Regulatory T cells infiltrate the tumor-induced tertiary lymphoïd structures and are associated with poor clinical outcome in NSCLC

On one hand, regulatory T cells (Tregs) play an immunosuppressive activity in most solid tumors but not all. On the other hand, the organization of tumor-infiltrating immune cells into tertiary lymphoid structures (TLS) is associated with long-term survival in most cancers. Here, we investigated the role of Tregs in the context of Non-Small Cell Lung Cancer (NSCLC)-associated TLS. We observed that Tregs show a similar immune profile in TLS and non-TLS areas. Autologous tumor-infiltrating Tregs inhibit the proliferation and cytokine secretion of CD4⁺ conventional T cells, a capacity which is recovered by antibodies against Cytotoxic T-Lymphocyte-Associated protein-4 (CTLA-4) and Glucocorticoid-Induced TNFR-Related protein (GITR) but not against other immune checkpoint (ICP) molecules. Tregs in the whole tumor, including in TLS, are associated with a poor outcome of NSCLC patients, and combination with TLS-dendritic cells (DCs) and CD8⁺ T cells allows higher overall survival discrimination. Thus, Targeting Tregs especially in TLS may represent a major challenge in order to boost anti-tumor immune responses initiated in TLS.

Tertiary Lymphoid Structure-B Cells Narrow Regulatory T Cells Impact in Lung Cancer Patients

The presence of tertiary lymphoid structures (TLS) in the tumor microenvironment is associated with better clinical outcome in many cancers. In non-small cell lung cancer (NSCLC), we have previously showed that a high density of B cells within TLS (TLS-B cells) is positively correlated with tumor antigen-specific antibody responses and increased intratumor CD4⁺ T cell clonality. Here, we investigated the relationship between the presence of TLS-B cells and CD4⁺ T cell profile in NSCLC patients. The expression of immune-related genes and proteins on B cells and CD4⁺ T cells was analyzed according to their relationship to TLS-B density in a prospective cohort of 56 NSCLC patients. We observed that tumor-infiltrating T cells showed marked differences according to TLS-B cell presence, with higher percentages of naïve, central-memory, and activated CD4⁺ T cells and lower percentages of both immune checkpoint (ICP)-expressing CD4⁺ T cells and regulatory T cells (Tregs) in the TLS-B^high tumors. A retrospective study of 538 untreated NSCLC patients showed that high TLS-B cell density was even able to counterbalance the deleterious impact of high Treg density on patient survival, and that TLS-B^high Treg^low patients had the best clinical outcomes. Overall, the correlation between the density of TLS-B^high tumors with early differentiated, activated and non-regulatory CD4⁺ T cell cells suggest that B cells may play a central role in determining protective T cell responses in NSCLC patients.

Natural killer cells in the human lung tumor microenvironment display immune inhibitory functions

BACKGROUND

Natural killer (NK) cells play a crucial role in tumor immunosurveillance through their cytotoxic effector functions and their capacity to interact with other immune cells to build a coordinated antitumor immune response. Emerging data reveal NK cell dysfunction within the tumor microenvironment (TME) through checkpoint inhibitory molecules associated with a regulatory phenotype.

OBJECTIVE

We aimed at analyzing the gene expression profile of intratumoral NK cells compared with non-tumorous NK cells, and to characterize their inhibitory function in the TME.

METHODS

NK cells were sorted from human lung tumor tissue and compared with non- tumoral distant lungs.

RESULTS

In the current study, we identify a unique gene signature of NK cell dysfunction in human non-small cell lung carcinoma (NSCLC). First, transcriptomic analysis reveals significant changes related to migratory pattern with a downregulation of sphingosine-1-phosphate receptor 1 (S1PR1) and CX3C chemokine receptor 1 (CX3CR1) and overexpression of C-X-C chemokine receptor type 5 (CXCR5) and C-X-C chemokine receptor type 6 (CXCR6). Second, cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and killer cell lectin like receptor (KLRC1) inhibitory molecules were increased in intratumoral NK cells, and CTLA-4 blockade could partially restore MHC class II level on dendritic cell (DC) that was impaired during the DCs/NK cell cross talk. Finally, NK cell density impacts the positive prognostic value of CD8⁺ T cells in NSCLC.

CONCLUSIONS

These findings demonstrate novel molecular cues associated with NK cell inhibitory functions in NSCLC.

