IDO1 + Paneth cells promote immune escape of colorectal cancer

Abstract: Tumors have evolved mechanisms to escape anti-tumor immunosurveillance. They limit humoral and cellular immune activities in the stroma and render tumors resistant to immunotherapy. Sensitizing tumor cells to immune attack is an important strategy to revert immunosuppression. However, the underlying mechanisms of immune escape are still poorly understood. Here we discover Indoleamine-2,3-dioxygenase-1 (IDO1)+ Paneth cells in the stem cell niche of intestinal crypts and tumors, which promoted immune escape of colorectal cancer (CRC). Ido1 expression in Paneth cells was strictly Stat1 dependent. Loss of IDO1+ Paneth cells in murine intestinal adenomas with tumor cell-specific Stat1 deletion had profound effects on the intratumoral immune cell composition. Patient samples and TCGA expression data suggested corresponding cells in human colorectal tumors. Thus, our data uncovered an immune escape mechanism of CRC and identify IDO1+ Paneth cells as a target for immunotherapy

IDO1 + Paneth cells promote immune escape of colorectal cancer

Abstract: Tumors have evolved mechanisms to escape anti-tumor immunosurveillance. They limit humoral and cellular immune activities in the stroma and render tumors resistant to immunotherapy. Sensitizing tumor cells to immune attack is an important strategy to revert immunosuppression. However, the underlying mechanisms of immune escape are still poorly understood. Here we discover Indoleamine-2,3-dioxygenase-1 (IDO1)+ Paneth cells in the stem cell niche of intestinal crypts and tumors, which promoted immune escape of colorectal cancer (CRC). Ido1 expression in Paneth cells was strictly Stat1 dependent. Loss of IDO1+ Paneth cells in murine intestinal adenomas with tumor cell-specific Stat1 deletion had profound effects on the intratumoral immune cell composition. Patient samples and TCGA expression data suggested corresponding cells in human colorectal tumors. Thus, our data uncovered an immune escape mechanism of CRC and identify IDO1+ Paneth cells as a target for immunotherapy

Specific roles for dendritic cell subsets during the initiation and progression of psoriasis

