CD27/CD70 pathway activation in primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder.

Primary cutaneous CD4+ small or medium T-cell lymphoproliferative disorder (PCSM-LPD) is a clonal T-cell proliferation disease confined to the skin. PCSM-LPD shares expression of T follicular helper (Tfh) cell markers with various mature T-cell lymphomas. However, the benign presentation of PCSM-LPD contrasts the clinical behavior of other Tfh-lymphomas. The aim of our study was to delineate the molecular similarities and differences between PCSM-LPD and other Tfh-derived lymphomas to explain the clinical behavior and unravel possible pathological mechanisms. We performed targeted next-generation sequencing of 19 genes recurrently mutated in T-cell neoplasms in n = 17 PCSM-LPD with high and in n = 21 PCSM-LPD with low tumor cell content. Furthermore, gene expression profiling was used to identify genes potentially expressed in the PD1-positive (PD1+) neoplastic cells. Expression of some of these genes was confirmed in situ using multistain immunofluorescence. We found that PCSM-LPD rarely harbored mutations recurrently detected in other T-cell neoplasms. PCSM-LPD is characterized by the invariable expression of the T-cell-receptor-associated LCK protein. CD70 and its ligand CD27 are co-expressed on PD1+ PCSM-LPD cells, suggestive of autoactivation of the CD70 pathway. In conclusion, PCSM-LPD differs from disseminated lymphomas of Tfh origin by their mutation profile. Activation of CD70 signaling also found in cutaneous T-cell lymphoma represents a potential driver of neoplastic proliferation of this benign neoplasia of Tfh. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Cyclin D1 expression, cell proliferation, and clonal persistence characterize primary cutaneous CD4+ small or medium T-cell lymphoproliferative disorder.

AIMS: The aim was to gain insight into the biology of primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder (PCSM-LPD). METHODS: We describe the histopathological and clinical characteristics of 177 PCSM-LPD diagnosed at our consultation centre. We performed immunohistochemical multistaining in a subset of cases (n = 46) including PD1, Cyclin D1, and multiple markers of proliferation. We evaluated clonal T-cell-receptor-(TCR) rearrangements and used tissue microdissection to analyse TCR-clonality of PD1(+) cells. RESULTS: The cohort of n = 177 PCSM-LPD included 84 males and 93 females (median age 57, range 13-85). Clinical presentation was as a solitary nodule or plaque (head and neck > trunk > extremities). Most patients were treated by local excision or steroids (96%, 69/72); relapses occurred in 12/65 (18%) of patients with follow up. Histopathology revealed the predominance of a nodular pattern (75%, 134/177) and frequent clustering of PD1(+) large cells (70%, 103/147). We detected Cyclin D1 and PD1 coexpression (>10% of PD1(+)-cells) in 26/46 (57%), which was not associated with CCND1 breaks or amplifications. PD1(+)-cells in PCSM-LPDs showed a significantly higher expression of proliferation-associated proteins compared to PD1(-)-cells. A clonal TCR-rearrangement was present in 176/177 (99%), with a clonal persistence in 7/8 patients at relapse including distant sites. Tissue-microdissection revealed PD1(+)-cells as the source of clonality, whilst PD1(-)-cells remained polyclonal. CONCLUSION: PCSM-LPD is a clinically indolent, albeit neoplastic, disease driven by clonal expansion of PD1(+)-cells. We demonstrate Cyclin D1-expression associated with accelerated proliferation as a surprising new biological feature of the disease.

[Lymphomas and other hematological neoplasms in the testicles]. / Lymphome und andere hämatologische Neoplasien im Hoden.

