Therapeutic Inducers of Natural Killer cell Killing (ThINKK): preclinical assessment of safety and efficacy in allogeneic hematopoietic stem cell transplant settings

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) remains the standard of care for chemotherapy-refractory leukemia patients, but cure rates are still dismal. To prevent leukemia relapse following HSCT, we aim to improve the early graft-versus-leukemia effect mediated by natural killer (NK) cells. Our approach is based on the adoptive transfer of Therapeutic Inducers of Natural Killer cell Killing (ThINKK). ThINKK are expanded and differentiated from HSC, and exhibit blood plasmacytoid dendritic cell (pDC) features. We previously demonstrated that ThINKK stimulate NK cells and control acute lymphoblastic leukemia (ALL) development in a preclinical mouse model of HSCT for ALL. Here, we assessed the cellular identity of ThINKK and investigated their potential to activate allogeneic T cells. We finally evaluated the effect of immunosuppressive drugs on ThINKK-NK cell interaction.

METHODS

ThINKK cellular identity was explored using single-cell RNA sequencing and flow cytometry. Their T-cell activating potential was investigated by coculture of allogeneic T cells and antigen-presenting cells in the presence or the absence of ThINKK. A preclinical human-to-mouse xenograft model was used to evaluate the impact of ThINKK injections on graft-versus-host disease (GvHD). Finally, the effect of immunosuppressive drugs on ThINKK-induced NK cell cytotoxicity against ALL cells was tested.

RESULTS

The large majority of ThINKK shared the key characteristics of canonical blood pDC, including potent type-I interferon (IFN) production following Toll-like receptor stimulation. A minor subset expressed some, although not all, markers of other dendritic cell populations. Importantly, while ThINKK were not killed by allogeneic T or NK cells, they did not increase T cell proliferation induced by antigen-presenting cells nor worsened GvHD in vivo. Finally, tacrolimus, sirolimus or mycophenolate did not decrease ThINKK-induced NK cell activation and cytotoxicity.

CONCLUSION

Our results indicate that ThINKK are type I IFN producing cells with low T cell activation capacity. Therefore, ThINKK adoptive immunotherapy is not expected to increase the risk of GvHD after allogeneic HSCT. Furthermore, our data predict that the use of tacrolimus, sirolimus or mycophenolate as anti-GvHD prophylaxis regimen will not decrease ThINKK therapeutic efficacy. Collectively, these preclinical data support the testing of ThINKK immunotherapy in a phase I clinical trial.

CHMP2A regulates broad immune cell-mediated antitumor activity in an immunocompetent in vivo head and neck squamous cell carcinoma model

BACKGROUND

Natural killer (NK) cells are key effector cells of antitumor immunity. However, tumors can acquire resistance programs to escape NK cell-mediated immunosurveillance. Identifying mechanisms that mediate this resistance enables us to define approaches to improve immune-mediate antitumor activity. In previous studies from our group, a genome-wide CRISPR-Cas9 screen identified Charged Multivesicular Body Protein 2A (CHMP2A) as a novel mechanism that mediates tumor intrinsic resistance to NK cell activity.

METHODS

Here, we use an immunocompetent mouse model to demonstrate that CHMP2A serves as a targetable regulator of not only NK cell-mediated immunity but also other immune cell populations. Using the recently characterized murine 4MOSC model system, a syngeneic, tobacco-signature murine head and neck squamous cell carcinoma model, we deleted mCHMP2A using CRISPR/Cas9-mediated knock-out (KO), following orthotopic transplantation into immunocompetent hosts.

RESULTS

We found that mCHMP2A KO in 4MOSC1 cells leads to more potent NK-mediated tumor cell killing in vitro in these tumor cells. Moreover, following orthotopic transplantation, KO of mCHMP2A in 4MOSC1 cells, but not the more immune-resistant 4MOSC2 cells enables both T cells and NK cells to better mediate antitumor activity compared with wild type (WT) tumors. However, there was no difference in tumor development between WT and mCHMP2A KO 4MOSC1 or 4MOSC2 tumors when implanted in immunodeficient mice. Mechanistically, we find that mCHMP2A KO 4MOSC1 tumors transplanted into the immunocompetent mice had significantly increased CD4+T cells, CD8+T cells. NK cell, as well as fewer myeloid-derived suppressor cells (MDSC).

CONCLUSIONS

Together, these studies demonstrate that CHMP2A is a targetable inhibitor of cellular antitumor immunity.

Respiratory complex I regulates dendritic cell maturation in explant model of human tumor immune microenvironment

BACKGROUND

Combining cytotoxic chemotherapy or novel anticancer drugs with T-cell modulators holds great promise in treating advanced cancers. However, the response varies depending on the tumor immune microenvironment (TIME). Therefore, there is a clear need for pharmacologically tractable models of the TIME to dissect its influence on mono- and combination treatment response at the individual level.

METHODS

Here we establish a patient-derived explant culture (PDEC) model of breast cancer, which retains the immune contexture of the primary tumor, recapitulating cytokine profiles and CD8+T cell cytotoxic activity.

RESULTS

We explored the immunomodulatory action of a synthetic lethal BCL2 inhibitor venetoclax+metformin drug combination ex vivo, discovering metformin cannot overcome the lymphocyte-depleting action of venetoclax. Instead, metformin promotes dendritic cell maturation through inhibition of mitochondrial complex I, increasing their capacity to co-stimulate CD4+T cells and thus facilitating antitumor immunity.

CONCLUSIONS

Our results establish PDECs as a feasible model to identify immunomodulatory functions of anticancer drugs in the context of patient-specific TIME.

Blocking senescence and tolerogenic function of dendritic cells induced by γδ Treg cells enhances tumor-specific immunity for cancer immunotherapy

BACKGROUND

Regulatory T (Treg) cells are a key component in maintaining the suppressive tumor microenvironment and immune suppression in different types of cancers. A precise understanding of the molecular mechanisms used by Treg cells for immune suppression is critical for the development of effective strategies for cancer immunotherapy.

METHODS

Senescence development and tolerogenic functions of dendritic cells (DCs) induced by breast cancer tumor-derived γδ Treg cells were fully characterized using real-time PCR, flow cytometry, western blot, and functional assays. Loss-of-function strategies with pharmacological inhibitor and/or neutralizing antibody were used to identify the potential molecule(s) and pathway(s) involved in DC senescence and dysfunction induced by Treg cells. Impaired tumor antigen HER2-specific recognition and immune response of senescent DCs induced by γδ Treg cells were explored in vitro and in vivo in humanized mouse models. In addition, the DC-based HER2 tumor vaccine immunotherapy in breast cancer models was performed to explore the enhanced antitumor immunity via prevention of DC senescence through blockages of STAT3 and programmed death-ligand 1 (PD-L1) signaling.

RESULTS

We showed that tumor-derived γδ Treg cells promote the development of senescence in DCs with tolerogenic functions in breast cancer. Senescent DCs induced by γδ Treg cells suppress Th1 and Th17 cell differentiation but promote the development of Treg cells. In addition, we demonstrated that PD-L1 and STAT3 signaling pathways are critical and involved in senescence induction in DCs mediated by tumor-derived γδ Treg cells. Importantly, our complementary in vivo studies further demonstrated that blockages of PD-L1 and/or STAT3 signaling can prevent γδ Treg-induced senescence and reverse tolerogenic functions in DCs, resulting in enhanced HER2 tumor-specific immune responses and immunotherapy efficacy in human breast cancer models.

CONCLUSIONS

These studies not only dissect the suppressive mechanism mediated by tumor-derived γδ Treg cells on DCs in the tumor microenvironment but also provide novel strategies to prevent senescence and dysfunction in DCs and enhance antitumor efficacy mediated by tumor-specific T cells for cancer immunotherapy.

