Prolonged and intense neuroinflammation after severe traumatic brain injury assessed by cerebral microdialysis with 300 kDa membranes.

BACKGROUND: A neuroinflammatory response that may lead to edema and secondary brain damage is elicited in severe traumatic brain injury (TBI). Previous studies using microdialysis (MD) membranes with 100 k Dalton (kDa) cut-off found a transient intracerebral release of cytokines and chemokines without significant correlations to clinical course, intracranial pressure (ICP) or metabolites. In this study, a (300 kDa) MD probe was used to measure the levels of cytokines and chemokines in relation to ICP and metabolites. METHODS: Seven patients with severe TBI received 2 MD catheters. In four patients sufficient dialysate could be retrieved for analysis from both catheters. MD samples were analyzed bedside, then frozen and analyzed for chemokines and cytokines using a multiplex assay (Mesoscale Discovery). RESULTS: MD sampling was performed from 9 to 350 h. In total, 17 chemokines and cytokines were detected. Of these, IL-6, IL-8, IP-10, MCP-1 and MIP-1ß were consistently elevated, and investigated further in relation to metabolites, and ICP. Levels of chemokines and cytokines were higher than previously reported from TBI patients, and partially higher than those reported in patients with cytokine release syndrome. There were no significant differences between the two catheters regarding cytokine/chemokine concentrations, except for IL-6 which was higher in the peri-contusional area. No correlation with metabolites and ICP was observed. No significant increase or decline of chemokine or cytokine secretion was observed during the study period. CONCLUSION: Our data suggest that cytokine and chemokine levels reflect a perpetual, potent and pan-cerebebral inflammatory response that persists beyond 15 days following TBI.

Antisecretory factor is safe to use as add-on treatment in newly diagnosed glioblastoma.

PURPOSE: Glioblastoma (GBM) is the most common primary malignant brain tumor in adults. Despite the best available treatment, prognosis remains poor. Current standard therapy consists of surgical removal of the tumor followed by radiotherapy and chemotherapy with the alkylating agent temozolomide (TMZ). Experimental studies suggest that antisecretory factor (AF), an endogenous protein with proposed antisecretory and anti-inflammatory properties, may potentiate the effect of TMZ and alleviate cerebral edema. Salovum is an egg yolk powder enriched for AF and is classified as a medical food in the European Union. In this pilot study, we evaluate the safety and feasibility of add-on Salovum in GBM patients. METHODS: Eight patients with newly diagnosed, histologically confirmed GBM were prescribed Salovum during concomitant radiochemotherapy. Safety was determined by the number of treatment-related adverse events. Feasibility was determined by the number of patients who completed the full prescribed Salovum treatment. RESULTS: No serious treatment-related adverse events were observed. Out of 8 included patients, 2 did not complete the full treatment. Only one of the dropouts was due to issues directly related to Salovum, which were nausea and loss of appetite. Median survival was 23 months. CONCLUSIONS: We conclude that Salovum is safe to use as an add-on treatment for GBM. In terms of feasibility, adherence to the treatment regimen requires a determined and independent patient as the large doses prescribed may cause nausea and loss of appetite. TRIAL REGISTRATION: ClinicalTrials.gov NCT04116138. Registered on 04/10/2019.

Low Morbidity and Mortality in Children with Severe Traumatic Brain Injury Treated According to the Lund Concept: A Population-Based Study.

Previous reports of mortality and morbidity in pediatric severe traumatic brain injury (TBI) vary considerably, with few population-based studies. Mortality rates from 3-33 % and varying morbidity have been reported, most commonly using the Extended Glasgow Outcome Scale (eGOS). The Lund concept is a treatment algorithm for severe TBI aiming at controlling intracranial pressure (ICP) by reducing cerebral perfusion pressure (CPP). The aim of the present study was to retrospectively assess mortality and morbidity in a population of pediatric TBI treated according to the Lund concept. All cases of severe pediatric TBI (age <18 years) in the southern region of Sweden during 19 years were identified. Patients were treated according to the Lund concept. Mortality, eGOS, ICP, CPP, time in the neurosurgical intensive care unit (NICU), drugs delivered and surgical procedures were recorded. Data were analyzed both by dichotomized outcomes and by ordinal statistics. A total of 135 cases of severe TBI <18 years of age were recorded (incidence 2.0/100000) and 86 patients were admitted to the tertiary NICU. Mortality including all cases was 43% (mortality rate 0.7/100,000) and in NICU 10%. Outcome was good in 60%, moderate in 25%, unfavorable in 15%, with none in a vegetative status. In both dichotomized and ordinal analyses, CPP <40 mm Hg and ICP >15 were associated with poor outcome, supporting current guidelines. However, high CPP also was associated with increased mortality and morbidity, supporting that elevated CPP might increase cerebral edema. In this study, the Lund concept resulted in low mortality and a favorable outcome in a majority of severe pediatric TBI patients; however, randomized controlled trials are warranted to verify this.

