcomes of therapies such as anti-VEGF therapies (11). In situ T-cell profiling of CRC tumors (n=1,113) showed that higher T-helper cells, cytotoxic-T cells, and memory T-cell densities in the epithelial and stromal tissue were correlated with better survival in both regions (12). CD4⁺ T-lymphocytes play several roles in the activation of other immune cells and cancer immunology (13). There are several subsets of CD4⁺ cells, including T helper (Th), Th17, T-regulatory cells, and others (13). Th cells include T-helper 1 (Th1) cells, which activate macrophages, T-cytotoxic cells, and NK cells under the effects of cytokines IFN-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-2 and IL-12 (14). Th2 cells provide immunity against extracellular pathogens and allergens. A previous study showed that adaptive immunity mainly T-cell responses have a crucial effect on the clinical outcomes of CRC (15). Higher densities of CD8⁺ TILs and CD45RO memory cells in the center and invasive margin of stage I and II CRC are associated with Th1-mediated immune responses and can predict disease clinical outcomes and patient survival (16). However, not all T cell subsets confer a better clinical outcome. Tosolini et al. studied the impact of various TILs (Th1, Th2, Treg, Th17, T-cytotoxic) on the clinical outcomes of CRC patients (125 CRC tumors and 3 normal tissues) (17). Patients with high expression of Th1 or cytotoxic T-cell genes (such as IFNG, TAP1, GZMB) had better survival and outcomes, while patients with high expression of the Th17 gene (IL-17A) had a poor prognosis, and Th2 cells did not have a significant impact on disease prognosis (17). The effect of Th2 on tumor prognosis is a query. On one side, Th2 cells can exert protective effects through IL-4, which mediates their interactions with macrophages, tumoricidal myeloid cells, eosinophils, and other cells, leading to tumor clearance (18). On the other hand, other studies showed that IL-10 promotes tumor growth by suppressing tumor killing by T-cytotoxic cells (19,20) or, during chronic stress, a possible shift of Th1 to Th2 responses that promote CRC progression (21). IL-10 is produced by Th2, Treg cells, and other myeloid and lymphoid cells (22,23).

Cytokine profiles, especially those associated with TILs, are linked to tumor stage and disease prognosis. The levels of cytokines, such as IL-4, IL-8, IL-10, IL-12, TNF-α, GM-CSF, IFN-γ, and VEGF, are higher in the tumor than in normal mucosa and serum (24). Higher levels of IL-6 and IL-8 in serum and IL-8 and VEGF in tumor correlated with advanced tumor-nodal-metastasis (TNM) stages of CRC (24). Most of these cytokines are inflammatory, supporting the strong correlation between inflammation and CRC (25,26).

Finding of Ojanperä et al. (27)

Ojanperä et al. (27) have recently examined the correlation between the densities of Th cell subsets within the TME and clinical outcomes. The authors also investigated the circulating cytokine profiles across multiple CRC cohorts and correlated them with the cell densities and patient outcomes (27). The authors used multiplex immunohistochemistry (IHC) to identify and quantify the densities of Th1 and Th2 cells in tumor samples (collected from tumor centers and invasive margins) from over 2,000 CRC patients (stages I to IV) across three independent cohorts. In addition, they measured serum cytokine levels associated with Th1/Th2 pathways in mesenteric and peripheral blood samples. The authors performed a survival analysis to correlate T-cell subsets and the circulating cytokines with patient outcomes (27). In this study, the authors used TBX21 (T-box protein expressed in T cells, T-bet) and GATA3 (GATA-binding protein 3) as markers for Th1 and Th2, respectively, which are the master transcription factors that regulate Th1 and Th2 differentiation and function, respectively (28,29). In addition to CD3⁺ and exclusion of CD8, the author identified Th1 as (CD3⁺CD8⁻T-bet⁺) and Th2 cells as (CD3⁺CD8⁻GATA-3⁺). The use of multiple markers per subset improves assay specificity and confirms its accuracy (27). The Th2 densities were higher (1.6–1.7×) than the densities of Th1 in cohorts 1 and 2 (27). Patients with high Th1 densities showed significantly improved survival compared to those with low densities (27). Importantly, similar findings were reported with Th2 densities; high Th2 densities were associated with better cancer-specific survival in both cohorts (27). High cell density was recorded in the tumor epithelial part of the tumor center, and Th1 density was high in these regions in cohort 1, while Th2 density was high in the second cohort (27).