BACKGROUND: The testis may be infiltrated by hematological neoplasias. However, only few entities present as primary testicular diseases. OBJECTIVES: To present hematological neoplasias in the testis, especially primary testicular hematological diseases. MATERIALS AND METHODS: Selective literature research ( http://www.ncbi.nlm.nih.gov ) was combined with the clinico-pathological experience of the authors. RESULTS: We present the experience of the lymph node registry Kiel with hematological neoplasias of the testis and develop a staining recommendation. According to our data, the testis is mainly involved by diffuse large B­cell lymphomas (~70% of cases) followed by precursor cell neoplasias (~20%). Most precursor cell neoplasias are disseminated diseases involving the testis. Primary testicular lymphomas are nearly exclusively diffuse large B­cell lymphomas that show specific clinical, pathological, and molecular features discriminating them from nodal/disseminated lymphomas. Primary testicular follicular lymphomas, which have been described in the literature, seem to be extremely rare. CONCLUSION: Primary testicular lymphomas are predominantly diffuse large B­cell lymphomas. The diagnosis is possible with few immunohistochemical stainings. However, histology cannot replace clinical staging to discriminate primary testicular lymphoma from secondary infiltration by a nodal/disseminated disease.

Molecular Cytogenetic Profiling Reveals Similarities and Differences Between Localized Nodal and Systemic Follicular Lymphomas.

Recently, we have developed novel highly promising gene expression (GE) classifiers discriminating localized nodal (LFL) from systemic follicular lymphoma (SFL) with prognostic impact. However, few data are available in LFL especially concerning hotspot genetic alterations that are associated with the pathogenesis and prognosis of SFL. A total of 144 LFL and 527 SFL, enrolled in prospective clinical trials of the German Low Grade Lymphoma Study Group, were analyzed by fluorescence in situ hybridization to detect deletions in chromosomes 1p, 6q, and 17p as well as BCL2 translocations to determine their impact on clinical outcome of LFL patients. The frequency of chromosomal deletions in 1p and 17p was comparable between LFL and SFL, while 6q deletions and BCL2 translocations more frequently occurred in SFL. A higher proportion of 1p deletions was seen in BCL2-translocation-positive LFL, compared with BCL2-translocation-negative LFL. Deletions in chromosomes 1p, 6q, and 17p predicted clinical outcome of patients with SFL in the entire cohort, while only deletions in chromosome 1p retained its negative prognostic impact in R-CHOP-treated SFL. In contrast, no deletions in one of the investigated genetic loci predicted clinical outcome in LFL. Likewise, the presence or absence of BCL2 translocations had no prognostic impact in LFL. Despite representing a genetic portfolio closely resembling SFL, LFL showed some differences in deletion frequencies. BCL2 translocation and 6q deletion frequency differs between LFL and SFL and might contribute to distinct genetic profiles in LFL and SFL.

Follicular lymphoma grade 3B and diffuse large B-cell lymphoma present a histopathological and molecular continuum lacking features of progression/ transformation.

The sole distinguishing feature of follicular lymphoma grade 3B and diffuse large B-cell lymphoma is the growth pattern assessed by histopathology. Diffuse growth defines diffuse large B-cell lymphoma but the clinical relevance of this finding when occurring in follicular lymphoma grade 3B is uncertain. To address this issue, individual and coexisting follicular lymphoma grade 3B and diffuse large B-cell lymphoma were separated and analyzed for immunophenotype and molecular genetic features by fluorescence in situ hybridization, targeted sequencing and gene expression profiling. Clinical features of follicular lymphoma grade 3B with and without coexisting diffuse large B-cell lymphoma were studied in homogeneously treated patients from a prospective randomized trial. Follicular lymphoma grade 3B and diffuse large B-cell lymphoma frequently show an intermediate growth pattern and/or occur simultaneously in the same tissue at the time of initial diagnosis. When occurring simultaneously follicular lymphoma grade 3B and diffuse large B-cell lymphoma do not differ significantly for genetic aberrations or phenotype but have distinct gene expression features reflecting a divergent microenvironment. Follicular lymphoma grade 3B with and without coexisting diffuse large B-cell lymphoma do not differ for major clinical parameters such as International Prognostic Index, response to immuno-chemotherapy, progression or overall survival. Follicular lymphoma grade 3B and simultaneous diffuse large B-cell lymphoma are molecularly homogenous. Histological detection of diffuse large B-cell lymphoma is not associated with features of a more aggressive disease and does not reflect transformation or progression of follicular lymphoma grade 3B.

