Immunolocalization of toll-like receptor 2 in viral warts and molluscum contagiosum

OBJECTIVE

To explore toll-like receptor 2 (TLR2) immunolocalization and its possible role in the innate immune response against viral warts and molluscum contagiosum (MC).

STUDY DESIGN

Using standard immunohistochemical techniques, we examined 50 cases (25 cases with viral warts and 25 cases with MC) together with normal skin biopsies of 25 age and sex-matched subjects who comprised the control group.

RESULTS

TLR2 was expressed in the epidermis of all controls and in 94% of study cases. Staining patterns were cytoplasmic, membranous, nuclear and combined. There was a significant difference between cases and controls regarding the intensity (p = 0.0001) and pattern (p = 0.001) of TLR2 expression, where intense expression was in favor of cases and membranous and nuclear pattern of staining was seen only in cases. The intensity of TLR2 expression was significantly associated with patients of young age (p = 0.04), short disease duration (p = 0.04), facial location (p = 0.009), and MC category (p = 0.02).

CONCLUSION

Our study suggests that upregulation of TLR2 is involved in the induction of defense mechanism against human papillomavirus and MC virus. Its nuclear localization may be related to virus pathogenesis, virus-TLR interaction, or to other unknown molecular events.

Expression of Toll-like receptors in verruca and molluscum contagiosum

Recent studies indicate that several Toll-like receptors (TLRs) are implicated in recognizing viral structures and instigating immune responses against viral infections. The aim of this study is to examine the expression of TLRs and proinflammatory cytokines in viral skin diseases such as verruca vulgaris (VV) and molluscum contagiosum (MC). Reverse transcription-polymerase chain reaction and immunostaining of skin samples were performed to determine the expression of specific antiviral and proinflammatory cytokines as well as 5 TLRs (TLR2, 3, 4, 7, and 9). In normal human skin, TLR2, 4, and 7 mRNA was constitutively expressed, whereas little TLR3 and 9 mRNA was detected. Compared to normal skin (NS), TLR3 and 9 mRNA was clearly expressed in VV and MC specimens. Likewise, immunohistochemistry indicated that keratinocytes in NS constitutively expressed TLR2, 4, and 7; however, TLR3 was rarely detected and TLR9 was only weakly expressed, whereas 5 TLRs were all strongly expressed on the epidermal keratinocytes of VV and MC lesions. In addition, the mRNA expression of IFN-beta and TNF-alpha was upregulated in the VV and MC samples. Immunohistochemistry indicated that IFN-beta and TNF-alpha were predominantly localized in the granular layer in the VV lesions and adjacent to the MC bodies. Our results indicated that VV and MC skin lesions expressed TLR3 and 9 in addition to IFN-beta and TNF-alpha. These viral-induced proinflammatory cytokines may play a pivotal role in cutaneous innate immune responses.

Treatment of molluscum contagiosum with 585 nm collagen remodeling pulsed dye laser

The inevitable regression of molluscum contagiosum (MC) has been the major argument in favor of leaving the lesions to spontaneous involution. But the infection is often widespread and recurrent. Conventional therapies are frequently ineffective and require multiple visits. Flashlamp-pumped pulsed dye laser is now recommended in the therapy of MC in case reports. There is no evaluation of a pulsed dye laser collagen remodeling (wavelength of 585 nm) as a possible therapeutic alternative. We treated 76 patients with cutaneous MC with 1 to 176 MC (mean 27 MC) in a prospective study from April 2002 to September 2002 (over a period of six months). The female/male sex ratio was of 1.2:1 (42 girls, and 34 boys). Patients were aged from 1 to 15 years, with a mean of 4.9 years. We used 585 nm collagen remodeling, double flashlamp excited pumped dye laser ED2000 (manufactured by Deka(c) MELA Calenzano, Italy), spot size 5 mm, energy density (fluence J/cm(2)) from 2 to 4 J/cm(2), emission modality (repetition rate) at 0.5 Hz, with a short pulse duration of 250 microsec in all cases. The therapy was well tolerated. No scars or pigment anomalies were observed. 96.3% of the lesions healed after the first treatment, the remaining 3.7% after the second (two weeks later). Laser photocoagulation causes selective damage to abnormal vessels and surrounding connective tissue. The heating effect in these skin layers triggers the release of various growth factors that stimulate collagen remodeling and tightening. It appears to be a cell-mediated reaction, which brings about an elevation in the T lymphocytes, capable of affecting pox viridae. Dye laser photocoagulation however, cannot protect against relapse. Hyperpigmentation may occur at nearly all sites, however this fades after 1 to 6 months. The pulsed dye laser for collagen remodeling is an effective, bloodless, quick, and easy therapeutic alternative for MC. The advantage of using a collagen remodeling pumped dye laser is the absence of pain, because of the short pulse duration (half that of a normal pulsed dye laser), and the use of low fluence (less than 4 J/cm(2)). It enables the treatment of young patients with a large number of lesions, which is impossible with a normal pulsed dye laser. There are no side effects.

