Skin infections and ageing

Elderly individuals have an increased susceptibility to skin infections due to age-related anatomical, physiological and environmental factors. The types of organisms that cause primary skin and soft tissue infections are diverse, and include bacterial, viral and fungal pathogens as well as parasites. In the elderly, these infections and infestations may present with atypical signs and symptoms or may complicate underlying chronic skin disorders. Clinical features, investigations and management of the following important and common skin infections are described in more detail: cellulitis, erysipelas, necrotizing fasciitis, impetigo, folliculitis, furunculosis and carbunculosis, erythrasma, herpes zoster and postherpetic neuralgia, herpes simplex, warts, molluscum contagiosum, dermatophytosis of the skin, hair and nails, candidiasis, and scabies. Treatment should be based on the results of the appropriate diagnostic tests. Correct diagnosis and therapy of skin infections lead to satisfactory outcome in the majority of elderly patients.

Vesicular and pustular eruption related to cytomegalovirus in an immunocompetent patient

Cytomegalovirus (CMV), a member of the herpesviridae family, can cause various dermatologic and systemic disorders especially in immunosuppressed subjects. However, immunocompetent individuals rarely present with cutaneous eruptions related to CMV. We describe an immunocompetent patient who developed a skin eruption and mild hepatitis related to CMV.

Stress-induced changes in pathophysiology and interferon gene expression during primary HSV-1 infection

Herpes simplex viruses (HSV) are the cause of the most common clinically recognized herpesvirus infections. The severity and duration of the primary HSV infection have been correlated with the frequency and severity of subsequent recurrences. Reactivation of latent HSV-1 can occur as a result of physical or emotional stress; however, the effects of stress on the modulation of the clinical pathophysiology of primary HSV-1 infections are not well understood. Although it is known that stress can be immunosuppresive, the immunological mechanisms by which stress modulates early immune responses, such as type I interferon gene expression during a primary HSV-1 infection are still not understood. It was hypothesized that due to suppressed early immune responses, stress would increase the severity of a cutaneous primary HSV-1 infection. In this investigation, a cutaneous HSV-1 model in the SKH-1 mouse was characterized and utilized to study the effect of restraint stress on the modulation of the clinical pathophysiology of primary HSV-1. Despite prolonged viral replication at the site of primary infection, restraint stress decreased the clinical severity of primary HSV-1 in the skin of SKH-1 mice. A decrease in type I and type II IFN expression was found in the skin of acutely infected restrained mice when compared to controls at day 3 post-infection using competitive RT-PCR. Using the glucocorticoid-receptor antagonist RU486, IFN-beta and INF-gamma expression were restored in restrained animals to control levels. Treatment with RU486 also increased the clinical severity of the cutaneous infection to control levels in restrained mice. Thus, RST masked the severity of an HSV-1 infection by decreasing its clinical signs while impairing the ability of the host to control viral replication prolonging the infectious period.

A kinetic analysis of immune mediators in the lungs of mice infected with vaccinia virus and comparison with intradermal infection

The early inflammatory response to a virus may be critical in restricting infection and in shaping the subsequent adaptive immune response. In this study we have examined the early inflammatory response of mice following infection with vaccinia virus (VV) strain Western Reserve (WR). Respiratory challenge of BALB/c mice with VV led to early virus replication in the lung and upper respiratory tract followed by dissemination of virus to other visceral organs and to the brain. The number of inflammatory cells, largely macrophages and T lymphocytes, recovered from bronchoalveolar lavage (BAL) fluid increased markedly during infection and coincided with the expression of CC chemokine ligands (CCL) 3, 2 and 11 and CXC chemokine ligands (CXCL) 1 and 2/3 in BAL. The peak of the inflammatory response occurred around day 10 and declined thereafter. The antiviral cytokines IFN-gamma and TNF-alpha, and the reactive nitrogen intermediate nitric oxide (NO), were also detected in BAL from VV-infected mice. A markedly different inflammatory response was observed after intradermal inoculation of WR into the ear pinnae of mice. Intradermal challenge was followed by highly localized virus replication and by a cellular influx, consisting largely of neutrophils and T lymphocytes, into the dermal compartment of the infected ear. Together these findings highlight differences in the pathogenesis and in the cellular inflammatory response to WR following intranasal and intradermal inoculation of mice.

