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.

Neuropeptide control mechanisms in cutaneous biology: physiological and clinical significance

The skin as a barrier and immune organ is exposed to omnipresent environmental challenges such as irradiation or chemical and biologic hazards. Neuropeptides released from cutaneous nerves or skin and immune cells in response to noxious stimuli are mandatory for a fine-tuned regulation of cutaneous immune responses and tissue maintenance and repair. They initialize host immune responses, but are equally important for counter regulation of proinflammatory events. Interaction of the nervous and immune systems occurs both locally - at the level of neurogenic inflammation and immunocyte activation - and centrally - by controlling inflammatory pathways such as mononuclear activation or lymphocyte cytokine secretion. Consequently, a deregulated neurogenic immune control results in disease manifestation and frequently accompanies chronic development of cutaneous disorders. The current understanding, therapeutic options, and open questions of the role that neuropeptides such as substance P, calcitonin gene-related peptide, vasoactive intestinal peptide/pituitary adenylate cyclase-activating polypeptide, neuropeptide Y, or others play in these events are discussed. Progress in this field will likely result in novel therapies for the management of diseases characterized by deregulated inflammation, tissue remodeling, angiogenesis, and neoplasm.

In vitro and in vivo evaluation of topical formulations of spantide II

The purpose of this study was to develop and evaluate topical formulations of Spantide II, a neurokinin-1 receptor (NK-1R) antagonist, for the treatment of inflammatory skin disorders. Spantide II lotion and gel was formulated with and without n-methyl-2-pyrrolidone (NMP) as a penetration enhancer. The release of Spantide II from gels was evaluated using microporous polyethylene and polypropylene membranes in a Franz Diffusion cell setup. In vitro percutaneous absorption of Spantide II from lotion and gel formulations was evaluated using the above setup by replacing the membranes with hairless rat skin. The in vivo anti-inflammatory activity of Spantide II formulations was evaluated in an allergic contact dermatitis (ACD) mouse model. Among different gels studied, PF127 gel showed highest (70-fold) release of Spantide II compared with hydroxypropyl methylcellulose (HPMC) and hydroxypropyl cellulose (HPC) gels. Lotion and gel formulations with or without NMP showed no detectable levels of Spantide II in the receiver compartment of the Franz diffusion cell until 24 hours. However, Spantide II showed significant retention in epidermis and dermis from lotion and gel formulations at 24 hours. The dermal levels increased approximately 3.5- and 2-fold when the lotion and gel formulations contained NMP as compared with the formulation with no NMP (P < .05). The in vivo studies indicated that Spantide II formulations with NMP were effective in significantly reducing ACD response, similar to dexamethasone (0.5 mM). In conclusion, Spantide II was stable as a topical formulation and delivered to target skin tissue (epidermis and dermis) for the treatment of ACD. In addition this study supports the role of cutaneous neurosensory system in modulating inflammatory responses in the skin.

Cutaneous allergic contact dermatitis responses are diminished in mice deficient in neurokinin 1 receptors and augmented by neurokinin 2 receptor blockage

Sensory neuropeptides such as neurokinin A (NKA) or particularly substance P (SP) by neurokinin receptor (NK-R) activation modulate skin and immune cells functions during neurogenic inflammation. In this study, we examined the relative importance of SP/NK-1Rs or NKA/NK-2Rs in a murine model for allergic contact dermatitis (ACD) and tested if the functional absence of NK-Rs will impair inflammatory response in vivo. Mice lacking NK-1Rs (C57BL/6J-NK-1R-/-) displayed a significantly reduced ACD inflammatory ear swelling response to dinitrofluorobenzene (DNFB) with histological less edema and 50% fewer infiltrating leukocytes compared with the ACD response in wild-type (+/+) animals. In NK-1R+/+ mice, transient NK-1R inhibition impaired ACD sensitization. In vitro haptenized bone marrow-derived dendritic cells from NK-1R+/+ mice matured in the presence of an NK-1R antagonist displayed a reduced capability to induce T cell proliferation in vitro and ACD after adoptive transfer into naïve wild-type mice in vivo. By contrast, NK-2R inhibition significantly enhanced the ACD response in NK-1R null or in wild-type mice, whereas epicutaneous application of NK-2R agonists diminished the ACD inflammation. In conclusion, NK-1R and SP are required for antigen sensitization and a full inflammatory response to cutaneous allergens and NKA and the NK-2R mediate a contrasting anti-inflammatory role in ACD. Thus, SP, NKA, NK-1R, and NK-2R have important but differential roles in the regulation of cutaneous inflammatory responses.

