Angelika Gutenberg

A Radiologic Score to Distinguish Autoimmune Hypophysitis from Nonsecreting Pituitary Adenoma Preoperatively

BACKGROUND AND PURPOSE: Autoimmune hypophysitis (AH) mimics the more common nonsecreting pituitary adenomas and can be diagnosed with certainty only histologically. Approximately 40% of patients with AH are still misdiagnosed as having pituitary macroadenoma and undergo unnecessary surgery. MR imaging is currently the best noninvasive diagnostic tool to differentiate AH from nonsecreting adenomas, though no single radiologic sign is diagnostically accurate. The purpose of this study was to develop a scoring system that summarizes numerous MR imaging signs to increase the probability of diagnosing AH before surgery. MATERIALS AND METHODS: This was a case-control study of 402 patients, which compared the presurgical pituitary MR imaging features of patients with nonsecreting pituitary adenoma and controls with AH. MR images were compared on the basis of 16 morphologic features besides sex, age, and relation to pregnancy. RESULTS: Only 2 of the 19 proposed features tested lacked prognostic value. When the other 17 predictors were analyzed jointly in a multiple logistic regression model, 8 (relation to pregnancy, pituitary mass volume and symmetry, signal intensity and signal intensity homogeneity after gadolinium administration, posterior pituitary bright spot presence, stalk size, and mucosal swelling) remained significant predictors of a correct classification. The diagnostic score had a global performance of 0.9917 and correctly classified 97% of the patients, with a sensitivity of 92%, a specificity of 99%, a positive predictive value of 97%, and a negative predictive value of 97% for the diagnosis of AH. CONCLUSIONS: This new radiologic score could be integrated into the management of patients with AH, who derive greater benefit from medical as opposed to surgical treatment.

Expression of tyrosine kinases FAK and Pyk2 in 331 human astrocytomas

The progression of malignancy from astrocytomas to glioblastomas remains clinically as well as histopathologically unpredictable. The focal adhesion kinase (FAK) and the proline-rich tyrosine kinase (Pyk2) show a high expression in glioma cell lines and have an influence on increased cell proliferation and migration of glioma cells in vitro and in vivo. The aim of this study was to correlate the coexpression of FAK and Pyk2 to the WHO grade of malignancy in human astrocytomas. Immunohistochemical staining scores of FAK and Pyk2 were analyzed in 331 astrocytomas and correlated to each other and to the WHO grade. Significant coexpression of FAK and Pyk2 in astrocytomas was demonstrated. Pyk2 expression occurred much more frequently and with higher expression scores within the different WHO grades. Beyond this, a significant correlation between the WHO grade of malignancy of astrocytomas and the expression of FAK, as well as of Pyk2, was detected. This connection and the roles of these two tyrosine kinases in the progression of tumors should be confirmed by further studies.

Immunopathology of primary hypophysitis: implications for pathogenesis.

The etiology of primary hypophysitis is still not fully elucidated. Histologically, primary hypophysitis includes three different main subtypes: lymphocytic (LYH), granulomatous (GRH), and xanthomatous (XH) hypophysitis. Clinical and laboratory findings suggest an autoimmune basis in primary hypophysitis. Controversy still exists about the composition of the inflammatory infiltrate and the relevant immunopathogenic effector mechanisms. Therefore, 21 cases of primary hypophysitis of different subtypes were analyzed with respect to the expression of lymphocyte and macrophage antigens as well as MHC class I and II molecules of the inflammatory infiltrate and the resident pituitary acinar cells. Lymphocyte infiltration in LYH (n = 15), but also in GRH (n = 4) and XH (n = 2), mainly consisted of T cells, while B cells were rare. Independent from the histopathologic subtype, T cell subsets showed equal ratios of CD4+ to CD8+ T cells. Highest numbers of activated CD8+ T cells were observed in LYH presenting during pregnancy, surrounding or even infiltrating preserved pituitary acinar cells. Moreover, an increased rate of activated CD8+ T cells correlated with a shorter duration of clinical symptoms. In LYH, aberrant expression of MHC class II antigens as well as overexpression of MHC class I molecules on pituitary cells were observed. Independent of the histologic subtype, macrophages mostly expressed markers of chronic activation and showed MHC class II positivity. LYH, GRH, and XH, although heterogeneous in their histologic appearance and in age distribution, exhibit a similar if not identical immunohistologic profile. It is highly likely that direct T cell-mediated cytotoxicity through CD8+ T cells, with the initial help of CD4+ T cells, is pivotal in the pathogenesis of primary hypophysitis, implicating a target autoantigen expressed by pituitary cells.