[Topical immunomodulators in dermatology]

Immunomodulators include both immunostimulatory and immunosuppressive agents. Obligate contact sensitizers such as diphencyprone or dinitrochlorobenzene have been used against viral and autoimmune diseases. Newer agents such as the toll-like receptor agonists imiquimod and resiquimod have been clinically used to treat viral infections and skin cancers in immunocompetent and immunosuppressed patients. On the other hand, the topical immunosuppressive agents tacrolimus and pimecrolimus have been used with great success in the treatment of chronic inflammatory diseases in children and adults. The introduction of this new class of drugs (i.e. Calcineurin inhibitors) marked the beginning of the post-cortisone era in clinical dermatology. Toll-like receptor agonists and calcineurin antagonists will supplement corticosteroids to improve specific dermatological therapy. Topical immunotherapy with both immunostimulatory and immunosuppressive agents show potential for effective and patient-friendly treatment of inflammatory, infectious and neoplastic skin diseases. Long-term evaluation will define the tolerability and the safety profile.

Rapid cytotoxic T lymphocyte activation occurs in the draining lymph nodes after cutaneous herpes simplex virus infection as a result of early antigen presentation and not the presence of virus

Localized cutaneous herpes simplex virus type 1 (HSV-1) infection leads to arming and initial expansion of cytotoxic T lymphocytes (CTLs) in the draining popliteal lymph nodes (PLNs) followed by migration and further proliferation in the spleen. To accurately characterize the sequence of events involved in the activation and generation of anti-HSV CTLs, we used T cell receptor (TCR) transgenic mice specific for the immunodominant epitope from HSV glycoprotein B (gB(498-505)). We describe the detection of the initiation of antigen presentation in the draining lymph nodes by 4-6 h after infection with HSV-1. Analysis of CD69 up-regulation revealed activation of gB-specific CD8(+) T cells by 6-8 h after infection. Furthermore, we show that T cell proliferation begins no sooner than 24 h after activation and is marked by the concurrent appearance of CTL activity in the PLNs. These events are not dependent on the presence of virus in the draining lymph nodes, and suggest a requirement for recruitment of professional antigen-presenting cells to the site of T cell activation. Consequently, we have defined the initiation of the CD8(+) T cell-mediated response to cutaneous HSV-1 infection, demonstrating that the immune response to localized viral infection depends only on the appearance of cells presenting virus-derived antigen and commences with remarkable swiftness.

Alterations in molecular killing mechanisms: implications in skin disease

Cytolytic T lymphocytes exert two main specific molecular killing mechanisms against target cells, namely (i) they can synthesize and release soluble cytolytic factors, and (ii) they can express effector molecules that act as ligands of receptors expressed by target cells on the cell surface; by these two pathways cytolytic T lymphocytes kill several targets, e.g. cells infected with intracellular pathogens, cells transformed by malignancy and cells producing autoantibodies. This review investigates the contribution from alterations in these molecular killing mechanisms to the pathogenesis of cutaneous diseases. In fact, molecular components involved in such killing mechanisms are often altered or distorted in skin pathology, e.g. cutaneous viral infections, skin cancer, contact hypersensitivity and autoimmune diseases with cutaneous involvement. Treatments capable of repairing the molecular components operating in such killing mechanisms could presumably favour the resolution of these skin diseases.