An immunohistochemical study of abnormal keratinocyte proliferation in molluscum contagiosum

BACKGROUND

Molluscum contagiosum is a common cutaneous tumour that is characterized by usually spontaneous involution and self-limited spreading in immunocompetent individuals.

OBJECTIVE

We aimed to investigate the apoptosis and the expression of cell-cycle proteins in molluscum contagiosum lesions.

METHODS

The terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL)-based apoptotic index and the expression of the cell-cycle proteins Ki-67, p53, p21WAF and Bcl-2 were investigated in molluscum contagiosum lesions obtained from the trunk of 20 immunocompetent patients and in normal skin samples from the trunk of six healthy volunteers.

RESULTS

Whereas molluscum contagiosum lesions displayed a TUNEL-based apoptotic index similar to that of normal skin, they exhibited an increased Ki-67 index, which was confined to the basal and first suprabasal layers (P < 0.001). Compared with normal non-sun-exposed skin, molluscum contagiosum lesions also exhibited increased p53 staining in basal cells (P < 0.01), increased p21WAF in suprabasal cells (P < 0.001) and loss of Bcl-2 expression.

CONCLUSIONS

These results indicate that molluscum contagiosum lesions exhibit an increased proliferation rate of keratinocytes, which is likely to be partially counteracted by accumulation of p53.

Counts and areas of S-100-positive epidermal dendritic cells in atypical molluscum contagiosum affecting HIV+ patients

Molluscum contagiosum is a common and self-limiting viral infection, that in HIV+ patients courses as an opportunist affection with atypical clinical features. Impaired cell-mediated immune response could be involved in such atypical growth. We evaluated the density and area of Langerhans cells (LC) using S-100 immunohistochemistry in seven atypical molluscum contagiosum. LC density was quantified by three different methods using computer-assisted morphometry as well as estimating the relative area of LC with respect to epidermal area. Results were compared with two control groups (normal skin specimens and molluscum contagiosum affecting non-AIDS healthy patients). We found a virtual absence of LC in areas of molluscum lesions affecting both HIV+ and non-AIDS patients. Likewise we observed an evident decrease in LC density in perilesional epidermis of atypical molluscum with respect to both control groups. Upon comparing the counts and areas, we observed that this reduction in LC count was statistically significant only when considering LC related to length of basement membrane in atypical molluscum with respect to normal skin specimens. Our finding of a reduced number of LC in the perilesional epidermis of HIV+ patients with atypical molluscum could explain the high frequency and clinical challenge of molluscum contagiosum in immunocompromised people. In spite of these results, further studies of LC kinetics and functions are required to precisely elucidate their role in the course of molluscum contagiosum in HIV+ patients.

An immunohistochemical study of abnormal keratinocyte differentiation in molluscum contagiosum

To investigate abnormalities in the keratinization process in lesional epidermis of molluscum contagiosum, production of filaggrin, loricrin, Ted-H-1 antigen, involucrin, cystatin A and CD95 ligand (CD95L) was investigated using specific antibodies. Anti-filaggrin monoclonal antibody (MoAb) did not react with keratohyalin granules (KHG), but with the substance around virus particles in the stratum corneum. KHG reacted with anti-loricrin polyclonal antibody (PoAb) and anti-Ted-H-1 MoAb. Anti-involucrin PoAb and anti-cystatin A PoAb reacted with materials in the cytoplasm of the middle stratum spinosum to the stratum granulosum. CD95L was expressed in the cell membrane region of the living cell layers in lesional epidermis. These observations suggest that the keratinization process may be altered in molluscum contagiosum.