To correlate the Th1 and Th2 density ratio with the systemic cytokine environment, the authors measured blood levels of Th1 cytokines (IFNG, IL-2, and TNF-α) and Th2 cytokines (IL-4, IL-5, IL-10, and IL-13). The correlation was stronger with mesenteric than with peripheral serum cytokines, suggesting that immune signals near the tumor site are more informative than circulating markers distant from the TME. Th1 cell density positively correlated with IL-12 and negatively with IL-10 in mesenteric serum, but there was no significant correlation between Th2 cells and mesenteric serum cytokines (27). The Th1:Th2 density ratio correlated with corresponding cytokine index ratios in mesenteric blood. Regarding the peripheral serum cytokines, there were weak correlations between Th2 cell density and (I) serum IL12, (II) the serum Th1:Th2-inducing cytokine index, and weak correlations between Th1:Th2 cell density ratio and (I) serum IFNG, (II) serum IFNG:IL4 index, and (III) the serum Th1:Th2-inducing cytokine index (27). The authors assessed the prognostic value of circulating cytokines as CRC biomarkers and found that high serum TNF levels and a higher Th1:Th2 cytokine index were associated with worse overall survival (27). In contrast, a high serum IL5 level was associated with better cancer-specific survival (27). However, the cytokine correlation was weaker than Th densities in the TME (27).

Strength of the findings

This article has several advantages. It enhances the understanding of the role of T-cell subsets in CRC progression and patient outcomes. It also provides new insights into the specific impact of Th2 on CRC. The main findings are high densities of Th1 and Th2 cells, and mesenteric-produced cytokines from these cells can serve as prognostic markers for patient outcomes, as they were associated with better survival (27). While the systemic cytokines produced by these cells had a weaker effect and a lower prognostic value than the mesenteric cytokines produced by these cells (27). As previously mentioned, several groups confirmed that high Th1 density is associated with improved CRC prognosis, whereas the impact of Th2 density remains controversial. This study confirmed the impact of high Th2 densities on patients’ survival. These findings can open a new direction for understanding the roles of immune cells that interact with Th2 in the prognosis of CRC at different stages. The fact that the Th1/Th2 cell density ratio is strongly correlated with mesenteric, not peripheral, cytokines indicates that local immune responses in the TME, rather than systemic responses, are prognostic markers for CRC. In future studies, it is important to focus primarily on immune responses in the TME, which can yield accurate biomarkers (Figure 1). In addition, the sample size is large, as the study was conducted across three large independent cohorts (>2,000 patients), which adds strength and accuracy to the conclusions.

Figure 1 Immune profiling in the colon tumor microenvironment. The work by Ojanperä et al. (27) reported a high Th1 and Th2 cell density in the TME. The Th1/ Th2 density correlates to the localized cytokine release at the TME. Future studies should focus on the densities of other immune cells and the produced cytokines from these cells at TME. IFN, interferon; IL, interleukin; NK, natural killer; TGF, transforming growth factor; Th, T helper; TME, tumor microenvironment; TNF, tumor necrosis factor.

Limitation of this study

However, this study has a few limitations and points that should be evaluated in the future. CRC tumors exhibit extensive heterogeneity, based on tumor location, genetic mutations, epigenetic factors, treatment history, disease stage, and other variable factors. This raises the question of whether the current findings can be applied to all CRC cases. Although the authors stated that patients who underwent chemotherapy or radiotherapy were excluded from the study, other variables remain. For example, the authors confirmed that rectal tumors were underrepresented and the patients were White; other background diversity was not included. In addition, the study lacks transcriptomic analysis of immune-mediated genes linked to T-helper activation. Furthermore, the study focused mainly on Th1 and Th2, while other T-cell subsets, such as Th9, Th17, Th22, and T regulatory cells, warrant future evaluation (Figure 1). Also, the manuscript did not cover the role T follicular helper cell (Tfh) and its role in antibody production and cancer outcomes. Tfh cells help B-lymphocytes and contribute to germinal center formation and production of high affinity antibodies and memory B cells (30).

Summary

This article outlines future directions for improving the outcomes of CRC patients through Th1 and Th2 modulation. Understanding the mechanisms by which T-helper cells prevent CRC progression will help identify new biomarkers and develop T-cell-mediated therapies. Researchers may consider assess the efficacy of repurposing drugs, such as as GLP-1 based therapy or new imidazo[2,1-b] quinazoline derivative or thymidylate synthase conformer-selective inhibitors as prophylactic approaches for CRC patients (31-33). Also, researchers should assess new roles and effects of cytokines released by cells, especially those released or mediating Th2 interactions with other immune cells, such as IL-4, IL-5, IL-10, IL-13, and IL-33.

In conclusion, the work by Ojanperä et al. (27) provides new insights on Th1 and Th2 roles in CRC. The findings challenge the previous assumption that Th2 cells promote tumor growth. Both Th1 and Th2 cell densities correlate with better prognosis, and the Th1/Th2 density ratio correlates strongly with localized, not systemic, immune signals. Clinicians and researchers should focus on more in-depth study and understanding of immune signals in the TME.

Acknowledgments

The figure in this commentary is designed using Biorender.com.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, Journal of Gastrointestinal Oncology. The article has undergone external peer review.

Peer Review File: Available at https://jgo.amegroups.com/article/view/10.21037/jgo-2026-1-0127/prf

Funding: None.

Conflicts of Interest: The author has completed the ICMJE uniform disclosure form (available at https://jgo.amegroups.com/article/view/10.21037/jgo-2026-1-0127/coif). The author has no conflicts of interest to declare.

Ethical Statement: The author is accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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