Psoriasis (Schuppenflechte) gehört zur Gruppe der autoinflammatorischen Erkrankungen, und ist durch die Ausprägung von geröteten, schuppigen Hautläsionen gekennzeichnet, welche oft mit intensivem Schmerz und Juckreiz verbunden sind. Dies und die Ausgrenzung, die mit den auffälligen Hautsymptomen verbunden ist, hat starke negative Auswirkungen auf die Lebensqualität von Psoriasis-Patienten. Mehrere verschiedene Unterarten von dendritischen Zellen sind Teil des entzündlichen Infiltrats der Psoriasis, ihre Funktion in dieser Erkrankung ist jedoch nur spärlich charakterisiert. In der nachfolgenden Arbeit versuchte ich, die Funktion von Langerhanszellen, einer Subklasse von dendritischen Zellen die in gesunder wie auch in krankhaft veränderter Haut vorkommt, sowie der der plasmazytoiden dendritischen Zellen (pDCs), die während des Entzündungsprozesses in die Haut einwandern, aufzuklären. Im Zuge dessen konnte ich zeigen, dass die Zahlen der Langerhanszellen in menschlichen psoriatischen Läsionen im Vergleich zur Normalhaut reduziert sind, während die der pDCs innerhalb psoriatischer Läsionen stark erhöht waren. Ähnliche Beobachtungen konnten in einem Mausmodell gezeigt werden, das auf einer induzierbaren epidermalen Deletion der zur Familie der AP-1 Transkriptionsfaktoren gehörenden Gene Jun und JunB beruht. Diese hat die Ausprägung der typischen Zeichen der Psoriasis auf unterschiedlichen Körperstellen der Maus zur Folge. Diese Mäuse werden als Jun/JunB[Delta]ep oder Doppelknockout-Mäuse, DKO*, bezeichnet. Durch Verkreuzen der DKO*-Mäuse mit zwei weiteren gentechnisch veränderten Mausmodellen, den Langerin-D(iphtherie)T(oxin)R(ezeptor)- sowie den BDCA2-DTR-Mäusen, in denen der humane DTR jeweils entsprechend spezifisch in Langerhanszellen oder pDCs exprimiert wird, konnten diese zwei Zelltypen nach Injektion von Diphtherietoxin depletiert werden. Die Depletion der pDCs vor Initiation des psoriatischen Phänotyps verhinderte die Ausprägung der psoriasisartigen Erkrankung der DKO*-Mäuse. Hingegen konnte die pDC-Depletion in DKO*- Mäusen mit bereits etablierter chronischer Psoriasis den Krankheitsverlauf nicht verbessern. Die Depletion von Langerhanszellen aus DKO* Mäusen während der chronischen Krankheitsphase führte zu einer starken Verschlimmerung des entzündlichen Hautphänotyps. Hingegen war kein Unterschied in der Ausprägung der psoriasisartigen Erkrankung zu beobachten, wenn Langerhanszellen bereits vor Krankheitsbeginn depletiert wurden. Mithilfe von Knochenmarkschimären konnte ich weiterhin zeigen, dass Langerhanszellen während dieser Art der Hautentzündung nicht von einem lokalen Vorläufer abstammen, sondern aus dem Knochenmark einwandern. Ich konnte auch besser erklären, dass die beobachtete Verschlimmerung des Phänotyps tatsächlich durch die Abwesenheit von Langerhanszellen, nicht aber durch die anderer Langerin-exprimierender Zellen bedingt ist. Mechanistisch konnte ich zeigen, dass Langerhanszellen, die aus psoriatischer Haut der DKO* Mäuse isoliert wurden höhere Konzentrationen des antiinflammatorischen Zytokins Interleukin (IL)- 10 aufwiesen, und dass die Depletion der Langerhanszellen zu einem Anstieg der Levels des proinflammatorischen Zytokins IL-23 in der Epidermis führte, worauf potenziell die beobachtete Krankheitsverschlimmerung zurückzuführen ist. Die kritische Rolle des IL-23 wird dadurch gestützt, dass die Konzentration dieses Zytokins in der Epidermis von pDC-depletierten Mäusen verringert war. Infolgedessen wurde ein Therapieversuch an DKO* Mäusen durchgeführt, im Zuge dessen ich zeigen konnte, dass die Inhibition der Signalweiterleitung des IL-23-Rezeptors die Symptome der psoriasisartigen Erkrankung stark verbessert. Diese Resultate zeigen, dass Langerhanszellen der Entzündung in der Psoriasis entgegenwirken,wogegen pDCs eine wichtige auslösende Funktion während der Erstentstehung der Erkrankung haben.Psoriasis is a chronic inflammatory skin disease characterized by red, scaly skin lesions that are often accompanied by intense pain, itching and disfiguration, having a considerably negative impact on the life quality of patients. Different subtypes of dendritic cells (DCs) are found in psoriatic lesions, however, their involvement in psoriasis pathogenesis is poorly understood. In the following thesis, I aimed at elucidating the function of two subtypes of DCs in psoriasis; LCs, that are resident in healthy and inflamed skin, as well as pDCs, that immigrate as a consequence of lesion formation. I could show that in lesional skin from psoriatic patients, the number of LCs was severely reduced compared to normal skin, while pDC numbers were increased. Additionally, I employed a genetic mouse model of psoriasis that is based on inducible genetic deletion of the AP-1 transcription factors Jun and JunB in the epidermis (Jun/JunB[Delta]ep =DKO* mice). DKO* mice develop skin symptoms that closely mirror human psoriasis lesions and exhibit a similar immunological phenotype as psoriasis patients. In skin of DKO* mice, pDCs and LCs behaved similarly as in the human situation. By crossing DKO* mice to two other genetically modified mouse lines, Langerin D(iptheria)T(oxin)R(eceptor) or BDCA2-DTR mice, in which the human DTR is expressed either specifically in LCs or in pDCs, these two cell types could be depleted following injection of DT. I found that depletion of pDCs in DKO* mice prior to disease induction could prevent the development of the psoriasis-like phenotype. In contrast, depletion of pDCs during chronic disease could not ameliorate the phenotype. The depletion of LCs in DKO* mice during the chronic disease phase led to severe aggravation of the skin inflammation. In contrast, the phenotype was unchanged when LCs were depleted before disease initiation. Using bone marrow chimeras, I could demonstrate that LCs that additionally populate the skin during psoriasis-like inflammation rather stem from bone marrow-derived than from local precursor cells. Additionally, I could confirm that the observed aggravation of the phenotype was caused by the absence of LCs but not other Langerin-expressing DC types. Mechanistically, I could show that LCs isolated from lesional skin of DKO* mice exhibited higher concentrations of the anti-inflammatory cytokine interleukin (IL)-10, and that depletion of LCs resulted in an increase of epidermal levels of the proinflammatory cytokine IL-23, likely being a cause for disease exacerbation. The critical role of IL-23 is furthermore supported by the finding that in the absence of pDCs during initiation, epidermal IL-23 production was reduced. Consequently, I applied a widely accepted therapeutic strategy for human psoriasis based on the inhibition of IL-23 receptor (IL-23R) signaling, which led to considerable amelioration of the psoriasis-like phenotype in DKO* mice. These results demonstrate that LCs counteract skin inflammation in psoriasis, while pDCs play an important instigatory role during disease initiation.Abweichender Titel laut Übersetzung der Verfasserin/des VerfassersEMBO Molecular Medicine, 2014, 6 (10), 13121327Wien, Med. Univ., Diss., 2014OeBB(VLID)171525

