Antiviral treatment of diseases in pediatric dermatology

Pediatric dermatologic disease that have specific therapies and/or specific prophylactic measures are reviewed. Herpes simplex virus and varicella-zoster virus infections, human papillomavirus infections, and molluscum contagiosum infections are discussed with special emphasis on recent advances of therapy and prophylaxis.     

Intracellular signaling by the chemokine receptor US28 during human cytomegalovirus infection

In patients with impaired cell-mediated immune responses (e.g., lung transplant recipients and AIDS patients), cytomegalovirus (CMV) infection causes severe disease such as pneumonitis. However, although immunocompetency in the host can protect from CMV disease, the virus persists by evading the host immune defenses. A model of CMV infection of the endothelium has been developed in which inflammatory stimuli, such as the CC chemokine RANTES, bind to the endothelial cell surface, stimulating calcium flux during late times of CMV infection. At 96 h postinfection, CMV-infected cells express mRNA of the CMV-encoded CC chemokine receptor US28 but do not express mRNA of other CC chemokine receptors that bind RANTES (CCR1, CCR4, CCR5). Cloning and stable expression of the receptor CMV US28 in human kidney epithelial cells (293 cells) with and without the heterotrimeric G protein alpha16 indicated that CMV US28 couples to both Galphai and Galpha16 proteins to activate calcium flux in response to the chemokines RANTES and MCP-3. Furthermore, cells that coexpress US28 and Galpha16 responded to RANTES stimulation with activation of extracellular signal-regulated kinase, which could be attributed, in part, to specific Galpha16 coupling. Thus, through expression of the CC chemokine receptor US28, CMV may utilize resident G proteins of the infected cell to manipulate cellular responses stimulated by chemokines.     

Human cytomegalovirus inhibits transcription of the CC chemokine MCP-1 gene

In primary human diploid fibroblasts, infection with an unpurified stock of human cytomegalovirus induced accumulation of the CC chemokine MCP-1 in the cell culture medium. By 24 h postinfection, the level of MCP-1 returned to that in uninfected cultures. When cells were infected with UV-inactivated human cytomegalovirus, the induction of MCP-1 was still observed, but no reduction was seen by 24 h postinfection or later. This effect was the result of a decrease in the level of MCP-1 mRNA present within the infected cell. Infection with purified virus revealed that the induction of MCP-1 was due to an activity found in the medium of infected cells; purified virions did not induce the expression of MCP-1. However, infection with purified virions repressed the level of MCP-1 mRNA below that found in uninfected cells. Additionally, infection with human cytomegalovirus prevented the induction of MCP-1 expression by tumor necrosis factor alpha and interleukin-1beta. The CC chemokine receptor encoded by the human cytomegalovirus US28 open reading frame (ORF) did not appear to play a role in this process, since a mutant virus in which the US28 ORF had been deleted downregulated MCP-1 in the same manner.     

Secondary lymphoid-tissue chemokine is a functional ligand for the CC chemokine receptor CCR7

Secondary Lymphoid-tissue Chemokine (SLC) is a recently identified CC chemokine that is constitutively expressed in various lymphoid tissues and is a potent and specific chemoattractant for lymphocytes. The SLC gene and the gene encoding another lymphocyte-specific CC chemokine, EBI1-ligand chemokine (ELC), form a mini-cluster at human chromosome 9p13. Here, we show that SLC is a high affinity functional ligand for chemokine receptor 7 (CCR7) that is expressed on T and B lymphocytes and a known receptor for ELC. SLC induced a vigorous calcium mobilization in murine L1.2 cells stably expressing human CCR7. SLC tagged with the secreted form of alkaline phosphatase (SLC-SEAP) showed specific binding to CCR7 that was fully competed by SLC with an IC50 of 0.5 nM. SLC also induced a vigorous chemotactic response in CCR7-expressing L1.2 cells with a typical bell-shaped dose-response curve and a maximal migration at 10 nM. When assessed using CCR7-transfected L1.2 cells, SLC and ELC were essentially equivalent in terms of cross desensitization in calcium mobilization via CCR7, cross-competition in binding to CCR7, and induction of chemotaxis via CCR7. SLC and ELC were also shown to fully share receptors expressed on cultured normal T cells known to express CCR7. Notably, however, SLC was somehow less efficient in cross-desensitization against ELC in calcium mobilization and in cross-competition with ELC for binding when assessed using cultured normal T cells. Thus, SLC and ELC, even though sharing only 32% amino acid identity, constitute a genetically and functionally highly related subgroup of CC chemokines.     