Tertiary lymphoid structures in cancer and beyond

Tertiary lymphoid structures (TLS) are ectopic lymphoid formations found in inflamed, infected, or tumoral tissues. They exhibit all the characteristics of structures in the lymph nodes (LN) associated with the generation of an adaptive immune response, including a T cell zone with mature dendritic cells (DC), a germinal center with follicular dendritic cells (FDC) and proliferating B cells, and high endothelial venules (HEV). In this review, we discuss evidence for the roles of TLS in chronic infection, autoimmunity, and cancer, and address the question of whether TLS present beneficial or deleterious effects in these contexts. We examine the relationship between TLS in tumors and patient prognosis, and discuss the potential role of TLS in building and/or maintaining local immune responses and how this understanding may guide therapeutic interventions.

Interictal psychosis following temporal lobe surgery: dentate gyrus pathology

BACKGROUND

De novo interictal psychosis, albeit uncommon, can develop in patients following temporal lobe surgery for epilepsy. Pathological alterations of the dentate gyrus, including cytoarchitectural changes, immaturity and axonal reorganization that occur in epilepsy, may also underpin co-morbid psychiatric disorders. Our aim was to study candidate pathways that may be associated with the development of interictal psychosis post-operatively in patients with hippocampal sclerosis (HS).

METHOD

A total of 11 patients with HS who developed interictal psychosis (HS-P) post-operatively were compared with a matched surgical HS group without psychosis (HS-NP). Resected tissues were investigated for the extent of granule cell dispersion, mossy fibre sprouting and calbindin expression in the granule cells. We quantified doublecortin, mini-chromosome maintenance protein 2 (MCM2) and reelin-expressing neuronal populations in the dentate gyrus as well as the distribution of cannabinoid type 1 receptor (CBR1).

RESULTS

The patterns of neuronal loss and gliosis were similar in both groups. HS-P patients demonstrated less mossy fibre sprouting and granule cell dispersion (p < 0.01) and more frequent reduction in calbindin expression in granule cells. There were no group differences in the densities of immature MCM2, doublecortin and reelin-positive cells. CBR1 labelling was significantly lower in Cornu ammonis area CA4 relative to other subfields (p < 0.01); although reduced staining in all hippocampal regions was noted in HS-P compared with HS-NP patients, the differences were not statistically significant.

CONCLUSIONS

The alterations in dentate gyrus pathology found in HS-P patients could indicate underlying differences in the cellular response to seizures. These mechanisms may predispose to the development of psychosis in epilepsy and warrant further investigation.

Systemic inflammation, nutritional status and tumor immune microenvironment determine outcome of resected non-small cell lung cancer

Background

Hypothesizing that nutritional status, systemic inflammation and tumoral immune microenvironment play a role as determinants of lung cancer evolution, the purpose of this study was to assess their respective impact on long-term survival in resected non-small cell lung cancers (NSCLC).

Methods and Findings

Clinical, pathological and laboratory data of 303 patients surgically treated for NSCLC were retrospectively analyzed. C-reactive protein (CRP) and prealbumin levels were recorded, and tumoral infiltration by CD8+ lymphocytes and mature dendritic cells was assessed. We observed that factors related to nutritional status, systemic inflammation and tumoral immune microenvironment were correlated; significant correlations were also found between these factors and other relevant clinical-pathological parameters. With respect to outcome, at univariate analysis we found statistically significant associations between survival and the following variables: Karnofsky index, American Society of Anesthesiologists (ASA) class, CRP levels, prealbumin concentrations, extent of resection, pathologic stage, pT and pN parameters, presence of vascular emboli, and tumoral infiltration by either CD8+ lymphocytes or mature dendritic cells and, among adenocarcinoma type, tumor grade (all p<0.05). In multivariate analysis, prealbumin levels (Relative Risk (RR): 0.34 [0.16–0.73], p = 0.0056), CD8+ cell count in tumor tissue (RR = 0.37 [0.16–0.83], p = 0.0162), and disease stage (RR 1.73 [1.03–2.89]; 2.99[1.07–8.37], p = 0.0374- stage I vs II vs III-IV) were independent prognostic markers. When taken together, parameters related to systemic inflammation, nutrition and tumoral immune microenvironment allowed robust prognostic discrimination; indeed patients with undetectable CRP, high (>285 mg/L) prealbumin levels and high (>96/mm2) CD8+ cell count had a 5-year survival rate of 80% [60.9–91.1] as compared to 18% [7.9–35.6] in patients with an opposite pattern of values. When stages I-II were considered alone, the prognostic significance of these factors was even more pronounced.

Conclusions

Our data show that nutrition, systemic inflammation and tumoral immune contexture are prognostic determinants that, taken together, may predict outcome.

