The major internal protein, p27, of a retrovirus-like particle is expressed in blood lymphocytes from psoriatic patients

New insights into HIV-1-primary skin disorders

Since the first reports of AIDS, skin involvement has become a burdensome stigma for seropositive patients and a challenging task for dermatologist and infectious disease specialists due to the severe and recalcitrant nature of the conditions. Dermatologic manifestations in AIDS patients act as markers of disease progression, a fact that enhances the importance of understanding their pathogenesis.

Broadly, cutaneous disorders associated with HIV type-1 infection can be classified as primary and secondary. While the pathogenesis of secondary complications, such as opportunistic infections and skin tumours, is directly correlated with a decline in the CD4⁺ T cell count, the origin of the certain manifestations primarily associated with the retroviral infection itself still remains under investigation.

The focus of this review is to highlight the immunological phenomena that occur in the skin of HIV-1-seropositive patients, which ultimately lead to skin disorders, such as seborrhoeic dermatitis, atopic dermatitis, psoriasis and eosinophilic folliculitis. Furthermore, we compile the latest data on how shifts in the cytokines milieu, impairments of the innate immune compartment, reactions to xenobiotics and autoimmunity are causative agents in HIV-1-driven skin diseases. Additionally, we provide a thorough analysis of the small animal models currently used to study HIV-1-associated skin complications, centering on transgenic rodent models, which unfortunately, have not been able to fully unveil the role of HIV-1 genes in the pathogenesis of their primarily associated dermatological manifestations.

Human RNA "rumor" viruses: the search for novel human retroviruses in chronic disease

Retroviruses are an important group of pathogens that cause a variety of diseases in humans and animals. Four human retroviruses are currently known, including human immunodeficiency virus type 1, which causes AIDS, and human T-lymphotropic virus type 1, which causes cancer and inflammatory disease. For many years, there have been sporadic reports of additional human retroviral infections, particularly in cancer and other chronic diseases. Unfortunately, many of these putative viruses remain unproven and controversial, and some retrovirologists have dismissed them as merely "human rumor viruses." Work in this field was last reviewed in depth in 1984, and since then, the molecular techniques available for identifying and characterizing retroviruses have improved enormously in sensitivity. The advent of PCR in particular has dramatically enhanced our ability to detect novel viral sequences in human tissues. However, DNA amplification techniques have also increased the potential for false-positive detection due to contamination. In addition, the presence of many families of human endogenous retroviruses (HERVs) within our DNA can obstruct attempts to identify and validate novel human retroviruses. Here, we aim to bring together the data on "novel" retroviral infections in humans by critically examining the evidence for those putative viruses that have been linked with disease and the likelihood that they represent genuine human infections. We provide a background to the field and a discussion of potential confounding factors along with some technical guidelines. In addition, some of the difficulties associated with obtaining formal proof of causation for common or ubiquitous agents such as HERVs are discussed.

Novel pharmacological approaches in the treatment of psoriasis

Progress in the understanding of psoriasis as a T-cell mediated inflammatory disease has led to the development of new immunomodulatory therapies. Currently the main focus is on the so-called biologics (or biological agents), including fusion proteins, monoclonal antibodies, cytokines and selective receptors. They mainly target single steps in the complex cascade of humoral and cellular inflammatory immuno-mechanisms that finally lead to the accelerated growth of epidermal and vascular cells in the psoriatic lesions. The most promising and advanced biological agents are discussed along with their influence on the critical pathophysiological steps in psoriasis, including depletion of T cells, blockade of initial T-cell activation and T-cell receptor (TCR) stimulation, blockade of costimulatory signals and T-cell proliferative signals as well as restoration of the T helper type 1 (Th1)/Th2 balance by diminishing type 1 cytokines and administration of type 2 cytokines. In addition to the biological agents, further development of 'classical' dermatological therapies, such as retinoids, or the discovery of new indications for non-dermatological agents contribute to the novel pharmacological approaches in the treatment of psoriasis.