Interplay between Caveolin-1 and body and tumor size affects clinical outcomes in breast cancer.

BACKGROUND: Caveolin-1 (CAV1) is associated with cholesterol-rich membrane raft domains and is a master regulator of cell signaling and membrane transport. Here, we investigated CAV1's role in cellular compartments of breast cancer in relation to signaling pathways, clinicopathological features, and clinical outcomes. METHODS: CAV1 levels were evaluated with immunohistochemistry in cytoplasm of invasive tumor cells and stromal cells in tumor tissue microarrays from a cohort of 1018 breast cancer patients (inclusion 2002-2012, Sweden). Cytoplasmic and stromal CAV1 were categorized as positive/negative and strong/not strong, respectively. CAV1 expression in relation to clinical outcomes was assessed with Cox regression. Investigations into CAV1 functional pathways was conducted in the STRING, GOBO, and TCGA databases. RESULTS: CAV1 expression was associated with non-luminal subtypes, cell cycle control, inflammation, epithelial-mesenchymal transition, and the IGF/Insulin system. Generally, CAV1 was not associated with recurrence risk. Stromal CAV1's impact on recurrence risk was modified by BMI ≥25 kg/m2 (Pinteraction = 0.002), waist ≥80 cm (Pinteraction = 0.005), and invasive tumor size (pT2/3/4) (Pinteraction = 0.028). In low-risk patients only, strong stromal CAV1 significantly increased recurrence risk (HRsadj ≥1.61). In all patients, positive cytoplasmic CAV1 conferred >2-fold risk for contralateral disease HRadj 2.63 (95% CI 1.36-5.10). Strong stromal CAV1 conferred nearly 2-fold risk for locoregional recurrence HRadj 1.88 (95% CI 1.09-3.24). CONCLUSIONS: CAV1's prognostic impact depended on its localization, anthropometric, and tumor factors. Stromal CAV1 predicted high recurrence risk in a group of supposedly 'low-risk' patients. Cytoplasmic CAV1 predicted metachronous contralateral disease. If confirmed, CAV1 could be used as treatment target and for risk-stratification.

Intratumoral administration of the antisecretory peptide AF16 cures murine gliomas and modulates macrophage functions.

Glioblastoma has remained the deadliest primary brain tumor while its current therapy offers only modest survival prolongation. Immunotherapy has failed to record notable benefits in routine glioblastoma treatment. Conventionally, immunotherapy relies on T cells as tumor-killing agents; however, T cells are outnumbered by macrophages in glioblastoma microenvironment. In this study, we explore the effect of AF16, a peptide from the endogenous antisecretory factor protein, on the survival of glioma-bearing mice, the tumor size, and characteristics of the tumor microenvironment with specific focus on macrophages. We elucidate the effect of AF16 on the inflammation-related secretome of human and murine macrophages, as well as human glioblastoma cells. In our results, AF16 alone and in combination with temozolomide leads to cure in immunocompetent mice with orthotopic GL261 gliomas, as well as prolonged survival in immunocompromised mice. We recorded decreased tumor size and changes in infiltration of macrophages and T cells in the murine glioma microenvironment. Human and murine macrophages increased expression of proinflammatory markers in response to AF16 treatment and the same effect was seen in human primary glioblastoma cells. In summary, we present AF16 as an immunomodulatory factor stimulating pro-inflammatory macrophages with a potential to be implemented in glioblastoma treatment protocols.

Prognostic impact of tumor-specific insulin-like growth factor binding protein 7 (IGFBP7) levels in breast cancer: a prospective cohort study.