Hybrid epithelial-mesenchymal status of lung cancer dictates metastatic success through differential interaction with NK cells

BACKGROUND

Epithelial to mesenchymal transition (EMT) endows cancer cells with pro-metastatic properties, which appear most effective when cells enter an intermediate hybrid (H) state, characterized by integrated mesenchymal (M) and epithelial (E) traits. The reasons for this advantage are poorly known and, especially, it is totally unexplored whether the interplay between H-cells and NK cells could have a role. Here we characterize the pro-metastatic mechanics of non-small cell lung cancer (NSCLC) H-cells and their subset of cancer-initiating cells (CICs), dissecting crucial interactions with NK cells.

METHODS

Human lung cancer cell lines and sublines representative of E, M, or H states, assessed by proteomics, were analyzed in vivo for their tumor-forming and disseminating capabilities. Interactions with NK cells were investigated in vitro using migration assays, cytotoxic degranulation assays, and evaluation of CD133+ CICs modulation after coculture, and validated in vivo through NK cell neutralization assays. Correlation between EMT status, NK cell infiltration, and survival data, was evaluated in a cohort of surgically resected NSCLC cases (n=79).

RESULTS

We demonstrated that H-cells, have limited dissemination capability but show the highest potential to initiate metastases in vivo. This property was related to their ability to escape NK cell surveillance. Mechanistically, H-cells expressed low levels of NK-attracting chemokines (CXCL1 and CXCL8), generating poorly infiltrated metastases. Accordingly, proteomics and GO enrichment analysis of E, H, M cell lines showed that the related secretory processes could change during EMT.Furthermore, H-CICs uniquely expressed high levels of the inhibitory ligand B7-H3, which protected H-CIC from NK cell-mediated clearance. In vivo neutralization assays confirmed that, indeed, the pro-metastatic properties of H-cells are poorly controlled by NK cells.Finally, the analysis of patients revealed that detection of hybrid phenotypes associated with low NK infiltration in NSCLC clinical specimens could identify a subset of patients with poor prognosis.

CONCLUSIONS

Our study demonstrates that H-cells play a central role in the metastatic spread in NSCLC. Such pro-metastatic advantage of H-cells is supported by their altered interaction with NK cells and by the critical role of B7-H3 in preserving their H-CIC component, indicating B7-H3 as a potential target in combined NK-based therapies.

Phase 1/2 study of monalizumab plus durvalumab in patients with advanced solid tumors

BACKGROUND

The combination of monalizumab (anti-NKG2A/CD94) and durvalumab (anti-programmed death ligand-1) may promote antitumor immunity by targeting innate and adaptive immunity. This phase 1/2 study of monalizumab and durvalumab evaluated safety, antitumor activity, and pharmacodynamics in patients with advanced solid tumors.

MAIN BODY

Immunotherapy-naïve patients aged ≥18 years with advanced disease, Eastern Cooperative Oncology Group performance status of 0-1, and 1-3 prior lines of systemic therapy in the recurrent/metastatic setting were enrolled. In part 1 (dose escalation), patients received durvalumab 1500 mg every 4 weeks (Q4W) with increasing doses of monalizumab Q2W/Q4W (n=15). Dose expansion in part 1 included patients with cervical cancer (n=15; durvalumab 1500 mg Q4W and monalizumab 750 mg Q2W) or metastatic microsatellite stable (MSS)-colorectal cancer (CRC) (n=15; durvalumab 1500 mg Q4W and monalizumab 750 mg Q4W). In part 2 (dose expansion), patients with MSS-CRC (n=40), non-small cell lung cancer (NSCLC; n=20), MSS-endometrial cancer (n=40), or ovarian cancer (n=40) received durvalumab 1500 mg Q4W and monalizumab 750 mg Q2W. The primary endpoint was safety. Secondary endpoints included antitumor activity per Response Evaluation Criteria In Solid Tumors version 1.1 (RECIST v1.1). Exploratory analyses included assessment of T-cell and natural killer (NK) cell activation and proliferation in peripheral blood and the tumor microenvironment (TME). The study enrolled 185 patients (part 1, 45; part 2, 140). No dose-limiting toxicities were observed and the maximum tolerated dose was not reached. In part 2, the most common treatment-related adverse events were fatigue (12.1%), asthenia (9.3%), diarrhea (9.3%), pruritus (7.9%), and pyrexia (7.1%). In the expansion cohorts, response rates were 0% (cervical), 7.7% (MSS-CRC), 10% (NSCLC), 5.4% (ovarian), and 0% (MSS-endometrial). Sustained NK cell activation, CD8+ T-cell proliferation, increased serum levels of CXCL10 (C-X-C motif chemokine ligand 10) and CXCL11, and increased tumor infiltration of CD8+ and granzyme B+ cells were observed.

CONCLUSIONS

Although efficacy was modest, monalizumab plus durvalumab was well tolerated and encouraging immune activation was observed in the peripheral blood and TME.

TRIAL REGISTRATION NUMBER

NCT02671435.

iPSC-derived natural killer cells expressing the FcγR fusion CD64/16A can be armed with antibodies for multitumor antigen targeting

BACKGROUND

Antibody therapies can direct natural killer (NK) cells to tumor cells, tumor-associated cells, and suppressive immune cells to mediate antibody-dependent cell-mediated cytotoxicity (ADCC). This antigen-specific effector function of human NK cells is mediated by the IgG Fc receptor CD16A (FcγRIIIA). Preclinical and clinical studies indicate that increasing the binding affinity and avidity of CD16A for antibodies improves the therapeutic potential of ADCC. CD64 (FcγRI), expressed by myeloid cells but not NK cells, is the only high affinity IgG Fc receptor and is uniquely capable of stably binding to free monomeric IgG as a physiological function. We have reported on the generation of the FcγR fusion CD64/16A, consisting of the extracellular region of CD64 and the transmembrane and cytoplasmic regions from CD16A, retaining its signaling and cellular activity. Here, we generated induced pluripotent stem cell (iPSC)-derived NK (iNK) cells expressing CD64/16A as a potential adoptive NK cell therapy for increased ADCC potency.

METHODS

iPSCs were engineered to express CD64/16A as well as an interleukin (IL)-15/IL-15Rα fusion (IL-15RF) protein and differentiated into iNK cells. iNK cells and peripheral blood NK cells were expanded using irradiated K562-mbIL21-41BBL feeder cells and examined. NK cells, ovarian tumor cell lines, and therapeutic monoclonal antibodies were used to assess ADCC in vitro, performed by a DELFIA EuTDA assay or in real-time by IncuCyte assays, and in vivo. For the latter, we developed a xenograft mouse model with high circulating levels of human IgG for more physiological relevance.

RESULTS

We demonstrate that (1) iNK-CD64/16A cells after expansion or thaw from cryopreservation can be coupled to therapeutic antibodies, creating armed iNK cells; (2) antibody-armed iNK-CD64/16A cells can be redirected by added antibodies to target new tumor antigens, highlighting additional potential of these cells; (3) cytokine-autonomous activity by iNK-CD64/16A cells engineered to express IL-15RF; and that (4) antibody-armed iNK-CD64/16A cells thawed from cryopreservation are capable of sustained and robust ADCC in vitro and in vivo, as determined by using a modified tumor xenograft model with high levels of competing human IgG.

CONCLUSIONS

iNK cells expressing CD64/16A provide an off-the-shelf multiantigen targeting platform to address tumor heterogeneity and mitigate antigen escape.