Anti-chemotactic activities of peptide-T: a possible mechanism of actions for its therapeutic effects on psoriasis

Peptide T is an octapeptide (ASTTTNYT) from the V2 region of gpl20 of HIV. D-[Ala]-Ser-Thr-Thr-Thr-Asn-Tyr-Thr-amide (DAPTA) is one of its analogue. DAPTA has been shown to resolve the psoriatic lesions. The mechanisms of action of peptide T for its therapeutic effect is not clearly understood. Lymphomononuclear cells play an important roles in inflammatory disease processes. Intraepidermal collection of lymphocytes is a unique feature of the inflammatory processes of psoriasis. It is believed that chemokine such as RANTES (C-C class) plays an important role for intraepidermal localization of the inflammatory infiltrates in psoriasis. In order to study the mechanisms, we have analyzed the effects of DAPTA on monocyte and lymphocyte chemotaxis. Chemotaxis of cells was measured by using Boyden chamber. DAPTA inhibited significantly the monocyte and lymphocyte chemotactic activity of RANTES (p < 0.005, < 0.001). Antichemotactic activities of peptide T analogue could be a possible explanation for its therapeutic efficacy in psoriasis.

Neuropeptides in skin

Neuropeptides are a heterogeneous group of more than 50 molecules that play a role in various cutaneous functions and diseases; they act as neuromodulators, neurotransmitters, neurohormones, and hormones. In the skin, neuropeptides are synthesized locally (i.e., in keratinocytes and in endothelial cells) and are transported by nerve fibers or immune cells (i.e., lymphocytes, monocytes, and polymorphonuclear cells). Specific receptors and binding sites for neuropeptides have been described in different cell lines in the skin (keratinocytes, endothelial cells, immune cells, fibroblasts). Many different biologic actions of neuropeptides have been demonstrated. Depletion of cutaneous neuropeptides (i.e., with capsaicin cream) or therapeutic use of neuropeptide agonists and/or antagonists may aid in the treatment of skin diseases.

An antigenic determinant is shared by psoriasis-associated p27 antigen and the Fc part of human IgG

Rabbit antisera against the major internal protein, p27, of retrovirus-like particles from psoriatic urine, and against the serologically cross-reacting antigen, pso p27, from psoriatic scale, reacted with the Fc part of human IgG. Evidence indicating that the p27 antigen and the pso p27 antigen are identical has been presented in previous reports. A commercial antiserum against human IgG recognized a component in the pso p27-containing solution used as the source of antigen for immunization of the rabbits. By means of monoclonal antibodies against the pso p27 antigen, it was demonstrated that the Fc-reacting antibodies, and the antiserum against human IgG, recognized an epitope on the pso p27 antigen. The data indicated that an antigenic determinant is shared by the p27 antigen(s) and human IgG, suggesting that p27 antigen(s) may act as antigen(s) eliciting the production of antibodies with rheumatoid factor activity in psoriatic patients.

The Expression of Retrovirus-Like Particles in Psoriasis

Retrovirus-like particles have been isolated from patients with psoriasis. Antigens crossreacting with the major internal proteins pso p27, of these particles have been demonstrated in the wall of dermal vessels and in a subfraction of cells in psoriatic lesions. The antigen has also been observed in blood lymphocytes from psoriatic patients. Pso p27 antigen and anti-pso p27 antibodies are present as complement-activating immune complexes in psoriatic scale and in the blood of patients with psoriasis and psoriatic arthritis. The potential contribution of the circulating immune complexes to the inflammatory process in psoriasis is discussed.

The psoriasis-associated antigen, pso p27, participates in the formation of complement activating immune-complexes in psoriatic scale

The psoriasis-associated antigen, pso p27, and antibodies recognizing this antigen were demonstrated in extracts from psoriatic scales. It was demonstrated that the antigen was present in complexes containing IgG as well as complement factor C1q. The complexes were studied with respect to complement-activating potential. This was measured as the ability of the complexes to induce the generation of the complement factor C5a using rabbit serum as the source of complement. The data obtained showed that the pso p27-containing complexes were able to activate the complement system, indicating that the pso p27 antigen may contribute to the inflammatory process in psoriasis.