Novel autoantigens in autoimmune hypophysitis

Backgroundu2002 Pituitary autoantibodies are found in autoimmune hypophysitis and other conditions. They are a marker of pituitary autoimmunity but currently have limited clinical value. The methods used for their detection lack adequate sensitivity and specificity, mainly because the pathogenic pituitary autoantigen(s) are not known and therefore antigen‐based immunoassays have not been developed.

Autoimmune hypophysitis of SJL mice: clinical insights from a new animal model.

Autoimmune hypophysitis (AH) is a rare but increasingly recognized disease of the pituitary gland. Its autoantigens are unknown, and the management is difficult because it is often misdiagnosed as a nonsecreting adenoma. By immunizing female SJL/J mice with mouse pituitary extracts, we established a new mouse model of experimental AH. Immunized mice developed severe lymphocytic infiltration in the anterior pituitary that closely mimicked the human pathology. In the early phase of experimental AH, the pituitary enlarged, consistent with the compression symptoms reported by hypophysitis patients at presentation. In the florid phase, adrenal insufficiency and pituitary antibodies developed, in strong correlation with the pituitary pathology. In the late phase, hypothyroidism ensued, and the pituitary gland became atrophic. Using immune sera as probes in a two-dimensional immunoblotting screen followed by mass spectrometry, we identified several proteins that could function as pituitary autoantigens. These findings provide new insights into the pathogenesis of AH, and establish a platform for developing novel diagnostic biomarkers and therapeutics.

Organotypic slice cultures of human glioblastoma reveal different susceptibilities to treatments

Background Glioblastoma multiforme is the most common lethal brain tumor in human adults, with no major therapeutic breakthroughs in recent decades. Research is based mostly on human tumor cell lines deprived of their organotypic environment or inserted into immune-deficient animals required for graft survival. Here, we describe how glioblastoma specimens obtained from surgical biopsy material can be sectioned and transferred into cultures within minutes. Methods Slices were kept in 6-well plates, allowing direct observation, application of temozolomide, and irradiation. At the end of experiments, slice cultures were processed for histological analysis including hematoxylin-eosin staining, detection of proliferation (Ki67), apoptosis/cell death (cleaved caspase 3, propidium iodide), DNA double-strand breaks (γH2AX), and neural subpopulations. First clinical trials employed irradiation with the heavy ion carbon for the treatment of glioblastoma patients, but the biological effects and most effective dose regimens remain to be established. Therefore, we developed an approach to expose glioblastoma slice cultures to 12C and X-rays. Results We found preservation of the individual histopathology over at least 16 days. Treatments resulted in activation of caspase 3, inhibition of proliferation, and cell loss. Irradiation induced γH2AX. In line with clinical observations, individual tumors differed significantly in their susceptibility to temozolomide (0.4%–2.5% apoptosis and 1%–15% cell loss). Conclusion Glioblastoma multiforme slice cultures provide a unique tool to explore susceptibility of individual tumors for specific therapies including heavy ions, thus potentially allowing more personalized treatments plus exploration of mechanisms of (and strategies to overcome) tumor resistance.

Microglia inflict delayed brain injury after subarachnoid hemorrhage

Inflammatory changes have been postulated to contribute to secondary brain injury after aneurysmal subarachnoid hemorrhage (SAH). In human specimens after SAH as well as in experimental SAH using mice, we show an intracerebral accumulation of inflammatory cells between days 4 and 28 after the bleeding. Using bone marrow chimeric mice allowing tracing of all peripherally derived immune cells, we confirm a truly CNS-intrinsic, microglial origin of these immune cells, exhibiting an inflammatory state, and rule out invasion of myeloid cells from the periphery into the brain. Furthermore, we detect secondary neuro-axonal injury throughout the time course of SAH. Since neuronal cell death and microglia accumulation follow a similar time course, we addressed whether the occurrence of activated microglia and neuro-axonal injury upon SAH are causally linked by depleting microglia in vivo. Given that the amount of neuronal cell death was significantly reduced after microglia depletion, we conclude that microglia accumulation inflicts secondary brain injury after SAH.