Detection of cellular cytokine mRNA expression during orf virus infection in sheep: differential interferon-gamma mRNA expression by cells in primary versus reinfection skin lesions

In sheep infected with the parapoxvirus orf virus, primary infection orf skin lesions developed and resolved within 8 weeks. Reinfection lesions were smaller and resolved within 3 weeks. The host response in the skin was characterized by an accumulation of neutrophils, dendritic cells, CD4+ T cells, CD8+ T cells, B cells and T19+ gammadelta T cells. The magnitude of this accumulation paralleled orf virus replication in the skin. In situ hybridization was used to detect cells expressing interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha) and interleukin-4 (IL-4) mRNAs in orf skin. Cells expressing IL-4 mRNA were not detected at any time after infection. Cells expressing IFN-gamma mRNA were detected after reinfection but not after primary infection. Cells expressing TNF-alpha mRNA included epidermal cells, vascular endothelium and uncharacterized cells that increased more rapidly in the skin after reinfection compared to primary infection. The results are consistent with a prominent role for IFN-gamma in the host immune response controlling the severity of the disease.

Understanding the pathogenesis of HSV-associated erythema multiforme

Erythema multiforme (EM) is a polymorphic, often recurring eruption caused by exposure to medication or various infections, notably herpes simplex virus (HSV). Understanding the pathogenesis of HSV-associated EM (HAEM) is essential for patient management. We suggest that HAEM results from the combination of viropathic effects mediated by HSV proteins, notably DNA polymerase (Pol), and an immunological reaction to viral antigens. Presumably, viral DNA and proteins ingested by macrophages at HSV lesion sites undergo fragmentation and processing for presentation to T cells with HSV memory. HSV DNA is deposited on the skin, where it is expressed. Activated T cells are recruited to the skin site of Pol expression, directly or indirectly resulting in the generation of an inflammatory cascade. Factors potentially involved in the incidence of recurrences, lesion severity and anatomical localization include the identity of the deposited HSV genes, cutaneous capillary size, degree of vasoconstriction and ambient temperature. Evidence in support of this interpretation is reviewed.

Current understanding of cytomegalovirus infection in immunocompetent individuals

Human cytomegalovirus (CMV) is a member of the herpes family of viruses. After primary infection, it undergoes latency/persistence. Significant progress has been made in the last few years in detecting CMV. The most available approach to the diagnosis of CMV infection is the direct detection of CMV antigen in nuclei of peripheral blood leukocytes, an assay known as pp65 direct antigenemia test. CMV infection is well controlled in the immunocompetent hosts; however, there are various immunological changes in immune function during and after recovery from CMV infections. Characteristic changes in lymphocyte subsets occur during CMV infection, mainly involving expansion and activation of CD8+ T lymphocytes and NK cells. On the other hand, CMV has an array of immune escape strategies for establishing a life long latent state: CMV inhibits major histocompatibility complex (MHC) class I expression within infected cells and impairs IFN-gamma-induced MHC class II-dependent antigen presentation by macrophages; it can also encode proteins that can interfere with the presentation of viral peptide antigens to T cells. While cutaneous manifestations of CMV seen in immunocompromised patients have been extensively reported, those in adult immunocompetent individuals have received relatively little attention: in this setting the primary CMV infection appears as CMV mononucleosis. At the time of occurrence of the mononucleosis syndrome, a variety of extracutaneous and cutaneous manifestations occur. These clinical symptoms are not the direct consequence of proliferation of CMV in given tissues but indicative of the immunological response toward CMV. The incidence of the appearance of eruptions in CMV mononucleosis is variable. Certain drugs given in the early stage of this disease play an important role in the development of eruption, just as with the ampicillin rashes in the Epstein-Barr virus mononucleosis. Although the mechanism by which drugs trigger the development of rashes in patients with CMV mononucleosis is unknown, it is assumed that CMV is likely to be a potential amplifier of drug rashes induced by activation of drug-specific T cells. By improving methods for detection of CMV, we can recognize that many types of eruptions other than CMV mononucleosis could be induced by primary infection or reactivation of CMV.

