Tadej Strojnik

Lysosomal Enzymes, Cathepsins in Brain Tumour Invasion

The expression patterns of different classes of peptidases in central nervous system (CNS) tumours have been most extensively studied in astrocytomas and meningiomas. Although the two types of tumours are very different in most respects, both may invade locally into normal brain. This process of invasion includes increased synthesis and secretion of lysosomal proteolytic enzymes – cathepsins.Aspartic endopeptidase cathepsin (Cat) D levels were found to be elevated in high-grade astrocytoma and partial inhibition of glioblastoma cell invasion by anti-Cat D antibody suggests that the enzyme activity is involved in the invasion process. Several studies on cysteine endopeptidase (CP) Cat B in gliomas agreed that transcript abundance, protein level and activity of Cat B increased in high-grade astrocytoma cultures compared with low-grade astrocytoma cultures and normal brain. Moreover, in glioma biopsies Cat B levels correlated with evidence of clinical invasion and it has been demonstrated that Cat B both in tumour cells and in endothelial cells can serve as a new biological marker for prognosis in glioblastoma patients. A high level of Cat B protein was also a diagnostic marker for invasive types of meningioma, distinguishing between histomorphologically benign, but invasive meningiomas and noninvasive, so-called clear–benign meningiomas. Cat L was also significantly increased in high-grade astrocytoma compared with low-grade astrocytoma and normal brain. Specific Cat L antibodies and antisense Cat L RNA transfection significantly lowered glioblastoma cell invasion. In meningioma, Cat L was a less-significant marker of invasion than Cat B. In contrast to cathepsins, the activities of endogenous cysteine peptidase inhibitors (CPIs), including stefins, cystatins and kininogens, were significantly higher in benign and atypical meningioma cell extracts than in malignant meningioma, and low-grade compared to high-grade astrocytoma. However, very low levels of stefins A and B were found in meningioma and glioblastoma tissues. Further studies on the expression levels and balance between cysteine endopeptidases (CPs) and CPIs would improve the clinical application of cathepsins in prognosis, which would lead to more-informed therapeutic strategies.

Cathepsins B and L are markers for clinically invasive types of meningiomas.

OBJECTIVEMeningiomas are benign neoplasms that derive from coverings of the brain. Approximately 10% of benign tumors progress into atypical, malignant tumors, thus constituting a subset of histopathologically benign tumors that are clinically invasive. The aim of this study was to evaluate cathepsins B and L and their inhibitors as new prognostic factors that could distinguish malignant from benign forms of meningiomas. METHODSUsing immunohistochemical analysis and specific monoclonal antibodies, we evaluated the levels of cathepsins B and L and the levels of the endogenous cysteine proteinase inhibitors stefin A and cystatin C in 88 meningiomas. Immunohistochemical scores were determined as the sum of the frequency (0–3) and intensity (0–3) of immunolabeling of the tumor cells. RESULTSOf the 88 tumors studied, 67 were benign meningiomas and 21 were atypical meningiomas. Among the benign group, nine tumors had certain features of malignancy. These tumors were classified as border benign meningiomas, and the rest were classified as clear benign meningiomas. A high immunohistochemical score (4–6) for cathepsin B was more frequent in atypical tumors than in clear benign tumors (P < 0.001). Compared with clear benign tumors, higher cathepsin B immunohistochemical scores were found in atypical tumors (P < 0.001) and border benign tumors (P < 0.03). No statistical difference in immunohistochemical staining of cathepsin B was found between atypical meningiomas and border benign meningiomas. Higher expression of cathepsin L was found in atypical tumors as compared with clear benign tumors (P < 0.03), but it was not observed in border benign as compared with clear benign meningiomas. No immunostaining for stefin A and cystatin C was detected in any of the tumors. CONCLUSIONWe show that the levels of cathepsin B and cathepsin L antigens are significantly higher in invasive types of benign meningioma. Specifically, cathepsin B may be used as a diagnostic marker to distinguish histomorphologically benign but invasive meningiomas from histomorphologically clear benign tumors.

Cathepsin B and its inhibitor stefin A in brain tumors.

Cysteine protease cathepsin B (CatB) and its endogenous inhibitor stefin A (StA) play an important role in tumor progression. Increase of CatB expression and lower levels of its inhibitors were associated with tumor malignancy in brain tumors. In this study of 100 patients, CatB was localized by immunostaining to both, tumor and endothelial cells of primary brain tissue. Significant correlation with poor prognosis was found by univariate Cox’s regression model. Intense overall immunostaining and immunostaining in endothelial cells alone were prognostic for survival (p=0.003 in both). When comparing CatB expression at mRNA level, we found considerable differences between center and periphery of a tumor as well as between different tumor samples. StA mRNA was only detected in benign, but not in malignant tissues. We suggest that screening of cysteine-protease genes expression can be applied in clinical prognosis of brain tumors.

Infections of external ventricular drainages

AimThe most common complication of the external ventricular drainage (EVD) is an infection, which is linked to different risk factors. We tried to investigate possible links between different risk factors and incidences of an infection of the EVD.Materials and MethodsWe used a retrospective method and examined records of 176 patients. These patients were admitted to the University clinical centre Maribor between January 2004–December 2005 and January 2009–December 2010 and had an EVD inserted.ResultsOur research had shown a high overall occurrence of infection, namely 23.3 %. We found a significantly higher incidence of infection in patients with a subarachnoid haemorrhage as an etiology. The likelihood of an infection increased with each catheter replacement and with EVDs inserted for more than 7 days. The incidence of infection in the group of patients with an impregnated catheter was significantly lower. The protective role of impregnated catheters is larger in terms of local effect and smaller in broader effect in CSF space.ConclusionsAn easy retrograde route for microorganisms to enter ventricular space should be prevented with appropriate wound care and by replacing EVDs only in cases of mechanical dysfunction or extraction.

Different approaches to surgical treatment of arachnoid cysts.

SummaryAlthough most arachnoid cysts remain static fluid-filled compartments throughout life, some become enlarged, exerting a mass effect on adjacent neural structures. The decision-making process for patients with arachnoid cysts still represents a challenge for the neurosurgeon. We report three cases of intracranial arachnoid cysts treated with different surgical approaches: (i) endoscopic fenestration of the cyst into the lateral ventricle; (ii) a cystoperitoneal shunt; (iii) a cystoperitoneal shunt and establishment of communication between the cyst and the fourth ventricle with the help of an endoscope. Given the advances in instrumentation over the past decade, it is probable that most arachnoid cysts will be managed endoscopically in the future.