Nogo-A expression in glial CNS tumors - A tool to differentiate between oligodendrogliomas and other gliomas?

Gliomas are the most frequent primary brain tumors. In a minority of cases, the differentiation between astrocytomas and oligodendrogliomas based on morphologic characteristics alone can be difficult; though it is important, as patients with oligodendrogliomas follow a more favorable clinical course. Here we report on the immunohistochemical expression pattern of the oligodendrocytic marker Nogo-A in 113 central nervous system tumors including 28 oligodendrogliomas [15, World Health Organization (WHO) grade II; 13, grade WHO III], 50 astrocytomas [10, grade WHO II; 11, grade WHO III; 29 glioblastoma multiforme (GBM)], 11 ependymomas WHO grade II, 7 central neurocytomas, 2 dysembryoplastic neuroepithelial tumors (DNTs), 5 clear cell meningiomas, and 10 metastases to the brain. The oligodendrocytic marker Nogo-A was found to be strongly expressed in 71% of oligodendrogliomas, but in 0% of ependymomas WHO grade II, astrocytomas WHO grade II or III, DNTs, central neurocytomas, or clear cell meningiomas. In GBM, a subgroup of tumors (24%) showed strong expression of Nogo-A coincidently with Ki67 positivity but glial fibrillary acidic protein-negativity. However, neither in oligodendrogliomas nor GBM was a correlation between the loss of 1p19q and the extent of Nogo-A expression observed. Our findings indicate that Nogo-A is strongly expressed in the majority of oligodendrogliomas and might be a helpful marker to distinguish oligodendrogliomas from astrocytomas WHO grades II and III as well as ependymomas. They also support the hypothesis that GBM may be a heterogeneous group of tumors derived from different progenitor cells.

Pregnancy, postpartum autoimmune thyroiditis, and autoimmune hypophysitis: Intimate relationships

Autoimmune diseases comprise a group of about 85 heterogeneous conditions that can affect virtually any organ and tissue in the body. Many autoimmune diseases change significantly during pregnancy: some ameliorate, some worsen, and others are unaffected. Two autoimmune diseases present prominently in relation to pregnancy: postpartum autoimmune thyroiditis and autoimmune hypophysitis. This article will review the current state of knowledge of the immunological changes that occur during normal pregnancy, and will explore the striking temporal association with pregnancy observed in thyroiditis and hypophysitis.

Pituitary and systemic autoimmunity in a case of intrasellar germinoma

Germinomas arising in the sella turcica are difficult to differentiate from autoimmune hypophysitis because of similar clinical and pathological features. This differentiation, nevertheless, is critical for patient care due to different treatments of the two diseases. We report the case of an 11-year-old girl who presented with diabetes insipidus and growth retardation, and was found to have an intra- and supra-sellar mass. Initial examination of the pituitary biopsy showed diffuse lymphocytic infiltration of the adenohypophysis and absent placental alkaline phosphatase expression, leading to a diagnosis of hypophysitis and glucocorticoid treatment. Because of the lack of clinical and radiological response, the pituitary specimen was re-examined, revealing this time the presence of scattered c-kit and Oct4 positive germinoma cells. The revised diagnosis prompted the initiation of radiotherapy, which induced disappearance of the pituitary mass. Immunological studies showed that the patient’s serum recognized antigens expressed by the patient’s own germinoma cells, as well as pituitary antigens like growth hormone and systemic antigens like the Sjögren syndrome antigen B and alpha-enolase. The study first reports the presence of pituitary and systemic antibodies in a patient with intrasellar germinoma, and reminds us that diffuse lymphocytic infiltration of the pituitary gland and pituitary antibodies does not always indicate a diagnosis of autoimmune hypophysitis.