Presence of simian virus 40 in diffuse large B-cell lymphomas in Tunisia correlates with germinal center B-cell immunophenotype, t(14;18) translocation, and P53 accumulation.

Previously we have reported the presence of simian virus 40 DNA in 56% of diffuse large B-cell lymphomas in Tunisia. Here, we investigated the relationship between the status of simian virus 40 and t(14;18) translocation, germinal center status, and P53 and BCL2 expression to assess the clinical and biological relevance of simian virus 40 presence in diffuse large B-cell lymphomas. Therefore, we evaluated by immunohistochemistry the expression patterns of CD10, BCL6, MUM1, BCL2, and P53 in 86 diffuse large B-cell lymphomas (48 simian virus 40-positive and 38 simian virus 40-negative cases). The t(14;18) translocation was investigated by polymerase chain reaction. Immunostaining patterns for CD10, BCL6, and MUM1 were used to subclassify diffuse large B-cell lymphoma cases as germinal center or non-germinal center phenotypes. Germinal center phenotype, t(14;18), P53, and BCL2 expression were found in 71, 30, 55, and 65% of cases, respectively. Interestingly, germinal center phenotype, t(14;18), and P53 accumulation were found to be more frequent in simian virus 40-positive cases than in simian virus 40-negative ones (81, 44, 69 vs 58, 13, 37%; P=0.018, 0.002, and 0.003, respectively). However, there were no correlations between the presence of simian virus 40 and the expression of CD10, BCL6, MUM1 and BCL2, patient's age and gender, clinical stage, or the International Prognosis Index. Multivariate logistic regression analyses revealed that the germinal center phenotype, P53 accumulation, and t(14;18) were independent factors for simian virus 40 association (P=0.029, 0.006, and 0.014, respectively). There were no significant differences in overall survival regarding P53, BCL2, or t(14;18) status. However, patients with germinal center phenotype or low International Prognosis Index scores displayed a significantly better survival than those with non-germinal center phenotype or high International Prognosis Index scores (P=0.003 and 0.0001, respectively). These two prognosis factors remain independent in multivariate analyses (P=0.001 and <0.0001, respectively). Interestingly, among patients with germinal center phenotype, simian virus 40-positive subgroup displayed a significantly shorter survival than simian virus 40-negative subgroup (P=0.034). In summary, these findings support a role of simian virus 40 in the pathogenesis of diffuse large B-cell lymphomas. On other hand, they suggest that a significant proportion of diffuse large B-cell lymphoma cases with germinal center phenotype may result from early transformation by simian virus 40, mainly those harboring the t(14;18).Modern Pathology (2008) 21, 282-296; doi:10.1038/modpathol.3800993; published online 28 December 2007.     

Association of hyperhomocysteinemia with genetic variants in key enzymes of homocysteine metabolism and methotrexate toxicity in rheumatoid arthritis patients

Objectives

The study investigated the association between plasma homocysteine, folate and vitamin B12 with 5,10 methylenetetrahydrofolate reductase (MTHFR C677T and A1298C), thymidylate synthase (TYMS 2R → 3R) and methionine synthase (MTR A2756G) polymorphisms and methotrexate (MTX) treatment and toxicity in Tunisian Rheumatoid arthritis (RA) patients.

Methods

A total of 185 patients with RA were included. Homocysteine (Hcy) was assessed by fluorescence polarization immunoassay, and folate and vitamin B12 were measured by chemiluminescence immunoassays. The genetic polymorphisms were analyzed by PCR or PCR-RFLP. Hyperhomocysteinemia (HHC) was considered for Hcy?>?15 µmol/L.

Results

MTHFR C677T polymorphism was associated with HHC in RA patients (multi-adjusted OR, 95% CI 2.18, [1.07–4.57]; p?=?0.031). No association was detected with the remaining polymorphisms. Plasma Hcy, folate, and vitamin B12 did not differ according to each polymorphism, or with MTX treatment or toxicity. However, HHC was more prevalent in patients with than those without MTX toxicity (32.7 vs. 16.7%; p?=?0.035).

Conclusions

The MTHFR 677TT genotype is an independent risk factor for HHC in Tunisians RA patients. HHC could be a useful marker of MTX toxicity in RA patients.

