Inflammatory bowel diseases (IBDs) are characterized by a persistent low-grade inflammation that leads to an increased risk of colorectal cancer (CRC) development. Several factors are implicated in this pathogenetic pathway, such as innate and adaptive immunity, gut microbiota, environment, and xenobiotics. At the gut mucosa level, a complex interplay between the immune system and gut microbiota occurs; a disequilibrium between these two factors leads to an alteration in the gut permeability, called ‘leaky gut’. Subsequently, an activation of several inflammatory pathways and an alteration of gut microbiota composition with a proliferation of pro-inflammatory bacteria, known as ‘pathobionts’, take place, leading to a further increase in inflammation. This narrative review provides an overview on the principal Pattern Recognition Receptors (PRRs), including Toll-like receptors (TLRs) and NOD-like receptors (NLRs), focusing on their recognition mechanisms, signaling pathways, and contributions to immune responses. We also report the genetic polymorphisms of TLRs and dysregulation of NLR signaling pathways that can influence immune regulation and contribute to the development and progression of inflammatory disease and cancer.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy that is characterized by an expansion of T-cell progenitors and DNA mutations that lead to overactive NOTCH1 signaling in >50% of T-ALL cases. Using synthetic models of human T-ALL, we report that NOTCH1 dimeric signaling was crucial for the leukemogenesis of human hematopoietic stem/progenitor cells (HSPCs) from cord blood. We also identified a Notch dimerization–dependent gene signature, including the HES4 transcription factor, which induced a proliferative advantage in human HSPCs and in Notch dimerization–dependent, patient-derived xenografts of T-ALL. Interestingly, in human T-ALL cells, HES4 enforced the expression of the Δ133p53 isoform with the concomitant block of proapoptotic p53 target genes and the induction of BCL2L1 gene expression and antiapoptotic B-cell lymphoma extra-large protein. In addition, through an integrated experimental approach that included genetically modified cell lines, RNA/chromatin immunoprecipitation sequencing, and single-cell RNA sequencing profiles of primary T-ALL samples, we revealed cell subsets with Notch dimerization–dependent gene signatures, which indirectly correlated with proapoptotic genes and directly associated with cell markers of poor clinical outcome in primary T-ALL samples. Taken together, these findings highlight the crucial role of NOTCH1 dimeric signaling in human T-cell leukemogenesis and T-ALL maintenance, suggesting that a possible benefit can be obtained with a therapeutic strategy that target NOTCH1 dimer signaling or its downstream effectors.

Background/Objectives: CD19-directed chimeric antigen receptor T (CAR-T) cell therapy induces profound immune remodeling. Nonetheless, biomarkers predicting complete remission (CR) remain poorly defined. We characterized longitudinal cytokine and immune-cell dynamics after CAR-T infusion and identified early immunological features associated with CR. Methods: Longitudinal immune profiling was performed in 18 patients with non-Hodgkin lymphoma, including 14 with relapsed/refractory diffuse large B-cell lymphoma treated with anti-CD19 CAR-T cells. Peripheral blood was collected at the baseline and days 7, 14, 21, 28, and 60 post-infusion. Multiparameter flow cytometry quantified lymphoid and myeloid subsets and Toll-like receptor (TLR)2 and TLR4 expression. Serum cytokines were measured by multiplex assays. Machine-learning-based feature selection identified variables associated with CR. Results: Two inflammatory waves were observed. The first, at day 7, featured elevated IL-6, IL-10, IFN-α, IFN-γ, and TNF-α, accompanied by increased CD4⁺ T cells, HLA-DR^high classical monocytes, and non-classical monocytes. The second, at days 21–28, showed increased IL-5, IL-6, IL-12, IFN-γ, and GM-CSF, with expansion of CD4⁺ and CD8⁺ T cells, regulatory T cells, NK-T cells, and non-classical monocytes. TLR2 expression was significantly upregulated at day 7 on T-cell subsets and on classical and intermediate monocytes. An exploratory feature-selection analysis identified baseline and day-7 TLR2 and TLR4 expression on lymphoid and myeloid cells, early IFN-γ levels, and monocyte frequencies as variables associated with CR. Conclusions: Together, these data show that anti-CD19 CAR-T therapy induces two coordinated waves of cytokine release and immune-cell activation. Moreover, the findings suggest that early modulation of innate immune features, particularly TLR2 expression, is associated with complete remission, although these biomarker relationships remain exploratory and require validation in larger cohorts.