Utilization of molecular genetics in the differentiation between adrenal cortical adenomas and carcinomas

Cutaneous pseudolymphomas have been defined as benign lymphocytic infiltrates of the skin that simulate cutaneous lymphoma clinically or histologically. The authors report on a 2-year-old boy with a lesion of molluscum contagiosum in which the inflammatory infiltrate that surrounded a cystlike structure containing molluscum bodies consisted of atypical hyperchromatic mononuclear cells with abundant mitotic figures, some of them atypical. Immunohistochemical investigation demonstrated that the infiltrate was predominantly composed of T lymphocytes. A previous report documented pseudoleukemia cutis associated with molluscum contagiosum, and this report expands the spectrum of histopathologic pseudomalignancies that may be seen in lesions of molluscum contagiosum.     

Macrophage-derived chemokine is a functional ligand for the CC chemokine receptor 4

Macrophage-derived chemokine (MDC) is a recently identified member of the CC chemokine family. MDC is not closely related to other chemokines, sharing most similarity with thymus- and activation-regulated chemokine (TARC), which contains 37% identical amino acids. Both chemokines are highly expressed in the thymus, with little expression seen in other tissues. In addition, the genes for MDC and TARC are encoded by human chromosome 16. To explore this relationship in greater detail, we have more precisely localized the MDC gene to chromosome 16q13, the same position reported for the TARC gene. We have also examined the interaction of MDC with CC chemokine receptor 4 (CCR4), recently shown to be a receptor for TARC. Using a fusion protein of MDC with secreted alkaline phosphatase, we observed high affinity binding of MDC-secreted alkaline phosphatase to CCR4-transfected L1.2 cells (Kd = 0.18 nM). MDC and TARC competed for binding to CCR4, while no binding competition was observed for six other chemokines (MCP-1, MCP-3, MCP-4, RANTES (regulated on activation normal T cell expressed and secreted), macrophage inflammatory protein-1 alpha, macrophage inflammatory protein-1 beta). MDC was tested for calcium mobilization in L1.2 cells tranfected with seven different CC chemokine receptors. MDC induced a calcium flux in CCR4-transfected cells, but other receptors did not respond to MDC. TARC, which also induced calcium mobilization in CCR4 transfectants, was unable to desensitize the response to MDC. In contrast, MDC fully desensitized a subsequent response to TARC. Both MDC and TARC functioned as chemoattractants for CCR4 transfectants, confirming that MDC is also a functional ligand for CCR4. Since MDC and TARC are both expressed in the thymus, one role for these chemokines may be to attract CCR4-bearing thymocytes in the process of T cell education and differentiation.     

Molluscum contagiosum virus: antibody responses in persons with clinical lesions and seroepidemiology in a representative Australian population

An ELISA for molluscum contagiosum virus (MCV) was used to determine the antibody status of 35 adults with clinical infections and known human immunodeficiency virus (HIV) serology and of 357 persons (ages, 1 week-69 years) considered representative of the Australian population. MCV antibody was identified in 77% of persons with molluscum lesions: in 17 of 24 HIV-1-negative persons and in 10 of 11 who were HIV-1-positive. No relationship was evident between the serologic responses and the number of lesions or the duration of infection. The population survey revealed an overall seropositivity rate of 23%. The lowest antibody prevalence was in children aged 6 months to 2 years (3%), and seropositivity increased with age to reach 39% in persons >/=50 years old. These findings indicate that MCV infections, including very mild or subclinical cases, may be more common in the general community than previously suspected.     