     

Immune tumoral microenvironment in gliomas: focus on CD3+ T cells,Vδ1+ T cells,and microglia/macrophages

Gliomas are histologically defined as low-grade gliomas (LGG) and high-grade gliomas (HGG). The most common type of HGG is the glioblastoma (GBM). We aimed to determine the immunological characteristics of CD3 T-cells, Vδ1 T-cells, and microglia/macrophages infiltrating brain gliomas. We collected 24 formalin-fixed paraffin-embedded samples issued from 19 cases of GBM and 5 cases of LGG. An immunohistochemical analysis was performed using anti-CD3, anti-Vδ1, and anti-iba-1 antibodies. Labelling indexes (LI) of CD3 and Vδ1 were evaluated quantitatively, and other CD3, Vδ1, and iba-1 staining characteristics were evaluated qualitatively. The median age of patients was 49 years in GBM and 52 years in LGG. The sex ratio was 1.4 and GBM predominated in males (p?=?0.05). In GBM, the medians of CD3-LI and Vδ1-LI were 30 and 3.5 respectively. CD3-LI inversely correlated with survival in GBM cases (r?=????0.543; p?=?0.016). CD3 staining intensity correlated with CD3-LI (p?<?0.0001) and with the survival in GBM cases (p?=?0.003). Compared to LGG, the CD3-LI, the intensity of intra-tumoral Vδ1 staining, and the amount of iba-1 were higher in GBM (p?=?0.042; p?=?0.014; and p?=?0.001 respectively). The iba-1 organization was more amoeboid in older patients and more branched in younger patients (p?=?0.028) and tended to be more amoeboid in cases with high iba-1 amount (p?=?0.09). Our results suggest that a high level of CD3-LI and a strong intra-tumoral infiltration of Vδ1 T-cells as well as a high involvement of TAM can be considered potential markers of poor prognosis of GBM. However, this requires further studies on more balanced GBM-LGG sample, including an expanded panel of biomarkers.

     

Adamantinoma of the tibia: a clinicoradiologic study of four cases

Adamantinoma of long bones is a malignant primitive bone tumor with epithelial origin, involving the tibia in a great majority of cases. It is a rare neoplasm with less than 200 cases reported in the world literature. The authors report four cases of tibial adamantinoma and describe the clinical, imaging and histologic features of this neoplasm with emphasis on preoperative imaging, surgical treatment and post-operative follow-up.     