The prognostic impact of insulin-like growth factor binding protein 7 (IGFBP7) in breast cancer is unclear. Host factors, including lifestyle, anthropometry and metabolic profile, might influence tumor-specific IGFBP7. This study aimed to investigate whether IGFBP7 levels and messenger ribonucleic acid (mRNA) expression are associated with the patient and tumor characteristics and prognosis in breast cancer. Patients with primary breast cancer in Lund, Sweden, were included preoperatively in the study between 2002 and 2012 (n = 1018). Tumor-specific IGFBP7 protein levels were evaluated with immunohistochemistry using tissue microarrays in tumors from 878 patients. IGFBP7 mRNA expression and its corresponding clinical data were obtained from The Cancer Genome Atlas and analyzed for 809 patients. Tumor-specific IGFBP7 protein levels were categorized based on Histo 300 scores into IGFBP7low (6.2%), IGFBP7intermediate (75.7%) and IGFBP7high (18.1%). Both low IGFBP7 protein levels and mRNA expression were associated with less aggressive tumor characteristics. Overall, IGFBP7low conferred low recurrence risk. The prognostic impact of IGFBP7high varied according to any alcohol consumption and tamoxifen treatment. IGFBP7high was associated with low recurrence risk in alcohol consumers but high recurrence risk in alcohol abstainers (Pinteraction= 0.039). Moreover, the combination of IGFBP7high and estrogen receptor-positive tumors was associated with low recurrence risk only in tamoxifen-treated patients (Pinteraction= 0.029). To conclude, IGFBP7low might be a good, independent prognosticator in breast cancer. The prognostic impact of IGFBP7high depends on host factors and treatment. IGFBP7 merits further investigation to confirm whether it could be a suitable biomarker for treatment selection.

Antisecretory Factor May Reduce ICP in Severe TBI-A Case Series.

Traumatic brain injury (TBI) constitutes a global epidemic. Overall outcome is poor, with mortality ranging from 10 to 70% and significant long-term morbidity. Several experimental reports have claimed effect on traumatic edema, but all clinical trials have failed. Antisecretory factor, an endogenous protein, is commercially available as Salovum®, which is classified as a medical food by the European Union and has been proven effective in experimental trauma models. It has, however, previously not been tested in humans with severe TBI. We hereby report a case series of five adult patients with severe TBI, treated with Salovum. The objective of the intervention was to evaluate safety and, if possible, its effect on intracranial pressure and outcome. Patients received 1 g Salovum per kilo of body weight divided into six doses per 24 h. Each dose was administered through the nasogastric tube. Patients were scheduled for 5 days of treatment with Salovum. Intracranial pressure was controlled in all patients. In three of five patients, intracranial pressure could be controlled with Salovum and deep sedation (no barbiturates), except during periods of gastroparesis. Five of five patients had a favorable short-term outcome, and four of five patients had a favorable long-term outcome. No toxicity was observed. We conclude that at least three of the five treated patients experienced an effect of Salovum with signs of reduction of intracranial pressure and signs of clinical benefit. In order to validate the potential of antisecretory factor in TBI, a prospective, randomized, double-blind, placebo-controlled trial with Salovum has been initiated. Primary outcome for the trial is 30-day mortality; secondary outcomes are treatment intensity level, intracranial pressure, and number of days at the neurointensive care unit.

Convection-enhanced delivery of temozolomide and whole cell tumor immunizations in GL261 and KR158 experimental mouse gliomas.

BACKGROUND: Glioblastomas (GBM) are therapy-resistant tumors with a profoundly immunosuppressive tumor microenvironment. Chemotherapy has shown limited efficacy against GBM. Systemic delivery of chemotherapeutic drugs is hampered by the difficulty of achieving intratumoral levels as systemic toxicity is a dose-limiting factor. Although some of its effects might be mediated by immune reactivity, systemic chemotherapy can also inhibit induced or spontaneous antitumor immune reactivity. Convection-enhanced delivery of temozolomide (CED-TMZ) can tentatively increase intratumoral drug concentration while reducing systemic side effects. The objective of this study was to evaluate the therapeutic effect of intratumorally delivered temozolomide in combination with immunotherapy and whether such therapy can generate a cellular antitumor immune response. METHODS: Single bolus intratumoral injection and 3-day mini-osmotic pumps (Alzet®) were used to deliver intratumoral TMZ in C57BL6 mice bearing orthotopic gliomas. Immunotherapy consisted of subcutaneous injections of irradiated GL261 or KR158 glioma cells. Tumor size and intratumoral immune cell populations were analyzed by immunohistochemistry. RESULTS: Combined CED-TMZ and immunotherapy had a synergistic antitumor effect in the GL261 model, compared to CED-TMZ or immunotherapy as monotherapies. In the KR158 model, immunization cured a small proportion of the mice whereas addition of CED-TMZ did not have a synergistic effect. However, CED-TMZ as monotherapy prolonged the median survival. Moreover, TMZ bolus injection in the GL261 model induced neurotoxicity and lower cure rate than its equivalent dose delivered by CED. In addition, we found that T-cells were the predominant cells responsible for the TMZ antitumor effect in the GL261 model. Finally, CED-TMZ combined with immunotherapy significantly reduced tumor volume and increased the intratumoral influx of T-cells in both models. CONCLUSIONS: We show that immunotherapy synergized with CED-TMZ in the GL261 model and cured animals in the KR158 model. Single bolus administration of TMZ was effective with a narrower therapeutic window than CED-TMZ. Combined CED-TMZ and immunotherapy led to an increase in the intratumoral influx of T-cells. These results form part of the basis for the translation of the therapy to patients with GBM but the dosing and timing of delivery will have to be explored in depth both experimentally and clinically.

