BACKGROUND: In triple-negative breast cancer (TNBC) therapy, insufficient tumor infiltration by lymphocytes significantly hinders the efficacy of immune checkpoint inhibitors. We have previously demonstrated that Hainanenin-1 (HN-1), a host defense peptide (HDP) identified from Hainan frog skin, induces breast cancer apoptosis and boots anti-tumor immunity via unknown mechanism.
METHODS: We used in vitro experiments to observe immunogenic cell death (ICD) indicators in HN-1-treated TNBC cell lines, a mouse tumor model to verify HN-1 promotion of mice anti-tumor immune response, and an in vitro drug sensitivity test of patient-derived breast cancer cells to verify the inhibitory effect of HN-1.
RESULTS: HN-1 induced ICD in TNBC in a process during which damage-associated molecular patterns (DAMPs) were released that could further increase the anti-tumor immune response. The secretion level of interleukin 2 (IL-2), IL-12, and interferon γ in the co-culture supernatant was increased, and dendritic cells (DCs) were activated via a co-culture with HN-1-pretreated TNBC cells. As a result, HN-1 increased the infiltration of anti-tumor immune cells (DCs and T lymphocytes) in the mouse model bearing both 4T1 and EMT6 tumors. Meanwhile, regulatory T cells and myeloid-derived suppressor cells were suppressed. In addition, HN-1 induced DNA damage, and double-strand DNA release in the cytosol was significantly enhanced, indicating that HN-1 might stimulate ICD via activation of STING pathway. The knockdown of STING inhibited HN-1-induced ICD. Of note, HN-1 exhibited inhibitory effects on patient-derived breast cancer cells under three-dimensional culture conditions.
CONCLUSIONS: Collectively, our study demonstrated that HN-1 could be utilized as a potential compound that might augment immunotherapy effects in patients with TNBC.

Dendritic cells (DCs) play a pivotal role in immune surveillance, acting as sentinels that coordinate immune responses within tissues. Although differences in the identity and functional states of DC subpopulations have been identified through multiparametric flow cytometry and single-cell RNA sequencing, these methods do not provide information about the spatial context in which the cells are located. This knowledge is crucial for understanding tissue organisation and cellular cross-talk. Recent developments in multiplex imaging techniques can now offer insights into this complex spatial and functional landscape. This review provides a concise overview of these imaging methodologies, emphasising their application in identifying DCs to delineate their tissue-specific functions and aiding newcomers in navigating this field.

BACKGROUND: Melanoma, the most lethal form of skin cancer, has undergone a transformative treatment shift with the advent of checkpoint blockade immunotherapy (CBI). Understanding the intricate network of immune cells infiltrating the tumor and orchestrating the control of melanoma cells and the response to CBI is currently of utmost importance. There is evidence underscoring the significance of tissue-resident memory (TRM) CD8 T cells and classic dendritic cell type 1 (cDC1) in cancer protection. Transcriptomic studies also support the existence of a TCF7+ (encoding TCF1) T cell as the most important for immunotherapy response, although uncertainty exists about whether there is a TCF1+TRM T cell due to evidence indicating TCF1 downregulation for tissue residency activation.
METHODS: We used multiplexed immunofluorescence and spectral flow cytometry to evaluate TRM CD8 T cells and cDC1 in two melanoma patient cohorts: one immunotherapy-naive and the other receiving immunotherapy. The first cohort was divided between patients free of disease or with metastasis 2 years postdiagnosis while the second between CBI responders and non-responders.
RESULTS: Our study identifies two CD8+TRM subsets, TCF1+ and TCF1-, correlating with melanoma protection. TCF1+TRM cells show heightened expression of IFN-γ and Ki67 while TCF1- TRM cells exhibit increased expression of cytotoxic molecules. In metastatic patients, TRM subsets undergo a shift in marker expression, with the TCF1- subset displaying increased expression of exhaustion markers. We observed a close spatial correlation between cDC1s and TRMs, with TCF1+TRM/cDC1 pairs enriched in the stroma and TCF1- TRM/cDC1 pairs in tumor areas. Notably, these TCF1- TRMs express cytotoxic molecules and are associated with apoptotic melanoma cells. Both TCF1+ and TCF1- TRM subsets, alongside cDC1, prove relevant to CBI response.
CONCLUSIONS: Our study supports the importance of TRM CD8 T cells and cDC1 in melanoma protection while also highlighting the existence of functionally distinctive TCF1+ and TCF1- TRM subsets, both crucial for melanoma control and CBI response.

