Chemoresistance of human monocyte-derived dendritic cells is regulated by IL-17A

A Multidisciplinary Approach to Patients with Psoriasis and a History of Malignancies or On-Treatment for Solid Tumors: A Narrative Literature Review

Psoriasis is a chronic immune-mediated disease that is linked to an increased risk of cancer. Although numerous studies have explored whether neoplasms are concurrent conditions or are induced by psoriasis, a definitive definition remains elusive. In this study, we conducted a comprehensive narrative literature review to offer practical guidance to oncologists and dermatologists regarding the initiation and discontinuation of biologics for psoriasis. The findings indicate that a customized approach is recommended for each patient, and that a history of malignancies does not constitute an absolute contraindication for biologics. Growing evidence supports the treatment of selected patients, emphasizing a nuanced assessment of benefits and risks. There is a lack of data specifying a safe timeframe to initiate biologics following a neoplasm diagnosis due to influences from cancer-related and patient-specific characteristics impacting prognosis. Some patients may continue anti-psoriasis therapy during cancer treatments. Enhanced comprehension of the biological mechanisms in cancer progression and the immune microenvironment of psoriasis holds promise for refining therapeutic strategies. In conclusion, a personalized treatment approach necessitates collaboration between oncologists and dermatologists, considering factors such as cancer prognosis, psoriasis clinical manifestations, patient characteristics, and preferences when making treatment decisions.

Myeloid cells from Langerhans cell histiocytosis patients exhibit increased vesicle trafficking and an altered secretome capable of activating NK cells

Langerhans cell histiocytosis (LCH) is a potentially life-threatening inflammatory myeloid neoplasia linked to pediatric neurodegeneration, whereby transformed LCH cells form agglomerated lesions in various organs. Although MAP-kinase pathway mutations have been identified in LCH cells, the functional consequences of these mutations and the mechanisms that cause the pathogenic behavior of LCH cells are not well understood. In our study, we used an in vitro differentiation system and RNA-sequencing to compare monocyte-derived dendritic cells from LCH patients to those derived from healthy controls or patients with Crohn's disease, a non-histiocytic inflammatory disease. We observed that interferon-γ treatment exacerbated intrinsic differences between LCH patient and control cells, including strikingly increased endo- and exocytosis gene activity in LCH patients. We validated these transcriptional patterns in lesions and functionally confirmed that LCH cells exhibited increased endo- and exocytosis. Furthermore, RNA-sequencing of extracellular vesicles revealed the enrichment of pathological transcripts involved in cell adhesion, MAP-kinase pathway, vesicle trafficking and T-cell activation in LCH patients. Thus, we tested the effect of the LCH secretome on lymphocyte activity and found significant activation of NK cells. These findings implicate extracellular vesicles in the pathology of LCH for the first time, in line with their established roles in the formation of various other tumor niches. Thus, we describe novel traits of LCH patient cells and suggest a pathogenic mechanism of potential therapeutic and diagnostic importance.

METTL3/14 and IL-17 signaling contribute to CEBPA-DT enhanced oral cancer cisplatin resistance

OBJECTIVES

Oral squamous cell carcinoma (OSCC) is the most common head and neck cancer. Chemotherapy has been recognized as an optional combination treatment, which enhance the overall survival of OSCC patients. However, the majority of patients would suffer therapeutic resistance, which led to the treatment failure and poor prognosis.

MATERIALS AND METHODS

To explore the mechanism of chemoresistance in OSCC, we first constructed two chemoresistant cell lines using Cal27 and HSC4. Then MeRIP sequencing together with bioinformatics analysis and a series of in vitro experiments were used to assess the possible regulation manner of RNA methylation on OSCC chemoresistance. Finally, xenograft models were constructed to confirm the relationship among OSCC chemoresistance.

RESULTS

METTL3/METTL14 upregulation could enhance OSCC chemoresistance. CEBPA-DT overexpression could regulate METTL3/METTL14 expression and further activate downstream BHLHB9. CEBPA-DT overexpression could inhibit the activity of IL-17 signaling, resulting in the homeostasis breakdown of immune infiltration and cytokine release. CEBPA-DT overexpression could significantly enhance chemoresistance through METTL3/METTL14/BHLHB9 in vivo, which accelerated the tumor growth.