Adoptive Cell Transfer of Allogeneic Epstein-Barr Virus-Specific T Lymphocytes for Treatment of Refractory EBV-Associated Posttransplant Smooth Muscle Tumors: A Case Report.

Posttransplant smooth muscle tumors (PTSMTs) are rare Epstein-Barr virus (EBV)-associated neoplasms, mostly occurring after solid organ transplantation. Current therapeutic strategies include surgery and reduction of immunosuppressive medication. We describe for the first time a novel treatment approach for PTSMT by adoptive cell transfer (ACT) of EBV-specific T cells to a 20-year-old patient with a medical history of cardiac transplantation, posttransplant lymphoproliferative disease, and multilocular PTSMT. During ACT, mild cytokine release syndrome occurred, while no unexpected safety signals were recorded. We observed in vivo expansion of EBV-specific T cells and reduction of EBV viremia. Best response was stable disease after 4 months with reduction of EBV viremia and normalization of lactate dehydrogenase levels. ACT with EBV-specific T cells may be a safe and efficacious therapeutic option for PTSMT that warrants further exploration.

Cause of Death in Patients in Radiation Oncology.

BACKGROUND: The accurate attribution of death in oncologic patients is a difficult task. The patient's death is often attributed to his or her underlying cancer and therefore judged as cancer-related. We hypothesized that even though our patient's cancers were either advanced or metastatic, not all patients had died simply because of their cancer. METHODS: A total of 105 patients were included in this retrospective analysis. Patient data were collected from digital and paper-based records. Cause of death was assessed from death certificate and compared to the medical autopsy reports. Discrepancies between premortem and postmortem diagnoses were classified as class I and II discrepancies. RESULTS: Of 105 patients included, autopsy consent was obtained in 56 cases (53%). Among them, 32 of 56 were palliatively sedated, and 42/56 patients died cancer-related as confirmed by autopsy. The most common cause of death by autopsy report was multiorgan failure followed by a combination of tumor and infection, predominantly lung cancer with pneumonia. Here, 21/56 cases (37%) showed major missed diagnoses: seven cases showed class I, 10 class II, and both discrepancies. The most commonly missed diagnoses in both categories were infections, again mainly pneumonia. CONCLUSIONS: Cancer was the leading cause of death in our study population. A quarter of the patients, however, did not die due to their advanced or metastatic cancers but of potentially curable causes. We therefore conclude that it is important to consider competing causes of death when treating palliative cancer patients. In a palliative setting, the treatment of a potentially curable complication should be discussed with the patients and their families in a shared decision-making process. From our experience, many patients will decline treatment or even further diagnostics when given the option of best supportive care.

The mycotoxin beauvericin impairs development, fertility and life span in the nematode Caenorhabditis elegans accompanied by increased germ cell apoptosis and lipofuscin accumulation.

Beauvericin is an ubiquitous mycotoxin with relevant occurrence in food and feed. It causes a high toxicity in several cell lines, but its general mechanism of action is not fully understood and only limited in vivo studies have been performed. We used Caenorhabditis elegans as a model organism to investigate effects of beauvericin. The mycotoxin displays a moderate acute toxicity at 100 µM; at this concentration also reproductive toxicity occurred (reduction of total progeny to 32.1 %), developmental toxicity was detectable at 250 µM. However, even lower concentrations were capable to reduce stress resistance and life span of the nematode: A significant reduction was detected at 10 µM beauvericin (decrease in mean survival time of 4.3 % and reduction in life span of 12.9 %). An increase in lipofuscin fluorescence was demonstrated starting at 10 µM suggesting oxidative stress as a mechanism of beauvericin toxicity. Beauvericin (100 µM) increases the number of apoptotic germ cells comparable to the positive control UV-C (400 J/m2). Conclusion: Low concentrations of beauvericin are capable to cause adverse effects in C. elegans, which may be relevant for hazard identification of this compound.