NKG2A gene variant predicts outcome of immunotherapy in AML and modulates the repertoire and function of NK cells

BACKGROUND

The natural killer (NK) complex (NKC) harbors multiple genes such as KLRC1 (encoding NKG2A) and KLRK1 (encoding NKG2D) that are central to regulation of NK cell function. We aimed at determining to what extent NKC haplotypes impact on NK cell repertoire and function, and whether such gene variants impact on outcome of IL-2-based immunotherapy in acute myeloid leukemia (AML).

METHODS

Genotype status of NKG2D rs1049174 and NKG2A rs1983526 was determined using the TaqMan-Allelic discrimination approach. To dissect the impact of single nucloetide polymorphim (SNP) on NK cell function, we engineered the K562 cell line with CRISPR to be killed in a highly NKG2D-dependent fashion. NK cells were assayed for degranulation, intracellular cytokine production and cytotoxicity using flow cytometry.

RESULTS

In AML patients receiving immunotherapy, the NKG2A gene variant, rs1983526, was associated with superior leukemia-free survival and overall survival. We observed that superior NK degranulation from individuals with the high-cytotoxicity NKG2D variant was explained by presence of a larger, highly responsive NKG2A+ subset. Notably, NK cells from donors homozygous for a favorable allele encoding NKG2A mounted stronger cytokine responses when challenged with leukemic cells, and NK cells from AML patients with this genotype displayed higher accumulation of granzyme B during histamine dihydrochloride/IL-2 immunotherapy. Additionally, among AML patients, the NKG2A SNP defined a subset of patients with HLA-B-21 TT with a strikingly favorable outcome.

CONCLUSIONS

The study results imply that a dimorphism in the NKG2A gene is associated with enhanced NK cell effector function and improved outcome of IL-2-based immunotherapy in AML.

PPARγ activation modulates the balance of peritoneal macrophage populations to suppress ovarian tumor growth and tumor-induced immunosuppression

BACKGROUND

Ovarian adenocarcinoma (OVAD) frequently metastasizes to the peritoneal cavity and manifests by the formation of ascites, which constitutes a tumor-promoting microenvironment. In the peritoneal cavity, two developmentally, phenotypically and functionally distinct macrophage subsets, immunocompetent large peritoneal macrophages (LPM) and immunosuppressive small peritoneal macrophages (SPM), coexist. Because peroxisome proliferator-activated receptor γ (PPARγ) is a critical factor participating in macrophage differentiation and cooperates with CCAAT/enhancer binding protein β (C/EBPβ), a transcription factor essential for SPM-to-LPM differentiation, PPARγ could be also involved in the regulation of SPM/LPM balance and could be a promising therapeutic target.

METHODS

To evaluate the 15(S)-hydroxyeicosatetraenoic acid (HETE), a PPARγ endogenous ligand, impact on ovarian tumor growth, we intraperitoneally injected 15(S)-HETE into a murine ovarian cancer model. This experimental model consists in the intraperitoneally injection of ID8 cells expressing luciferase into syngeneic C57BL/6 female mice. This ID8 orthotopic mouse model is a well-established experimental model of end-stage epithelial OVAD. Tumor progression was monitored using an in vivo imaging system. Peritoneal immune cells in ascites were analyzed by flow cytometry and cell sorting. To determine whether the impact of 15(S)-HETE in tumor development is mediated through the macrophages, these cells were depleted by injection of liposomal clodronate. To further dissect how 15(S)-HETE mediated its antitumor effect, we assessed the tumor burden in tumor-bearing mice in which the PPARγ gene was selectively disrupted in myeloid-derived cells and in mice deficient of the recombination-activating gene Rag2. Finally, to validate our data in humans, we isolated and treated macrophages from ascites of individuals with OVAD.

RESULTS

Here we show, in the murine experimental model of OVAD, that 15(S)-HETE treatment significantly suppresses the tumor growth, which is associated with the differentiation of SPM into LPM and the LPM residency in the peritoneal cavity. We demonstrate that C/EBPβ and GATA6 play a central role in SPM-to-LPM differentiation and in LPM peritoneal residence through PPARγ activation during OVAD. Moreover, this SPM-to-LPM switch is associated with the increase of the effector/regulatory T-cell ratio. Finally, we report that 15(S)-HETE attenuates immunosuppressive properties of human ovarian tumor-associated macrophages from ascites.

CONCLUSION

Altogether, these results promote PPARγ as a potential therapeutic target to restrain OVAD development and strengthen the use of PPARγ agonists in anticancer therapy.

Defining the spatial distribution of extracellular adenosine revealed a myeloid-dependent immunosuppressive microenvironment in pancreatic ductal adenocarcinoma

BACKGROUND

The prognosis for patients with pancreatic ductal adenocarcinoma (PDAC) remains extremely poor. It has been suggested that the adenosine pathway contributes to the ability of PDAC to evade the immune system and hence, its resistance to immuno-oncology therapies (IOT), by generating extracellular adenosine (eAdo).

METHODS

Using genetically engineered allograft models of PDAC in syngeneic mice with defined and different immune infiltration and response to IOT and autochthonous tumors in KPC mice we investigated the impact of the adenosine pathway on the PDAC tumor microenvironment (TME). Flow cytometry and imaging mass cytometry (IMC) were used to characterize the subpopulation frequency and spatial distribution of tumor-infiltrating immune cells. Mass spectrometry imaging (MSI) was used to visualize adenosine compartmentalization in the PDAC tumors. RNA sequencing was used to evaluate the influence of the adenosine pathway on the shaping of the immune milieu and correlate our findings to published data sets in human PDAC.

RESULTS

We demonstrated high expression of adenosine pathway components in tumor-infiltrating immune cells (particularly myeloid populations) in the murine models. MSI demonstrated that extracellular adenosine distribution is heterogeneous in tumors, with high concentrations in peri-necrotic, hypoxic regions, associated with rich myeloid infiltration, demonstrated using IMC. Protumorigenic M2 macrophages express high levels of the Adora2a receptor; particularly in the IOT resistant model. Blocking the in vivo formation and function of eAdo (Adoi), using a combination of anti-CD73 antibody and an Adora2a inhibitor slowed tumor growth and reduced metastatic burden. Additionally, blocking the adenosine pathway improved the efficacy of combinations of cytotoxic agents or immunotherapy. Adoi remodeled the TME, by reducing the infiltration of M2 macrophages and regulatory T cells. RNA sequencing analysis showed that genes related to immune modulation, hypoxia and tumor stroma were downregulated following Adoi and a specific adenosine signature derived from this is associated with a poorer prognosis in patients with PDAC.

CONCLUSIONS

The formation of eAdo promotes the development of the immunosuppressive TME in PDAC, contributing to its resistance to conventional and novel therapies. Therefore, inhibition of the adenosine pathway may represent a strategy to modulate the PDAC immune milieu and improve therapy response in patients with PDAC.

Autologous humanized PDX modeling for immuno-oncology recapitulates features of the human tumor microenvironment

BACKGROUND

Interactions between immune and tumor cells are critical to determining cancer progression and response. In addition, preclinical prediction of immune-related drug efficacy is limited by interspecies differences between human and mouse, as well as inter-person germline and somatic variation. To address these gaps, we developed an autologous system that models the tumor microenvironment (TME) from individual patients with solid tumors.

METHOD

With patient-derived bone marrow hematopoietic stem and progenitor cells (HSPCs), we engrafted a patient's hematopoietic system in MISTRG6 mice, followed by transfer of patient-derived xenograft (PDX) tissue, providing a fully genetically matched model to recapitulate the individual's TME. We used this system to prospectively study tumor-immune interactions in patients with solid tumor.

