Therapeutic use of cytokines in dermatology

The role of interleukin 10 in the pathogenesis and potential treatment of skin diseases

Interleukin 10 (IL-10) is a key cytokine produced by a multitude of immune effector cells and possesses distinct regulatory effects on immune functioning in the skin. In this article we report the current understanding of the immunobiology of IL-10 and identify the role of IL-10 in cutaneous infection as well as in autoimmune and neoplastic processes. We reviewed the literature to examine the function of IL-10 in different cutaneous disorders. IL-10 can influence and potentially treat T1/T2 differentiation, antigen-presenting cell functioning, antigen-presenting cell-mediated T-cell activation, and T-cell, B-cell, and mast cell growth and differentiation that is aberrant in various disease processes. The literature consensus is that the multitude of effects of IL-10 contribute to the pathogenesis of different skin disorders. In certain circumstances IL-10 could represent novel therapeutic approaches to treating cutaneous diseases.

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should be acquainted with the role of IL-10 in many infectious diseases, autoimmune skin disease, inflammatory processes, and malignancy. Its possible role in the resolution of various skin diseases should be better understood.

Immunomodulation and immunodeficiency

This article briefly reviews the concepts of immunodeficiency and immunomodulation as they relate to selected skin diseases in the dog and cat. Immunodeficiency states are uncommon and may be associated with a subnormal or down-regulated immune system, including humoral deficiencies, such as IgA, and abnormal lymphocyte or neutrophil function. Establishing a causal relationship between a skin disease and presumed immunodeficient state has been difficult due to the rarity of such conditions, and the limited nature of the techniques used to characterise the immune system response. Severe combined immunodeficiency in dogs is a well characterised primary immunodeficiency state involving lymphocytes; retrovirus infection in cats may lead to an acquired immunodeficient state with some association with certain dermatological conditions although it remains unclear that infection is causally linked with disease. Immunomodulation usually implies stimulating the immune system along a beneficial pathway. Such a therapeutic approach may involve a wide variety of agents, for example intravenous immunoglobulin. There are few randomised controlled trials with veterinary patients that unequivocally demonstrate beneficial responses to immunomodulatory agents. Interferons are cytokines of major interest in human and veterinary medicine for their antiviral, anti-tumour and immunomodulatory effects. The advent of veterinary-licensed products containing recombinant interferon may enable demonstration of the efficacy of interferons for conditions such as canine papillomatosis and feline eosinophilic granuloma complex. Canine pyoderma has been treated with a number of presumed immunomodulatory agents with limited success. With more detailed knowledge of the pathogenesis of pyoderma it may be possible to develop efficacious immunomodulators.

Interferon-beta from melanoma cells suppresses the proliferations of melanoma cells in an autocrine manner

Interferon (IFN)-alpha and IFN-beta have been utilized in the treatment of melanoma as a form of cytokine therapy. While previous studies have demonstrated that melanocytes and melanoma cells produce a number of cytokines, it remains unclear whether or not melanocytes and melanoma cells per se produce IFN-alpha or IFN-beta. In the present study, we investigated the expression of IFN-alpha or IFN-beta in human melanocytes and five melanoma cell lines: G-361, C32TG, MMAc, MEWO and VMRC-MELG at both mRNA and protein levels. Both IFN-alpha and IFN-beta mRNA were detected in normal human melanocytes. Likewise, IFN-alpha mRNA was detected in all five melanoma cell lines. However, IFN-beta mRNA was only detected in one melanoma cell line, VMRC-MELG. When melanocytes and melanoma cells were treated with a potent IFN inducer, polyinosinic:polycytidylic acid (poly I:C), the mRNA expression of both IFN-alpha and IFN-beta was significantly upregulated. Poly I:C was not able to induce melanocytes or melanoma cells to produce detectable amounts of IFN-alpha protein, but able to induce a significant amount of IFN-beta in melanocytes and two of the melanoma cell lines: MMAc and VMRC-MELG. Moreover, similar to exogenous IFN-alpha and IFN-beta, poly I:C significantly inhibited the proliferation of all five melanoma cell lines. This suppressive effect was partially blocked by anti-IFN-beta antibody treatment in the IFN-beta-producing melanoma cell lines: MMAc and VMRC-MELG, but not in the non-IFN-beta-producing cell lines: G-361, C32TG and MEWO. Collectively, these studies have demonstrated for the first time that human melanocytes and melanoma cells produce IFN-beta. Furthermore, melanoma cells are capable of suppressing their own proliferation via secretion of endogenous IFN-beta. This finding may have important implications for melanoma therapy.

