Anna Brunn

Activating L265P mutations of the MYD88 gene are common in primary central nervous system lymphoma.

Primary central nervous system lymphoma (PCNSL) is a special lymphoma entity. Although being a rare disease, the incidence of PCNSL has significantly raised in the last decades [3, 4], however, a specific standard therapeutic regimen is still a matter of debate [2]. Despite the fact that PCNSL histopathologically resemble diffuse large B cell lymphoma (DLBCL) [3, 4], they are characterized by unique clinical and molecular features [6], including their exclusive manifestation in the unique microenvironment of the immunologically privileged CNS. Activation of the nuclear factor jB (NF-jB) pathway is a hallmark of PCNSL [1, 5]. Various mechanisms of NF-jB activation have been identified in PCNSL. These include gains in chromosome 18q21 being present in 37% of PCNSL and activating mutations of the CARD11 gene being present in 16% of PCNSL [5, 6]. Moreover, NF-jB activation might be triggered by stimulation of either the B cell receptor pathway, the tumor necrosis factor or the toll-like receptor (TLR) pathway. Here, we provide evidence for deregulation of the TLR pathway in the pathogenesis of PCNSL through mutation of the myeloid differentiation primary response gene 88 (MYD88). Analysis of the MYD88 gene, the central integrator of the TLR pathway, in a series of 14 PCNSL by a biphased PCR approach followed by sequencing of all the exons revealed mutations in seven (50%) of the tumors (for details see supplementary information). Interestingly, in five of these seven (71%) PCNSL, i.e. 36% of all tumors analyzed, mutations were identified as a leucine to proline exchange at position 265 (L265P), which is an oncogenically activating mutation and has recently been shown to be of somatic origin [7]. In the remaining two PCNSL, MYD88 mutations resided at positions 103 and 143, respectively. In one tumor a nucleotide exchange corresponded to a silent mutation (L103L). In the other PCNSL the mutation resulted in an amino acid exchange (Q143E), which has not been reported before and the functional impact of which remains to be elucidated. Till date, MYD88 mutations have been described only in 9% of gastric mucosa-associated lymphoid tissue lymphoma, in 3% of chronic lymphocytic leukemia, in 5% of Burkitt’s lymphoma, and in systemic DLBCL, affecting 39% of the activated B cell like (ABC)-DLBCL subtype and 6% of the germinal center B cell like subgroup, respectively [7, 8]. Interestingly, 29% of systemic ABCDLBCL harbored the MYD88 L265P mutation [7]. Two of the five PCNSL (40%) with the recurrent MYD88 L265P mutation concomitantly harbored a CARD11 mutation, which results in the constitutive activation of the CARD11 protein [5]. While either the MYD88 L265P or the CARD11 mutation activates the NF-jB pathway, the combined presence of these mutations may act synergistically; thus, further enhancing NFjB activation [1, 5]. In addition to a direct effect on the NF-jB pathway, MYD88 mutations may alter the Electronic supplementary material The online version of this article (doi:10.1007/s00401-011-0891-2) contains supplementary material, which is available to authorized users.

Methyl-L-11C-methionine PET as a diagnostic marker for malignant progression in patients with glioma

Methyl-l-11C-methionine (11C-MET) PET has been shown to detect brain tumors with a high sensitivity and specificity. In this study, we investigated the potential of 11C-MET PET to noninvasively detect tumor progression in patients with gliomas. Moreover, we analyzed the relationship between changes in 11C-MET uptake on PET and changes in various molecular immunohistochemical markers during progression of gliomas. Methods: Twenty-four patients with histologically proven glioma were investigated repeatedly with 11C-MET PET. 11C-MET uptake was determined for a circular region of interest. Histologic and molecular analyses for tumor progression were performed after open surgery and stereotactic biopsy, respectively. Results: In patients with malignant progression, the mean increase in 11C-MET uptake was 54.4% (SD, 45.5%; range, 3.1%−162.2%), whereas in patients without a change in tumor grade, mean 11C-MET uptake did not significantly change (3.9%; SD, 13.7%; range, −24.4% to 26.3%). The difference in the change in 11C-MET uptake between the group with malignant progression and the group without malignant progression was highly significant (P < 0.001). Receiver-operating-curve analysis revealed a sensitivity of 90% and a specificity of 92.3% for the detection of malignant transformation by an increase in 11C-MET uptake of more than 14.6%. Increased 11C-MET uptake of more than 14.6% was indicative of malignant progression in all but 3 leave-one-out iterations. A detailed immunohistochemical analysis demonstrated a significant correlation between changes in 11C-MET uptake and the expression of vascular endothelial growth factor. Conclusion: These data suggest that 11C-MET-PET represents a noninvasive method to detect malignant progression in patients with gliomas. Moreover, the increase in 11C-MET uptake during malignant progression is reflected by an increase in angiogenesis-promoting markers as vascular endothelial growth factor.