The immune microenvironment: a major player in human cancers

Cancer is a major public health issue and figures among the leading causes of death in the world. Cancer development is a long process, involving the mutation, amplification or deletion of genes and chromosomal rearrangements. The transformed cells change morphologically, enlarge, become invasive and finally detach from the primary tumor to metastasize in other organs through the blood and/or lymph. During this process, the tumor cells interact with their microenvironment, which is complex and composed of stromal and immune cells that penetrate the tumor site via blood vessels and lymphoid capillaries. All subsets of immune cells can be found in tumors, but their respective density, functionality and organization vary from one type of tumor to another. Whereas inflammatory cells play a protumoral role, there is a large body of evidence of effector memory T cells controlling tumor invasion and metastasis. Thus, high densities of memory Th1/CD8 cytotoxic T cells in the primary tumors correlate with good prognosis in most tumor types. Tertiary lymphoid structures, which contain mature dendritic cells (DC) in a T cell zone, proliferating B cells and follicular DC, are found in the tumor stroma and they correlate with intratumoral Th1/CD8 T cell and B cell infiltration. Eventually, tumors undergo genetic and epigenetic modifications that allow them to escape being controlled by the immune system. This comprehensive review describes the immune contexture of human primary and metastatic tumors, how it impacts on patient outcomes and how it could be used as a predictive biomarker and guide immunotherapies.

Tertiary lymphoid structures in human lung cancers, a new driver of antitumor immune responses

T-cell infiltrates are robust prognostic biomarkers in the majority of human cancers. However, the mechanisms that shape a protective T-cell response remain unclear. Our recent study implicates tertiary lymphoid structures in the shaping of an efficient and beneficial immune response in lung cancer patients.

Presence of B cells in tertiary lymphoid structures is associated with a protective immunity in patients with lung cancer

RATIONALE

It is now well established that immune responses can take place outside of primary and secondary lymphoid organs. We previously described the presence of tertiary lymphoid structures (TLS) in patients with non-small cell lung cancer (NSCLC) characterized by clusters of mature dendritic cells (DCs) and T cells surrounded by B-cell follicles. We demonstrated that the density of these mature DCs was associated with favorable clinical outcome.

OBJECTIVES

To study the role of follicular B cells in TLS and the potential link with a local humoral immune response in patients with NSCLC.

METHODS

The cellular composition of TLS was investigated by immunohistochemistry. Characterization of B-cell subsets was performed by flow cytometry. A retrospective study was conducted in two independent cohorts of patients. Antibody specificity was analyzed by ELISA.

MEASUREMENTS AND MAIN RESULTS

Consistent with TLS organization, all stages of B-cell differentiation were detectable in most tumors. Germinal center somatic hypermutation and class switch recombination machineries were activated, associated with the generation of plasma cells. Approximately half of the patients showed antibody reactivity against up to 7 out of the 33 tumor antigens tested. A high density of follicular B cells correlated with long-term survival, both in patients with early-stage NSCLC and with advanced-stage NSCLC treated with chemotherapy. The combination of follicular B cell and mature DC densities allowed the identification of patients with the best clinical outcome.

CONCLUSIONS

B-cell density represents a new prognostic biomarker for NSCLC patient survival, and makes the link between TLS and a protective B cell-mediated immunity.

Dendritic cells in tumor-associated tertiary lymphoid structures signal a Th1 cytotoxic immune contexture and license the positive prognostic value of infiltrating CD8+ T cells

Tumor-infiltrating T cells, particularly CD45RO(+)CD8(+) memory T cells, confer a positive prognostic value in human cancers. However, the mechanisms that promote a protective T-cell response in the tumor microenvironment remain unclear. In chronic inflammatory settings such as the tumor microenvironment, lymphoid neogenesis can occur to create local lymph node-like structures known as tertiary lymphoid structures (TLS). These structures can exacerbate a local immune response, such that TLS formation in tumors may help promote an efficacious immune contexture. However, the role of TLS in tumors has yet to be investigated carefully. In lung tumors, mature dendritic cells (DC) present in tumor-associated TLS can provide a specific marker of these structures. In this study, we evaluated the influence of TLS on the characteristics of the immune infiltrate in cohorts of prospective and retrospective human primary lung tumors (n = 458). We found that a high density of mature DC correlated closely to a strong infiltration of T cells that are predominantly of the effector-memory phenotype. Moreover, mature DC density correlated with expression of genes related to T-cell activation, T-helper 1 (Th1) phenotype, and cytotoxic orientation. Lastly, a high density of TLS-associated DC correlated with long-term survival, which also allowed a distinction of patients with high CD8(+) T-cell infiltration but a high risk of death. Taken together, our results show how tumors infiltrated by TLS-associated mature DC generate a specific immune contexture characterized by a strong Th1 and cytotoxic orientation that confers the lowest risk of death. Furthermore, our findings highlight the pivotal function of TLS in shaping the immune character of the tumor microenvironment, in promoting a protective immune response mediated by T cells against cancer.