RESULTS

Autologous PDX mice generated innate and adaptive immune populations; these cells populated the TME; and tumors from autologously engrafted mice grew larger than tumors from non-engrafted littermate controls. Single-cell transcriptomics revealed a prominent vascular endothelial growth factor A (VEGFA) signature in TME myeloid cells, and inhibition of human VEGF-A abrogated enhanced growth.

CONCLUSIONS

Humanization of the interleukin 6 locus in MISTRG6 mice enhances HSPC engraftment, making it feasible to model tumor-immune interactions in an autologous manner from a bedside bone marrow aspirate. The TME from these autologous tumors display hallmarks of the human TME including innate and adaptive immune activation and provide a platform for preclinical drug testing.

Carbohydrate ligand engagement with CD11b enhances differentiation of tumor-associated myeloid cells for immunotherapy of solid cancers

BACKGROUND

Efforts to modulate the function of tumor-associated myeloid cell are underway to overcome the challenges in immunotherapy and find a cure. One potential therapeutic target is integrin CD11b, which can be used to modulate the myeloid-derived cells and induce tumor-reactive T-cell responses. However, CD11b can bind to multiple different ligands, leading to various myeloid cell functions such as adhesion, migration, phagocytosis, and proliferation. This has created a major challenge in understanding how CD11b converts the differences in the receptor-ligand binding into subsequent signaling responses and using this information for therapeutic development.

METHODS

This study aimed to investigate the antitumor effect of a carbohydrate ligand, named BG34-200, which modulates the CD11b⁺ cells. We have applied peptide microarrays, multiparameter FACS (fluorescence-activated cell analysis) analysis, cellular/molecular immunological technology, advanced microscopic imaging, and transgenic mouse models of solid cancers, to study the interaction between BG34-200 carbohydrate ligand and CD11b protein and the resulting immunological changes in the context of solid cancers, including osteosarcoma, advanced melanoma, and pancreatic ductal adenocarcinoma (PDAC).

RESULTS

Our results show that BG34-200 can bind directly to the activated CD11b on its I (or A) domain, at previously unreported peptide residues, in a multisite and multivalent manner. This engagement significantly impacts the biological function of tumor-associated inflammatory monocytes (TAIMs) in osteosarcoma, advanced melanoma, and PDAC backgrounds. Importantly, we observed that the BG34-200-CD11b engagement triggered endocytosis of the binding complexes in TAIMs, which induced intracellular F-actin cytoskeletal rearrangement, effective phagocytosis, and intrinsic ICAM-1 (intercellular adhesion molecule I) clustering. These structural biological changes resulted in the differentiation in TAIMs into monocyte-derived dendritic cells, which play a crucial role in T-cell activation in the tumor microenvironment.

CONCLUSIONS

Our research has advanced the current understanding of the molecular basis of CD11b activation in solid cancers, revealing how it converts the differences in BG34 carbohydrate ligands into immune signaling responses. These findings could pave the way for the development of safe and novel BG34-200-based therapies that modulate myeloid-derived cell functions, thereby enhancing immunotherapy for solid cancers.

Irreversible electroporation augments β-glucan induced trained innate immunity for the treatment of pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic cancer (PC) is a challenging diagnosis that is yet to benefit from the advancements in immuno-oncologic treatments. Irreversible electroporation (IRE), a non-thermal method of tumor ablation, is used in treatment of select patients with locally-advanced unresectable PC and has potentiated the effect of certain immunotherapies. Yeast-derived particulate β-glucan induces trained innate immunity and successfully reduces murine PC tumor burden. This study tests the hypothesis that IRE may augment β-glucan induced trained immunity in the treatment of PC.

METHODS

β-Glucan-trained pancreatic myeloid cells were evaluated ex vivo for trained responses and antitumor function after exposure to ablated and unablated tumor-conditioned media. β-Glucan and IRE combination therapy was tested in an orthotopic murine PC model in wild-type and Rag-/- mice. Tumor immune phenotypes were assessed by flow cytometry. Effect of oral β-glucan in the murine pancreas was evaluated and used in combination with IRE to treat PC. The peripheral blood of patients with PC taking oral β-glucan after IRE was evaluated by mass cytometry.

RESULTS

IRE-ablated tumor cells elicited a potent trained response ex vivo and augmented antitumor functionality. In vivo, β-glucan in combination with IRE reduced local and distant tumor burden prolonging survival in a murine orthotopic PC model. This combination augmented immune cell infiltration to the PC tumor microenvironment and potentiated the trained response from tumor-infiltrating myeloid cells. The antitumor effect of this dual therapy occurred independent of the adaptive immune response. Further, orally administered β-glucan was identified as an alternative route to induce trained immunity in the murine pancreas and prolonged PC survival in combination with IRE. β-Glucan in vitro treatment also induced trained immunity in peripheral blood monocytes obtained from patients with treatment-naïve PC. Finally, orally administered β-glucan was found to significantly alter the innate cell landscape within the peripheral blood of five patients with stage III locally-advanced PC who had undergone IRE.

CONCLUSIONS

These data highlight a relevant and novel application of trained immunity within the setting of surgical ablation that may stand to benefit patients with PC.

Intravesical BCG in patients with non-muscle invasive bladder cancer induces trained immunity and decreases respiratory infections

BACKGROUND

BCG is recommended as intravesical immunotherapy to reduce the risk of tumor recurrence in patients with non-muscle invasive bladder cancer (NMIBC). Currently, it is unknown whether intravesical BCG application induces trained immunity.

METHODS

The aim of this research was to determine whether BCG immunotherapy induces trained immunity in NMIBC patients. We conducted a prospective observational cohort study in 17 NMIBC patients scheduled for BCG therapy and measured trained immunity parameters at 9 time points before and during a 1-year BCG maintenance regimen. Ex vivo cytokine production by peripheral blood mononuclear cells, epigenetic modifications, and changes in the monocyte transcriptome were measured. The frequency of respiratory infections was investigated in two larger cohorts of BCG-treated and non-BCG treated NMIBC patients as a surrogate measurement of trained immunity. Gene-based association analysis of genetic variants in candidate trained immunity genes and their association with recurrence-free survival and progression-free survival after BCG therapy was performed to investigate the hypothesized link between trained immunity and clinical response.

RESULTS

We found that intravesical BCG does induce trained immunity based on an increased production of TNF and IL-1β after heterologous ex vivo stimulation of circulating monocytes 6-12 weeks after intravesical BCG treatment; and a 37% decreased risk (OR 0.63 (95% CI 0.40 to 1.01)) for respiratory infections in BCG-treated versus non-BCG-treated NMIBC patients. An epigenomics approach combining chromatin immuno precipitation-sequencing and RNA-sequencing with in vitro trained immunity experiments identified enhanced inflammasome activity in BCG-treated individuals. Finally, germline variation in genes that affect trained immunity was associated with recurrence and progression after BCG therapy in NMIBC.

CONCLUSION

We conclude that BCG immunotherapy induces trained immunity in NMIBC patients and this may account for the protective effects against respiratory infections. The data of our gene-based association analysis suggest that a link between trained immunity and oncological outcome may exist. Future studies should further investigate how trained immunity affects the antitumor immune responses in BCG-treated NMIBC patients.

Antibody-induced erythrophagocyte reprogramming of Kupffer cells prevents anti-CD40 cancer immunotherapy-associated liver toxicity

BACKGROUND

Agonistic anti-CD40 monoclonal antibodies (mAbs) have emerged as promising immunotherapeutic compounds with impressive antitumor effects in mouse models. However, preclinical and clinical studies faced dose-limiting toxicities mediated by necroinflammatory liver disease. An effective prophylactic treatment for liver immune-related adverse events that does not suppress specific antitumor immunity remains to be found.