Mutations of CARD11 but not TNFAIP3 may activate the NF-κB pathway in primary CNS lymphoma

Primary CNS lymphoma (PCNSL), the intracerebral subgroup of diffuse large B cell lymphoma (DLBCL), shows evidence for aberrant activation of the nuclear factor (NF)-κB pathway. In order to identify potential activators of the NF-κB complex, we analyzed the CARD11 and TNFAIP3 genes for the presence of somatic mutations and TNFAIP3 for aberrant promoter methylation in PCNSL. We also compared PCNSL to spinal DLBCL, because CARD11 and TNFAIP3 mutations have been described in systemic DLBCL. CARD11 mutations, located in the coiled-coil region, which may activate NF-κB, were detected in 16% (5/32) of PCNSL, while TNFAIP3 mutations were detected in 3% (1/32) of PCNSL. In PCNSL, all CARD11 mutations were heterozygous, in-frame, induced amino acid exchanges, and presumably led to activation of this oncogene. Spinal DLBCL harbored mutations of CARD11 and TNFAIP3 in 10% (1/10) and 20% (2/10) of cases, respectively. In both PCNSL and spinal DLBCL, mutations in CARD11 and TNFAIP3 were mutually exclusive. TNFAIP3 was unmethylated in all PCNSLs (30/30) and spinal DLBCLs (10/10). We conclude that mutations of the oncogene CARD11 may contribute to NF-κB activation and thereby play a role in the pathogenesis of PCNSL, while, in contrast to systemic DLBCL, inactivation of TNFAIP3 either by mutation or methylation seems to be of minor significance.

Gp130-Dependent Astrocytic Survival Is Critical for the Control of Autoimmune Central Nervous System Inflammation

Astrocytes are activated in experimental autoimmune encephalomyelitis (EAE) and have been suggested to either aggravate or ameliorate EAE. However, the mechanisms leading to an adverse or protective effect of astrocytes on the course of EAE are incompletely understood. To gain insight into the astrocyte-specific function of gp130 in EAE, we immunized mice lacking cell surface expression of gp130, the signal-transducing receptor for cytokines of the IL-6 family, with myelin oligodendrocyte glycoprotein35–55 peptide. These glial fibrillary acid protein (GFAP)-Cre gp130fl/fl mice developed clinically a significantly more severe EAE than control mice and succumbed to chronic EAE. Loss of astrocytic gp130 expression resulted in apoptosis of astrocytes in inflammatory lesions of GFAP-Cre gp130fl/fl mice, whereas gp130fl/fl control mice developed astrogliosis. Astrocyte loss of GFAP-Cre gp130fl/fl mice was paralleled by significantly larger areas of demyelination and significantly increased numbers of CD4 T cells in the CNS. Additionally, loss of astrocytes in GFAP-Cre gp130fl/fl mice resulted in a reduction of CNS regulatory Foxp3+ CD4 T cells and an increase of IL-17–, IFN-γ–, and TNF-producing CD4 as well as IFN-γ– and TNF-producing CD8 T cells, illustrating that astrocytes regulate the phenotypic composition of T cells. An analysis of mice deficient in either astrocytic gp130– Src homology region 2 domain-containing phosphatase 2/Ras/ERK or gp130–STAT1/3 signaling revealed that prevention of astrocyte apoptosis, restriction of demyelination, and T cell infiltration were dependent on the astrocytic gp130–Src homology region 2 domain-containing phosphatase 2/Ras/ERK, but not on the gp130–STAT1/3 pathway, further demonstrating that gp130-dependent astrocyte activation is crucial to ameliorate EAE.

Diagnosis of leptomeningeal disease in diffuse large B-cell lymphomas of the central nervous system by flow cytometry and cytopathology.