A YAC contig of the human CC chemokine genes clustered on chromosome 17q11.2

CC chemokines are cytokines that attract and activate leukocytes. The human genes for the CC chemokines are clustered on chromosome 17. To elucidate the genomic organization of the CC chemokine genes, we constructed a YAC contig comprising 34 clones. The contig was shown to contain all 10 CC chemokine genes reported so far, except for one gene whose nucleotide sequence is not available. The contig also contains 4 CC chemokine-like genes, which were deposited in GenBank as ESTs and are here referred to as NCC-1, NCC-2, NCC-3, and NCC-4. Within the contig, the CC chemokine genes were localized in two regions. In addition, the CC chemokine genes were more precisely mapped on chromosome 17q11.2 using a somatic cell hybrid cell DNA panel containing various portions of human chromosome 17. Interestingly, a reciprocal translocation t(Y;17) breakpoint, contained in the hybrid cell line Y1741, lay between the two chromosome 17 chemokine gene regions covered by our YAC contig. From these results, the order and the orientation of CC chemokine genes on chromosome 17 were determined as follows: centromere-neurofibromatosis 1-(MCP-3, MCP-1, NCC-1, I-309)-Y1741 breakpoint-RANTES-(LD78gamma, AT744.2, LD78beta)-(NCC-3, NCC-2, AT744.1, LD78alpha)-NCC-4-retinoic acid receptor alpha- telomere.     

Acyclic nucleoside phosphonates in the chemotherapy of DNA virus and retrovirus infections

The acyclic nucleoside phosphonates [HPMPC (cidofovir), PMEA (adefovir) and PMPA] have proved to the effective in vitro (cell culture systems) and in vivo (animal models, clinical studies) against a wide variety of DNA virus and retrovirus infections: i.e., HPMPC against herpesvirus (herpes simplex virus type 1 and 2, varicella-zoster virus, cytomegalovirus, Epstein-Barr virus, human herpesvirus types 6, 7, and 18), polyoma-, papilloma-, adeno-, and poxvirus (vaccinia virus, molluscum contagiosum virus) infections; PMEA against herpesvirus, hepadnavirus (human hepatitis B virus) and retrovirus (human immunodeficiency virus type 1 and 2, simian immunodeficiency virus, and feline immunodeficiency virus) infections; and PMPA against both hepadna- and retrovirus infections.     

Secreted poxvirus chemokine binding proteins

Poxviruses encode a variety of immunomodulatory proteins that subvert the cytokine networks of infected hosts. Myxoma virus, a poxvirus pathogen of rabbits, expresses two distinct 35- to 40-kDa secreted glycoproteins that bind a broad spectrum of chemokines. The first of these, designated M-T7, is encoded by the T7 gene and is the first example of what is here referred to as type-I chemokine binding protein (CBP-I). M-T7 was initially discovered as a secreted viral homologue of cellular interferon-gamma receptor but binding studies indicate that purified M-T7 protein also interacts with members of the CXC, CC, and C chemokine families through the conserved heparin-binding domains. The second myxoma protein, M-T1, also called CBP-II, is a member of a larger superfamily of poxvirus proteins that includes related secreted 35-kDa proteins encoded by a wide variety of orthopoxviruses. Deletion analysis of either CBP-I or -II genes within recombinant poxvirus constructs revealed profound alterations in the trafficking of infiltrating leukocytes into virus-infected lesions. It is proposed that the interaction of CBP-I with the conserved heparin-binding domains found on most chemokines represents a novel mechanism for altering multiple chemokine functions in vivo. In summary, CBP-I and CBP-II are the first examples of secreted virus proteins that bind to multiple chemokine family members as part of a strategy to prevent the early phase of inflammatory cell migration into virus-infected tissues.     

Bacterial superantigens induce down-modulation of CC chemokine responsiveness in human monocytes via an alternative chemokine ligand-independent mechanism

Staphylococcal superantigens (SAgs) are very potent T cell mitogens, but they can also activate monocytes by binding directly to MHC class II molecules in a manner independent of TCR coengagement. Induction of proinflammatory cytokines and chemokine expression in monocytes by superantigens has recently been reported. Here we report that superantigen stimulation of human peripheral blood monocytes results in a rapid, dose-dependent, and specific down-regulation of chemokine (macrophage inflammatory protein-1alpha (MIP-1alpha), monocyte chemotactic protein-1 and MIP-1beta) binding sites (e.g., CCR1, CCR2, and CCR5), which correlates with a concomitant hyporesponsiveness of human monocytes to these CC chemokine ligands. This down-regulation occurs 15-30 min following superantigen stimulation and is specific to chemokine receptors, in that binding and responsiveness of monocytes to the chemoattractant formyl-tripeptide FMLP are not affected. We further demonstrate that SAg-induced down-modulation of chemokine binding and monocyte hyporesponsiveness to the chemokines MIP-1alpha, monocyte chemotactic protein-1, and MIP-1beta is mediated through cellular protein tyrosine kinases, and the down-modulation can be mimicked by an MHC class II-specific mAb. Additionally, our observations indicate that SAg-induced loss of chemokine binding and monocyte responsiveness is probably mediated by secreted serine proteinases. Bacterial SAg-induced down-modulation of chemokine responsiveness represents a previously unrecognized strategy by some bacteria to subvert immune responses by affecting the intricate balance between chemokine and chemokine receptor expression and function.     