Cancer stem cells (CSCs) can self-renew and differentiate, contributing to tumor heterogeneity, metastasis, and recurrence. Their resistance to therapies, including immunotherapy, underscores the importance of targeting them for complete remission and relapse prevention. Olfactomedin 4 (OLFM4), a marker associated with various cancers such as colorectal cancer, is expressed on CSCs promoting immune evasion and tumorigenesis. However, its potential as a target for CSC-specific immunotherapy remains underexplored. The primary aim of this study is to evaluate the effectiveness of targeting OLFM4 with dendritic cell (DC)-based vaccines in inhibiting tumor growth and metastasis. To improve antigen delivery and immune response, OLFM4 was conjugated with a protein-transduction domain (PTD) from the antennapedia of Drosophila called penetratin, creating a fusion protein (P-OLFM4). The efficacy of DCs pulsed with P-OLFM4 (DCs [P-OLFM4]) was compared to DCs pulsed with OLFM4 (DCs [OLFM4]) and PBS (DCs [PBS]). DCs [P-OLFM4] inhibited tumor growth by 91.2 % and significantly reduced lung metastasis of OLFM4+ melanoma cells by 97 %, compared to the DCs [PBS]. DCs [OLFM4] also demonstrated a reduction in lung metastasis by 59.7 % compared to DCs [PBS]. Immunization with DCs [P-OLFM4] enhanced OLFM4-specific T-cell proliferation, interferon-γ production, and cytotoxic T cell activity in mice. The results indicate that OLFM4 is a viable target for CSC-focused immunotherapy. DC [P-OLFM4] vaccines can elicit robust immune responses, significantly inhibiting tumor growth and metastasis. This strategy holds promise for developing more effective cancer treatments that specifically target CSCs, potentially leading to better patient outcomes by reducing the likelihood of tumor relapse and metastasis.

BACKGROUND: Esophageal cancer (ESCA) is a form of malignant tumor associated with chronic inflammation and immune dysregulation. However, the specific immune status and key mechanisms of immune regulation in this disease require further exploration.
METHODS: To investigate the features of the human ESCA tumor immune microenvironment and its possible regulation, we performed mass cytometry by time of flight, single-cell RNA sequencing, multicolor fluorescence staining of tissue, and flow cytometry analyses on tumor and paracancerous tissue from treatment-naïve patients.
RESULTS: We depicted the immune landscape of the ESCA and revealed that CD8+ (tissue-resident memory CD8+ T cells (CD8+ TRMs) were closely related to disease progression. We also revealed the heterogeneity of CD8+ TRMs in the ESCA tumor microenvironment (TME), which was associated with their differentiation and function. Moreover, the subset of CD8+ TRMs in tumor (called tTRMs) that expressed high levels of granzyme B and immune checkpoints was markedly decreased in the TME of advanced ESCA. We showed that tTRMs are tumor effector cells preactivated in the TME. We then demonstrated that conventional dendritic cells (cDC2s) derived from intermediate monocytes (iMos) are essential for maintaining the proliferation of CD8+ TRMs in the TME. Our preliminary study showed that hypoxia can promote the apoptosis of iMos and impede the maturation of cDC2s, which in turn reduces the proliferative capacity of CD8+ TRMs, thereby contributing to the progression of cancer.
CONCLUSIONS: Our study revealed the essential antitumor roles of CD8+ TRMs and preliminarily explored the regulation of the iMo/cDC2/CD8+ TRM immune axis in the human ESCA TME.

Pulmonary fibrosis (PF) is a chronic, irreversible interstitial lung disease. The pathogenesis of PF remains unclear, and there are currently no effective treatments or drugs that can completely cure PF. The primary cause of PF is an imbalance of inflammatory response and inappropriate repair following lung injury. Dendritic cells (DCs), as one of the immune cells in the body, play an important role in regulating immune response, immune tolerance, and promoting tissue repair following lung injury. However, the role of DCs in the PF process is ambiguous or even contradictory in the existing literature. On the one hand, DCs can secrete transforming growth factor β(TGF-β), stimulate Th17 cell differentiation, stimulate fibroblast proliferation, and promote the generation of inflammatory factors interleukin-6(IL-6) and tumor necrosis factor-α(TNF-α), thereby promoting PF. On the other hand, DCs suppress PF through mechanisms including the secretion of IL-10 to inhibit effector T cell activity in the lungs and promote the function of regulatory T cells (Tregs), as well as by expressing matrix metalloproteinases (MMPs) which facilitate the degradation of the extracellular matrix (ECM). This article will infer possible reasons for the different roles of DCs in PF and analyze possible reasons for the functional imbalance of DCs in pulmonary fibrosis from the complexity and changes of the pulmonary microenvironment, autophagy defects of DCs, and changes in the pulmonary physical environment.