Reliable detection of leptomeningeal disease has the potential of facilitating the diagnosis of central nervous system (CNS) lymphoma and is important for therapeutic considerations. Currently, the standard diagnostic procedure for the detection of lymphoma in the cerebrospinal fluid is cytopathology. To improve the limited specificity and sensitivity of cytopathology, flow cytometry has been suggested as an alternative. Here, we evaluated multi‐parameter flow cytometry in combination with conventional cytopathology in cerebrospinal fluid (CSF) samples from 30 patients with primary CNS lymphoma and seven patients with secondary CNS lymphoma. Overall, in 11 of 37 (29.7%) patients with CNS lymphoma, lymphoma cells were detected in CSF by flow cytometry, while cytopathology was less sensitive displaying unequivocally malignant CSF cells in only seven of all 37 (18.9%) patients. Six (16.2%) patients showed cytopathological results suspicious of lymphoma; however, in only one of these patients, the diagnosis of CSF lymphoma cells could be confirmed by flow cytometry. In primary CNS lymphomas (PCNSL), seven of 30 (23.3%) patients were positive for CSF lymphoma cells in flow cytometry, in contrast to four (13.3%) patients with PCNSL with definitely positive cytopathology. In summary, our results suggest that multi‐parameter flow cytometry increases the sensitivity and specificity of leptomeningeal disease detection in CNS lymphomas. Both methods should be applied concurrently for complementary diagnostic assessment in patients with CNS lymphoma.

Recurrent Inactivation of the PRDM1 Gene in Primary Central Nervous System Lymphoma

Primary lymphomas of the CNS (PCNSLs) show molecular features of the late germinal center exit B-cell phenotype and are impaired in their terminal differentiation as indicated by a lack of immunoglobulin class switching. Because the positive regulatory domain I protein with ZNF domain (PRDM1/BLIMP1) is a master regulator of terminal B-cell differentiation into plasma cells, we investigated a series of 21 PCNSLs for the presence of mutations in the PRDM1 gene and alterations in the expression pattern of the PRDM1 protein. Direct sequencing of all coding exons of the PRDM1 gene identified deleterious mutations associated with abrogation of PRDM1 protein expression in 4 of 21 (19%) PCNSLs. Thus, similar to systemic diffuse large B-cell lymphomas, PRDM1 may be a tumor suppressor in some PCNSL and contribute to lymphomagenesis by impairing terminal differentiation.

Expression pattern and cellular sources of chemokines in primary central nervous system lymphoma

The expression pattern of a subset of chemokines and their corresponding receptors was investigated in primary central nervous system lymphomas (PCNSL). The tumor cells consistently expressed CXCR4, CXCL12, CXCR5, and CXCL13, both at mRNA and protein levels. Cerebral endothelial cells were positive for CXCL12 and CXCL13, while reactive astrocytes and microglial cells expressed CXCL12, CCR5, and CCR6. Inflammatory T cells in PCNSL were characterized by CCR5 and CCR6 positivity. Taken together, our data indicate a cell type-specific repertoire of chemokine and chemokine receptor expression in PCNSL suggesting that chemokine-mediated interactions facilitate crossing of the blood-brain barrier as well as intracerebral dissemination of PCNSL cells. In addition, chemokines expressed by tumor cells may contribute to induction of reactive glial changes and influence the composition of inflammatory infiltrates in PCNSL. Therefore, cell type specific expression of distinct chemokine profiles likely plays a role in the pathogenesis of PCNSL and may contribute to their characteristic histological appearance.

Transcriptional Profiling of the Nuclear Factor-κB Pathway Identifies a Subgroup of Primary Lymphoma of the Central Nervous System With Low BCL10 Expression

Abstract Recent studies point to a role of nuclear factor (NF)-&kgr;B signaling in a subset of diffuse large B cell lymphomas. We have analyzed the expression of 21 genes encoding NF-&kgr;B family members, upstream modulators, and targets in 32 primary central nervous system lymphomas (PCNSLs) by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Compared with nonmalignant germinal center centroblasts, expression of BCL10, REL, IAP1, and TRAF1 was significantly lower in PCNSLs, whereas that of BAX, BCLXL, BCL2, MALT1, CARD9, CARD10, CARD11, CARD14, CCND2, cFLIP, RELA, RELB, NFKB1, NFKB2, and IRF4 was higher. Hierarchical clustering of gene expression data revealed two distinct subgroups of PCNSLs, which were characterized by significantly different transcriptional levels, predominantly of BCL10, but also of REL and IAP1. Thus, these quantitative RT-PCR data with expression of genes of the NF-&kgr;B family as well as NF-&kgr;B-regulated genes together with immunohistochemical detection of nuclear RELA and REL indicate activation of the NF-&kgr;B pathway in PCNSLs, which may contribute to their high proliferative activity and the low level of apoptosis.

