Immunohistochemical Method and Histopathology Judging for the Systemic Synuclein Sampling Study (S4).

Immunohistochemical (IHC) α-synuclein (Asyn) pathology in peripheral biopsies may be a biomarker of Parkinson disease (PD). The multi-center Systemic Synuclein Sampling Study (S4) is evaluating IHC Asyn pathology within skin, colon and submandibular gland biopsies from 60 PD and 20 control subjects. Asyn pathology is being evaluated by a blinded panel of specially trained neuropathologists. Preliminary work assessed 2 candidate immunoperoxidase methods using a set of PD and control autopsy-derived sections from formalin-fixed, paraffin-embedded blocks of the 3 tissues. Both methods had 100% specificity; one, utilizing the 5C12 monoclonal antibody, was more sensitive in skin (67% vs 33%), and was chosen for further use in S4. Four trainee neuropathologists were trained to perform S4 histopathology readings; in subsequent testing, their scoring was compared to that of the trainer neuropathologist on both glass slides and digital images. Specificity and sensitivity were both close to 100% with all readers in all tissue types on both glass slides and digital images except for skin, where sensitivity averaged 75% with digital images and 83.5% with glass slides. Semiquantitative (0-3) density score agreement between trainees and trainer averaged 67% for glass slides and 62% for digital images.

A Gain-Of-Function Mutation in the Plcg2 Gene Protects Mice from Helicobacter felis-Induced Gastric MALT Lymphoma.

Gastric mucosa-associated lymphoid tissue (MALT) lymphomas develop from a chronic Helicobacter infection. Phospholipase C gamma 2 (PLCG2) is important for B-cell survival and proliferation. We used BALB/c mice with a gain-of-function mutation in the Plcg2 gene (Ali5) to analyze its role in the development of gastric MALT lymphoma. Heterozygous BALB/c Plcg2Ali5/+ and wildtype (WT) mice were infected with Helicobacter felis (H. felis) and observed up to 16 months for development of gastric MALT lymphomas. In contrast to our initial hypothesis, Plcg2Ali5/+ mice developed MALT lymphomas less frequently than their WT littermates after long-term infection of 16 months. Infected Plcg2Ali5/+ mice showed downregulation of proinflammatory cytokines and decreased H. felis-specific IgG1 and IgG2a antibody responses. These results suggested a blunted immune response of Plcg2Ali5/+ mice towards H. felis infection. Intriguingly, Plcg2Ali5/+ mice harboured higher numbers of CD73 expressing regulatory T cells (Tregs), possibly responsible for impaired immune response towards Helicobacter infection. We suggest that Plcg2Ali5/+ mice may be protected from developing gastric MALT lymphomas as a result of elevated Treg numbers, reduced response to H. felis and decrease of proinflammatory cytokines.

Expression and pro-survival function of phospholipase Cγ2 in diffuse large B-cell lymphoma.

Diffuse large B-cell lymphoma (DLBCL) can be cured in about 60% of cases with immuno-chemotherapy. However, a large subset of patients with DLBCL do not go into remission, or relapse after first-line therapy. Further therapy options are therefore needed. Phospholipase Cγ2 (PLCγ2) is one of the key regulators of the B cell receptor signaling pathway, which targets several pro-proliferative factors, such as nuclear factor κB (NFκB), Ras and Akt. Using immunohistochemistry, we found that PLCγ2 was strongly expressed in 63% of cases of DLBCL. The PLC inhibitor U73122 had an inhibitory effect on cell proliferation and induced apoptosis and G0/G1 cell cycle arrest. Co-treatment with enzastaurin or the Src inhibitor pp2 together with U73122 had an additive effect on cell proliferation compared to U73122 alone. Unexpectedly, strong PLCγ2 expression was associated with better overall survival. In conclusion, PLCγ2 is strongly expressed in a significant number of DLBCLs and has prognostic implications. Inhibition of PLCγ2 could be a new target for lymphoma treatment.