The effect of locally delivered cisplatin is dependent on an intact immune function in an experimental glioma model.

Several chemotherapeutic drugs are now considered to exert anti-tumour effects, by inducing an immune-promoting inflammatory response. Cisplatin is a potent chemotherapeutic agent used in standard medulloblastoma but not glioblastoma protocols. There is no clear explanation for the differences in clinical efficacy of cisplatin between medulloblastomas and glioblastomas, despite the fact that cisplatin is effective in vitro against the latter. Systemic toxicity is often dose limiting but could tentatively be reduced by intratumoral administration. We found that intratumoral cisplatin can cure GL261 glioma-bearing C57BL/6 mice and this effect was abolished in GL261-bearing NOD-scid IL2rγnull (NSG) mice. Contrary to previous results with intratumoral temozolomide cisplatin had no additive or synergistic effect with whole cell either GL261 wild-type or GM-CSF-transfected GL261 cells whole cell vaccine-based immunotherapy. While whole tumour cell immunizations increased CD8+ T-cells and decreased F4/80+ macrophages intratumorally, cisplatin had no effect on these cell populations. Taken together, our results demonstrate that intratumoral cisplatin treatment was effective with a narrow therapeutic window and may be an efficient approach for glioma or other brain tumour treatment.

Establishment and characterization of an orthotopic patient-derived Group 3 medulloblastoma model for preclinical drug evaluation.

Medulloblastomas comprise a heterogeneous group of tumours and can be subdivided into four molecular subgroups (WNT, SHH, Group 3 and Group 4) with distinct prognosis, biological behaviour and implications for targeted therapies. Few experimental models exist of the aggressive and poorly characterized Group 3 tumours. In order to establish a reproducible transplantable Group 3 medulloblastoma model for preclinical therapeutic studies, we acquired a patient-derived tumour sphere culture and inoculated low-passage spheres into the cerebellums of NOD-scid mice. Mice developed symptoms of brain tumours with a latency of 17-18 weeks. Neurosphere cultures were re-established and serially transplanted for 3 generations, with a negative correlation between tumour latency and numbers of injected cells. Xenografts replicated the phenotype of the primary tumour, including high degree of clustering in DNA methylation analysis, high proliferation, expression of tumour markers, MYC amplification and elevated MYC expression, and sensitivity to the MYC inhibitor JQ1. Xenografts maintained maintained expression of tumour-derived VEGFA and stromal-derived COX-2. VEGFA, COX-2 and c-Myc are highly expressed in Group 3 compared to other medulloblastoma subgroups, suggesting that these molecules are relevant therapeutic targets in Group 3 medulloblastoma.

Preoperative systemic levels of VEGFA, IL-7, IL-17A, and TNF-ß delineate two distinct groups of children with brain tumors.

