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Background: The spatial distribution and functional heterogeneity of tumor-infiltrating lymphocytes (TILs) significantly impact patient outcomes in non-small cell lung cancer (NSCLC). While T cell factor 1 (TCF1) expressing TILs have emerged as key players in sustaining anti-tumor immunity, their subset characterization, localization, and clinical significance within the tumor microenvironment remain poorly defined.

Method: We performed multiplex immunohistochemistry and immunofluorescence to characterize TCF1+ immune cell subsets, in 102 NSCLC tumors, separately analyzing the tumor center (TC) and invasive front (IF). We integrated this data with publicly available single-cell RNA-sequencing datasets and clinical outcome analyses.

Results: CD4+ T cells and CD79α+ B cells, dominate the TCF1+ landscape, while CD8+ T cells constitute a minority of TCF1+ immune cells, particularly in the TC. We demonstrated the presence of tumor-infiltrating IgG+/IgA+ plasma cells co-expressing TCF1. PD1+TCF1- cells were more frequent than PD1+TCF1+ cells both in the TC and IF, reflecting that terminally differentiated exhausted TILs predominate within the tumor microenvironment. Survival analyses revealed significantly different prognostic impact of TILs including TCF1-expressing cells based on topography. Multivariate analysis showed that increased CD8+TCF1+ cells (HR: 2.5; p=0.039) and increased TCF1 expression by cancer cells (HR: 2,7; p=0.041) in the TC and CD4+TCF1+ cells (HR: 0.4; p=0.043) in the IF emerged as negative and positive independent prognostic markers for Disease-free survival (DFS), respectively. Integrating PD-L1 expression with TILs, PD-L1 immunopositivity was correlated with increased CD8+ and PD1+TCF1- cell infiltration and was associated with favorable DFS especially in the TC.

Conclusions: Our findings support a more refined framework for TCF1+ TIL assessment and TCF1 expression across cellular populations in the tumor microenvironment, with implications for prognostication in operable NSCLC.

Introduction: Novel predictive biomarkers are needed to optimize immunotherapy-based treatment response in non-small cell lung carcinoma (NSCLC). T cell modulatory features may limit the ability of T cells to mount effective anti-tumor responses and could predict immune fitness and responsiveness to therapy. We investigated the prognostic and predictive value of CD8+ T cells with an exhausted phenotype, specifically those co-expressing Programmed Death 1 (PD-1) and T cell factor 1 (TCF-1), in peripheral blood of NSCLC patients before any systemic treatment.

Methods: Two patient cohorts were analyzed: a) 32 patients with early and locally advanced disease (stage I–IIIA; cohort A) who did not receive immunotherapy, and b) 47 patients with advanced disease (stage IIIB-IV) who received chemo-immunotherapy. Multicolor flow cytometry was used to assess CD8+ T cell subpopulations co-expressing PD-1 and TCF-1.

Results: PD-1+TCF1+ progenitor (early) exhausted T cells were found at high frequencies in all NSCLC patients compared with healthy donors, regardless of tumor stage. In cohort A, patients with high levels of CD3+CD8+PD-1+TCF1+ T cells had significantly improved DFS (p= 0.038), while those with high CD3+CD8+PD-1+TCF1− T cells had significantly worse DFS (p= 0.028). In cohort B, high levels of CD3+CD8+PD-1+TCF1+ T cells were associated with shorter PFS (p= 0.027). No association with OS was observed in cohort A. Conversely, in cohort B, high CD3+CD8+PD-1+TCF1+ T cell levels correlated with shorter OS (p= 0.045), while high CD3+CD8+PD-1+TCF1− T cell levels correlated with longer OS (p= 0.010).

Conclusion: Therefore, here we show that circulating PD-1⁺TCF1+ T cells correlated differentially with treatment outcome in early and late NSCLC stage patients.