CONCLUSIONS

Our results suggest that CEBPA-DT might regulate OSCC chemoresistance through BHLHB9 gene manipulated by METTL3/METTL14 as well as through IL-17 signaling inhibition, which may contribute to the assessment of potential therapeutic targets in OSCC chemoresistance.

Comparison of the immunomodulatory potential of platinum-based anti-cancer drugs and anthracyclins on human monocyte-derived cells

Macrophages and dendritic cells (DCs) are important contributors to anti-tumor immune responses. However, these highly plastic cells are also the primary targets of tumor manipulation, which may result in the development of tumor-promoting subtypes. The effect of chemotherapeutic agents on tumor cells is an area of intense study, but little is known about their effects on innate immune cells.We investigated the effects of four chemotherapeutic drugs (two platinum-based agents; oxaliplatin and cisplatin, and two anthracyclines; doxorubicin and epirubicin) on the differentiation, function, and viability of macrophages and DCs. Macrophages and DCs were differentiated from monocytes in the presence of these chemotherapeutic drugs and we compared their cell surface receptor expression, cytokine production, and chemotactic- and T-cell-polarizing ability.We have shown that differentiation in the presence of anthracyclines dose-dependently increases CTLA-4 expression in DCs. Antineoplastic agent-driven differentiation strongly modified the CCL2- or CCL5-induced chemotactic activity of both macrophages and DCs. DCs differentiated in the presence of high-dose cisplatin and a low dose of epirubicin promoted regulatory T-cell development, whereas oxaliplatin at specific doses induced both DCs and macrophages to enhance cytotoxic T-cell responses. Furthermore, we found that inflammatory macrophages are more sensitive to doxorubicin-induced cell death than their counterparts.In summary, our results confirm that chemotherapeutic agents acting on a similar basis may have different effects on the anti-tumor immune response. Treatment with optimal dose, combinations, and timing of chemotherapy may determine tumor immunity and the metastatic potential of tumors.

Neutralizing Anti-IL-17A Antibody Demonstrates Preclinical Activity Enhanced by Vinblastine in Langerhans Cell Histiocytosis

Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasm characterised by the accumulation into granulomas of apoptosis-resistant pathological dendritic cells (LCH-DCs). LCH outcome ranges from self-resolving to fatal. Having previously shown that, (i) monocyte-derived DCs (Mo-DCs) from LCH patients differentiate into abnormal and pro-inflammatory IL-17A-producing DCs, and (ii) recombinant IL-17A induces survival and chemoresistance of healthy Mo-DCs, we investigated the link between IL-17A and resistance to apoptosis of LCH-DCs. In LCH granulomas, we uncovered the strong expression of BCL2A1 (alias BFL1), an anti-apoptotic BCL2 family member. In vitro, intracellular IL-17A expression was correlated with BCL2A1 expression and survival of Mo-DCs from LCH patients. Based on the chemotherapeutic drugs routinely used as first or second line LCH therapy, we treated these cells with vinblastine, or cytarabine and cladribine. Our preclinical results indicate that high doses of these drugs decreased the expression of Mcl-1, the main anti-apoptotic BCL2 family member for myeloid cells, and killed Mo-DCs from LCH patients ex vivo, without affecting BCL2A1 expression. Conversely, neutralizing anti-IL-17A antibodies decreased BCL2A1 expression, the downregulation of which lowered the survival rate of Mo-DCs from LCH patients. Interestingly, the in vitro combination of low-dose vinblastine with neutralizing anti-IL-17A antibodies killed Mo-DCs from LCH patients. In conclusion, we show that BCL2A1 expression induced by IL-17A links the inflammatory environment to the unusual pro-survival gene activation in LCH-DCs. Finally, these preclinical data support that targeting both Mcl-1 and BCL2A1 with low-dose vinblastine and anti-IL-17A biotherapy may represent a synergistic combination for managing recurrent or severe forms of LCH.

