Anti-CD20 inhibits T cell-mediated pathology and microgliosis in the rat brain.

OBJECTIVE: The mechanism of action of anti-B cell therapy in multiple sclerosis (MS) is not fully understood. Here, we compared the effect of anti-CD20 therapy on microglial activation in two distinct focal rat models of MS. METHODS: The effect of anti-CD20 therapy on lesion formation and extralesional microglial activation was evaluated in the fDTH-EAE (experimental allergic encephalomyelitis) model, which is a focal demyelinating type-IV delayed-type hypersensitivity lesion. For comparison, effects were also assessed in the focal humoral MOG model induced by intracerebral injection of cytokine in myelin oligodendrocyte glycoprotein immunized rats. Microglial activation was assessed in situ and in vivo using the TSPO SPECT ligand [(125)I]DPA-713, and by immunostaining for MHCII. The effect of treatment on demyelination and lymphocyte recruitment to the brain were evaluated. RESULTS: Anti-CD20 therapy reduced microglial activation, and lesion formation in the humoral model, but it was most effective in the antibody-independent fDTH-EAE. Immunohistochemistry for MHCII also demonstrated a reduced volume of microglial activation in the brains of anti-CD20-treated fDTH-EAE animals, which was accompanied by a reduction in T-cell recruitment and demyelination. The effect anti-CD20 therapy in the latter model was similarly strong as compared to the T-cell targeting MS compound FTY720. INTERPRETATION: The suppression of lesion development by anti-CD20 treatment in an antibody-independent model suggests that B-cells play an important role in lesion development, independent of auto-antibody production. Thus, CD20-positive B-cell depletion has the potential to be effective in a wider population of individuals with MS than might have been predicted from our knowledge of the underlying histopathology.

Glial activation in the early stages of brain metastasis: TSPO as a diagnostic biomarker.

UNLABELLED: Metastatic spread of cancer cells to the brain is associated with high mortality, primarily because current diagnostic tools identify only well-advanced metastases. Brain metastases have been shown to induce a robust glial response, including both astrocyte and microglial activation. On the basis of these findings, we hypothesized that this stromal response may provide a sensitive biomarker of tumor burden, in particular through the use of SPECT/PET imaging agents targeting the translocator protein (TSPO) that is upregulated on activated glia. Our goals, therefore, were first to determine the spatial and temporal profile of glial activation during early metastasis growth in vivo and second to assess the potential of the radiolabeled TSPO ligand (123)I-DPA-713 for early detection of brain metastases. METHODS: Metastatic mouse mammary carcinoma 4T1-green fluorescent protein cells were injected either intracerebrally or intracardially into female BALB/c mice to induce brain metastases. Astrocyte and microglial activation was assessed immunohistochemically over a 28-d period, together with immunofluorescence detection of TSPO upregulation. Subsequently, SPECT imaging and autoradiography were used to determine in vivo binding of (123)I-DPA-713 at metastatic sites. RESULTS: Dynamic astrocyte and microglial activation was evident throughout the early stages of tumor growth, with the extent of astrocyte activation correlating significantly with tumor size (P < 0.0001). Microglial activation appeared to increase more rapidly than astrocyte activation at the earlier time points, but by later time points the extent of activation was comparable between the glial cell types. Upregulation of TSPO expression was found on both glial populations. Both autoradiographic and in vivo SPECT data showed strong positive binding of (123)I-DPA-713 in the intracerebrally induced model of brain metastasis, which was significantly greater than that observed in controls (P < 0.05). (123)I-DPA-713 binding was also evident autoradiographically in the intracardially induced model of brain metastasis but with lower sensitivity because of smaller tumor size (∼ 100-µm diameter vs. ∼ 600-µm diameter in the intracerebral model). CONCLUSION: These data suggest that the glial response to brain metastasis may provide a sensitive biomarker of tumor burden, with a tumor detection threshold lying between 100 and 600 µm in diameter. This approach could enable substantially earlier detection of brain metastases than the current clinical approach of gadolinium-enhanced MR imaging.

C-H···X (X = O, N or π) interactions in benzyl carbamate.

The crystal packing and interaction energy of benzyl carbamate, C(8)H(9)NO(2), have been analysed in detail by the PIXEL method. Benzyl carbamate forms layers of hydrogen-bonded molecules, with the layers connected by weaker C-H...π interactions. According to the PIXEL analysis, combinations of C-H...X (X = O, N or π) interactions are comparable in energy with hydrogen bonding. These interactions are necessary for explaining the geometry and the assembly of the layers.

A synthetic approach to ervatamine-silicine alkaloids. Enantioselective total synthesis of (-)-16-episilicine.

Starting from an appropriate unsaturated phenylglycinol-derived oxazolopiperidone lactam, the synthesis of (-)-16-episilicine is reported, the key steps being a stereoselective conjugate addition, a stereoselective alkylation, and a ring-closing metathesis reaction. This represents the first enantioselective total synthesis of an alkaloid of the silicine group.

An unexpected oxidation in the generation of cyclopenta[c]piperidines by ring-closing metathesis.

Ring-closing metathesis reaction of dienes A (n = 1, R = CO(2)R') leads to fused cyclopentenones C instead of the expected cyclopentene derivatives B. RCM reaction of the other dienes A takes place satisfactorily, affording the expected fused cycloalkene derivatives B. Cyclohexene B (n = 2, R = CO(2)R') also undergoes oxidation to the corresponding cyclohexenone C.

New approach to the stereoselective synthesis of tertiary methyl ethers.

The Lewis acid-mediated addition of titanium enolates from 1 to dimethyl ketals of aliphatic methyl ketones followed by removal of the chiral auxiliary furnishes enantiomerically pure derivatives containing a tertiary methyl ether and a contiguous stereocenter in a straightforward manner.

Enantioselective total synthesis of the indole alkaloid 16-episilicine.

The first total synthesis of (-)-16-episilicine has been completed from a phenylglycinol-derived bicyclic lactam, the key steps being stereoselective conjugate addition and alkylation reactions, and a ring-closing metathesis.