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Extending the success of cellular immunotherapies against blood cancers to the realm of solid tumors will require improved in vitro models that reveal therapeutic modes of action at the molecular level. Here we describe a system, called BEHAV3D, developed to study the dynamic interactions of immune cells and patient cancer organoids by means of imaging and transcriptomics. We apply BEHAV3D to live-track >150,000 engineered T cells cultured with patient-derived, solid-tumor organoids, identifying a ‘super engager’ behavioral cluster comprising T cells with potent serial killing capacity. Among other T cell concepts we also study cancer metabolome-sensing engineered T cells (TEGs) and detect behavior-specific gene signatures that include a group of 27 genes with no previously described T cell function that are expressed by super engager killer TEGs. We further show that type I interferon can prime resistant organoids for TEG-mediated killing. BEHAV3D is a promising tool for the characterization of behavioral-phenotypic heterogeneity of cellular immunotherapies and may support the optimization of personalized solid-tumor-targeting cell therapies.

The lacrimal gland is essential for lubrication and protection of the eye. Disruption of lacrimal fluid production, composition, or release results in dry eye, causing discomfort and damage to the ocular surface. Here, we describe the establishment of long-term 3D organoid culture conditions for mouse and human lacrimal gland. Organoids can be expanded over multiple months and recapitulate morphological and transcriptional features of lacrimal ducts. CRISPR-Cas9-mediated genome editing reveals the master regulator for eye development Pax6 to be required for differentiation of adult lacrimal gland cells. We address cellular heterogeneity of the lacrimal gland by providing a single-cell atlas of human lacrimal gland tissue and organoids. Finally, human lacrimal gland organoids phenocopy the process of tear secretion in response to neurotransmitters and can engraft and produce mature tear products upon orthotopic transplantation in mouse. Together, this study provides an experimental platform to study the (patho-)physiology of the lacrimal gland.

Innate lymphoid cells (ILCs) guard epithelial tissue integrity during homeostasis, but can be potent immune effector cells during inflammation. Precursors to all ILC subsets (ILC precursors [ILCP]) have been identified in human peripheral blood (PB). We found that during homeostasis, ILCP in PB of mouse and human expressed homing receptors for secondary lymphoid organs, mainly CD62L. These ILCP entered mouse lymph nodes in a CD62L-dependent way and relied on S1P receptors for their exit. Importantly, CD62L expression was absent on human ILCs expressing NKp44 in tonsils and PB of Crohn disease patients, and relatively fewer CD62L+ ILCP were present in PB of Crohn disease patients. These data are in agreement with selective expression of CD62L on nonactivated ILCP. As such, we conclude that CD62L not only serves as a functional marker of ILCP, but has potential to be used in the clinic as a diagnostic marker in inflammatory disorders.

SummaryCellular immunotherapies are rapidly gaining clinical importance, yet predictive platforms for modeling their mode of action are lacking. Here, we developed a dynamic immuno-organoid 3D imaging-transcriptomics platform; BEHAV3D, to unravel the behavioral and underlying molecular mechanisms of solid tumor targeting. Applied to an emerging cancer metabolome-sensing immunotherapy: TEGs, we first demonstrate targeting of multiple breast cancer subtypes. Live-tracking of over 120,000 TEGs revealed a diverse behavioral landscape and identified a ‘super engager’ cluster with serial killing capability. Inference of single-cell behavior with transcriptomics identified the gene signature of ‘super engager’ killer TEGs, which contained 27 genes with no previously described T cell function. Furthermore, guided by a dynamic type 1 interferon (IFN-I) signaling module induced by high TEG-sensitive organoids, we show that IFN-I can prime resistant organoids for TEG-mediated killing. Thus, BEHAV3D characterizes behavioral-phenotypic heterogeneity of cellular immunotherapies and holds promise for improving solid tumor-targeting in a patient-specific manner.

Enteroendocrine cells (EECs) sense intestinal content and release hormones to regulate gastrointestinal activity, systemic metabolism, and food intake. Little is known about the molecular make-up of human EEC subtypes and the regulated secretion of individual hormones. Here, we describe an organoid-based platform for functional studies of human EECs. EEC formation is induced in vitro by transient expression of NEUROG3. A set of gut organoids was engineered in which the major hormones are fluorescently tagged. A single-cell mRNA atlas was generated for the different EEC subtypes, and their secreted products were recorded by mass-spectrometry. We note key differences to murine EECs, including hormones, sensory receptors, and transcription factors. Notably, several hormone-like molecules were identified. Inter-EEC communication is exemplified by secretin-induced GLP-1 secretion. Indeed, individual EEC subtypes carry receptors for various EEC hormones. This study provides a rich resource to study human EEC development and function.

Much of our knowledge regarding the interactions between epithelial tissues and the immune system has been gathered from animal models and co-cultures with cell lines. However, unique features of human cells cannot be modelled in mice, and cell lines are often transformed or genetically immortalized. Organoid technology has emerged as a powerful tool to maintain epithelial cells in a near-native state. In this Review, we discuss how organoids are being used in immunological research to understand the role of epithelial cell-immune cell interactions in tissue development and homeostasis, as well as in diseases such as cancer.