Quality Verification with a Cluster-Controlled Manufacturing System to Generate Monocyte-Derived Dendritic Cells

Dendritic cell (DC) vaccines for cancer immunotherapy have been actively developed to improve clinical efficacy. In our previous report, monocyte−derived DCs induced by interleukin (IL)−4 with a low−adherence dish (low−adherent IL-4−DCs: la−IL-4−DCs) improved the yield and viability, as well as relatively prolonged survival in vitro, compared to IL-4−DCs developed using an adherent culture protocol. However, la−IL-4−DCs exhibit remarkable cluster formation and display heterogeneous immature phenotypes. Therefore, cluster formation in la−IL-4−DCs needs to be optimized for the clinical development of DC vaccines. In this study, we examined the effects of cluster control in the generation of mature IL-4−DCs, using cell culture vessels and measuring spheroid formation, survival, cytokine secretion, and gene expression of IL-4−DCs. Mature IL-4−DCs in cell culture vessels (cluster−controlled IL-4−DCs: cc−IL-4−DCs) displayed increased levels of CD80, CD86, and CD40 compared with that of la−IL-4−DCs. cc−IL-4−DCs induced antigen−specific cytotoxic T lymphocytes (CTLs) with a human leukocyte antigen (HLA)−restricted melanoma antigen recognized by T cells 1 (MART−1) peptide. Additionally, cc−IL-4−DCs produced higher levels of IFN−γ, possessing the CTL induction. Furthermore, DNA microarrays revealed the upregulation of BCL2A1, a pro−survival gene. According to these findings, the cc−IL-4−DCs are useful for generating homogeneous and functional IL-4−DCs that would be expected to promote long−lasting effects in DC vaccines.

IL-17 controls central nervous system autoimmunity through the intestinal microbiome

Interleukin-17A- (IL-17A) and IL-17F-producing CD4⁺ T helper cells (T_H17 cells) are implicated in the development of chronic inflammatory diseases, such as multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). T_H17 cells also orchestrate leukocyte invasion of the central nervous system (CNS) and subsequent tissue damage. However, the role of IL-17A and IL-17F as effector cytokines is still confused with the encephalitogenic function of the cells that produce these cytokines, namely, T_H17 cells, fueling a long-standing debate in the neuroimmunology field. Here, we demonstrated that mice deficient for IL-17A/F lose their susceptibility to EAE, which correlated with an altered composition of their gut microbiota. However, loss of IL-17A/F in T_H cells did not diminish their encephalitogenic capacity. Reconstitution of a wild-type-like intestinal microbiota or reintroduction of IL-17A specifically into the gut epithelium of IL-17A/F-deficient mice reestablished their susceptibility to EAE. Thus, our data demonstrated that IL-17A and IL-17F are not encephalitogenic mediators but rather modulators of intestinal homeostasis that indirectly alter CNS-directed autoimmunity.

Network- and systems-based re-engineering of dendritic cells with non-coding RNAs for cancer immunotherapy

Dendritic cells (DCs) are professional antigen-presenting cells that induce and regulate adaptive immunity by presenting antigens to T cells. Due to their coordinative role in adaptive immune responses, DCs have been used as cell-based therapeutic vaccination against cancer. The capacity of DCs to induce a therapeutic immune response can be enhanced by re-wiring of cellular signalling pathways with microRNAs (miRNAs). Methods: Since the activation and maturation of DCs is controlled by an interconnected signalling network, we deploy an approach that combines RNA sequencing data and systems biology methods to delineate miRNA-based strategies that enhance DC-elicited immune responses. Results: Through RNA sequencing of IKKβ-matured DCs that are currently being tested in a clinical trial on therapeutic anti-cancer vaccination, we identified 44 differentially expressed miRNAs. According to a network analysis, most of these miRNAs regulate targets that are linked to immune pathways, such as cytokine and interleukin signalling. We employed a network topology-oriented scoring model to rank the miRNAs, analysed their impact on immunogenic potency of DCs, and identified dozens of promising miRNA candidates, with miR-15a and miR-16 as the top ones. The results of our analysis are presented in a database that constitutes a tool to identify DC-relevant miRNA-gene interactions with therapeutic potential (https://www.synmirapy.net/dc-optimization). Conclusions: Our approach enables the systematic analysis and identification of functional miRNA-gene interactions that can be experimentally tested for improving DC immunogenic potency.