Characteristics of tertiary lymphoid structures in primary cancers

Tumors are sustained by complex networks of interactions between malignant cells, stromal cells and tumor-infiltrating immune cells. These networks differ from patient to patient in terms of nature, composition and organization as well as with regard to the precise localization of tumor-infiltrating cells. Of note, the heterogeneity of the immunological component of the tumor microenvironment, as opposed to its mere abundance, has been shown to influence disease outcome. However, a key question remains: where does the activation of tumor-specific T cells take place? The recently described, tumor-associated lymph node-like entities termed “tertiary lymphoid structures” exhibit a structural organization that is reminiscent of secondary lymphoid organs, and thus may imprint the local immune contexture. Here, we discuss how cancer-associated tertiary lymphoid structures impact on the tumor micro-architecture, immune microenvironment, and ultimately, patient survival.

Characterization of chemokines and adhesion molecules associated with T cell presence in tertiary lymphoid structures in human lung cancer

De novo formation of tertiary lymphoid structures (TLS) has been described in lung cancers. Intratumoral TLS seem to be functional and are associated with a long-term survival for lung cancer patients, suggesting that they represent an activation site for tumor-specific T cells. Here, we characterized T-cell recruitment to TLS in human lung cancer to identify the adhesion molecules and chemoattractants orchestrating this migration. We found that most TLS T cells were CD62L+ and mainly of CD4+ memory phenotype, but naive T cells were highly enriched in these structures as compared with the rest of the tumor. A specific gene expression signature associated with T cell presence was identified in TLS, which included chemokines (CCL19, CCL21, CXCL13, CCL17, CCL22, and IL16), adhesion molecules (ICAM-2, ICAM-3, VCAM-1, and MAdCAM-1) and integrins (alphaL, alpha4, and alphaD). The presence of the corresponding receptors on TLS T cells was confirmed. Intratumoral PNAd+ high endothelial venules also were exclusively associated with TLS and colocalized with CD62L+ lymphocytes. Together, these data bring new insights into the T-cell recruitment to intratumoral TLS and suggest that blood T cell enter into TLS via high endothelial venules, which represent a new gateway for T cells to the tumor. Findings identify the molecules that mediate migration of tumor-specific T cells into TLS where T cell priming occurs, suggesting new strategies to enhance the efficacy of cancer immunotherapies.

The influence of the presence of lipid on the aggregation of 8,12-diethyl farnesyl bacteriochlorophyll c located in adsorbed layers and monolayers

The photoacoustic spectra and time-resolved delayed luminescence spectra in the microsecond time range were measured for layers of 8,12-diethyl farnesyl bacteriochlorophyll c adsorbed on quartz supports by solvent evaporation and as Langmuir-Blodgett monolayers. Both types of model system were also investigated with the addition of lipid. The data showed a very strong influence of lipid addition on pigment aggregation. In samples with synthetic and natural lipid addition, the pigments were found to be predominantly in the monomeric and dimeric states, whereas in the same type of sample without lipid, the pigments were aggregated to a higher degree. The influence of the presence of lipid on the aggregation of bacteriochlorophyll c in monolayers and adsorbed layers may also suggest that the contact of various pigment molecules with the lipids surrounding the chlorosome may influence the formation of various pigment aggregates in vivo. The synthetic lipid L-alpha-phosphatidylcholine dipalmitoyl and the natural lipid L-alpha-phosphatidylcholine type IVS from soy beans were used. In the latter case, only adsorbed layers were investigated. Our interpretation is preliminary as only one 8,12-diethyl farnesyl bacteriochlorophyll c homologue was present in our systems.

Interactions between chlorophyll a and beta-carotene in nematic liquid crystals

Fluorescence lifetime in the ps range, polarized absorption, polarized fluorescence spectra and delayed luminescence time resolved spectra were measured for chlorophyll a solutions with and without beta-carotene addition in nematic liquid crystal. Photoacoustic spectra of the same samples at various frequencies of light modulation were also taken. The frequency dependence of the photoacoustic spectra suggests that part of the excitation is converted into heat in a slow process (with a decay time of the order of ms). The lifetime results suggest that at used concentration some aggregation of the chlorophyll a occurs. The chlorophyll a molecules interact strongly with the beta-carotene forming some nonfluorescent or weakly fluorescent aggregates characterized by having various thermal deactivation yields and orientations in anisotropic matrix when compared to those of separated pigments. It seems that the aggregated forms of the chlorophylls are partially disrupted as a result of the their interaction with the beta-carotene. Singlet excitation of beta-carotene is not transferred to the fluorescent form of chlorophyll a. Delayed (in microsecond time range) luminescence of chlorophyll a is quenched by beta-carotene. This luminescence is located in the same spectral region as prompt fluorescence. Interactions between chlorophyll a and beta-carotene depend on the degree of pigment orientation and their aggregation.