Transforming growth factor-beta isoforms differently stimulate proalpha2 (I) collagen gene expression during wound healing process in transgenic mice

The role of many growth factors and cytokines in the process of wound healing has been intensively investigated in recent two decades. Among them, transforming growth factor-betas (TGF-betas) are well known to have a potent stimulatory effect on collagen synthesis as shown in various in vivo experimental systems. In the present study, we examined the effects of various growth factors on the promoter activity of the proalpha2 (I) collagen gene (COL1A2) during the wound healing process. For this purpose, we utilized transgenic mice harboring the -17 kb promoter sequence of the mouse COL1A2 linked to either a firefly luciferase or a bacterial beta-galactosidase gene. These mice exhibited normal phenotypic expression and the wound healing process was not impaired. Full thickness wounds were made by punch biopsy. We examined the effects of TGF-beta1, -beta2, -beta3, basic fibroblast growth factor, platelet-derived growth factor, and connective tissue growth factor by applying them locally to the open wound every 2 days. Among the growth factors examined, all of the three isoforms of TGF- exhibited a more potent stimulatory effect on COL1A2 promoter activity than did other factors. In addition, while TGF-beta1 and -beta2 significantly increased the number of fibroblasts which were positive for X-Gal staining, TGF-beta3 treatment did not change the number of beta-galactosidase expressing cells. Accumulation of collagen fibers was observed to the same extent in the mice treated with TGF-beta1 and those with TGF-beta3. These findings suggest that TGF-beta1 and -beta3 have similar but not identical regulatory mechanisms of COL1A2 expression, and that their pathophysiological roles in wound healing might be different from each other.

Growth regulation of skin fibroblasts

The growth of skin fibroblasts is regulated in a complex manner by various growth factors. Representative growth factors are platelet-derived growth factor (PDGF), basic fibroblast growth factor (b-FGF), transforming growth factor-beta (TGF-beta), and connective tissue growth factor (CTGF). These growth factors have various biological activities besides growth regulation of skin fibroblasts, and are involved in wound healing and in the pathogenesis of various disorders. For example, PDGF and CTGF stimulate chemotaxis of skin fibroblasts, b-FGF stimulates angiogenesis, and TGF-beta stimulates production of matrix proteins. First, the properties of these growth factors are reviewed briefly. Our skin fibrosis model in newborn mice are also described here. In 1986, Roberts et al. reported that subcutaneous injection of TGF-beta in newborn mice caused granulation tissue formation followed by fibrosis (Roberts et al. Proc Natl Acad Sci USA 1986;83:4167-71). We conducted similar experiments, and found that TGF-beta1, beta2 or beta3 caused skin fibrosis after 3 consecutive days of injection; this change was transient and disappeared after 7 consecutive days of injection. In contrast, irreversible fibrosis was observed upon stimultaneous injection of TGF-beta and b-FGF or TGF-beta and CTGF, or TGF-beta injection for the first 3 days and b-FGF or CTGF injection for the next 4 days (Shinozaki et al. Biochem Biophys Res Commun 1997;237:292-7; Mori et al. J Cell Physiol 1999;181:153-9). These observations suggest that TGF-beta induces skin fibrosis and b-FGF or CTGF maintains it in various skin fibrotic disorders. In the 21st century, we speculate that cocktails of various growth factors may permit subtle growth regulation of skin fibroblasts; such technology would have applications in the treatment of many skin diseases.