miR-126-5p regulates H9c2 cell proliferation and apoptosis under hypoxic conditions by targeting IL-17A

Accumulating evidence has indicated that microRNAs (miRNAs/miRs) regulate the occurrence and development of various diseases, including diabetes, osteoporosis and cardiovascular conditions. However, the role of miRNAs in acute myocardial infarction (AMI) is not completely understood. The present study aimed to evaluate the therapeutic efficacy and mechanisms underlying the effects of miR-126-5p on H9c2 cell proliferation and apoptosis by targeting interleukin (IL)-17A. A total of 40 patients with AMI and 40 healthy volunteers were recruited in the present study and the expression levels of serum miR-126-5p and IL-17A were determined. Following confirmation that IL-17A was a target of miR-126-5p via a dual-luciferase reporter assay, H9c2 cells were exposed to hypoxic conditions. H9c2 cell viability and apoptosis were subsequently assessed. Additionally, the protein expression levels of apoptosis-associated proteins were detected following transfection. Compared with healthy individuals, miR-126-5p expression was significantly decreased in the serum samples of patients with AMI, whereas IL-17A, the target of miR-126-5p, was significantly increased. Following hypoxic treatment, miR-126-5p overexpression enhanced H9c2 cell viability compared with the NC group, which was subsequently reversed following co-transfection with pcDNA3.1-IL-17A. Additionally, the results indicated that hypoxia-induced H9c2 cell apoptosis was significantly reduced following transfection with miR-126-5p mimics via the PI3K/AKT signaling pathway compared with the NC group. The present study indicated that miR-126-5p may serve as a novel miRNA that regulates H9c2 cell viability and apoptosis by targeting IL-17A under hypoxic conditions. Therefore, miR-126-5p may serve as a crucial biomarker for the diagnosis of AMI.

IL-17 for therapy

The cytokine IL-17 is now a target for an array of therapeutic monoclonal antibodies supposed to treat a variety of inflammatory diseases. The forerunner Secukinumab, an IL-17A neutralizing antibody, is meanwhile approved as first-line treatments for moderate-to-severe plaque psoriasis, and as second-line treatment for psoriatic arthritis and ankylosing spondylitis. Ixekizumab and Brodalumab, both also targeting the IL-17 pathway, were also recently approved by the FDA for plaque psoriasis. Using mice overexpressing IL-17A in a tissue of choice, we showed that the ectopic expression of this cytokine in keratinocytes resulted in a spontaneous and very strong form of psoriasis-like dermatitis. Interestingly, this model showed some typical comorbidities found in humans with psoriasis. In this review, we will discuss why IL-17 is a good target especially in psoriasis and what we learned from mouse models about its functions in pathological situations.

Anti-apoptotic proteins BCL-2, MCL-1 and A1 summate collectively to maintain survival of immune cell populations both in vitro and in vivo

Survival of various immune cell populations has been proposed to preferentially rely on a particular anti-apoptotic BCL-2 family member, for example, naive T cells require BCL-2, while regulatory T cells require MCL-1. Here we examined the survival requirements of multiple immune cell subsets in vitro and in vivo, using both genetic and pharmacological approaches. Our findings support a model in which survival is determined by quantitative participation of multiple anti-apoptotic proteins rather than by a single anti-apoptotic protein. This model provides both an insight into how the sum of relative levels of anti-apoptotic proteins BCL-2, MCL-1 and A1 influence survival of T cells, B cells and dendritic cells, and a framework for ascertaining how these different immune cells can be optimally targeted in treatment of immunopathology, transplantation rejection or hematological cancers.