Juvenile Blastic Plasmacytoid Dendritic Cell Neoplasm.

is missing (Short communication).

Hibiscus sabdariffa L. extract prolongs lifespan and protects against amyloid-ß toxicity in Caenorhabditis elegans: involvement of the FoxO and Nrf2 orthologues DAF-16 and SKN-1.

PURPOSE: Hibiscus sabdariffa L. is commonly used as an ingredient for herbal teas and food supplements. Several studies demonstrated the beneficial effects of Hibiscus sabdariffa L. extracts (HSE); however, the bioactive components and their mode of action still remain unclear. Caenorhabditis elegans (C. elegans) was used to study health-related effects and the underlying molecular mechanisms of HSE in this model organism as well as effects of hydroxycitric acid (HCA), a main compound of HSE, and its structural analogue isocitric acid (ICA). METHODS: Survival and locomotion were detected by touch-provoked movement. Thermotolerance was analysed using the nucleic acid stain SYTOX green, and intracellular ROS accumulation was measured via oxidation of H2DCF. Localisation of the transcription factors DAF-16 and SKN-1 was analysed in transgenic strains (DAF-16::GFP, SKN-1::GFP). The involvement of DAF-16 and SKN-1 was further investigated using loss-of-function strains as well as gene silencing by feeding RNAi-inducing bacteria. Protection against amyloid-ß toxicity was analysed using a transgenic strain with an inducible expression of human amyloid-ß peptides in body wall muscle cells (paralysis assay). RESULTS: HSE treatment resulted in a prominent extension of lifespan (up to 24%) and a reduction of the age-dependent decline in locomotion. HCA, a main compound of HSE increased lifespan too, but to a lesser extent (6%) while ICA was not effective. HSE and HCA did not modulate resistance against thermal stress conditions and did not exert antioxidative effects: HSE rather increased intracellular ROS levels, suggesting a pro-oxidative effect of the extract in vivo. HSE and HCA increased the nuclear localisation of the pivotal transcription factors DAF-16 and SKN-1 indicating an activation of these factors. Consistent with this result, lifespan prolongation by HSE was dependent on both transcription factors. In addition to the positive effect on lifespan, HSE treatment also elicited a (strong) protection against amyloid-ß induced toxicity in C. elegans in a DAF-16- and SKN-1-dependent manner. CONCLUSION: Our results demonstrate that HSE increases lifespan and protects against amyloid-ß toxicity in the model organism C. elegans. These effects were mediated, at least in parts via modulation of pathways leading to activation/nuclear localisation of DAF-16 and SKN-1. Since HCA, a main component of HSE causes only minor effects, additional bioactive compounds like flavonoids or anthocyanins as well as synergistic effects of these compounds should be investigated.

Stereotactic body radiotherapy for ventricular tachycardia (cardiac radiosurgery) : First-in-patient treatment in Germany.

PURPOSE: Single-session cardiac stereotactic body radiotherapy, called cardiac radiosurgery (CRS) or radioablation (RA), may offer a potential treatment option for patients with refractory ventricular tachycardia (VT) and electrical storm who are otherwise ineligible for catheter ablation. However, there is only limited clinical experience. We now present the first-in-patient treatment using (CRS/RA) for VT in Germany. METHODS: A 78-year-old male patient with dilated cardiomyopathy and significantly reduced ejection fraction (15%) presented with monomorphic VT refractory to poly-anti-arrhythmic medication and causing multiple implantable cardioverter-defibrillator (ICD) interventions over the course of several weeks, necessitating prolonged treatment on an intensive care unit. Ultra-high-resolution electroanatomical voltage mapping (EVM) revealed a re-entry circuit in the cardiac septum inaccessible for catheter ablation. Based on the EVM, CRS/RA with a single session dose of 25 Gy (83% isodose) was delivered to the VT substrate (8.1 cc) using a c-arm-based high-precision linear accelerator on November 30, 2018. RESULTS: CRS/RA was performed without incident and dysfunction of the ICD was not observed. Following the procedure, a significant reduction in monomorphic VT from 5.0 to 1.6 episodes per week and of ICD shock interventions by 81.2% was observed. Besides periprocedural nausea with a single episode of vomiting, no treatment-associated side effects were noted. Unfortunately, the patient died 57 days after CRS/RA due to sepsis-associated cardiac circulatory failure after Clostridium difficile-associated colitis developed during rehabilitation. Histopathologic examination of the heart as part of a clinical autopsy revealed diffuse fibrosis on most sections of the heart without apparent differences between the target area and the posterior cardiac wall serving as a control. CONCLUSION: CRS/RA appears to be a possible treatment option for otherwise untreatable patients suffering from refractory VT and electrical storm. A relevant reduction in VT incidence and ICD interventions was observed, although long-term outcome and consequences of CRS/RA remain unclear. Clinical trials are strongly warranted and have been initiated.