Cutaneous vaccination: the skin as an immunologically active tissue and the challenge of antigen delivery

Vaccination is one of the major achievements of modern medicine. As a result of vaccination, diseases such as polio and measles have been controlled and small pox has been eradicated. However, despite these successes there are still many microbial diseases that cause tremendous suffering because there is no vaccine or the vaccines available are inadequate. In addition, even if vaccines were available for all infectious diseases there is no guarantee that people would use them routinely. One of the major impediments to ensuring vaccine efficacy and compliance is that of delivery. Presently most vaccines are given by intramuscular administration. Unfortunately this is often traumatic, especially in infants. Thus, if it was possible to replace intramuscular immunization by mucosal (oral/intranasal) or transdermal delivery it may be possible to both enhance mucosal immunity as well as improve overall compliance rates. The transdermal route has been used by the pharmaceutical industry for the delivery of various low molecular weight drugs. Some of the approaches used for smaller compounds may also have potential for delivery of either protein or polynucleotide vaccines. However, there is a greater challenge to delivering large molecular weight molecules through the skin due to size, charge and other physicochemical properties. This review will describe the recent advances that have been made in dermal and topical delivery as related to vaccines.

Interferon-induced cutaneous necrosis

BACKGROUND

Due to advances in recombinant DNA technology, interferons are now readily available and are frequently used in all branches of medicine. These potent biologic response modifiers carry a number of systemic and local side effects. These cytokines are usually administered subcutaneously, and recent studies have described the occurrence of inflammation or necrosis at the site of injection.

OBJECTIVE

We report a case of cutaneous necrosis at the sites of interferon injections in a 35-year-old man treated for chronic myeloid leukemia with high, daily doses of interferon alfa. In addition, we review the existing literature on interferon-induced cutaneous necrosis and discuss preventive strategies.

CONCLUSION

Cutaneous inflammation or necrosis at interferon injection sites is not uncommon. Although interferon beta-1b is most commonly responsible for this complication, it is now increasingly reported with interferon alfa. It appears to be secondary to the proinflammatory effects of these cytokines or to their unmasking of a subtle hypercoagulable state.

The expression and modulation of IFN-alpha and IFN-beta in human keratinocytes

In addition to leukocytes and fibroblasts, the classic sources of human interferons (IFN), many other human cells are now known to be capable of producing IFN. Keratinocytes (KC) are abundant in the skin and provide the first line of defense against viruses and other noxious agents. Human KC are a potent source of cytokines and were implicated as forming IFN-like protein(s). We have investigated whether KC form IFN. We found that culture supernatants from unstimulated human KC did not contain detectable amounts of IFN-alpha or IFN-beta. However, those from KC activated with the potent IFN inducer, polyriboinosinic:polriboycytidylic acid (poly rI:rC), had appreciable antiviral activity, which studies with neutralizing sera showed to be caused by IFN-beta. In ELISA tests, we detected IFN-beta protein in the supernatants but not IFN-alpha protein. Nevertheless, reverse transcription PCR showed that both IFN-alpha and IFN-beta mRNA were upregulated in poly rI:rC-treated KC. The levels of these mRNA were also increased in KC exposed to ultraviolet B (UVB) irradiation, interleukin-1alpha (IL-1alpha), tumor necrosis factor-alpha (TNF-alpha), or lipopolysaccharide (LPS). These results show that IFN-beta is among the cytokines secreted from human KC and, together with IFN-alpha, may have a role in host defense mechanisms in the skin.

Postsurgical adjuvant therapy for melanoma. Evaluation of a 3-year randomized trial with recombinant interferon-alpha after 3 and 5 years of follow-up

BACKGROUND

Early surgical intervention is still the most successful therapy for patients with melanoma. The results obtained with medical therapies are still quite disappointing, with better results observed in soft tissue and lymph node metastasis. There currently is no standardized adjuvant therapy for primary melanoma. On the basis of the activity demonstrated in vitro against melanoma cell lines and the results obtained in many clinical trials in patients with advanced melanoma, the authors chose to study the use of recombinant interferon-alpha (IFN-alpha) as adjuvant therapy for patients with Stage I and Stage II melanoma.

METHODS

A randomized multicenter trial based on the use of recombinant IFN-alpha-2b for 3 years at the dose of 3 MU given intramuscularly 3 times a week for a period of 6 months with a 1-month interval between cycles was conducted in Stage I and Stage II melanoma patients (using the American Joint Committee on Cancer classification). The efficacy of this treatment was evaluated calculating the incidence of recurrence after 3 and 5 years.

RESULTS

Results were collected at the end of the treatment period and after 5 years of follow-up for a smaller number of patients. Statistical evaluation showed a significant difference between treated patients and untreated controls with regard to progression of the disease. In particular, IFN-alpha appears to be more effective in patients with worse prognosis lesions.