The aim of this study was to evaluate the immunomodulatory potential of two α-D-glucans from Limosilactobacillus reuteri L26 Biocenol™ (EPS-L26) and L. reuteri DSM17938 (EPS-DSM17938), with respect to their influence on in vitro activation of porcine dendritic cells (DCs). We used immature DCs differentiated from porcine blood monocytes under in vitro conditions. Based on the surface expression of MHC II and costimulatory CD80/86 molecules, we showed that both used EPSs favour the maturation of monocyte-derived DCs (MoDCs) similarly to the commonly used stimulant tumour necrosis factor α (TNF-α). In contrast to TNF-α stimulation, MoDCs treated with both used EPSs significantly up-regulated the mRNA levels not only for interleukin (IL)-10 (P < 0.0001 for EPS-DSM17938; P = 0.0037 for EPS-L26), but also for IL-12 (P = 0.0176 for EPS-DSM17938; P = 0.0019 for EPS-L26). These cytokines are known to regulate T-cell kinetics and play a key role in maintaining immune homeostasis. Interestingly, only relatively linear α-D-glucan (EPS-DSM17938) significantly increased gene expression of the major pro-inflammatory cytokine IL-1β (P = 0.0011) and the \"SOS\" cytokine IL-6 (P = 0.0127). However, it is important to highlight the need for further studies aimed at cytokine kinetics in DCs, as well as a co-culture study with allogenic T-lymphocytes.

Therapeutic vaccines based on monocyte-derived dendritic cells have been shown to be promising strategies and may act as complementary treatments for viral infections, cancers, and, more recently, autoimmune diseases. Alpha-type-1-polarized dendritic cells (aDC1s) have been shown to induce type-1 immunity with a high capacity to produce interleukin-12p70 (IL-12p70). In the clinical use of cell-based therapeutics, injectable solutions can affect the morphology, immunophenotypic profile, and viability of cells before delivery and their survival after injection. In this sense, preparing a cell suspension that maintains the quality of aDC1s is essential to ensure effective immunotherapy. In the present study, monocytes were differentiated into aDC1s in the presence of IL-4 and GM-CSF. On day 5, the cells were matured by the addition of a cytokine cocktail consisting of IFN-α, IFN-γ, IL-1β, TNF-α, and Poly I:C. After 48 hr, mature aDC1s were harvested and suspended in two different solutions: normal saline and Ringer\'s lactate. The maintenance of cells in suspension was evaluated after 4, 6, and 8 hr of storage. Cell viability, immunophenotyping, and apoptosis analyses were performed by flow cytometry. Cellular morphology was observed by electron microscopy, and the production of IL-12p70 by aDC1s was evaluated by ELISA. Compared with normal saline, Ringer\'s lactate solution was more effective at maintaining DC viability for up to 8 hr of incubation at 4 or 22°C.

BACKGROUND: Histiocytoses are rare disorders characterized by the accumulation of macrophages, dendritic cells, or monocyte-derived cells in various tissues and organs of children and adults, with a wide range of clinical manifestations, presentations, and histology. The histiocytoses are classified according to the WHO Classification, the last version of which was published in 2022, or according to the Histiocyte Society Classification, with the last version published in 2016.
OBJECTIVE: This text provides an overview of histiocytoses as described in the WHO Classification 2022.

A pleiotropic immunoregulatory cytokine, TGF-β, signals via the receptor-regulated SMADs: SMAD2 and SMAD3, which are constitutively expressed in normal cells. Here, we show that selective repression of SMAD3 induces cDC differentiation from the CD115+ common DC progenitor (CDP). SMAD3 was expressed in haematopoietic cells including the macrophage DC progenitor. However, SMAD3 was specifically down-regulated in CD115+ CDPs, SiglecH- pre-DCs, and cDCs, whereas SMAD2 remained constitutive. SMAD3-deficient mice showed a significant increase in cDCs, SiglecH- pre-DCs, and CD115+ CDPs compared with the littermate control. SMAD3 repressed the mRNA expression of FLT3 and the cDC-related genes: IRF4 and ID2. We found that one of the SMAD transcriptional corepressors, c-SKI, cooperated with phosphorylated STAT3 at Y705 and S727 to repress the transcription of SMAD3 to induce cDC differentiation. These data indicate that STAT3 and c-Ski induce cDC differentiation by repressing SMAD3: the repressor of the cDC-related genes during the developmental stage between the macrophage DC progenitor and CD115+ CDP.