Immune escape has been recognised as one of the hallmarks of cancer. Overcoming this immunomodulatory process by tumour cells has become a major therapeutic target. Here we utilize organoid technology to study immune-cancer interactions and assess immunomodulation by colorectal cancer (CRC). Transcriptional profiling and flow cytometry revealed that organoids maintain differential expression of immunomodulatory molecules present in primary tumours. Finally, we established a method to model antigen-specific epithelial cell killing and cancer immunomodulation in vitro using CRC organoids co-cultured with cytotoxic T cells. Our method may serve as a first step to rebuilding the tumor microenvironment in vitro.

A substantial number of human and mouse group 3 innate lymphoid cells (ILC3s) reside in secondary lymphoid organs, yet the phenotype and function of these ILC3s is incompletely understood. Here, we employed an unbiased cross-tissue transcriptomic approach to compare human ILC3s from non-inflamed lymph nodes and spleen to their phenotypic counterparts in inflamed tonsils and from circulation. These analyses revealed that, in the absence of inflammation, lymphoid organ-residing ILC3s lack transcription of cytokines associated with classical ILC3 functions. This was independent of expression of the natural cytotoxicity receptor NKp44. However, and in contrast to ILC3s from peripheral blood, lymphoid organ-residing ILC3s express activating cytokine receptors and have acquired the ability to be recruited into immune responses by inflammatory cytokines. This comprehensive cross-tissue dataset will allow for identification of functional changes in human lymphoid organ ILC3s associated with human disease. Bar-Ephraim et al. describe a cross-tissue transcriptional comparison of human ILC3s and show that ILC3s in lymph nodes and spleen share a transcriptional profile that is distinct from that of tonsil ILC3s. Lymphoid organ ILC3s are a substantial pool of resting cells that can be recruited into immune responses upon local activation.

The family of innate lymphoid cells (ILCs) has attracted attention in recent years as its members are important regulators of immunity, while they can also cause pathology. In both mouse and man, ILCs were initially discovered in developing lymph nodes as lymphoid tissue inducer (LTi) cells. These cells form the prototypic members of the ILC family and play a central role in the formation of secondary lymphoid organs (SLOs). In the absence of LTi cells, lymph nodes (LN) and Peyer's Patches (PP) fail to form in mice, although the splenic white pulp can develop normally. Besides LTi cells, the ILC family encompasses helper-like ILCs with functional distinctions as seen by T-helper cells, as well as cytotoxic natural killer (NK) cells. ILCs are still present in adult SLOs where they have been shown to play a role in lymphoid tissue regeneration. Furthermore, ILCs were implicated to interact with adaptive lymphocytes and influence the adaptive immune response. Here, we review the recent literature on the role of ILCs in secondary lymphoid tissue from the formation of SLOs to mature SLOs in adults, during homeostasis and pathology.

The stromal compartment of secondary lymphoid organs is classicaly known for providing a mechanical scaffold for the complex interactions between hematopoietic cells during immune activation as well as for providing a niche which is favorable for survival of lymphocytes. In recent years, it became increasingly clear that these cells also play an active role during such a response. Currently, knowledge of the interactions between human lymphoid stroma and hematopoietic cells is still lacking and most insight is based on murine systems. Although methods to isolate stromal cells from tonsils have been reported, data on stability in culture, characterization, and functional properties are lacking. Here, we describe a reproducible and easy method for isolation and in vitro culture of functional human lymphoid stromal cells from palatine tonsils. The cells isolated express markers and characteristics of T cell zone fibroblastic reticular cells (FRCs) and react to inflammatory stimuli by upregulating inflammatory cytokines and chemokines as well as adhesion molecules, as previously described for mouse lymphoid stroma. Also, cultured tonsil stromal cells support survival of human innate lymphoid cells, showing that these stromal cells can function as bone fide FRCs, providing a favorable microenvironment for hematopoietic cells.

Background: The bacterial pathogen Salmonella causes worldwide disease. A major route of intestinal entry involves M cells, providing access to B cell-rich Peyer's Patches. Primary human B cells phagocytose Salmonella typhimurium upon recognition by the specific surface Ig receptor (BCR). As it is unclear how Salmonella disseminates systemically, we studied whether Salmonella can use B cells as a transport device for spreading. Methodology/Principal Findings: Human primary B cells or Ramos cell line were incubated with GFP-expressing Salmonella. Intracellular survival and escape was studied in vitro by live cell imaging, flow cytometry and flow imaging. HEL-specific B cells were transferred into C57BL/6 mice and HEL-expressing Salmonella spreading in vivo was analyzed investigating mesenteric lymph nodes, spleen and blood. After phagocytosis by B cells, Salmonella survives intracellularly in a non-replicative state which is actively maintained by the B cell. Salmonella is later excreted followed by reproductive infection of other cell types. Salmonella-specific B cells thus act both as a survival niche and a reservoir for reinfection. Adoptive transfer of antigen-specific B cells before oral infection of mice showed that these B cells mediate in vivo systemic spreading of Salmonella to spleen and blood. Conclusions/Significance: This is a first example of a pathogenic bacterium that abuses the antigen-specific cells of the adaptive immune system for systemic spreading for dissemination of infection. Citation: Souwer Y, Griekspoor A, de Wit J, Martinoli C, Zagato E, et al. (2012) Selective Infection of Antigen-Specific B Lymphocytes by Salmonella Mediates Bacterial Survival and Systemic Spreading of Infection. PLoS ONE 7(11): e50667. doi: 10.1371/journal.pone.0050667