CONCLUSIONS

IFN-alpha appears to be effective as adjuvant therapy for high risk melanoma patients and the risk/benefit ratio appears to be very favorable. The authors' next goal is to separate those patients who might benefit from adjuvant therapy from those who are cured after the surgical intervention only.

Adverse cutaneous reactions to chemotherapeutic agents and cytokine therapy

This article reviews the adverse cutaneous reactions to antineoplastic chemotherapeutic agents and cytokine therapy. The article details specific reactions such as acral erythemas and flushing reactions. It also discusses nonspecific reactions with specific histological features such as neutrophilic eccrine hidradenitis and syringosquamous metaplasia. The wide variety of cutaneous reactions to cytokine therapy such as from recombinant interleukins and the colony stimulating factors are reviewed.

Keratinocytes and cytokine/growth factors

Cytokines are polypeptide growth factors produced by most nucleated cells in the body, including epithelial cells, keratinocytes, and Langerhans cells in the skin. Cytokines can be classified into interleukins, tumor necrosis factors, chemokines, colony-stimulating factor, interferons, and growth factors. Like classic hormones, cytokines bind to specific receptors to transmit their messages to target cells. Cytokine receptors can be divided into three cytokine receptor superfamilies: the immunoglobulin superfamily, the hematopoietin family, and the tumor necrosis factor family. Following cytokine/cytokine-receptor binding (first messenger), a signal transduction pathway is initiated. Factors affecting homeostasis in the skin and oral mucosa include a delicate balance between cytokines/cytokine-receptors and their antagonists. An imbalance in these variables can influence the development of cutaneous and oral diseases-such as lichen planus, autoimmune disorders, and some neoplastic processes- and can affect wound healing. Potential uses of cytokines include cancer and antiviral therapy.

Successful treatment of generalized lichen planus with recombinant interferon alfa-2b

Three patients with generalized lichen planus were treated with interferon alfa-2b. The therapy was tolerated well by all patients with only minor side effects. A response was observed within 2 to 3 weeks. Itching and erythema decreased first, followed by gradual flattening and disappearance of papules and plaques after 8 to 10 weeks of treatment. After 12 weeks, therapy was discontinued after stepwise dosage reduction. In two patients, minor lesions recurred during dosage reduction. Both flares were controlled by readministration of interferon.

Cutaneous reactions to recombinant cytokine therapy

Cytokines are critical to several fundamental homeostatic mechanisms such as fever, acute phase reactions, wound healing, hematopoiesis, inflammation, cellular and humoral immune responses, and tumor regression. As a result of advances in recombinant DNA technology, recombinant cytokines are available as therapeutic agents. They have been used for metastatic cancers and immunodeficiencies, as a therapy for naturally occurring or drug-induced anemias or leukopenias, and they have also been applied to some cutaneous disorders. Cytokine therapy can result in toxic reactions that affect many organ systems, especially the skin. These reactions are common and diverse, ranging from minor injection site reactions, pruritus, and flushing to life-threatening autoimmune disorders, severe erythroderma, or bullous skin reactions. This review focuses on the major cytokines that are in current clinical use or under investigation and describes the cutaneous complications of these agents.

Mast cells as modulators of hair follicle cycling

While the central role of mast cells (MC) in allergy and inflammation is well-appreciated, much less is known about their physiological functions. The impressive battery of potent growth modulatory MC products, and increasing evidence of MC involvement in hyperproliferative and fibrotic disorders suggest that tissue remodelling may be one of those, namely in the skin. Here, we delineate why this may best be studied by analysing the potential role of MC in hair growth regulation. On the background of numerous, yet widely under-appreciated hints from the older literature, we summarize and discuss our recent observations from the C57BL/6 mouse model for hair research which support the concept that MC are functionally important modulators of hair follicle cycling, specifically during anagen development. This invites to exploit the murine hair cycle as a model for dissecting the physiological growth modulatory functions of MC and encourages the exploration of MC-targeting pharmaceutical strategies for the treatment of hair growth disorders.