Localized- and advanced-stage follicular lymphomas differ in their gene expression profiles.

The genetic background of follicular lymphomas (FLs) diagnosed in advanced clinical stages III/IV, and which are frequently characterized by t(14;18), has been substantially unraveled. Molecular features, as exemplified in the clinicogenetic risk model m7FLIPI, are important tools in risk stratification. In contrast, little information is available concerning localized-stage FL (clinical stages I/II), which accounts for ∼20% of newly diagnosed FL in which the detection rate of t(14;18) is only ∼50%. To investigate the genetic background of localized-stage FL, patient cohorts with advanced-stage FL or localized-stage FL, uniformly treated within phase 3 trials of the German Low-Grade Lymphoma Study Group, were comparatively analyzed. Targeted gene expression (GE) profiling of 184 genes using nCounter technology was performed in 110 localized-stage and 556 advanced-stage FL patients. By penalized Cox regression, a prognostic GE signature could not be identified in patients with advanced-stage FL, consistent with results from global tests and univariate regression. In contrast, it was possible to define robust GE signatures discriminating localized-stage and advanced-stage FL (area under the curve, 0.98) by penalized logistic regression. Of note, 3% of samples harboring an "advanced-stage signature" in the localized-stage cohort exhibited inferior failure-free survival (hazard ratio [HR], 7.1; P = .0003). Likewise, in the advanced-stage cohort, 7% of samples with a "localized-stage signature" had prolonged failure-free survival (HR, 2.3; P = .017) and overall survival (HR, 3.4; P = .072). These data support the concept of a biological difference between localized-stage and advanced-stage FL that might contribute to the superior outcome of localized FL.

Abyssinone V, a prenylated flavonoid isolated from the stem bark of Erythrina melanacantha increases oxidative stress and decreases stress resistance in Caenorhabditis elegans.

OBJECTIVES: Recent studies showed that distinct extracts of Erythrina species used in the traditional medicine of sub-Saharan Africa are protective against stress conditions. However, the underlying molecular mechanisms as well as relevant compounds remain unclear. METHODS: We used the model organism Caenorhabditis elegans to investigate compounds isolated from the stem bark of Erythrina melanacantha (abyssinone V (1), abyssinon-4'O-methylether (2), sigmoidin B-4'O-methylether (3), glabranin (4), 8-prenylnaringenin (5), citflavanone (6), exiguaflavanone (7) and homoeriodictyol (8)). Antioxidative capacity in vitro (trolox equivalent antioxidative capacity assay) and modulation of oxidative stress in vivo (2', 7'-dichlorofluorescein assay) were investigated; stress resistance was analysed using the nucleic acid stain SYTOX green. KEY FINDINGS: None of the prenylated flavonoids caused protection against thermal stress; in contrast, most of the compounds (1, 4, 5, 8) decreased stress resistance. None of the compounds decreased the accumulation of reactive oxygen species, but abyssinone V (1) caused an increase in oxidative stress. In line with these results, none of these compounds showed radical-scavenging effects in vitro. CONCLUSIONS: The stem bark of E. melanacantha contains various prenylated flavonoids, but no compound protected C. elegans against stress conditions. In contrast, abyssinone V increases oxidative stress and reduces stress resistance in this model organism.