METHODS

We used different mouse models and time-resolved single-cell RNA-sequencing to characterize the pathogenesis of anti-CD40 mAb induced liver toxicity. Subsequently, we developed an antibody-based treatment protocol to selectively target red blood cells (RBCs) for erythrophagocytosis in the liver, inducing an anti-inflammatory liver macrophage reprogramming.

RESULTS

We discovered that CD40 signaling in Clec4f⁺ Kupffer cells is the non-redundant trigger of anti-CD40 mAb-induced liver toxicity. Taking advantage of the highly specific functionality of liver macrophages to clear antibody-tagged RBCs from the blood, we hypothesized that controlled erythrophagocytosis and the linked anti-inflammatory signaling by the endogenous metabolite heme could be exploited to reprogram liver macrophages selectively. Repeated low-dose administration of a recombinant murine Ter119 antibody directed RBCs for selective phagocytosis in the liver and skewed the phenotype of liver macrophages into a Hmox^high/Marco^high/MHCII^low anti-inflammatory phenotype. This unique mode of action prevented necroinflammatory liver disease following high-dose administration of anti-CD40 mAbs. In contrast, extrahepatic inflammation, antigen-specific immunity, and antitumor activity remained unaffected in Ter119 treated animals.

CONCLUSIONS

Our study offers a targeted approach to uncouple CD40-augmented antitumor immunity in peripheral tissues from harmful inflammatoxicity in the liver.

PP4 inhibition sensitizes ovarian cancer to NK cell-mediated cytotoxicity via STAT1 activation and inflammatory signaling

BACKGROUND

Increased infiltration of T cells into ovarian tumors has been repeatedly shown to be predictive of enhanced patient survival. However, despite the evidence of an active immune response in ovarian cancer (OC), the frequency of responses to immune checkpoint blockade (ICB) therapy in OC is much lower than other cancer types. Recent studies have highlighted that deficiencies in the DNA damage response (DDR) can drive increased genomic instability and tumor immunogenicity, which leads to enhanced responses to ICB. Protein phosphatase 4 (PP4) is a critical regulator of the DDR; however, its potential role in antitumor immunity is currently unknown.

RESULTS

Our results show that the PP4 inhibitor, fostriecin, combined with carboplatin leads to increased carboplatin sensitivity, DNA damage, and micronuclei formation. Using multiple OC cell lines, we show that PP4 inhibition or PPP4C knockdown combined with carboplatin triggers inflammatory signaling via Nuclear factor kappa B (NF-κB) and signal transducer and activator of transcription 1 (STAT1) activation. This resulted in increased expression of the pro-inflammatory cytokines and chemokines: CCL5, CXCL10, and IL-6. In addition, IFNB1 expression was increased suggesting activation of the type I interferon response. Conditioned media from OC cells treated with the combination of PP4 inhibitor and carboplatin significantly increased migration of both CD8 T cell and natural killer (NK) cells over carboplatin treatment alone. Knockdown of stimulator of interferon genes (STING) in OC cells significantly abrogated the increase in CD8 T-cell migration induced by PP4 inhibition. Co-culture of NK-92 cells and OC cells with PPP4C or PPP4R3B knockdown resulted in strong induction of NK cell interferon-γ, increased degranulation, and increased NK cell-mediated cytotoxicity against OC cells. Stable knockdown of PP4C in a syngeneic, immunocompetent mouse model of OC resulted in significantly reduced tumor growth in vivo. Tumors with PP4C knockdown had increased infiltration of NK cells, NK T cells, and CD4⁺ T cells. Addition of low dose carboplatin treatment led to increased CD8⁺ T-cell infiltration in PP4C knockdown tumors as compared with the untreated PP4C knockdown tumors.

CONCLUSIONS

Our work has identified a role for PP4 inhibition in promoting inflammatory signaling and enhanced immune cell effector function. These findings support the further investigation of PP4 inhibitors to enhance chemo-immunotherapy for OC treatment.

Activated NK cells reprogram MDSCs via NKG2D-NKG2DL and IFN-γ to modulate antitumor T-cell response after cryo-thermal therapy

BACKGROUND

Myeloid-derived suppressor cells (MDSCs) can potently inhibit T-cell activity, promote growth and metastasis of tumor and contribute to resistance to immunotherapy. Targeting MDSCs to alleviate their protumor functions and immunosuppressive activities is intimately associated with cancer immunotherapy. Natural killer (NK) cells can engage in crosstalk with multiple myeloid cells to alter adaptive immune responses, triggering T-cell immunity. However, whether the NK-cell-MDSC interaction can modulate the T-cell immune response requires further study. Cryo-thermal therapy could induce the maturation of MDSCs by creating an acute inflammatory environment to elicit a CD4⁺ Th1-dominant immune response, but the mechanism regulating this process remains unclear.

METHODS

NK cells were depleted and NKG2D was blocked with monoclonal antibodies in vivo. MDSCs, NK cells and T cells were assessed by flow cytometry and isolated by magnetic-activated cell sorting (MACS). MDSCs and NK cells were cocultured with T cells to determine their immunological function. The transcriptional profiles of MDSCs were measured by qRT-PCR and RNA-sequencing. Isolated NK cells and MDSCs by MACS were cocultured to study the viability and maturation of MDSCs regulated by NK cells. TIMER was used to comprehensively examine the immunological, clinical, and genomic features of tumors.

RESULTS

NK-cell activation after cryo-thermal therapy decreased MDSC accumulation and reprogrammed immunosuppressive MDSCs toward a mature phenotype to promote T cell antitumor immunity. Furthermore, we discovered that NK cells could kill MDSCs via the NKG2D-NKG2DL axis and promote MDSC maturation by interferon gamma (IFN-γ) in response to NKG2D. In addition, CD4⁺ Th1-dominant antitumor immune response was dependent on NKG2D, which promoted the major histocompatibility complex Ⅱ pathway of MDSCs. High activated NK-cell infiltration and NKG2D level in tumors were positively correlated with better clinical outcomes.

CONCLUSIONS

Cryo-thermal therapy induces effective CD4⁺ Th1-dominant antitumor immunity by activating NK cells to reprogram MDSCs, providing a promising therapeutic strategy for cancer immunotherapy.

Z-DNA enhances immunotherapy by triggering death of inflammatory cancer-associated fibroblasts

Cancer-associated fibroblasts (CAFs) are a heterogeneous population of cells. At one end of the spectrum are alpha-smooth muscle actin expressing myoCAFs (myofibroblast CAFs) and at the other end are the interferon (IFN) and Janus Kinase/Signal Transducer and Activator of Transcription responsive iCAFs (inflammatory CAFs). Both types of CAFs promote tumor growth. While myoCAFs foster immune exclusion and limit tumor spread, iCAFs create a highly immunosuppressive environment and foster the seeding of distant metastases. However, iCAFs also represent a tumor vulnerability. They are competent to undergo necroptosis, a highly immunogenic form of cell death that is triggered when Z-DNA or Z-RNA (collectively called ZNA) is sensed by the IFN-induced ZNA binding protein 1 (ZBP1). The sequestering of ZNA ligands by the p150 isoform of the double-stranded RNA-specific deaminase ADAR1 protects iCAFs from cell death. ZBP1-dependent necroptosis in iCAFs can be triggered by administering an orally available small molecule that generates sufficient amounts of ZNA to bypass ADAR1 inhibition. The therapeutic approach of targeting Z-prone sequences (called flipons) is agnostic to the mutations driving cancer progression. By exploiting the tumor vulnerability posed by expression of ZBP1-dependent immunogenic cell death pathways in iCAFs, flipon therapeutics offer new hope for improved clinical outcomes.