The IL-17A G-197A and IL-17F 7488T/C polymorphisms are associated with increased risk of cancer in Asians: a meta-analysis

Background

Interleukin-17 (IL-17) is a family of emerged pro-inflammatory cytokines. The IL-17A and IL-17F are two important members of IL-17 family. Previous studies have shown that the functional IL-17A G-197A and IL-17F 7488T/C polymorphisms may contribute to susceptibility to cancer but the results were inconclusive. This meta-analysis was performed to determine the exact association between IL-17 polymorphisms and cancer risk.

Methods

Online databases were searched to identify eligible case–control studies. Pooled odds ratios (ORs) and confidence intervals (CIs) were calculated by fixed-effect models or random-effect models. Publication bias was detected by Egger’s test and Begg’s test.

Results

Nine eligible case–control studies of IL-17A G-197A and seven studies of IL-17F 7488T/C, including 3,181 cases and 4,005 controls, were identified. Pooled analysis suggested the variant IL-17A-197A allele was associated with increased risk cancer (GA/AA vs GG, OR =1.27, 95% CI: 1.15, 1.41, P_{heterogeneity} =0.374; and A vs G, OR =1.30, 95% CI: 1.17, 1.45, P_{heterogeneity} =0.021). For IL-17F 7488T/C, the homozygote 7488CC genotype significantly increased risk of cancer (CC vs TC/TT, OR =1.36, 95% CI: 0.97, 1.91, P_{heterogeneity} =0.875; and CC vs TT, OR =1.39, 95% CI: 1.03, 1.88, P_{heterogeneity} =0.979), especially for gastric cancer.

Conclusion

The variant IL-17A-197A allele and IL-17F 7488CC genotype were associated with increased risk of cancer, especially for gastric cancer.

Human monocyte-derived dendritic cells turn into foamy dendritic cells with IL-17A

Interleukin 17A (IL-17A) is a proinflammatory cytokine involved in the pathogenesis of chronic inflammatory diseases. In the field of immunometabolism, we have studied the impact of IL-17A on the lipid metabolism of human in vitro-generated monocyte-derived dendritic cells (DCs). Microarrays and lipidomic analysis revealed an intense remodeling of lipid metabolism induced by IL-17A in DCs. IL-17A increased 2-12 times the amounts of phospholipids, cholesterol, triglycerides, and cholesteryl esters in DCs. Palmitic (16:0), stearic (18:0), and oleic (18:ln-9c) acid were the main fatty acid chains present in DCs. They were strongly increased in response to IL-17A while their relative proportion remained unchanged. Capture of extracellular lipids was the major mechanism of lipid droplet accumulation, visualized by electron microscopy and Oil Red O staining. Besides this foamy phenotype, IL-17A induced a mixed macrophage-DC phenotype and expression of the nuclear receptor NR1H3/liver X receptor-α, previously identified in the context of atherosclerosis as the master regulator of cholesterol homeostasis in macrophages. These IL-17A-treated DCs were as competent as untreated DCs to stimulate allogeneic naive T-cell proliferation. Following this first characterization of lipid-rich DCs, we propose to call these IL-17A-dependent cells "foamy DCs" and discuss the possible existence of foamy DCs in atherosclerosis, a metabolic and inflammatory disorder involving IL-17A.

Interleukin-17 Indirectly Promotes M2 Macrophage Differentiation through Stimulation of COX-2/PGE2 Pathway in the Cancer Cells

PURPOSE

Interleukin-17 (IL-17) is a proinflammatory cytokine that plays important roles in inflammation, autoimmunity, and cancer. The purpose of this study was to determine if IL-17 indirectly regulates macrophage differentiation through up-regulation of cyclooxygenase-2 (COX-2) expression in the cancer cell lines.

MATERIALS AND METHODS

Human cervical cancer HeLa, human lung cancer A549, and mouse prostate cancer Myc-CaP/CR cell lines were treated with recombinant IL-17; Western blot analysis, enzyme-linked immunosorbent assay, and quantitative real-time polymerase chain reaction analysis were utilized to examine the cellular responses.