Molecular cloning of a novel human CC chemokine liver and activation-regulated chemokine (LARC) expressed in liver. Chemotactic activity for lymphocytes and gene localization on chromosome 2

Partial overlapping cDNA sequences likely to encode a novel human CC chemokine were identified from the GenBank Expressed Sequence Tag data base. Using these sequences, we isolated full-length cDNA encoding a protein of 96 amino acid residues with 20-28% identity to other CC chemokines. By Northern blot, this chemokine was mainly expressed in liver among various tissues and strongly induced in several human cell lines by phorbol myristate acetate. We thus designated this chemokine as LARC from Liver and Activation-Regulated Chemokine. We mapped the LARC gene close to the chromosomal marker D2S159 at chromosome 2q33-q37 by somatic cell and radiation hybrid mappings and isolated two yeast artificial chromosome clones containing the LARC gene from this region. To prepare LARC, we subcloned the cDNA into a baculovirus vector and expressed it in insect cells. The secreted protein started at Ala-27 and was significantly chemotactic for lymphocytes. At a concentration of 1 microg/ml, it also showed a weak chemotactic activity for granulocytes. Unlike other CC chemokines, however, LARC was not chemotactic for monocytic THP-1 cells or blood monocytes. LARC tagged with secreted alkaline phosphatase-(His)6 bound specifically to lymphocytes, the binding being competed only by LARC and not by other CC or CXC chemokines. Scatchard analysis revealed a single class of receptors for LARC on lymphocytes with a Kd of 0.4 nM and 2100 sites/cell. Collectively, LARC is a novel CC chemokine, which may represent a new group of CC chemokines localized on chromosome 2.     

Laser therapy of eyelid and conjunctival tumors, especially in AIDS patients

We treated patients with Kaposi's sarcoma of the lid or conjunctiva, molluscum contagiosum and papilloma of the lid with dye laser photocoagulation. This therapeutic device is extremely efficient as the chosen wavelength of 577 nm is absorbed selectively by haemoglobin. Since Kaposi's sarcoma is a haemoglobin-containing tumour composed of endothelial cells and papilloma is a benign tumour composed of connective tissue and branching vessels, dye laser photocoagulation causes selective damage to abnormal vessels and surrounding connective tissue. After local anaesthesia a small incision was made at the margin of the lesion five patients each with papilloma and with molluscum contagiosum. In six patients with Kaposi's sarcoma no incision had to be done. Starting from the incision or the margin of the Kaposi's sarcoma 50-100 shots of 0.3-0.5 mm diameter and 1 s duration were applied until the lesion was completely gone. We used a dye laser with 577 nm wavelength and 1 W energy. In patients with papilloma, the tumour basis was coagulated and the tumour itself underwent histological examination. There was a marked decrease of the size of the lesion or even complete disappearance. Since Kaposi's sarcoma in AIDS patients can be relatively fast growing, resulting in cosmetically irritating manifestations and, rarely, haemorrhages, treatment may become necessary. AIDS patients with molluscum contagiosum may also benefit from treatment, as spreading of DNA virus particles may result in viral follicular conjunctivitis. Dye laser photocoagulation, however, cannot protect against relapse.     

Blockade of CC chemokine receptor 5 (CCR5)-tropic human immunodeficiency virus-1 replication in human lymphoid tissue by CC chemokines

The CC chemokines MIP-1alpha, MIP-1beta, and RANTES suppress replication of certain HIV-1 strains in cultured PBMC and T cell lines by blocking interaction of gp120 with CC chemokine receptor 5 (CCR5). However, the same chemokines can enhance HIV-1 replication in cultured macrophages. The net effect of chemokines on HIV-1 infection in intact lymphoid tissue, the major reservoir of HIV-1 in vivo, is unknown and unpredictable since the tissue contains both T lymphocytes and macrophages. Here we show that exogenous MIP-1alpha, MIP-1beta, and RANTES markedly suppressed replication of CCR5-tropic HIV-1 strains in blocks of human lymphoid tissue infected ex vivo. Moreover, endogenous MIP-1alpha, MIP-1beta, and RANTES were upregulated in tissues infected ex vivo with CXC chemokine receptor 4-tropic but not CCR5-tropic HIV-1. Such an upregulation may contribute to the virus phenotype shift in the course of HIV disease in vivo.     