Immunosuppressive lncRNA LINC00624 promotes tumor progression and therapy resistance through ADAR1 stabilization

BACKGROUND

Despite the success of HER2-targeted therapy in achieving prolonged survival in approximately 50% of treated individuals, treatment resistance is still an important challenge for HER2+ breast cancer (BC) patients. The influence of both adaptive and innate immune responses on the therapeutic outcomes of HER2+BC patients has been extensively demonstrated.

METHODS

Long non-coding RNAs expressed in non-pathological complete response (pCR) HER2 positive BC were screened and validated by RNA-seq. Survival analysis were made by Kaplan-Meier method. Cell death assay and proliferation assay were performed to confirm the phenotype of LINC00624. RT-qPCR and western blot were used to assay the IFN response. Xenograft mouse model were used for in vivo confirmation of anti-neu treatment resistance. RNA pull-down and immunoblot were used to confirm the interaction of ADAR1 and LINC00624. ADAR1 recombinant protein were purified from baculovirus expression system. B16-OVA cells were used to study antigen presentation both in vitro and in vivo. Flow cytometry was used to determine the tumor infiltrated immune cells of xenograft model. Antisense oligonucleotides (ASOs) were used for in vivo treatment.

RESULTS

In this study, we found that LINC00624 blocked the antitumor effect of HER2- targeted therapy both in vitro and in vivo by inhibiting type I interferon (IFN) pathway activation. The double-stranded RNA-like structure of LINC00624 can bind and be edited by the adenosine (A) to inosine (I) RNA-editing enzyme adenosine deaminase RNA specific 1 (ADAR1), and this editing has been shown to release the growth inhibition and attenuate the innate immune response caused by the IFN response. Notably, LINC00624 promoted the stabilization of ADAR1 by inhibiting its ubiquitination-induced degradation triggered by β-TrCP. In contrast, LINC00624 inhibited major histocompatibility complex (MHC) class I antigen presentation and limited CD8+T cell infiltration in the cancer microenvironment, resulting in immune checkpoint blockade inhibition and anti-HER2 treatment resistance mediated through ADAR1.

CONCLUSIONS

In summary, these results suggest that LINC00624 is a cancer immunosuppressive lncRNA and targeting LINC00624 through ASOs in tumors expressing high levels of LINC00624 has great therapeutic potential in future clinical applications.

Antitumor strategies targeting macrophages: the importance of considering the differences in differentiation/polarization processes between human and mouse macrophages

Macrophages are the immune cells that accumulate the most in the majority of established tumors and this accumulation is associated with a poor prognosis. Tumor-associated macrophages (TAMs) produce inflammatory cytokines and growth factors that promote tumor expansion and metastasis. TAMs have recently emerged as targets of choice to restore an efficient antitumor response and to limit tumor growth. Many molecules targeting TAMs are actually evaluated in clinical trials, alone or in combination. While these molecules induce tumor regression and stimulate cytotoxic responses in mouse models of tumor development, results from early clinical trials are less impressive. In this review, we list the biological differences between human and mouse macrophages that help explain the different efficacy of antitumor strategies targeting TAMs between human and animal studies. Differences in the impact of survival and polarization factors and in the cytokines produced and markers expressed as well as the limitations of extrapolations based on in vitro models of TAM-like generation should be considered in order to improve the design and efficacy of antitumor drugs targeting TAMs.

Label-free metabolic imaging for sensitive and robust monitoring of anti-CD47 immunotherapy response in triple-negative breast cancer

Background

Immunotherapy is revolutionizing cancer treatment from conventional radiotherapies and chemotherapies to immune checkpoint inhibitors which use patients’ immune system to recognize and attack cancer cells. Despite the huge clinical success and vigorous development of immunotherapies, there is a significant unmet need for a robust tool to identify responders to specific immunotherapy. Early and accurate monitoring of immunotherapy response is indispensable for personalized treatment and effective drug development.

Methods

We established a label-free metabolic intravital imaging (LMII) technique to detect two-photon excited autofluorescence signals from two coenzymes, NAD(P)H (reduced nicotinamide adenine dinucleotide (phosphate) hydrogen) and FAD (flavin adenine dinucleotide) as robust imaging markers to monitor metabolic responses to immunotherapy. Murine models of triple-negative breast cancer (TNBC) were established and tested with different therapeutic regimens including anti-cluster of differentiation 47 (CD47) immunotherapy to monitor time-course treatment responses using the developed metabolic imaging technique.

Results

We first imaged the mechanisms of the CD47-signal regulatory protein alpha pathway in vivo, which unravels macrophage-mediated antibody-dependent cellular phagocytosis and illustrates the metabolism of TNBC cells and macrophages. We further visualized the autofluorescence of NAD(P)H and FAD and found a significant increase during tumor growth. Following anti-CD47 immunotherapy, the imaging signal was dramatically decreased demonstrating the sensitive monitoring capability of NAD(P)H and FAD imaging for therapeutic response. NAD(P)H and FAD intravital imaging also showed a marked decrease after chemotherapy and radiotherapy. A comparative study with conventional whole-body bioluminescence and fluorescent glucose imaging demonstrated superior sensitivity of metabolic imaging. Flow cytometry validated metabolic imaging results. In vivo immunofluorescent staining revealed the targeting ability of NAD(P)H imaging mainly for tumor cells and a small portion of immune-active cells and that of FAD imaging mainly for immunosuppressive cells such as M2-like tumor-associated macrophages.

Conclusions

Collectively, this study showcases the potential of the LMII technique as a powerful tool to visualize dynamic changes of heterogeneous cell metabolism of cancer cells and immune infiltrates in response to immunotherapy thus providing sensitive and complete monitoring. Leveraged on ability to differentiate cancer cells and immunosuppressive macrophages, the presented imaging approach provides particularly useful imaging biomarkers for emerged innate immune checkpoint inhibitors such as anti-CD47 therapy.

Complement downregulation promotes an inflammatory signature that renders colorectal cancer susceptible to immunotherapy

BACKGROUND AND AIMS

The role of inflammatory immune responses in colorectal cancer (CRC) development and response to therapy is a matter of intense debate. While inflammation is a known driver of CRC, inflammatory immune infiltrates are a positive prognostic factor in CRC and predispose to response to immune checkpoint blockade (ICB) therapy. Unfortunately, over 85% of CRC cases are primarily unresponsive to ICB due to the absence of an immune infiltrate, and even the cases that show an initial immune infiltration can become refractory to ICB. The identification of therapy supportive immune responses in the field has been partially hindered by the sparsity of suitable mouse models to recapitulate the human disease. In this study, we aimed to understand how the dysregulation of the complement anaphylatoxin C3a receptor (C3aR), observed in subsets of patients with CRC, affects the immune responses, the development of CRC, and response to ICB therapy.

METHODS

We use a comprehensive approach encompassing analysis of publicly available human CRC datasets, inflammation-driven and newly generated spontaneous mouse models of CRC, and multiplatform high-dimensional analysis of immune responses using microbiota sequencing, RNA sequencing, and mass cytometry.

RESULTS

We found that patients' regulation of the complement C3aR is associated with epigenetic modifications. Specifically, downregulation of C3ar1 in human CRC promotes a tumor microenvironment characterized by the accumulation of innate and adaptive immune cells that support antitumor immunity. In addition, in vivo studies in our newly generated mouse model revealed that the lack of C3a in the colon activates a microbiota-mediated proinflammatory program which promotes the development of tumors with an immune signature that renders them responsive to the ICB therapy.