RESULTS

IL-17 up-regulated expression of COX-2 mRNA and protein in HeLa, A549, and Myc- CaP/CR cell lines. IL-17's effects were mediated through nuclear factor-κB and ERK1/2 signaling pathways as the inhibitors of these pathways could inhibit IL-17- induced COX-2 expression. The conditional medium obtained from the cancer cells contained prostaglandin E2, the levels of which were increased by IL-17 treatment. When treated with the conditional medium, particularly with the IL-17-induced conditional medium, mouse RAW264.7 macrophages and human THP-1 monocytes expressed higher levels of IL-10 (a marker of M2 macrophages) than inducible nitric oxide synthase or tumor necrosis factor α (markers of M1 macrophages). In contrast, when RAW264.7 and THP-1 cells were treated directly with IL-17, expression of these marker genes was not markedly changed.

CONCLUSION

The results of this study suggest that IL-17 indirectly promotes M2 macrophage differentiation through stimulation of the COX-2/PGE2 pathway in the cancer cells, thus IL-17 plays an indirect role in regulating the tumor immune microenvironment.

Blood spotlight on Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a rare disease affecting people of any age, with widely variable clinical manifestations and different outcomes. The precise chain of events driving lesional granuloma formation has remained elusive for many years. There is evidence for inherited predisposition to and derangement of apoptosis and inflammation in lesional dendritic cells. Recently somatic BRAF(V600E) mutation in myeloid precursor dendritic cells was associated with the more aggressive form of the disease, although the same mutation in a more differentiated dendritic cell might drive a less aggressive disease. Whether this picture convincingly put LCH in the field of myeloid neoplasm remains to be determined. Altogether, these findings suggest that future therapeutic strategy might incorporate a screening of this genetic mutation for high-risk patients potentially suitable for target therapy.

Interleukin-8 and interleukin-17 for cancer

Pro-inflammatory cytokines have been associated with chronic inflammation and inflammatory diseases. Increased levels of interleukins (ILs) have been associated with inflammatory disease exacerbation. ILs levels have been observed to be associated with advance stage cancer for several types of cancer and a poor prognostic maker for malignant disease. Moreover; increased levels of cytokines induce tumorigenesis. There are several paradigms such as the hepatocellular carcinoma induced from chronic inflammation of an underlying hepatitis. In the current review, we will focus on IL-8 and -17. These two ILs as in the case of others, induce neo-angiogenesis through activation of the vascular endothelial growth (VEGF) factor pathway. Additionally, they enhance the activity of matrix metalloproteinase-2 and -9 (MMP-2,-9) which in turn increase the metastatic activity of the underlying malignancy. Inhibition of cytokine production could be a potential treatment both for chronic inflammatory diseases and tumor modulation. Local microenvironment modulation could be applied in surgery resected patients as in the case of lung cancer in order to enhance the local immune activity.

New insights into the molecular pathogenesis of langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a rare proliferative disorder characterized by an accumulation of cells sharing the major phenotypic features of cutaneous Langerhans cells. Given its variable clinical evolution, ranging from self-limiting lesions to multisystemic forms with a poor prognosis, in the last decades it has been debated whether LCH might not have a neoplastic rather than an inflammatory nature. However, although the fundamental events underlying the pathogenesis of LCH are still elusive, recent advances have strikingly improved our understanding of the disease. In particular, the identification of multiple interplays between LCH cells and their tumor microenvironment, along with the recognition of the lesional cytokine storm as a key determinant of LCH progression, has substantiated new opportunities for devising targeted therapeutic approaches. Strikingly, the detection of the rapidly accelerated fibrosarcoma isoform B(V600E) gain-of-function mutation as a genetic alteration recurring in more than 50% of patients has fueled the paradoxical picture of LCH as a tumor of the antigen-presenting cells that can evade rejection by the immune system. Thus, new evidence regarding the ontogeny of LCH cells, as well as a better understanding of the putative immune system frustrating strategy in LCH, may help to define the precise pathogenesis.