Pleomorphic T-cell infiltrate associated with molluscum contagiosum

The authors observed a pleomorphic lymphocytic infiltrate composed of CD8 cytotoxic/suppressor T-cells in two pediatric cases associated with molluscum contagiosum. T-cell clonality was not detected. In both cases, the lesions resolved after the biopsy was performed. The patients were otherwise healthy, and no evidence of lymphoproliferative process was detected on follow-up. The authors believe the pleomorphic lymphoid infiltrate is inflammatory and reactive in nature. The close apposition of lymphocytes to molluscum bodies and cytoid bodies with high expression of CD30 and the proliferating marker Ki67 is suggestive of a cytotoxic cell-mediate blastic reaction against poxvirus antigens.

Proinflammatory properties of molluscum bodies

Molluscum contagiosum, a condition characterized by benign viral tumours, occasionally becomes inflamed and regresses spontaneously, an event probably initiated by a host cell-mediated immune rejection against the lesion, but it inevitably involves the disruption of the epidermal tissue to expose the molluscum bodies to the tissue fluids of the dermis. It has been suggested that the molluscum bodies induce inflammation by a mechanism similar to that involved in ruptured epidermal cysts or in acne. Despite the occasional development of inflammation in molluscum contagiosum, the proinflammatory properties of molluscum bodies have never been studied in vitro. Thus, in the present study we sought to determine whether molluscum bodies exert a proinflammatory effect by inducing neutrophil chemotaxis. When exposed to fresh serum in vitro, water-insoluble components of molluscum bodies activated the alternative complement pathway to produce chemotactic C5a/C5a des Arg. We also found that an aqueous extract of molluscum bodies exerted potent chemotactic activity for neutrophils. Remarkably high amounts of the immunoreactive proinflammatory cytokines IL-8 and GRO alpha were present in the extract even when compared with psoriatic scale extracts. Gel filtration HPLC of the extract demonstrated the presence of neutrophil chemotactic activity over a wide range of molecular mass. These data suggest that disruption of the epidermal wall of molluscum bodies induces acute inflammatory changes by activation of the alternative complement pathway on exposure to the tissue fluids, and that the molluscum bodies themselves release proinflammatory cytokines and other neutrophil chemotactic factors on decomposition.

Immunocompetent cells and epithelial cell modifications in molluscum contagiosum

We studied lesions of molluscum contagiosum with a panel of monoclonal antibodies to determine the phenotype of infiltrating cells and antigen modifications of infected keratinocytes. Our data indicate (1) a complete lack of immunocompetent cells in the viral lesions, and simultaneously a loss of B2-microglobulin reactivity by molluscum bodies, a cellular activation of EGF and transferrin receptors and expression of CD36 antigen of these bodies; (2) a moderate infiltrate of activated T cells and monocytes in the underlying epidermis; (3) an increase of Langerhans cell density and a CD36 expression by the surface of upper layer keratinocytes in the perilesional epidermis.

Differences of expression of cytokeratin polypeptides in various epithelial skin tumors

In normal skin, cytokeratin polypeptides are expressed in different cell-type-specific patterns, in the keratinocytes of the different epidermal cell strata as well as in different lateral epithelial domains. Using light microscopically controlled microdissection of defined regions from frozen sections of biopsies, we have prepared cytoskeletons of various benign and malignant keratinocyte-derived tumors of human skin and analyzed their cytokeratin polypeptide patterns by two-dimensional gel electrophoresis. Premalignant fibroepitheliomas and basal cell epitheliomas display a relatively simple cytokeratin pattern (cytokeratins nos. 5, 14, 15, and 17). Pseudocarcinomatous hyperplasia, some squamous cell carcinomas, and a certain subtype of condylomata acuminata present a hair-follicle-like pattern (nos. 5, 6, 14, 16, 17). In addition to these components, variable, mostly low amounts of cytokeratins nos. 1 (Mr 68,000), and 11 are detected in most squamous cell carcinomas, in keratoacanthomas, verruca vulgaris, and another type of condylomata acuminata. In molluscum contagiosum, verruca plana, solar keratosis, and seborrheic keratosis, the cytokeratin expression is shifted more towards the normal epidermal pattern (polypeptides nos. 1, 2, 5, 10, 11, 14, 15 and traces of nos. 6 and 16 in the latter two tumors). No tumor-specific cytokeratins have been found. We conclude that keratinocyte-derived skin tumors contain various combinations of cytokeratins of the subset typical for normal keratinocytes of skin, but no cytokeratins typical for internal, simple epithelia. Different groups of tumors can be distinguished by their specific cytokeratin patterns. Possible applications of cytokeratin typing in clinical diagnosis are discussed.