CONCLUSIONS

Our findings reveal that C3aR may act as a previously unrecognized checkpoint to enhance antitumor immunity in CRC. C3aR can thus be exploited to overcome ICB resistance in a larger group of patients with CRC.

Hyperbaric oxygen facilitates teniposide-induced cGAS-STING activation to enhance the antitumor efficacy of PD-1 antibody in HCC

BACKGROUND

Emerging evidence indicates that the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) axis plays a pivotal role in intrinsic antitumor immunity. Previous studies demonstrate that the conventional chemotherapy agent, teniposide, effectively promotes the therapeutic efficacy of programmed cell death protein-1 antibody (PD-1 Ab) through robust cGAS-STING activation. Unfortunately, the cGAS expression of tumor cells is reported to be severely suppressed by the hypoxic status in solid tumor. Clinically, enhancing chemotherapy-induced, DNA-activated tumor STING signaling by alleviating tumor hypoxia might be one possible direction for improving the currently poor response rates of patients with hepatocellular carcinoma (HCC) to PD-1 Ab.

METHODS

Teniposide was first screened out from several chemotherapy drugs according to their potency in inducing cGAS-STING signaling in human HCC cells. Teniposide-treated HCC cells were then cultured under hypoxia, normoxia or reoxygenation condition to detect change in cGAS-STING signaling. Next, oxaliplatin/teniposide chemotherapy alone or combined with hyperbaric oxygen (HBO) therapy was administered on liver orthotopic mouse tumor models, after which the tumor microenvironment (TME) was surveyed. Lastly, teniposide alone or combined with HBO was performed on multiple mouse tumor models and the subsequent anti-PD-1 therapeutic responses were observed.

RESULTS

Compared with the first-line oxaliplatin chemotherapy, teniposide chemotherapy induced stronger cGAS-STING signaling in human HCC cells. Teniposide-induced cGAS-STING activation was significantly inhibited by hypoxia inducible factor 1α in an oxygen-deficient environment in vitro and the inhibition was rapidly removed via effective reoxygenation. HBO remarkably enhanced the cGAS-STING-dependent tumor type Ⅰ interferon and nuclear factor kappa-B signaling induced by teniposide in vivo, both of which contributed to the activation of dendritic cells and subsequent cytotoxic T cells. Combined HBO with teniposide chemotherapy improved the therapeutic effect of PD-1 Ab in multiple tumor models.

CONCLUSIONS

By combination of two therapies approved by the Food and Drug Administration, we safely stimulated an immunogenic, T cell-inflamed HCC TME, leading to further sensitization of tumors to anti-PD-1 immunotherapy. These findings might enrich therapeutic strategies for advanced HCC andwe can attempt to improve the response rates of patients with HCC to PD-1 Ab by enhancing DNA-activated STING signaling through effective tumor reoxygenation.

ELK3 modulates the antitumor efficacy of natural killer cells against triple negative breast cancer by regulating mitochondrial dynamics

Background

Triple negative breast cancer (TNBC) is the most lethal subtype of breast cancer due to its aggressive behavior and frequent development of resistance to chemotherapy. Although natural killer (NK) cell-based immunotherapy is a promising strategy for overcoming barriers to cancer treatment, the therapeutic efficacy of NK cells against TNBC is below expectations. E26 transformation-specific transcription factor ELK3 (ELK3) is highly expressed in TNBCs and functions as a master regulator of the epithelial-mesenchymal transition.

Methods

Two representative human TNBC cell lines, MDA-MB231 and Hs578T, were exposed to ELK3-targeting shRNA or an ELK3-expressing plasmid to modulate ELK3 expression. The downstream target genes of ELK3 were identified using a combined approach comprising gene expression profiling and molecular analysis. The role of ELK3 in determining the immunosensitivity of TNBC to NK cells was investigated in terms of mitochondrial fission–fusion transition and reactive oxygen species concentration both in vitro and in vivo.

Results

ELK3-dependent mitochondrial fission–fusion status was linked to the mitochondrial superoxide concentration in TNBCs and was a main determinant of NK cell-mediated immune responses. We identified mitochondrial dynamics proteins of 51 (Mid51), a major mediator of mitochondrial fission, as a direct downstream target of ELK3 in TNBCs. Also, we demonstrated that expression of ELK3 correlated inversely with that of Mid51, and that the ELK3-Mid51 axis is associated directly with the status of mitochondrial dynamics. METABRIC analysis revealed that the ELK3-Mid51 axis has a direct effect on the immune score and survival of patients with TNBC.

Conclusions

Taken together, the data suggest that NK cell responses to TNBC are linked directly to ELK3 expression levels, shedding new light on strategies to improve the efficacy of NK cell-based immunotherapy of TNBC.

Low-dose irradiation for reversing immunotherapy resistance: how to translate?

The use of low-dose irradiation (LDI) for mobilizing innate and adaptive immunity is gaining interest among the scientific community. Recent evidence suggests that LDI can reprogramme the tumor microenvironment, induce inflammation and turn cold tumors susceptible to immunecheckpoint blockade therapy. Translating immuno-radiation preclinical findings in the clinic is more challenging than expected. We propose therapeutic strategies for combining LDI with immunotherapy, and emphasize the importance of pursuing clinical research to determine optimal radiation dosage, fractionation, volumes, and sequencing to stimulate immune-mediated tumor responses.

Characterization of antifungal C-type lectin receptor expression on murine epithelial and endothelial cells in mucosal tissues

Our data reveal that selection of enzymes for generating single cell suspensions from murine tissues influences detection of surface expression of antifungal CLRs. Using a method that most preserves receptor expression, we show that non-myeloid expression of antifungal CLRs is limited to MelLec on endothelial cells in murine mucosal tissues.

Associations between markers of cellular and humoral immunity to rubella virus following a third dose of measles-mumps-rubella vaccine

INTRODUCTION

Rubella virus (RV) was eliminated in the United States in 2004, although a small portion of the population fails to develop long-term immunity against RV even after two doses of the measles-mumps-rubella (MMR) vaccine. We hypothesized that inherent biological differences in cytokine and chemokine signaling likely govern an individual's response to a third dose of the vaccine.

METHODS

Healthy young women (n = 97) were selected as study participants if they had either low or high extremes of RV-specific antibody titer after two previous doses of MMR vaccine. We measured cytokine and chemokine secretion from RV-stimulated PBMCs before and 28 days after they received a third dose of MMR vaccine and assessed correlations with humoral immune response outcomes.

RESULTS

High and low antibody vaccine responders exhibited a strong pro-inflammatory cellular response, with an underlying Th1-associated signature (IL-2, IFN-γ, MIP-1β, IP-10) and suppressed production of most Th2-associated cytokines (IL-4, IL-10, IL-13). IL-10 and IL-4 exhibited significant negative associations with neutralizing antibody titers and memory B cell ELISpot responses among low vaccine responders.

CONCLUSION

IL-4 and IL-10 signaling pathways may be potential targets for understanding and improving the immune response to rubella vaccination or for designing new vaccines that induce more durable immunity.