BMPR1a Is Required for the Optimal TGFβ1-Dependent CD207+ Langerhans Cell Differentiation and Limits Skin Inflammation through CD11c+ Cells

The cytokine TGFβ1 induces epidermal Langerhans cell (LC) differentiation from human precursors, an effect mediated through BMPR1a/ALK3 signaling, as revealed from ectopic expression and receptor inhibition studies. Whether TGFβ1‒BMPR1a signaling is required for LC differentiation in vivo remained incompletely understood. We found that TGFβ1-deficient mice show defective perinatal expansion and differentiation of LCs. LCs can be identified within the normal healthy human epidermis by anti-BMPR1a immunohistology staining. Deletion of BMPR1a in all (vav+) hematopoietic cells revealed that BMPR1a is required for the efficient TGFβ1-dependent generation of CD207+ LC-like cells from CD11c+ intermediates in vitro. Similarly, BMPR1a was required for the optimal induction of CD207 by preformed major histocompatibility complex II‒positive epidermal resident LC precursors in the steady state. BMPR1a expression is strongly upregulated in epidermal cells in psoriatic lesions, and BMPR1aΔCD11c mice showed a defect in the resolution phase of allergic and psoriatic skin inflammation. Moreover, whereas LCs from these mice expressed CD207, BMPR1a counteracted LC activation and migration from skin explant cultures. Therefore, TGFβ1‒BMPR1a signaling seems to be required for the efficient induction of CD207 during LC differentiation in the steady state, and bone marrow‒derived lesional CD11c+ cells may limit established skin inflammation through enhanced BMPR1a signaling

Epidermal autonomous VEGFA/Flt1/Nrp1 functions mediate psoriasis-like disease.

Psoriasis is a common chronic skin disorder characterized by keratinocyte hyperproliferation with altered differentiation accompanied by inflammation and increased angiogenesis. It remains unclear whether the first events that initiate psoriasis development occur in keratinocytes or inflammatory cells. Here, using different psoriasis mouse models, we showed that conditional deletion of Flt1 or Nrp1 in epidermal cells inhibited psoriasis mediated by Vegfa overexpression or c-Jun/JunB deletion. Administration of anti-Nrp1 antibody reverted the psoriasis phenotype. Using transcriptional and chromatin profiling of epidermal cells following Vegfa overexpression together with Flt1 or Nrp1 deletion, we identified the gene regulatory network regulated by Vegfa/Nrp1/Flt1 during psoriasis development and uncovered a key role of Fosl1 in regulating the chromatin remodeling mediated by Vegfa overexpression in keratinocytes. In conclusion, our study identifies an epidermal autonomous function of Vegfa/Nrp1/Flt1 that mediates psoriatic-like disease and demonstrates the clinical relevance of blocking Vegfa/Nrp1/Flt1 axis in psoriasis.info:eu-repo/semantics/publishe

BMP7 aberrantly induced in the psoriatic epidermis instructs inflammation-associated Langerhans cells.

BACKGROUND Epidermal hyperplasia represents a morphologic hallmark of psoriatic skin lesions. Langerhans cells (LCs) in the psoriatic epidermis engage with keratinocytes (KCs) in tight physical interactions; moreover, they induce T cell-mediated immune responses critical to psoriasis. OBJECTIVE Epidermal factors in psoriasis pathogenesis remain poorly understood. METHODS We phenotypically characterized BMP7-LCs vs. TGF-β1-LCs and analyzed their functional properties using flow cytometry, cell kinetic studies, co-culture with CD4 T-cells and cytokine measurements. Furthermore, immunohistology of healthy and psoriatic skin was performed. Additionally, in vivo experiments with Junf/fJunBf/fK5creER mice were carried out to assess the role of BMP signaling in psoriatic skin inflammation. RESULTS Here we identified a KC-derived signal, i.e. bone morphogenetic protein (BMP) signaling, to promote epidermal changes in psoriasis. Whereas BMP7 is strictly confined to the basal KC layer in the healthy skin, it is expressed at high levels throughout the lesional psoriatic epidermis. BMP7 instructs precursor cells to differentiate into LCs that phenotypically resemble psoriatic LCs. These BMP7-LCs exhibit proliferative activity and increased sensitivity to bacterial stimulation. Moreover, aberrant high BMP signaling in the lesional epidermis is mediated by a KC intrinsic mechanism, as suggested from murine data and clinical outcome after topical anti-psoriatic treatment in human patients. CONCLUSION Our data indicate that available TGF-β family members within the lesional psoriatic epidermis preferentially signal through the canonical BMP signaling cascade to instruct inflammatory-type LCs and to promote psoriatic epidermal changes. Targeting BMP signaling might allow to therapeutically interfere with cutaneous psoriatic manifestations