Peripheral neuropathy in systemic lupus erythematosus: pathomorphological features and distribution pattern of matrix metalloproteinases

Matrix metalloproteinases (MMPs) are endoproteases that have been implicated in the pathogenesis of inflammatory and vasculitic neuropathies. In systemic lupus erythematosus (SLE), a peripheral neuropathy is frequently seen that is thought to be caused by ischemic nerve damage due to vasculopathy and/or vasculitis of the nutritional vessels. However, the exact pathomechanisms causing SLE neuropathy are largely unknown. Elevated MMP levels have been reported in the serum of SLE patients. Supposing that altered expression of MMPs may contribute to vessel wall damage in SLE neuropathy, we investigated the expression of MMP-1, -2, -3, -9, -10 and -13, and their tissue inhibitors (TIMP-1 and -2) in sural nerves from 12 SLE patients in comparison to normal controls. All MMPs could be detected within blood vessel walls from SLE nerves, whereas in controls MMP-3 and MMP-9 was not found. TIMP-1 and TIMP-2, on the other hand, were not informative. Generally, small and large nutritional vessels in the epineurium were immunoreactive for MMPs and TIMPs. Mononuclear cells, which expressed MMP-1, - 3, -10, -13, and TIMP-1 were also observed in most of the SLE nerves, mostly around epineurial blood vessels, but only occasionally in controls. This indicates that expression of MMPs in mononuclear cells may be related to leukocyte trafficking through the vessel walls. However, the density of TIMP-positive and MMP-positive inflammatory cells did not correlate with morphometric parameters regarding the severity of the neuropathy. Our findings suggest that especially the up-regulation of MMP-3 and MMP-9 within the vessel walls may be responsible for the vascular damage seen in SLE and the resulting chronic combined axonal and demyelinating type of neuropathy frequently found in SLE.

Stereotactic interstitial radiosurgery for intracranial Rosai-Dorfman disease

Background:Rosai-Dorfman disease is an idiopathic, histoproliferative disorder characterized by massive painless lymphadenopathy. The favorable treatment of Rosai-Dorfman disease affecting the central nervous system is surgical resection. Histological and immunohistochemical confirmation is essential for a definitive diagnosis.Case Report:The authors report on a 10-year-old patient with Rosai-Dorfman disease of the central nervous system who presented with increased intracranial pressure. She was treated by stereotactic interstitial irradiation using iodine-125 seeds (interstitial radiosurgery).Result:Stereotactic surgery was performed without complications. The patient recovered well to a normal neurologic status. MR images showed a complete remission 49 months after treatment.Conclusion:The presented case demonstrates the high efficacy and safety of interstitial irradiation for intracranial Rosai-Dorfman disease. Hence, interstitial radiosurgery could be an appropriate therapeutic option for high-risk resectable intracranial Rosai-Dorfman disease.Hintergrund:Das Rosai-Dorfman-Syndrom ist eine idiopathische, proliferative Erkrankung, welche durch eine schmerzlose Lymphknotenschwellung charakterisiert ist. Bei Befall des zentralen Nervensystems ist die mikrochirurgische Resektion die Therapie der ersten Wahl. Die histologische und immunhistochemische Analyse ist entscheidend für die definitive Diagnose.Fallbericht:Die Autoren berichten über eine 10-jährige Patientin mit erhöhten Hirndruckzeichen und einem zerebralen Rosai-Dorfman-Syndrom. Primär wurde eine stereotaktisch geführte interstitielle Brachytherapie mit Jod-125-Seeds durchgeführt.Ergebnis:Die Behandlung konnte ohne Komplikationen durchgeführt werden. Der neurologische Zustand normalisierte sich. MRT-Veraufskontrollen zeigten 49 Monate nach der Behandlung eine komplette Tumorremission.Schlussfolgerung:Der vorliegende Fall veranschaulicht die Effizienz der stereotaktisch geführten interstitiellen Seedbestrahlung zur Behandlung eines intrakraniellen Rosai-Dorfman-Syndroms und sollte insbesondere bei inoperablen Tumoren als Therapieoption berücksichtigt werden.