BACKGROUND: Primary brain tumors are the most common solid tumors in children. Increasing evidence demonstrates diverse intratumoral immune signatures, which are tentatively reflected in peripheral blood. PROCEDURE: Twenty cytokines were analyzed in preoperative plasma samples from five healthy children and 45 children with brain tumors, using a multiplex platform (MesoScale Discovery V-PLEX® ). Tumor types included medulloblastoma (MB), ependymoma, sarcoma, high-grade glioma, pilocytic astrocytoma, and other low-grade gliomas. RESULTS: A panel of four cytokines [VEGFA, interleukin (IL)-7, IL-17A, and tumor necrosis factor (TNF)-ß] delineated two distinct patient groups, identified as VEGFAhigh IL-7high IL-17Alow TNF-ßlow (Group A) and VEGFAlow IL-7low IL-17Ahigh TNF-ßhigh (Group B). Healthy controls and the vast majority of patients with MB were found within Group A, whereas patients with other tumor types were equally distributed between the two groups. Unrelated to A/B affiliation, we detected trends toward increased IL-10 and decreased IL-12/23 and TNF-α in several tumor types. Finally, a small number of patients displayed evidence of enhanced systemic immune activation, including elevated levels of interferon-γ, granulocyte monocyte colony-stimulating factor, IL-6, IL-12/23, and TNF-α. Following tumor resection, cytokine levels in a MB patient approached the levels of healthy controls. CONCLUSIONS: We identify common features and individual differences in the systemic immune profiles of children with brain tumors. Overall, patients with MB displayed a uniform cytokine profile, whereas other tumor diagnoses did not predict systemic immunological status in single patients. Future characterization and monitoring of systemic immune responses in children with brain tumors will have important implications for the development and implementation of immunotherapy.

A standardized and reproducible protocol for serum-free monolayer culturing of primary paediatric brain tumours to be utilized for therapeutic assays.

In vitro cultured brain tumour cells are indispensable tools for drug screening and therapeutic development. Serum-free culture conditions tentatively preserve the features of the original tumour, but commonly comprise neurosphere propagation, which is a technically challenging procedure. Here, we define a simple, non-expensive and reproducible serum-free cell culture protocol for establishment and propagation of primary paediatric brain tumour cultures as adherent monolayers. The success rates for establishment of primary cultures (including medulloblastomas, atypical rhabdoid tumour, ependymomas and astrocytomas) were 65% (11/17) and 78% (14/18) for sphere cultures and monolayers respectively. Monolayer culturing was particularly feasible for less aggressive tumour subsets, where neurosphere cultures could not be generated. We show by immunofluorescent labelling that monolayers display phenotypic similarities with corresponding sphere cultures and primary tumours, and secrete clinically relevant inflammatory factors, including PGE2, VEGF, IL-6, IL-8 and IL-15. Moreover, secretion of PGE2 was considerably reduced by treatment with the COX-2 inhibitor Valdecoxib, demonstrating the functional utility of our newly established monolayer for preclinical therapeutic assays. Our findings suggest that this culture method could increase the availability and comparability of clinically representative in vitro models of paediatric brain tumours, and encourages further molecular evaluation of serum-free monolayer cultures.

Aberrant immunostaining pattern of the CD24 glycoprotein in clinical samples and experimental models of pediatric medulloblastomas.

The CD24 glycoprotein is a mediator of neuronal proliferation, differentiation and immune suppression in the normal CNS, and a proposed cancer biomarker in multiple peripheral tumor types. We performed a comparative analysis of CD24 gene expression in a large cohort of pediatric and adult brain tumors (n = 813), and further characterized protein expression in tissue sections (n = 39), primary brain tumor cultures (n = 12) and a novel orthotopic group 3 medulloblastoma xenograft model. Increased CD24 gene expression was demonstrated in ependymomas, medulloblastomas, anaplastic astrocytomas and glioblastomas, although medulloblastomas displayed higher expression than all other tumor entities. Preferential expression of CD24 in medulloblastomas was confirmed at protein level by immunostaining and computerized image analysis of cryosections. Morphologies and immunophenotyping of CD24(+) cells in tissue sections tentatively suggested disparate functions in different tumor subsets. Notably, protein staining of medulloblastoma cells was associated with prominent cytoplasmic and membranous granules, enabling rapid and robust identification of medulloblastoma cells in clinical tissue samples, as well as in experimental model systems. In conclusion, our results implicate CD24 as a clinically and experimentally useful medulloblastoma immunomarker. Although our results encourage further functional studies of CD24 as a potential molecular target in subsets of brain tumors, the promiscuous expression of CD24 in vivo highlights the importance of specificity in the future design of such targeted treatment.

Immunizations with unmodified tumor cells and simultaneous COX-2 inhibition eradicate malignant rat brain tumors and induce a long-lasting CD8(+) T cell memory.

