Faculty of Health Sciences
School of Dentistry
Department of Oral Pathology and Oral Biology
Selected Highlights from Research Findings
Two of the research focus areas of the Department of Oral Pathology and Oral Biology are oral cancer and HIV, as well as the combination of these two diseases. Recently, the department established an Oral HIV Clinic at the Tshwane District Hospital to provide comprehensive oral health care to HIV-infected individuals in the public sector. Oral lesions may be indicative of a decrease in the current immune function. Furthermore, treatment of oral infection eliminates foci of possible systemic infections in these frail individuals.
The presence of HIV-1 in oral epithelial cells is a controversial subject and, although it had previously been reported by a few authors, it remains an uncertain entity with more questions than answers. A molecular study was therefore performed to determine the presence of HIV-1 in the oral epithelial cells, as well as in the dendritic cells of oral immunity called the Langerhans cells of HIV-1 positive patients. The study also evaluated the possible use of a non-invasive brush biopsy technique for future in vivo HIV research.
Although 10 of the 35 patients in this study had HIV-1 DNA in one or more of the sampled anatomical locations during PCR analysis of the whole brush samples, no HIV-1 DNA could be demonstrated in any of the purified epithelial or Langerhans cell specimens after cell sorting and cell microdissection were performed. This study showed the use of non-invasive oral brush biopsies as an experimental model for future in vivo oral HIV research to be very possible and will be investigated further. The work was accepted for publication in the official international journal of oral pathology.
Contact person: Prof WFP van Heerden.
Another HIV-related project that was performed recently and published early in 2009 was to compare the human papilloma virus (HPV) strains found in the oral mucosa with that found in the cervical mucosa of HIV-1 infected women. This has never been done in South Africa and is therefore a crucial study if one considers the strong association of HPV with cervical, as well as certain forms of head and neck cancers. Individuals with HIV-related immunodeficiency are at an increased risk for oral HPV infection and the prevalence of this infection is higher in HIV-positive than in HIV-negative patients. What is even more important in this regard is the fact that highly active antiretroviral therapy (HAART) does not decrease the oral persistence of this virus and the implications for transmission to sexual partners are far-reaching. The possibility of cancer after sexual transmission of HPV is therefore a strong research focus on which work is also currently being done in the Department of Oral Pathology.
Lymphoma is classified as a Group 1 lesion, which means that it is strongly associated with HIV infection. Oral plasmablastic lymphoma (PBL) was originally described in 1997 as an AIDS-associated tumour and less than 200 cases of the oral mucosa have since been reported in the literature. Once more, due to the high number of people living with HIV in South Africa, a substantial sample of cases diagnosed as PBL is available in oral pathology laboratories, which include the Department of Oral Pathology.
Firstly, it is virtually impossible to distinguish PBLs from plasma cell neoplasms with plasmablastic differentiation. Contradiction with regard to the true nature of these neoplasms exists. It was decided to do a study on cases diagnosed as PBL in the Department of Oral Pathology at the University of Pretoria, as well as cases in the Department of Oral Pathology from the University of Limpopo in order to describe the molecular profile of these neoplasms, which will make it possible to find better management strategies for patients with this aggressive form of lymphoma.
The aim of the first aspect of the study was to describe the immunohistochemical profile of PBL affecting the oral mucosa, to determine tumour clonality through examination of cytoplasmic immunoglobulin light chain restriction and to evaluate the role of Epstein Barr (EBV) and Human Herpes 8 Virus (HHV-8) in this South African population sample.
The study represents the largest series of plasmablastic lymphomas (PBL) affecting the oral cavity published to date and some of the results and conclusions are the first to be described in the literature. Forty-five cases of PBL in the oral cavities were retrieved from the files. PBL is currently microscopically classified into two groups due to certain morphologic criteria described in the literature, namely PBL of the oral mucosa type and PBL with plasmacytic differentiation. In this large cohort of cases, it was shown that this morphologic classification has no diagnostic or clinical advantages and its use should be reconsidered and even discarded. What is even more important is the fact that 21 of 45 cases (47%) showed clear light chain restriction by immunohistochemical examination and it is proposed that all cases of PBL with clear light chain restriction should be reclassified as plasmablastic extramedullary plasmacytomas.
The second aspect of the study was done in collaboration with the Somatic Cell Genetics Unit Department of Haematology and Molecular Medicine at the University of the Witwatersrand and the National Health Laboratory Services (NHLS). Only a single case report on the cytogenetic features of these neoplasms has been described in the literature.
Due to the findings of the first aspect of the study, it was decided to evaluate the possible presence of a break in the immunoglobulin heavy chain (IGH) and C-MYC genes and then to evaluate cases positive for the break-apart probes for possible translocation partners through further FISH analysis. All cases will also be evaluated for the presence of deletion of the long arm of chromosome 13, as this represents an abnormality commonly described in multiple myelomas and plasmacytomas. This work has never been performed and will be published as soon as all the results are available.
Contact person: Prof WFP van Heerden.
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