Nail features in Langerhans cell histiocytosis

We report the case of an infant who presented with isolated cutaneous manifestations of Langerhans cell histiocytosis before the evolution of systemic features. In the transition period, at 9 months of age, nail unit changes became prominent, and persisted throughout the duration of systemic treatment. A change in clinical features coincided with a course of systemic gamma-interferon, which was given because immune paresis was suspected. Nail unit changes are rare in Langerhans cell histiocytosis, and this case illustrates the range of findings, including paronychia, nail fold destruction, onycholysis with subungual expansion, and nail plate loss. The significance of these changes as a prognostic indicator is controversial.

The cutaneous histopathology of chemotherapeutic reactions

The histological diagnosis of chemotherapy-induced cutaneous reactions is a difficult problem for the dermatopathologist. The initial effort should be directed towards obtaining as much clinical history as possible since the provided information is often incomplete and clinical correlation is usually required. The biopsy should be examined in a systematic fashion to assess the presence of damage to specific cutaneous structures. A recommended approach is to initially examine the epidermis and then proceed to hair follicles, eccrine sweat glands, vessels and dermis. The degree and pattern of damage will usually indicate whether or not a cytotoxic reaction is present. The intensity, pattern, and components of the inflammatory response should be assessed since they provide clues to whether a hypersensitivity reaction or immunomodulating chemotherapeutic reaction is present. In addition to the possibility of a chemotherapeutic reaction, the dermatopathologist must also consider the possibility of an infection since the host is usually immunocompromised and must also exclude the presence of a residual malignancy. After examination of the biopsy specimen and determination of the pathologic process or precesses, the observed findings should be correlated with the clinical history before rendering an interpretation.

Expression of neuron-specific enolase immunoreactivity by cutaneous and extracutaneous Langerhans-cell histiocytoses ("X")

The immunohistochemical expression of Neuron-Specific Enolase (NSE) and of S100 protein was studied in 10 cases of cutaneous and 19 cases of extracutaneous Langerhans cell histiocytoses (LCH), including acute/proliferative forms (cutaneous Letterer-Siwe disease) and chronic/granulomatous forms (eosinophilic granuloma, Hand-Schüller-Christian disease). Of the LCH cases, 18 (62%) exhibited detectable NSE-immunoreactivity as compared to 82.8% for S100. NSE expression was found more frequently and intensely within acute (as compared to chronic) forms of LCH. This result lends further support to the cellular unicity of LCH, but also suggests some degree of heterogeneity among LCH cells. It can be speculated that NSE-expression is correlated with the proliferation/activation state of (abnormal) Langerhans cells.

Differential effects of structurally unrelated chemical irritants on the density of proliferating keratinocytes in 48 h patch test reactions

Alterations in the proliferative capacity of human epidermis following topical exposure to structurally unrelated chemical irritants were investigated, with the aim of improving our understanding of the cellular changes that take place during the development of irritant contact dermatitis (ICD). Healthy volunteers were patch tested for 48 h with the following six irritants and their appropriate vehicle and occlusion controls: 5% sodium lauryl sulphate (SLS), 0.5% benzalkonium chloride, 80% nonanoic acid (NAA), 0.02% dithranol, 0.8% croton oil, and 100% propylene glycol (PG). After the degree of inflammation induced was visually graded, biopsy samples were removed and the dividing keratinocytes were identified immunocytochemically by using the monoclonal antibody Ki-67, with quantification being performed on the basis of the number of positive cells/100 basal keratinocytes. Statistically significant increases in the density of proliferating cells occurred in the reactions to SLS, NAA, and PG, whereas, in contrast, dithranol caused a marked decrease in the number of dividing keratinocytes. Overall, the density of proliferating keratinocytes did not show a linear relationship with the visually assessed intensity of inflammation, indicating that the changes observed were related to the chemical nature of the individual irritants and their specific biochemical interactions with the keratinocytes, rather than being the consequence of a generalized inflammatory response. Differential release of epidermal cytokines and mediators by the six irritants may account for these varying states of keratinocyte proliferation. Application of the Spearman rank coefficient of correlation revealed that the changes in mitotic activity of keratinocytes were unrelated either to the total density of leukocytes infiltrating the epidermis and dermis, or to the individual densities of the major phenotypic classes of inflammatory cells present. This makes it unlikely that the localized release of cytokines by infiltrating leukocytes is, by itself, the primary factor in the alteration in epidermal cell kinetics seen in ICD. Our results provide a further demonstration of the diverse actions of different chemical irritants on human skin and emphasize the need to regard ICD as a heterogeneous disorder.