Malignant brain tumors induce pronounced immunosuppression, which diminishes immune responses generated by immunotherapy. Here we report that peripheral immunotherapy, using irradiated unmodified whole tumor cells, and systemic cyclooxygenase-2 inhibition induce cure in glioma-bearing rats (60% cure rate), whereas neither monotherapy was sufficient to cure any animal. Moreover, the combined therapy protected against secondary tumor challenges (89% cure rate) and the secondary immune response was correlated with increased plasma interferon-gamma levels and CD8(+) T cells systemically and intratumorally. In conclusion, we demonstrate that cyclooxygenase-2 inhibition is sufficient to render unmodified tumor cells immunogenic in immunotherapy of experimental brain tumors.

Intratumoral COX-2 inhibition enhances GM-CSF immunotherapy against established mouse GL261 brain tumors.

Immunotherapy has shown effectiveness against experimental malignant brain tumors, but the clinical results have been less convincing most likely due to immunosuppression. Prostaglandin E2 (PGE2 ) is the key immunosuppressive product of cyclooxygenase-2 (COX-2) and increased levels of PGE2 and COX-2 have been shown in several tumor types, including brain tumors. In the current study, we report enhanced cure rate of mice with established mouse GL261 brain tumors when immunized with granulocyte macrophage-colony stimulating factor (GM-CSF) secreting tumor cells and simultaneously treated with the selective COX-2 inhibitors parecoxib systemically (5 mg/kg/day; 69% cure rate) or valdecoxib intratumorally (5.3 µg/kg/day; 63% cure rate). Both combined therapies induced a systemic antitumor response of proliferating CD4(+) and CD8(+) T cells, and further analysis revealed T helper 1 (Th 1) cell supremacy. The GL261 tumor cell line produced low levels of PGE2 in vitro, and co-staining at the tumor site demonstrated that a large fraction of the COX-2(+) cells were derived from CD45(+) immune cells and more specifically macrophages (F4/80(+)), indicating that tumor-infiltrating immune cells constitute the primary source of COX-2 and PGE2 in this model. We conclude that intratumoral COX-2 inhibition potentiates GM-CSF immunotherapy against established brain tumors at substantially lower doses than systemic administration. These findings underscore the central role of targeting COX-2 during immunotherapy and implicate intratumoral COX-2 as the primary target.

Intratumoral temozolomide synergizes with immunotherapy in a T cell-dependent fashion.

Despite temozolomide (TMZ) treatment, the prognosis for patients with glioblastoma multiforme is still dismal. As dose escalation of TMZ is limited by systemic toxicity, intratumoral delivery emerges as an attractive treatment modality, which may sustain cytotoxic drug concentrations intratumorally and induce immunogenic cell death. Both clinical and experimental gliomas have responded to immunotherapy, but the benefit of simultaneous chemo- and immunotherapy is inadequately studied. Here, we monitored survival of GL261-bearing C57BL/6 mice following a 3-day treatment with either intratumoral TMZ (micro-osmotic pump, 4.2 mg/kg/day) or systemic TMZ (i.p. injections, 50 mg/kg/day) alone, or combined with immunization using GM-CSF secreting GL261 cells. Peripheral and intratumoral leukocytes were analyzed by flow cytometry and immunohistochemistry. Intratumoral TMZ induced higher survival rate than systemic TMZ (45 vs. 8%). When T cells were depleted following intratumoral TMZ, the therapeutic effect was completely abrogated (0 % survival). Intratumoral TMZ synergistically increased survival rate of immunized mice (from 25 to 83%), while systemic TMZ failed (0%). While systemic TMZ induced a transient leukopenia, intratumoral TMZ and immunotherapy sustained the proliferation of CD8+ T cells and decreased the number of intratumoral immunosuppressive cells. In conclusion, intratumoral TMZ alone or in combination with immunotherapy could cure glioma-bearing mice, due to attenuation of local immunosuppression and increase in potential effector immune cells.

IFNγ in combination with IL-7 enhances immunotherapy in two rat glioma models.

Peripheral immunization, using a combination of interferon-gamma (IFNγ)- and interleukin-7 (IL-7)-producing tumor cells, eradicated 75% of pre-established intracerebral N32 rat glioma tumors, and prolonged survival in the more aggressive RG2 model. Rats immunized with IFNγ- and IL7-transduced N32 cells displayed increases in IFNγ plasma levels and proliferating circulating T cells when compared with rats immunized with N32-wild type cells. Following irradiation, the expression of MHC I and II was high on N32-IFNγ cells, but low on RG2-IFNγ cells. In conclusion, IFNγ and IL-7 immunizations prolong survival in two rat glioma models.