Langerhans cells migrate to local lymph nodes following cutaneous infection with an arbovirus

Whereas there has been recent interest in interactions between dendritic cells and pathogenic viruses, the role of dendritic cells in the initiation of protective immunity to such organisms has not been elucidated. The aim of this study was to examine whether a resident dendritic cell population in the skin, Langerhans cells, respond to cutaneous viral infections which are effectively cleared by the immune system. We therefore characterized the ability of Langerhans cells to migrate to local draining lymph nodes following infection with the arthropod-borne viruses, West Nile virus or Semliki Forest virus. The data show that major histocompatibility complex class II+/NLDC145+/E-cadherin+ Langerhans cell numbers are increased in the draining lymph nodes of infected mice and this increase is accompanied by a concomitant decrease in the Langerhans cell density in the epidermis. Langerhans cell migration is associated with an accumulation of leukocytes in the lymph node, which is one of the earliest events in the initiation of an immune response. Both the migratory response and the draining lymph node leukocyte accumulation were abrogated if ultraviolet-inactivated instead of live viruses were used, suggesting the activation and subsequent migration of Langerhans cells requires a live, replicating antigen. Our findings are likely to have wider implications for the development of epidermally delivered vaccines and suggest that mobilization of dendritic cells may be involved in the development of immune responses to arthropod-borne viruses.

Complications of varicella zoster virus reactivation in HIV-infected homosexual men

OBJECT

To study the complication rate of varicella zoster virus (VZV) reactivation and the relationship between complications, presentation and localization of zoster and immune function in HIV disease.

DESIGN AND METHODS

A total of 142 episodes of VZV reactivation in 113 out of 544 HIV-1-infected participants in the Amsterdam Cohort Study of homosexual men were studied. Persistent hyperkeratotic or necrotic skin lesions, post-herpetic neuralgia, other neurological events, ocular events and pneumonitis occurring within 6 months of the onset of the last episode of VZV reactivation were defined as complications, provided that other possible diagnoses were excluded and the event had been previously described in the literature as related to VZV reactivation.

RESULTS

Twenty-four complications occurred in 15 (11%) of these 142 episodes. Complications occurred exclusively in the 40 episodes with either multidermatomal or disseminated presentation, or a trigeminal localization, or both. In the group of episodes of unidermatomal zoster at a non-trigeminal localization no complications occurred. Twenty-one episodes of herpes zoster were localized in the trigeminal area. Localization was not significantly associated with the level of immune function. Compared to unidermatomal presentation (n = 120), multidermatomal (n = 15) and disseminated presentation (n = 7) occurred at lower median CD4+ cell counts (330, 240 and 50 x 10(6)/l, respectively; P = 0.003) and significantly lower levels of CD3 monoclonal antibodies or phytohaemagglutinin-induced T-cell reactivity in vitro. Complications were related to CD4+ cell counts, but in the cases of disseminated, multidermatomal or trigeminal zoster a CD4+ cell measurement provided no additional information on the risk of complications.

CONCLUSION

In HIV-infected individuals the extent of the clinical presentation and the occurrence of complications of VZV reactivation are related to the degree of immunodeficiency. In episodes of VZV reactivation with either multidermatomal or disseminated presentation or a trigeminal localization, or both the complication rate was high. CD4+ cell counts provided no additional information on the complication risk. Oral acyclovir appears to be sufficient as therapy for unidermatomal zoster at a non-trigeminal localization.

Characteristic but unfamiliar--the cowpox infection, transmitted by a domestic cat

An 11-year-old girl had been suffering from 2 recently developed reddish ulcerated nodules on the right side of her neck and, concomitantly, from a very hard swelling as well as from painless lymphadenopathy. Subsequently, thick black eschars appeared on the surface of the ulcers. Using the negative staining technique, an orthopox virus infection could be identified by electron microscopy. The patient's characteristic history as well as her close contact with a cat frequently hunting nice indicated the diagnosis of a cowpox infection, which was unequivocally confirmed by identification of both the viral culture and specific antibodies in the serum of the patient.