Chronic infection is important for the transmission of Salmonella enterica serovar Typhi (S. Typhi), an obligate human pathogen responsible for typhoid fever. The immunomodulatory action of typhoid toxin helps establish an initial stealth invasion of the intestinal tract that can lead to systemic spread, colonization of the gallbladder, and persistent shedding. Typhoid toxin contains a cell-binding pentamer and two catalytic subunits: cytolethal distending toxin B (CdtB, a DNase) and pertussis-like toxin A (PltA, an ADP-ribosyltransferase). It undergoes endocytosis and transport to the endoplasmic reticulum (ER) where toxin disassembly occurs. This allows the catalytic subunits to exit the ER for interaction with their nuclear or cytosolic targets. However, all known cellular and physiological effects of typhoid toxin are attributed to CdtB. These effects reduce the severity of intestinal inflammation, promoting host survival and long-term infections. PltA has in vitro enzymatic activity but does not affect cells challenged with typhoid toxin. It is thought that the cytosolic action of PltA will be identified in future work. We instead propose that PltA never reaches the cytosol: it is retained in the ER to limit toxin potency, thereby allowing the anti-inflammatory effects of CdtB to promote intestinal colonization. The absence of Salmonella ADP-ribosylating toxin AB (ArtAB) from all strains of S. Typhi may serve a similar purpose. We accordingly propose a model of balanced pathogenicity in which the lack of toxin ADP-ribosyltransferase activity is essential for S. Typhi pathogenesis.

Colorectal cancer (CRC), the third-most prevalent and second deadliest cancer, requires new therapeutic strategies due to the significant side effects of current treatments. We investigated the anticancer properties of MakA, a cytotoxin from Vibrio cholerae, administered systemically in a mouse model, with a focus on its impact on the tumor microenvironment (TME) and immune cell infiltration. Our findings demonstrate that MakA administration is non-toxic and does not cause systemic tissue damage. It increases immune cell abundance in the TME, suppresses tumor growth, promotes cancer cell apoptosis, and enhances leukocyte recruitment and activation. Elevated neutrophil and macrophage densities were associated with increased production of pro-inflammatory mediators with anti-neoplastic properties. These findings highlight MakA’s potential as a targeted, less harmful CRC therapy by modulating the TME immune response.

Understanding complex pathophysiological processes involves studying intercellular responses and phenotypes within the organ microenvironment, preserving the spatial tissue architecture. This chapter explores a practical and cost-effective method for combining techniques such as in situ immunostaining and transcriptomics analysis. These protocols are adaptable to various mRNA targets, antibodies, tissue types, and tissue fixation appealing to a wide scientific community. We demonstrate their application in studying the host response to infection with a Salmonella enterica strain producing a toxin that induces DNA breaks. Specifically, we assessed the: (i) innate immune response to DNA breaks; (ii) co-detection of Salmonella mRNA fljB with the DNA damage marker γH2AX; (iii) co-detection of mRNAs for the cell cycle arrest marker p16INK4A and the proinflammatory and anti-inflammatory cytokines, Il6 and Il10, respectively. Considering that DNA damage is one of the leading causes of oncogene- and stress-induced-senescence, these protocols can be suitable to assess the cytokine profile associated with cellular phenotype and types of DNA damage of senescent cells in situ.

In the setting of pronounced inflammation, changes in the epithelium may overlap with neoplasia, often rendering it impossible to establish a diagnosis with certainty in daily clinical practice. Here, we discuss the underlying molecular mechanisms driving tissue response during persistent inflammatory signaling along with the potential association with cancer in the gastrointestinal tract, pancreas, extrahepatic bile ducts, and liver. We highlight the histopathological challenges encountered in the diagnosis of chronic inflammation in routine practice and pinpoint tissue-based biomarkers that could complement morphology to differentiate reactive from dysplastic or cancerous lesions. We refer to the advantages and limitations of existing biomarkers employing immunohistochemistry and point to promising new markers, including the generation of novel antibodies targeting mutant proteins, miRNAs, and array assays. Advancements in experimental models, including mouse and 3D models, have improved our understanding of tissue response. The integration of digital pathology along with artificial intelligence may also complement routine visual inspections. Navigating through tissue responses in various chronic inflammatory contexts will help us develop novel and reliable biomarkers that will improve diagnostic decisions and ultimately patient treatment.

In situ hybridization visualizes RNA in cells, but image analysis is complex. We present a protocol based on open-source software for automated high-content multiplex fluorescence in situ transcriptomics analysis. Steps include nuclei segmentation with a Fiji macro and quantification of up to 14 mRNA probes per image. We describe procedures for storing raw data, quality control images, and the use of a Python app to summarize all the results in one spreadsheet detailing the number of single or co-positive cells.