Activation of mTORC1 Signaling Pathway in AIDS-Related Lymphomas

Using immunohistochemistry with antibodies against the phosphoserine residues in both S6rp and 4E binding protein 1, we identified the activation of the mammalian target of rapamycin (mTORC)1 pathway in 29 cases of AIDS-related lymphoma. These cases represented a diverse spectrum of histological types of non-Hodgkin lymphoma (24 cases) and classic Hodgkin lymphoma (five cases). mTORC1 was also activated in the hyperplastic but not involuted follicles of HIV-associated lymphadenopathy in eight cases, supporting the notion that mTORC1 activation is a common feature of transformed lymphocytes irrespective of either their reactive or malignant phenotype. We also found that in B-cell lines that represent diffuse large B-cell lymphoma, Burkitt lymphoma, Epstein-Barr virus-infected lymphocytes, and human herpesvirus 8-positive primary effusion lymphoma, inhibitors of Syk, MEK, and, seemingly, phosphoinositide 3 kinases suppressed mTORC1 activation, in particular when these inhibitors were used in combination. These findings indicate that AIDS-related lymphoma and other histologically similar types of lymphomas that are derived from transformed B lymphocytes may display clinical responses to inhibitors that directly target mTORC1 or, possibly, upstream activators of the mTORC1 pathway.The incidence of lymphomas in HIV-positive patients is nearly 200 times higher than in those uninfected by the virus. Lymphomas accounts for an increasing percentage of AIDS-defining illness, particularly from the advent of highly active antiretroviral therapy therapy.^1,2 These AIDS-related lymphomas (ARLs) typically represent the proliferation of enlarged, transformed B lymphocytes, which usually fall into the category of diffuse large cell lymphoma (DLBCL), with morphology ranging from centroblasts to immunoblasts. Other histological types such as Burkitt lymphoma (BL), Hodgkin lymphoma, and T/null cell anaplastic large cell lymphoma are also overrepresented among ARLs.^1,2,3,4 The pathogenesis of ARL is poorly understood. It has been postulated that cell proliferation occurring in the setting of severe immunosuppression and driven by chronic antigenemia resulting at first in the polyclonal and ultimately in the monoclonal lymphoproliferation plays a key role in lymphomagenesis in HIV patients. In addition, cell infection by the Epstein-Barr virus (EBV) and human herpesvirus 8 (HHV8) most likely contributes to the malignant cell phenotype in some subtypes of ARL, with the association of primary effusion lymphoma with HHV8 being essentially universal.^1,2,3,4 Regardless of the histological type of ARL, chemotherapy is typically ineffective and new treatment approaches are clearly needed to combat this group of lymphomas. In addition to ARL, HIV patients develop a benign reactive lymphadenopathy, particularly early after the infection as an overall ineffective response to the virus. This immune response is characterized by florid follicular hyperplasia that over time may lead to follicular involution and lymphocyte depletion.Mammalian target of rapamycin (mTOR) is a ubiquitously expressed serine/threonine kinase involved in key cellular functions including protein synthesis and proliferation.^5,6 mTOR associates with several proteins including either raptor or rictor to form the mTORC1 and mTORC2 complexes, respectively, with the signaling pathways activated by mTORC1 being much better characterized.^4,5,6,7 Accordingly, it is well established that mTORC1 activates p70S6 kinase 1 and inhibits 4E binding protein 1 (4E-BP1). In turn, p70S6 kinase 1 phosphorylates an S6 protein of the 40S ribosomal subunit (S6rp) at several sites including serines 235 and 236. The exact mechanisms of mTORC1 activation are less understood but both phosphoinositide 3 kinases (PI3K)/Akt^8,9,10 and extracellular regulated (ERK)/mitogen-activated kinase (MEK) kinases^11,12 signaling pathways have been found to activate mTORC1 with members of the insulin growth factor family providing the primary signal, at least in some instances. The highly potent and specific inhibitors from the rapamycin family can functionally inactivate mTORC1. In addition to being used as immunosuppressants, mTORC1 inhibitors are evaluated as therapeutic agents in various types of cancer,^5,6 with high efficacy already documented in renal cell carcinoma.¹³Syk is a protein tyrosine kinase expressed in B lymphocytes,¹⁴ monocytes/macrophages,¹⁵ mast cells,¹⁶ and other cell types. Syk has been found to be involved in signal transduction through several types of receptors including the antigen B-cell receptor¹⁷ and at least three different receptors for the Fc component of immunoglobulins G and E.^{14,15,16,18,19,20} A recent report suggests that Syk may be involved in mTORC1 activation in a follicular and possibly other types of B-cell lymphoma.²¹ Although inhibitors of either PI3K/Akt or MEK/ERK signaling pathways did fully inhibit mTORC1 activation in transformed B lymphocytes, at least when applied alone,²² these pathways have been found to contribute to mTORC1 stimulation in two types of T-cell lymphoma.^23,24In this study, we identified the activation of the mTORC1 pathway in all ARL cases examined, regardless of their specific histological classification and immunophenotype. mTORC1 was also activated in the hyperplastic follicles of the HIV-associated lymphadenopathy. Furthermore, we found that in the different types of transformed B-lymphocytes cell lines, inhibition of Syk, MEK, and, seemingly, PI3K resulted in suppression of the mTORC1 activation, in particular when the combination of the inhibitors was used. These findings indicate that ARL and histologically similar types of lymphoma may benefit from targeted therapy with inhibitors of mTORC1 or, possibly, its upstream activators.     

Distribution of HLA-B*27 subtypes in Tunisians and their association with ankylosing spondylitis

ObjectiveThe human leukocyte antigen HLA-B27 is a class I antigen of the major histocompatibility complex strongly associated with ankylosing spondylitis (AS) and other related spondyloarthropathies (SpAs). The mechanism of this association remains unknown. HLA-B27 is a serologic specificity that represents a family of at least 25 different HLA-B27 alleles (2701–2725). These alleles are closely related by nucleotide sequence homology, but differ in ethnic distribution. The purpose of the present study is to investigate the distribution of HLA-B27 alleles in healthy controls and in patients with ankylosing spondylitis (AS).MethodsWe selected 160 HLA-B27-positive individuals (39 controls and 121 patients with ankylosing spondylitis). Typing of HLA-B27, and Cw alleles were performed by polymerase chain reaction amplification with sequence specific primers (PCR–SSP), and by serological typing (microlymphocytotoxicity).ResultsSeven B27 subtypes were identified: B*2702, 03, 04, 05, 07, 09 and B*2714. The distribution of these alleles in the population of patients was B*2702 (47.1%) and B*2705 (47.1%). These subtypes were also detected in 16 (41%) and 16 (41%), respectively of the 39 control subjects. HLA-B*2707 was detected in 4 (3.31%) patients and in 3 (7.6%) controls. B*2704, 09 and B*2714 were relatively rare and were detected in one subject each. No significant differences were noticed in the frequencies and distribution of HLA-B27 alleles between patients and controls.ConclusionsOur results show a restricted number of HLA B27 subtypes associated with AS. B*2702 and B*2705 were equally common in patients and controls. The most prominent B27/Cw haplotypes in the patient groups and controls were B*2702/Cw02022 and B*2705/Cw02022.