Decreased CD7 expression in cutaneous infiltrates of HIV-1+ patients. Military Medical Consortium for the Advancement of Retroviral Research (MMCARR)

CD7 is an early T-cell marker that has been used in the diagnosis of stem cell leukemias. Loss of expression of CD7 with a battery of other mature T-cell markers has also been used as one criteria in the diagnosis cutaneous T-cell lymphomas. More recently, CD7-negative T cells have been shown to be a normal population of T cells in the peripheral blood and the skin, and may represent a mature T-cell population with a different pattern of maturation and activation. In addition, in HIV-1 disease expansion of CD7-negative T cells has been found in the peripheral blood. We evaluated the number of CD7-negative T cells in skin infiltrates to determine whether there was an increase of CD7-negative T cells. We studied T-cell markers including CD3, CD4, CD7, CD8, CD20, CD29, and HLA-DR on cutaneous biopsy material from inflammatory dermatoses in 57 patients with HIV-1 disease in Walter Reed stages (WR) 1-6, and in 14 HIV-1-negative patients WR0. The inflammatory infiltrates showed a moderate to marked decrease in CD7 expression on CD3+ T cells in benign inflammatory infiltrates of the majority of HIV-1+ patients. The majority of HIV-1-negative patients showed no decrease in CD7 expression, although 5 of 14 showed a moderate decrease and 1 of 14 showed a marked decrease. Although the nature of CD7- T cells has not been clearly defined, this population of mature T cells appears to have distinct immunologic properties as well as a trophism for skin. Better characterization of these T cells, as well as factors that promote their maturation and activation, may give clues to the high incidence as well as the pathogenesis of skin disease in HIV-1+ patients.

Involvement of LFA-1 and ICAM-1 in the herpetic disease resulting from HSV-1 corneal infection

Herpes simplex virus type 1 (HSV-1) corneal infection in immunologically normal mice results in a transient epithelial lesion followed in about 2 weeks by a potentially blinding inflammatory response in the corneal stroma, and a mild blepharitis. Similarly infected T cell-deficient mice do not develop corneal stromal inflammation, but exhibit severe periocular skin disease and succumb to viral encephalitis. The role of certain adhesion molecules in both T cell activation, and in the extravasation of inflammatory cells from the blood into inflammatory sites is now being established. These studies investigated the involvement of the adhesion pair LFA-1/ICAM-1 in the disease that results from HSV-1 corneal infection in mice. Treatment of mice with mAb to LFA-1 beginning 1 day before HSV-1 corneal infection resulted in a delay in the onset of stromal inflammation, but ultimately stromal inflammation developed to a normal extent. This treatment also caused a significant exacerbation of periocular skin disease, but did not render mice susceptible to encephalitis. Treatment with mAb to ICAM-1 beginning 1 day before HSV-1 corneal infection caused an acceleration of both stromal inflammation and periocular skin disease, and rendered mice uniformly susceptible to lethal encephalitis. Treatment with either mAb beginning 6 days after HSV-1 corneal infection did not significantly affect the clinical course of herpetic disease. Our findings suggest that LFA-1 may play a role in the early phase of corneal stromal inflammation following HSV-1 corneal infection. Both LFA-1 and ICAM-1 appear to be important for protection of the skin from HSV-1 infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Viral glycoproteins in herpesviridae granulomas

Granulomatous reactions after varicella zoster virus (VZV) and herpes simplex virus (HSV) infections are rare, and their pathogenesis remains unclear. We studied by immunohistochemistry and in situ hybridization early granulomatous reactions after VZV and HSV infections. In the five cases studied, the VZV glycoproteins gp I and gp II were present in cells abutted to altered vessels, but the corresponding genome sequences were disclosed in similar locations in only one of these cases. In an immunocompromised patient with diffuse HSV eruption, HSV I antigens were present in cells of the reticular dermis, while viral nucleic acids were not evident. Immunophenotyping of the granulomas showed strong Mac 387 and CD68 positive labelings of macrophages/monocytes, without any involvement of Factor XIIIa-positive cells. These findings suggest that the major viral envelope glycoproteins, rather than complete viral particles could trigger granuloma formation following HSV and VZV skin infections.