Agrimonia procera Wallr. Extract Increases Stress Resistance and Prolongs Life Span in Caenorhabditis elegans via Transcription Factor DAF-16 (FoxO Orthologue).

Agrimonia procera is a pharmacologically interesting plant which is proposed to protect against various diseases due to its high amount of phytochemicals, e.g., polyphenols. However, in spite of the amount of postulated health benefits, studies concerning the mechanistic effects of Agrimonia procera are limited. Using the nematode Caenorhabditis elegans, we were able to show that an ethanol extract of Agrimonia procera herba (eAE) mediates strong antioxidative effects in the nematode: Beside a strong radical-scavenging activity, eAE reduces accumulation of reactive oxygen species (ROS) accumulation and protects against paraquat-induced oxidative stress. The extract does not protect against amyloid-ß-mediated toxicity, but efficiently increases the life span (up to 12.7%), as well as the resistance to thermal stress (prolongation of survival up to 22%), of this model organism. Using nematodes deficient in the forkhead box O (FoxO)-orthologue DAF-16, we were able to demonstrate that beneficial effects of eAE on stress resistance and life span were mediated via this transcription factor. We showed antioxidative, stress-reducing, and life-prolonging effects of eAE in vivo and were able to demonstrate a molecular mechanism of this extract. These results may be important for identifying further molecular targets of eAE in humans.

T-Cell Clustering in Neoplastic Follicles of Follicular Lymphoma.

The nonneoplastic microenvironment is abundant in follicular lymphoma. Its composition has been reported to be associated with the course of the disease. Lack of animal models hampers studies of interaction between lymphoma and bystander cells. We aimed to identify indicators of cellular interaction exemplified by nonrandom distribution of cell types within neoplastic follicles. Physiological germinal centers and follicles in follicular lymphoma were stained to identify macrophages, all T, follicular T-helper, dendritic and B cells. Density of cell types and cell distribution (spatial point pattern) were analyzed by digital image analysis. The density of all T, follicular T-helper and dendritic cells was higher in the dark zone than in the light zone of physiological germinal centers. Densities of cell types in follicular lymphoma were intermediate between the light and the dark zone. All cell types analyzed showed a completely random spatial distribution pattern within the dark and the light zone, respectively. In follicular lymphoma B cells and macrophages displayed complete spatial randomness. In contrast, all T cells, follicular T-helper cells and dendritic cells showed clustering of each individual cell type within a radius of 6-10 µm in the lymphoma. We conclude that the distribution of nonneoplastic cells within follicles of follicular lymphoma is not random. T cells and dendritic cells form clusters within the follicles, suggestive of sites of interaction between microenvironment and lymphoma cells. These clusters might help to understand the interaction of lymphoma cells with the microenvironment and might provide a structure for therapeutic intervention.

Polygonum multiflorum Extract Exerts Antioxidative Effects and Increases Life Span and Stress Resistance in the Model Organism Caenorhabditis elegans via DAF-16 and SIR-2.1.

Extracts of the Chinese plant Polygonum multiflorum (PME) are used for medicinal purposes as well as food supplement due to anti-aging effects. Despite of the common use of these food supplements, experimental data on physiological effects of PME and its underlying molecular mechanisms in vivo are limited. We used the model organism Caenorhabditis elegans to analyze anti-aging-effects of PME in vivo (life span, lipofuscin accumulation, oxidative stress resistance, thermal stress resistance) as well as the molecular signaling pathways involved. The effects of PME were examined in wildtype animals and mutants defective in the sirtuin-homologue SIR-2.1 (VC199) and the FOXO-homologue DAF-16 (CF1038). PME possesses antioxidative effects in vivo and increases oxidative stress resistance of the nematodes. While the accumulation of lipofuscin is only slightly decreased, PME causes a significant elongation (18.6%) of mean life span. DAF-16 is essential for the reduction of thermally induced ROS accumulation, while the resistance against paraquat-induced oxidative stress is dependent on SIR-2.1. For the extension of the life span, both DAF-16 and SIR-2.1 are needed. We demonstrate that PME exerts protective effects in C. elegans via modulation of distinct intracellular pathways.