The T cell-directed CC chemokine TARC is a highly specific biological ligand for CC chemokine receptor 4

Thymus and activation-regulated chemokine (TARC) is a recently identified CC chemokine that is expressed constitutively in thymus and transiently in stimulated peripheral blood mononuclear cells. TARC functions as a selective chemoattractant for T cells that express a class of receptors binding TARC with high affinity and specificity. To identify the receptor for TARC, we produced TARC as a fusion protein with secreted alkaline phosphatase (SEAP) and used it for specific binding. By stably transfecting five orphan receptors and five known CC chemokine receptors (CCR1 to -5) into K562 cells, we found that TARC-SEAP bound selectively to cells expressing CCR4. TARC-SEAP also bound to K562 cells stably expressing CCR4 with a high affinity (Kd = 0.5 nM). Only TARC and not five other CC chemokines (MCP-1 (monocyte chemoattractant protein-1), RANTES (regulated upon activation, normal T cells expressed and secreted), MIP-1alpha (macrophage inflammatory protein-1alpha), MIP-1beta, and LARC (liver and activation-regulated chemokine)) competed with TARC-SEAP for binding to CCR4. TARC but not RANTES or MIP-1alpha induced migration and calcium mobilization in 293/EBNA-1 cells stably expressing CCR4. K562 cells stably expressing CCR4 also responded to TARC in a calcium mobilization assay. Northern blot analysis revealed that CCR4 mRNA was expressed strongly in human T cell lines and peripheral blood T cells but not in B cells, natural killer cells, monocytes, or granulocytes. Taken together, TARC is a specific functional ligand for CCR4, and CCR4 is the specific receptor for TARC selectively expressed on T cells.     

Kaposi's sarcoma-associated herpesvirus (KSHV) chemokine vMIP-II and human SDF-1alpha inhibit signaling by KSHV G protein-coupled receptor

Kaposi's sarcoma-associated herpesvirus (KSHV) encodes two proteins that are similar to human CC chemokines and a G protein-coupled receptor (KSHV-GPCR) that is constitutively active. KSHV-GPCR binds a number of human CXC and CC chemokines. We showed that interferon gamma-inducible protein-10 (IP-10), a human CXC chemokine, inhibits KSHV-GPCR signaling (Geras-Raaka et al., J. Exp. Med. 188, 405-408, 1998). Here we show that viral monocyte inflammatory protein-II (vMIP-II), one of the KSHV-encoded CC chemokines, and stromal cell-derived factor 1alpha (SDF-1alpha), a human CXC chemokine that blocks infection by human immunodeficiency virus-type 1, inhibit KSHV-GPCR signaling also. If KSHV-GPCR signaling is involved in viral pathogenesis, then these chemokines may affect the course of Kaposi's sarcoma and primary effusion lymphoma.     

Ultrasound detection of plantar bursitis of the forefoot in patients with early rheumatoid arthritis

BACKGROUND: Molluscum contagiosum nodules are common viral-induced lesions that are troublesome to treat, especially in children. I report the first study, to my knowledge, demonstrating effective, well-tolerated, and quick treatment of these lesions with the 585-nm pulsed dye laser. OBJECTIVE: To determine the effectiveness and ease of 585-nm pulsed dye laser treatment of molluscum contagiosum. METHODS: Eighty-eight lesions were treated by double-pulsing them at 1 Hz (one pulse per second) with a 3-mm spot size (fluence, 7.0-8.0 J/cm2) or 5-mm spot size (fluence, 6.8-7.2 J/cm2). RESULTS: Eighty-seven of the 88 lesions resolved completely with one treatment. CONCLUSION: The 585-nm pulsed dye laser is an effective, well-tolerated, and quick treatment for molluscum contagiosum.