IL-17A is produced by breast cancer TILs and promotes chemoresistance and proliferation through ERK1/2

The proinflammatory cytokine Interleukin 17A (hereafter named IL–17A) or IL-17A producing cells are elevated in breast tumors environment and correlate with poor prognosis. Increased IL-17A is associated with ER(−) or triple negative tumors and reduced Disease Free Survival. However, the pathophysiological role of IL-17A in breast cancer remains unclear although several studies suggested its involvement in cancer cell dissemination. Here we demonstrated that a subset of breast tumors is infiltrated with IL-17A-producing cells. Increased IL-17A seems mainly associated to ER(−) and triple negative/basal-like tumors. Isolation of tumor infiltrating T lymphocytes (TILs) from breast cancer biopsies revealed that these cells secreted significant amounts of IL-17A. We further established that recombinant IL-17A recruits the MAPK pathway by upregulating phosphorylated ERK1/2 in human breast cancer cell lines thereby promoting proliferation and resistance to conventional chemotherapeutic agents such as docetaxel. We also confirmed here that recombinant IL-17A stimulates migration and invasion of breast cancer cells as previously reported. Importantly, TILs also induced tumor cell proliferation, chemoresistance and migration and treatment with IL-17A-neutralizing antibodies abrogated these effects. Altogether these results demonstrated the pathophysiological role of IL-17A-producing cell infiltrate in a subset of breast cancers. Therefore, IL-17A appears as potential therapeutic target for breast cancer.

Comparative transcriptomics reveals RhoE as a novel regulator of actin dynamics in bone-resorbing osteoclasts

Two-step transcriptomic profiling of bone-resorbing OCs versus nonresorbing MGCs generated a list of 115 genes potentially involved in bone resorption. Of these, RhoE was investigated. Its role in podosome dynamics is central for OC migration, SZ formation, and, ultimately, bone resorption.

The function of osteoclasts (OCs), multinucleated giant cells (MGCs) of the monocytic lineage, is bone resorption. To resorb bone, OCs form podosomes. These are actin-rich adhesive structures that pattern into rings that drive OC migration and into “sealing-zones” (SZs) that confine the resorption lacuna. Although changes in actin dynamics during podosome patterning have been documented, the mechanisms that regulate these changes are largely unknown. From human monocytic precursors, we differentiated MGCs that express OC degradation enzymes but are unable to resorb the mineral matrix. We demonstrated that, despite exhibiting bona fide podosomes, these cells presented dysfunctional SZs. We then performed two-step differential transcriptomic profiling of bone-resorbing OCs versus nonresorbing MGCs to generate a list of genes implicated in bone resorption. From this list of candidate genes, we investigated the role of Rho/Rnd3. Using primary RhoE-deficient OCs, we demonstrated that RhoE is indispensable for OC migration and bone resorption by maintaining fast actin turnover in podosomes. We further showed that RhoE activates podosome component cofilin by inhibiting its Rock-mediated phosphorylation. We conclude that the RhoE-Rock-cofilin pathway, by promoting podosome dynamics and patterning, is central for OC migration, SZ formation, and, ultimately, bone resorption.

Targeting BCL2 family in human myeloid dendritic cells: a challenge to cure diseases with chronic inflammations associated with bone loss

Rheumatoid arthritis (RA) and Langerhans cell histiocytosis (LCH) are common and rare diseases, respectively. They associate myeloid cell recruitment and survival in inflammatory conditions with tissue destruction and bone resorption. Manipulating dendritic cell (DC), and, especially, regulating their half-life and fusion, is a challenge. Indeed, these myeloid cells display pathogenic roles in both diseases and may be an important source of precursors for differentiation of osteoclasts, the bone-resorbing multinucleated giant cells. We have recently documented that the proinflammatory cytokine IL-17A regulates long-term survival of DC by inducing BCL2A1 expression, in addition to the constitutive MCL1 expression. We summarize bibliography of the BCL2 family members and their therapeutic targeting, with a special emphasis on MCL1 and BCL2A1, discussing their potential impact on RA and LCH. Our recent knowledge in the survival pathway, which is activated to perform DC fusion in the presence of IL-17A, suggests that targeting MCL1 and BCL2A1 in infiltrating DC may affect the clinical outcomes in RA and LCH. The development of new therapies, interfering with MCL1 and BCL2A1 expression, to target long-term surviving inflammatory DC should be translated into preclinical studies with the aim to increase the well-being of patients with RA and LCH.