The adult human brain harbors multipotent perivascular mesenchymal stem cells.

Blood vessels and adjacent cells form perivascular stem cell niches in adult tissues. In this perivascular niche, a stem cell with mesenchymal characteristics was recently identified in some adult somatic tissues. These cells are pericytes that line the microvasculature, express mesenchymal markers and differentiate into mesodermal lineages but might even have the capacity to generate tissue-specific cell types. Here, we isolated, purified and characterized a previously unrecognized progenitor population from two different regions in the adult human brain, the ventricular wall and the neocortex. We show that these cells co-express markers for mesenchymal stem cells and pericytes in vivo and in vitro, but do not express glial, neuronal progenitor, hematopoietic, endothelial or microglial markers in their native state. Furthermore, we demonstrate at a clonal level that these progenitors have true multilineage potential towards both, the mesodermal and neuroectodermal phenotype. They can be epigenetically induced in vitro into adipocytes, chondroblasts and osteoblasts but also into glial cells and immature neurons. This progenitor population exhibits long-term proliferation, karyotype stability and retention of phenotype and multipotency following extensive propagation. Thus, we provide evidence that the vascular niche in the adult human brain harbors a novel progenitor with multilineage capacity that appears to represent mesenchymal stem cells and is different from any previously described human neural stem cell. Future studies will elucidate whether these cells may play a role for disease or may represent a reservoir that can be exploited in efforts to repair the diseased human brain.

Inhibition of cyclooxygenase-2 enhances immunotherapy against experimental brain tumors.

Glioblastoma multiforme is the most common and aggressive malignant brain tumor in humans, and the prognosis is very poor despite conventional therapy. Immunotherapy represents a novel treatment approach, but the effect is often weakened by release of immune-suppressive molecules such as prostaglandins. In the current study, we investigated the effect of immunotherapy with irradiated interferon-γ (IFN-γ)-secreting tumor cells and administration of the selective cyclooxygenase-2 (COX-2) inhibitor parecoxib as treatment of established rat brain tumors. COX-2 inhibition and immunotherapy significantly enhanced the long-term cure rate (81% survival) compared with immunotherapy alone (19% survival), and there was a significant increase in plasma IFN-γ levels in animals treated with the combined therapy, suggesting a systemic T helper 1 immune response. COX-2 inhibition alone, however, did neither induce cure nor prolonged survival. The tumor cells were identified as the major source of COX-2 both in vivo and in vitro, and unmodified tumor cells produced prostaglandin E(2) in vitro, while the IFN-γ expressing tumor cells secreted significantly lower levels. In conclusion, we show that immunotherapy of experimental brain tumors is greatly potentiated when combined with COX-2 inhibition. Based on our results, the clinically available drug parecoxib may be added to immunotherapy against human brain tumors. Furthermore, the discovery that IFN-γ plasma levels can be used to determine the ongoing in vivo immune response has translational potential.

Immunizations with IFNgamma secreting tumor cells can eliminate fully established and invasive rat gliomas.

Immunotherapy of malignant primary brain tumors holds the potential to improve the dismal prognosis after current clinical therapy. Although immunotherapy of experimental gliomas has been demonstrated to have the capacity to cure intracerebral tumors no convincing effects of immunotherapy have been shown in clinical trials. One reason for this could be that some of the models used do not display full features of human glioblastomas. The N29 rat gliomas exhibited all the histologic features of human glioblastoma multiforme including nuclear atypia, mitotic figures, necrosis, and diffuse infiltration into the normal brain tissue. Surprisingly, immunotherapy with autologous interferon gamma producing tumor cells against preestablished intracerebral N29 tumors yielded a higher cure rate than immunotherapy against less invasive tumors. Furthermore, when immunizations were postponed until day 5 after tumor establishment 50% of the animals survived. When immunizations were postponed until day 11 after tumor establishment no glioma-bearing animals were cured but survival was significantly prolonged. The superior effect of immunotherapy in the invasive N29 model compared with the less invasive tumors could depend on combined effects of up-regulation of major histocompatibility complex I and induction of major histocompatibility complex II plus CD80 after transfection and irradiation of the tumor cells used for immunizations. This study demonstrates that immunotherapy against experimental brain tumors indeed is feasible even against highly invasive and established tumors. These results strengthen the translational potential of immunotherapy against malignant brain tumors.