Alphaproteobacteria include organisms living in close association with plants or animals. This interaction relies partly on orthologous two-component regulatory systems (TCS), with sensor and regulator proteins modulating the expression of conserved genes related to symbiosis/virulence. We assessed the ability of the exoS⁺_Sm gene, encoding a sensor protein from the plant endosymbiont Sinorhizobium meliloti to substitute its orthologous bvrS in the related animal/human pathogen Brucella abortus. ExoS phosphorylated the B. abortus regulator BvrR in vitro and in cultured bacteria, showing conserved biological function. Production of ExoS in a B. abortus bvrS mutant reestablished replication in host cells and the capacity to infect mice. Bacterial outer membrane properties, the production of the type IV secretion system VirB, and its transcriptional regulators VjbR and BvrR were restored as compared to parental B. abortus. These results indicate that conserved traits of orthologous TCS from bacteria living in and sensing different environments are sufficient to achieve phenotypic plasticity and support bacterial survival. The knowledge of bacterial genetic networks regulating host interactions allows for an understanding of the subtle differences between symbiosis and parasitism. Rewiring these networks could provide new alternatives to control and prevent bacterial infection.

Introduction: Typhoid toxin-expressing Salmonella enterica causes DNA damage in the intestinal mucosa in vivo, activating the DNA damage response (DDR) in the absence of inflammation. To understand whether the tissue microenvironment constrains the infection outcome, we compared the immune response and DDR patterns in the colon and liver of mice infected with a genotoxigenic strain or its isogenic control strain.

Methods: In situ spatial transcriptomic and immunofluorescence have been used to assess DNA damage makers, activation of the DDR, innate immunity markers in a multiparametric analysis.

Result: The presence of the typhoid toxin protected from colonic bacteria-induced inflammation, despite nuclear localization of p53, enhanced co-expression of type-I interferons (IfnbI) and the inflammasome sensor Aim2, both classic features of DNA-break-induced DDR activation. These effects were not observed in the livers of either infected group. Instead, in this tissue, the inflammatory response and DDR were associated with high oxidative stress-induced DNA damage.

Conclusions: Our work highlights the relevance of the tissue microenvironment in enabling the typhoid toxin to suppress the host inflammatory response in vivo.

Background: Chemotherapy (CT) is central to the treatment of triple negative breast cancer (TNBC), but drug toxicity and resistance place strong restrictions on treatment regimes. Fasting sensitizes cancer cells to a range of chemotherapeutic agents and also ameliorates CT-associated adverse effects. However, the molecular mechanism(s) by which fasting, or short-term starvation (STS), improves the efficacy of CT is poorly characterized.

Methods: The differential responses of breast cancer or near normal cell lines to combined STS and CT were assessed by cellular viability and integrity assays (Hoechst and PI staining, MTT or H2DCFDA staining, immunofluorescence), metabolic profiling (Seahorse analysis, metabolomics), gene expression (quantitative real-time PCR) and iRNA-mediated silencing. The clinical significance of the in vitro data was evaluated by bioinformatical integration of transcriptomic data from patient data bases: The Cancer Genome Atlas (TCGA), European Genome-phenome Archive (EGA), Gene Expression Omnibus (GEO) and a TNBC cohort. We further examined the translatability of our findings in vivo by establishing a murine syngeneic orthotopic mammary tumor-bearing model.

Results: We provide mechanistic insights into how preconditioning with STS enhances the susceptibility of breast cancer cells to CT. We showed that combined STS and CT enhanced cell death and increased reactive oxygen species (ROS) levels, in association with higher levels of DNA damage and decreased mRNA levels for the NRF2 targets genes NQO1 and TXNRD1 in TNBC cells compared to near normal cells. ROS enhancement was associated with compromised mitochondrial respiration and changes in the metabolic profile, which have a significant clinical prognostic and predictive value. Furthermore, we validate the safety and efficacy of combined periodic hypocaloric diet and CT in a TNBC mouse model.

Conclusions: Our in vitro, in vivo and clinical findings provide a robust rationale for clinical trials on the therapeutic benefit of short-term caloric restriction as an adjuvant to CT in triple breast cancer treatment.