ABSTRACT
Kaposi's sarcoma [KS] is a multifocal angioproliferative disease characterized by the proliferation of spindle-shaped cells predominantly of vascular origin considered to be the neoplastic element of KS, neoangiogenesis, inflammatory cell infiltration and oedema. The presence of high levels of inflammatory cytokines [IC] such as IFN, TNF, IL-1, IL-6 and angiogenic molecules mediates lesion formation. Recently a new viral agent termed human herpes virus-8 [HHV-8] also known as Kaposi's sarcoma associated herpes virus [KSHV] has been found in all forms suggesting a common etiopathogenesis for all forms of KS. Human IL-6, [H-IL6] is a multifunctional cytokine that acts on a wide variety of cells, serves as a growth factor for myeloma and plasmocytoma cells. Bcl[2] is a proto-oncogene known to prolong survival of quiescent non proliferating cells by inhibiting the process of programmed cell death. KSHV contains a gene that has functional and sequence homology to the apoptotic Bcl[2] family of proteins. The PCNA is now recognized as one of the key proteins in DNA metabolic events because of its direct interactions with many proteins involved in important cellular processes. The aim of this study was to acertain the value of HHV-8 DNA sequences in routinely processed, formalin fixed embedded tissues as a cause of KS and to estimate the level of human interleukin-6 [H-IL-6] in its different stages with or without HIV seropositive case. This study also aimed at evaluating the expression of Bcl2 and PCNA in the progressive stages of KS and highlight their role in this progression
Patients and Method: 20 cases of KS [17 classical KS and 3 AIDS related KS] with 8 plaque stage [group I] and 12 nodular [group II] were tested for HHV-8 DNA sequences by PCR assay, conventional H and E staining for histopathological diagnosis. Immunohistochemical staining of Bcl[2] and PCNA on paraffin fixed embeded tissue. Blood samples were taken from all patients as well as from 10 control subjects for estimation of H-IL-6 by immunoassay
Results: Human herpes virus 8 - DNA was detected in 16 out of the 20 [80%] formalin fixed embedded tissue sections. All nodular lesions [group II] were found to be positive for HHV-8 [100%]. While 50% of the plaque lesions were positive for HHV-8 [group I]. All HIV cases [n=3] [100%] previously described were also positive for HHV-8 and belonged to the nodular stage [group III]. The mean value of serum HIL-6 in the 16 cases were [10.23+/2.9 pg/ml], and in group I [plaque stage] was [7.5 +/ 1.3 pg/ml]. In group II [nodular stage] was [11.1 +/ 1.9 pg/ml]. Whereas in group III [nodular stage with seropositive HIV] was 14.4 +/ 1.9 pg/ml]. The mean value in the control group was [3.27 +/ 0.72 pg/ml]. There is highly significant difference between group I and group II [P = 0.0001] compared to the control group but, no statistically significant differences were found between group I or II and group III. The relation between H-IL-6 levels and HHV-8 DNA in paraffin embedded tissue was statistically significant [P= 0.045]. This study also showed 4 cases in plaque stage [50%] were negative for HHV-8 but still their mean value of H-IL-6 was [10.5 +/ 3.9 pg/ml] which is significant to the control group [P= 0.045]. No significant relation was detected between H-IL-6, and the different parameters [Bcl[2], PCNA, and sex]. Bcl[2] positivity was detected in 70% of studied cases. Bcl[2] immunoexpression increased from plaque stage [28.67%] to the nodular stage [71.4%] and this relation was statistically significant [P=0.046] 75% of HHV-8 positive cases showed Bcl[2] positivity and this relation was also statistically significant. [P=0.039]. PCNA immunohistochemical expression was detected in 80% of studied cases PCNA labeling index [PCNA LI] was grade 1, in 20%, grade 2 in 35% and grade 3 in 45% of studied cases. No statistical significant relation was detected between PCNA LI and chemical stage, or HHV-8 positivity. All AIDS associated KS were Bcl[2] positive and showed grade 3 PCNA LI and inspite of the fact that this relation were statistically significant in both, the small number of AIDS positive cases [3 cases] made this statistical significant not reliable