Retroviruses and chronic arthritis. Possible significance of some recent observations

Retroviruses have been proposed as etiologic agents for the development of chronic arthritis in humans. The arthritis seen in goats infected by caprine arthritis encephalitis virus and the spontaneous arthritis of inbred MRL/l mice illustrate how retroviruses may cause the development of a disorder closely resembling human rheumatoid arthritis. Several investigators have searched for evidence of retrovirus infection in patients with chronic arthritis, but in most cases the results have been disappointing. However, in 1983, Iversen isolated a virus-like particle from a patient with psoriasis. The particle had a buoyant density in sucrose and a protein composition that closely resembled murine and primate retroviruses. Particle proteins participate in immune complex formation in psoriasis, in psoriatic arthritis, and in ankylosing spondylitis. Particle proteins are also present in deposits in psoriatic lesions and in affected synovial tissue resembling immune complex deposits. The possible role for retrovirus-like antigens in the inflammatory process in psoriasis and seronegative arthritis is discussed.

Monoclonal antibodies against the major internal protein, p27, of a psoriasis-associated retrovirus-like particle

Four murine monoclonal antibodies (MoAb) were raised against p27 isolated from psoriatic scale. The MoAb recognized the antigen on a subfraction (0.1-1%) of psoriatic lymphocytes as well as in skin biopsies from psoriatic patients. In contrast, the antigen could not be detected on lymphocytes or in skin biopsies from healthy controls. A sandwich ELISA assay using the MoAb for detection of p27 is described. This method, together with a competition antibody-binding assay for distinction of epitopes, demonstrates that the MoAb recognize four different antigenic determinants on p27.

Decreased production of interferon in whole blood cultures derived from patients with psoriasis

Patients suffering from psoriasis show many alterations with respect to their immune system as documented by in vitro test systems. In the present study we investigated the in vitro production of interferons (IFN) of leukocytes from psoriatic patients to stimulation with a variety of IFN inducers. Furthermore, the lymphoproliferative responses were tested. Whole blood cultures of 30 psoriatic patients showing moderate to severe disease activity and 21 cultures from healthy controls were stimulated with the mitogens PHA, ConA, and PWM, with PPD and Tetanus Antigen as IFN gamma inducers and with C. parvum, PolyI-PolyC, and Herpes simplex virus as inducers of IFN alpha. Interferon activity was tested in the supernatant of 48-h cultures by using an antiviral assay. Lymphoproliferation was assayed in 5-d cultures in parallel. Psoriatic patients showed a significantly decreased IFN production to all the stimuli tested. There were no significant differences in the lymphoproliferative responses; only the response to PWM was slightly decreased. The decreased IFN production by leukocytes from psoriatic patients seems to be very remarkable since increased susceptibility to infections is not generally known in these patients.

Analysis of circulating immune complexes from patients with ankylosing spondylitis by gel electrophoresis and immunoblotting using antiserum against a psoriasis associated retrovirus-like particle

Circulating immune complexes (CIC) were isolated from patients with ankylosing spondylitis (AS) and healthy blood donors by isopycnic ultracentrifugation in sucrose gradients. The CIC were analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. The major components of the CIC were identified as albumin, immunoglobulins, and complement factors. A 70 kD component and several low molecular weight components (Mr 19 kD and 14 kD (doublet] were detectable only in CIC from patients with AS. An antiserum raised against the envelope glycoprotein, gp70, of a psoriasis associated retrovirus-like particle was applied to check for cross reacting activity. This antiserum reacted with both a 70 kD and a 40-45 kD component in CIC from three out of six patients but not with CIC from any of the blood donors.

Rabbit antibodies against the major internal protein of a retrovirus-like particle bind to epidermal cells in psoriatic skin. Brief report

A rabbit antiserum against the major internal protein, p27, of a psoriasis associated retrovirus-like particle has been used in indirect fluorescence microscopy of biopsies from psoriatic skin. The analysis indicate expression of p27 antigen in epithelial cells in psoriatic lesions and in clinically uninvolved psoriatic skin. A reaction of the antiserum with dermal vessel walls in the lesion was also observed.

The major internal protein, p27, of a retrovirus-like particle participates in immune complex formation in psoriasis

The major internal protein, p27, of a retrovirus-like particle isolated from the urine of a patient with psoriasis has been purified and used in an indirect ELISA to detect human antibodies against the virus antigen. Rabbit anti-p27 antiserum has been applied to detect p27 antigen present in clinical specimens. p27 and anti-p27 antibodies have been demonstrated in extracts from psoriatic scales. Insignificant amounts of free anti-p27 antibodies are present in serum, but both p27 and anti-p27 antibodies have been detected in circulating immune complexes obtained from serum or synovial fluid from patients with psoriatic arthritis.