Specific roles for dendritic cell subsets during initiation and progression of psoriasis

Abstract Several subtypes of APCs are found in psoriasis patients, but their involvement in disease pathogenesis is poorly understood. Here, we investigated the contribution of Langerhans cells (LCs) and plasmacytoid DCs (pDCs) in psoriasis. In human psoriatic lesions and in a psoriasis mouse model (DKO* mice), LCs are severely reduced, whereas pDCs are increased. Depletion of pDCs in DKO* mice prior to psoriasis induction resulted in a milder phenotype, whereas depletion during active disease had no effect. In contrast, while depletion of Langerin‐expressing APCs before disease onset had no effect, depletion from diseased mice aggravated psoriasis symptoms. Disease aggravation was due to the absence of LCs, but not other Langerin‐expressing APCs. LCs derived from DKO* mice produced increased IL‐10 levels, suggesting an immunosuppressive function. Moreover, IL‐23 production was high in psoriatic mice and further increased in the absence of LCs. Conversely, pDC depletion resulted in reduced IL‐23 production, and therapeutic inhibition of IL‐23R signaling ameliorated disease symptoms. Therefore, LCs have an anti‐inflammatory role during active psoriatic disease, while pDCs exert an instigatory function during disease initiation

Impaired neural stem cell expansion and hypersensitivity to epileptic seizures in mice lacking the EGFR in the brain

Mice lacking the epidermal growth factor receptor (EGFR) develop an early postnatal degeneration of the frontal cortex and olfactory bulbs and show increased cortical astrocyte apoptosis. The poor health and early lethality of EGFR/ mice prevented the analysis of mechanisms responsible for the neurodegeneration and function of the EGFR in the adult brain. Here, we show that postnatal EGFRdeficient neural stem cells are impaired in their selfrenewal potential and lack clonal expansion capacity in vitro. Mice lacking the EGFR in the brain (EGFRbrain) show low penetrance of cortical degeneration compared to EGFR/ mice despite genetic recombination of the conditional allele. Adult EGFR mice establish a proper bloodbrain barrier and perform reactive astrogliosis in response to mechanical and infectious brain injury, but are more sensitive to Kainic acidinduced epileptic seizures. EGFRdeficient cortical astrocytes, but not midbrain astrocytes, have reduced expression of glutamate transporters Glt1 and Glast, and show reduced glutamate uptake in vitro, illustrating an excitotoxic mechanism to explain the hypersensitivity to Kainic acid and regionspecific neurodegeneration observed in EGFRdeficient brains.(VLID)340592

EGFR is required for FOS‐dependent bone tumor development via RSK2/CREB signaling

Abstract Osteosarcoma (OS) is a rare tumor of the bone occurring mainly in young adults accounting for 5% of all childhood cancers. Because of the limited therapeutic options, there has been no survival improvement for OS patients in the past 40 years. The epidermal growth factor receptor (EGFR) is highly expressed in OS; however, its clinical relevance is unclear. Here, we employed an autochthonous c‐Fos‐dependent OS mouse model (H2‐c‐fosLTR) and human OS tumor biopsies for preclinical studies aimed at identifying novel biomarkers and therapeutic benefits of anti‐EGFR therapies. We show that EGFR deletion/inhibition results in reduced tumor formation in H2‐c‐fosLTR mice by directly inhibiting the proliferation of cancer‐initiating osteoblastic cells by a mechanism involving RSK2/CREB‐dependent c‐Fos expression. Furthermore, OS patients with co‐expression of EGFR and c‐Fos exhibit reduced overall survival. Preclinical studies using human OS xenografts revealed that only tumors expressing both EGFR and c‐Fos responded to anti‐EGFR therapy demonstrating that c‐Fos can be considered as a novel biomarker predicting response to anti‐EGFR treatment in OS patients