The resveratrol derivatives trans-3,5-dimethoxy-4-fluoro-4'-hydroxystilbene and trans-2,4',5-trihydroxystilbene decrease oxidative stress and prolong lifespan in Caenorhabditis elegans.

OBJECTIVES: Resveratrol (trans-3,4',5-trihydroxystilbene (1)) was previously shown to extend the lifespan of different model organisms. However, its pharmacological efficiency is controversially discussed. Therefore, the bioactivity of four newly synthesized stilbenes (trans-3,5-dimethoxy-4-fluoro-4'-hydroxystilbene (3), trans-4'-hydroxy-3,4,5-trifluorostilbene (4), trans-2,5-dimethoxy-4'-hydroxystilbene (5), trans-2,4',5-trihydroxystilbene (6)) was compared to (1) and pterostilbene (trans-3,5-dimethoxy-4'-hydroxystilbene (2)) in the established model organism Caenorhabditis elegans. METHODS: Trolox equivalent antioxidant capacity (TEAC), 2',7'-dichlorofluorescein (DCF), thermotolerance assays, C. elegans lifespan analyses. KEY FINDINGS: All compounds exert a strong in-vitro radical scavenging activity (6 > 1 > 5 > 2 = 3 = 4), but in vivo, only (3) and (6) reduce reactive oxygen species (ROS) accumulation. Furthermore, (3) and (6) increased the mobility of aged nematodes and prolonged their mean lifespans, while these compounds decreased the thermal stress resistance. Using daf-16 (FoxO), skn-1 (Nrf2) and sir-2.1 (sirtuin) loss-of-function mutant strains, the in vivo antioxidant effects of compounds (3) and (6) were abolished, showing the necessity of these evolutionary highly conserved factors. However, short-time treatment with stilbenes (3) and (6) did not modulate the cellular localization of the transcription factors DAF-16 and SKN-1. CONCLUSION: In contrast to resveratrol, the synthetic stilbene derivatives (3) and (6) increase the lifespan of C. elegans, rendering them promising candidates for pharmacological anti-ageing purposes.

Isoxanthohumol, a constituent of hop (Humulus lupulus L.), increases stress resistance in Caenorhabditis elegans dependent on the transcription factor DAF-16.

PURPOSE: The flavanone isoxanthohumol (IX) has gained attention as antioxidative and chemopreventive agent, but the molecular mechanism of action remains unclear. We investigated effects of this secondary plant compound in vivo using the model organism Caenorhabditis elegans. METHODS: Adult C. elegans nematodes were incubated with IX, and then, the stress resistance was analysed in the SYTOX assay; lifespan was monitored by touch-provoked movement method, the amount of reactive oxygen species (ROS) was measured in the DCF assay, and the nuclear localisation of the transcription factor DAF-16 was analysed by using a transgenic strain. By the use of a DAF-16 loss-of-function strain, we analysed whether the effects are dependent on DAF-16. RESULTS: IX increases the resistance of the nematode against thermal stress. Additionally, a reduction in ROS in vivo was caused by IX. Since the flavanone only has a marginal radical-scavenging capacity (TEAC assay), we suggest that IX mediates its antioxidative effects indirectly via activation of DAF-16 (homologue to mammalian FOXO proteins). The nuclear translocation of this transcription factor is increased by IX. In the DAF-16-mutated strain, the IX-mediated increase in stress resistance was completely abolished; furthermore, an increased formation of ROS and a reduced lifespan was mediated by IX. CONCLUSION: IX or a bacterial metabolite of IX causes antioxidative effects as well as an increased stress resistance in C. elegans via activation of DAF-16. The homologous pathway may have implications in the molecular mechanism of IX in mammals.