Nonalcoholic fatty liver disease and alcohol-related liver disease: From clinical aspects to pathophysiological insights

Two major causes of steatohepatitis are alcohol and metabolic syndrome. Although the underlying causes of alcohol-related liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH) differ, there are certain similarities in terms of the mode of disease progression and underlying pathophysiological mechanisms. Further, excessive alcohol consumption is often seen in patients with metabolic syndrome, and alcoholic hepatitis exacerbation by comorbidity with metabolic syndrome is an emerging clinical problem. There are certain ethnic differences in the development of both NAFLD and ALD. Especially, Asian populations tend to be more susceptible to NAFLD, and genetic polymorphisms in patatin-like phospholipase domain-containing 3 (PNPLA3) play a key role in both NAFLD and ALD. From the viewpoint of pathophysiology, cellular stress responses, including autophagy and endoplasmic reticulum (ER) stress, are involved in the development of cellular injury in steatohepatitis. Further, gut-derived bacterial products and innate immune responses in the liver most likely play a profound role in the pathogenesis of both ALD and NASH. Though the recent progress in the treatment of viral hepatitis has reduced the prevalence of viral-related development of hepatocellular carcinoma (HCC), non-viral HCC is increasing. Alcohol and metabolic syndrome synergistically exacerbate progression of steatohepatitis, resulting in carcinogenesis. The gut-liver axis is a potential therapeutic and prophylactic target for steatohepatitis and subsequent carcinogenesis.

Lower Levels of Urinary Nerve Growth Factor Might Predict Recurrent Urinary Tract Infections in Women

PURPOSE

To investigate the changes in urinary nerve growth factor (uNGF) levels after acute urinary tract infection (UTI) and to assess the role of uNGF in predicting UTI recurrence in women.

METHODS

Women with uncomplicated, symptomatic UTIs were enrolled. Cephalexin 500 mg (every 6 hours) was administered for 7-14 days to treat acute UTIs. Subsequently, the patients were randomized to receive either sulfamethoxazole/trimethoprim 800 mg/160 mg daily at bedtime, or celecoxib 200 mg daily for 3 months and were monitored for up to 12 months. NGF levels in the urine were determined at baseline, 1, 4, and 12 weeks after the initiation of prophylactic therapy, and were compared between women with first-time UTIs and recurrent UTIs, sulfamethoxazole/trimethoprim and celecoxib-treated women, and no UTI recurrence and UTI recurrence that occurred during the follow-up period. Twenty women free of UTIs served as controls.

RESULTS

A total of 139 women with UTI and 20 controls were enrolled in the study, which included 50 women with a first-time UTI and 89 women with recurrent UTIs. Thirty-seven women completed the study. Women with recurrent UTIs (n=23) had a trend of lower uNGF levels than women with first-time UTIs (n=14). During follow-up, 9 women had UTI recurrence. The serial uNGF levels in women with UTI recurrence were significantly lower than those in women who did not have UTI recurrence during the follow-up period.

CONCLUSIONS

The lower levels of uNGF in women with recurrent UTI and the incidence of UTI recurrence during follow-up suggest that lower uNGF might reflect the defective innate immunity in women with recurrent UTI.

Identification and characterization of human dendritic cell subsets in the steady state: a review of our current knowledge

Dendritic cells (DC) are generally categorized as a group of rare antigen presenting cells that are to the crucial development of immune responses to pathogens and also of tolerance to self-antigens. Therefore, having the ability to identify DC in specific tissues and to test their functional abilities in the steady state are scientific gaps needing attention. Research on primary human DC is lacking due to their rarity and the difficulty of obtaining tissue samples. However, recent findings have shown that several different DC subsets exist, and that these subsets vary both by markers expressed and functions depending on their specific microenvironment. After discriminating from other cell types, DC can be split into myeloid and plasmacytoid fractions. While plasmacytoid DC express definite markers, CD123 and BDCA-2, myeloid DC encompass several different subsets with overlapping markers expressed. Such markers include the blood DC antigens BDCA-1 and BDCA-3, along with Langerin, CD1a and CD14. Marker specificity is further reduced when accounting for microenvironmental differences, as observed in the blood, primary lymphoid tissues, skin and lungs. The mixed leukocyte reaction (MLR) has been used to measure the strength of antigen presentation by specific DC subsets. Surface markers and MLR require standardization to enable consistent identification of and comparisons between DC subsets. To alleviate these issues, researchers have begun comparing DC subsets at the transcriptional level. This has allowed degrees of relatedness to be determined between DC in different microenvironments, and should be a continued area of focus in years to come.

Systematic Review of the Relation Between Intestinal Microbiota and Toll-Like Receptors in the Metabolic Syndrome: What Do We Know So Far?

INTRODUCTION

Metabolic syndrome is an emerging problem in developed countries and presents itself as a potential threat worldwide. The role of diabetes, dyslipidaemia and hepatic steatosis as pivotal components of the metabolic syndrome is well known. However, their common persistent chronic inflammation and its potential cause still elude. This systematic review aims to present evidence of the mechanisms that link the intestinal microbioma, innate immunity and metabolic syndrome.

METHODS

A comprehensive research was made using PubMed database and 35 articles were selected.

RESULTS

We found that metabolic syndrome is associated to increased levels of innate immunity receptors, namely, Toll-like receptors, both in intestine and systemically and its polymorphisms may change the risk of metabolic syndrome development. Microbioma dysbiosis is also present in metabolic syndrome, with lower prevalence of Bacteroidetes and increased prevalence of Firmicutes populations. The data suggest that the link between intestinal microbiota and Toll-like receptors can negatively endanger the metabolic homeostasis.

CONCLUSION

Current evidence suggests that innate immunity and intestinal microbiota may be the hidden link in the metabolic syndrome development mechanisms. In the near future, this can be the key in the development of new prophylactic and therapeutic strategies to treat metabolic syndrome patients.

Role of innate immunity in the pathogenesis of type 1 and type 2 diabetes

The importance of innate immunity in host defense is becoming clear after discovery of innate immune receptors such as Toll-like receptor or Nod-like receptor. Innate immune system plays an important role in diverse pathological situations such as autoimmune diseases. Role of innate immunity in the pathogenesis of metabolic disorders such as type 2 diabetes, metabolic syndrome or atherosclerosis that has not been previously considered as inflammatory disorders, is also being appreciated. Here, the role of innate immunity in the development of type 1 diabetes, a classical organ-specific autoimmune disease, and type 2 diabetes will be discussed, focusing on the role of specific innate immune receptors involved in these disease processes.

Distinct Toll-like Receptor 3 and 7 Expression in Peripheral Blood Mononuclear Cells From Patients with Chronic Hepatitis C Infection

BACKGROUND

Hepatitis C virus (HCV) is a major cause of chronic liver disease, with around 130 million infected people worldwide. HCV is recognized by Toll-like receptors (TLRs), which are key mediators of innate immune response. Up on activation of TLRs, anti-viral cytokines and pre-inflammatory are produced.

OBJECTIVES

In this study, we compared the expression levels of two members of the TLR family (TLR3 and TLR7) that recognize viral RNA in peripheral blood mononuclear cell (PBMC) of patients with chronic HCV infection and healthy controls.

PATIENTS AND METHODS

In this case-control study, blood samples were collected from patients admitted to Blood Transfusion Research Center, Tehran, Iran. PBMC was isolated from blood of chronic HCV patients (n = 25) and age and sex-matched healthy controls (n = 25). RNA was extracted from PBMC and cDNA was synthesized from total RNA templates using reverse transcriptase. The relative level of expression was quantified by real-time PCR using Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as reference gene and the results were compared by Pfaffl method. Data were analyzed using non-parametric Wilcoxon test. P < 0.05 was considered significant.

RESULTS

In both groups, we had 13 males and 12 females with a mean age of 48.7 ± 16. TLR3 (6.23 ± 0.91 vs. 3.89 ± 0.85, P < 0.001) and TLR7 (1.48 ± 0.82 vs-1.33 ± 1.18, P < 0.001) expressions were significantly lower in patients with chronic HCV infection when compared with healthy controls.

CONCLUSIONS

This study suggests that decrease in levels of TLR3 and TLR7 expression is a mechanism that may enable HCV to evade the host innate immune response.