The role of calcitonin gene-related peptide in cutaneous immunosuppression induced by repeated subinflammatory ultraviolet irradiation exposure

Ultraviolet (UV) light is an effective treatment for skin disorders like psoriasis in which the cutaneous neurosensory system may have a pathogenic role. In this study, we examined the possibility that UV modulation of the cutaneous neurosensory system and calcitonin gene-related peptide (CGRP) may contribute to local immunosuppression mediated by repeated subinflammatory UV irradiation. Our results indicated that exposure of hairless mice to subinflammatory UV three times weekly for 4 weeks significantly increased the number of epidermal nerve fibers (ENFs) immunoreactive for CGRP without altering the total number of ENFs. The skin content of CGRP as measured by enzyme-linked immunosorbent assay was also significantly increased after exposure to this dose of UV. These effects were most apparent 1 day after the last UV exposure and declined 1 week after UV. The role of CGRP in UV-induced immunosuppression of contact hypersensitivity was then examined. Our results indicated that UV suppression of epicutaneous 2,4-dinitro-1-fluorobenzene (DNFB) sensitization could be significantly inhibited by a systemically administered CGRP receptor antagonist. A broad-spectrum sunscreen applied before UV exposure inhibited increased cutaneous CGRP and blocked immunosuppression. These findings support a role for CGRP in the local immunosuppression caused by chronic, repeated subinflammatory UV exposure.

Percutaneous Absorption and Anti-Inflammatory Effect of a Substance P Receptor Antagonist: Spantide II

PURPOSE

There is accumulating evidence that neurogenic mediators such as substance P (SP) and alpha-melanocyte stimulating hormone (alpha-MSH) contribute to inflammation following chemical and thermal injuries or in disease conditions such as psoriasis and contact dermatitis. Spantide II is a peptide with a molecular weight of 1670.2 which binds to neurokinin-1 receptor (NKR-1) and blocks proinflammatory activities associated with SP. The aim of this study was to investigate in vitro permeation and distribution of spantide II through hairless rat skin and the anti-inflammatory effect of topically delivered spantide II in an allergic contact dermatitis (ACD) mouse model.

METHODS

The in vitro permeation and distribution of spantide II with or without cysteine HCl (CH) as a penetration enhancer through hairless rat skin was studied using Franz diffusion cells. The anti-inflammatory effect of spantide II was studied by measuring the reduction of ACD in C57BL/6 mice after application of spantide II as a topical solution.

RESULTS

The skin permeation experiments with or without cysteine HCl (as penetration enhancer) showed no detectable levels of spantide II permeation across rat skin over a period of 48 h. Cysteine HCl significantly increased the distribution of spantide II in skin layers; also, the reduction in ACD response was significantly higher with the formulation containing cysteine HCl (p < 0.05). Spantide II at different concentrations showed a dose-dependent reduction of ACD response in mice.

CONCLUSIONS

The current study demonstrates that spantide II can effectively be delivered to epidermis and dermis to exert a significant anti-inflammatory activity on the reduction of inflammation in a mouse model of ACD.

Modern Aspects of Cutaneous Neurogenic Inflammation

Recent findings have shed new light on the role of peripheral nerves in the skin and established a modern concept of cutaneous neurobiology. Closely related monodirectional and/or bidirectional pathways exist in which the central and peripheral nervous system, the endocrine and immune system, and almost all skin cells are involved. Information is emerging about the factors involved in these immunomodulatory mechanisms, which are defined as neuropeptides, neurotransmitters, neurotrophins, and neurohormones. The interaction between peripheral nerves and the immune system is mediated by different types of cutaneous nerve fibers that release neuromediators and activate specific receptors on target cells in the skin such as keratinocytes, mast cells, Langerhans cells, microvascular endothelial cells, fibroblasts, and infiltrating immune cells. These interactions influence a variety of physiologic and pathophysiologic functions including cellular development, growth, differentiation, immunity, vasoregulation, leukocyte recruitment, pruritus, and wound healing. A variety of mechanisms lead to the termination of cellular responses to released neuropeptides under physiologic circumstances. Herein, we highlight some of the recent advances of neurocutaneous biology and discuss the role of nerves in mediating cutaneous inflammation. Understanding the mechanisms and the factors controlling neuromediators and their receptors and degrading enzymes will lead to the identification of novel therapeutic targets for the treatment of cutaneous diseases.

Human corneal epithelial cells express functional PAR-1 and PAR-2

PURPOSE

The objective of this study was to examine whether HCECs express functional proteinase-activated receptor (PAR)-1 and -2 and evaluate the effects of receptor activation on corneal epithelial cell proinflammatory cytokine production.

METHODS

Expression of PAR-1 and -2 mRNAs was determined by RT-PCR in cultured primary human corneal epithelial cells (HCECs) and the human corneal epithelial cell line HCE-T. Localization of PAR-1 and -2 in whole normal human corneas was determined by immunofluorescence with PAR-1 and -2 antibodies. The functional competence of PAR-1 and -2 in corneal epithelial cells was assessed by measuring the rapid induction of intracellular [Ca(2+)] in response to thrombin, trypsin, and specific receptor-activating peptides derived from the tethered ligands of the PAR receptors. HCE-T expression of cytokines (IL-6, IL-8, and TNFalpha) in response to activation of PAR-1 and -2 was measured by quantitative RT-PCR and ELISA.

RESULTS

Functional PAR-1 and -2 were expressed in both HCECs and HCE-T cells. Immunoreactivity for PAR-1 and -2 was detected in the outer epithelial layer of the cornea in whole human corneal sections. Activation of PAR-1 and -2 led to upregulation in HCE-T cells of both expression of mRNA and secretion of the proinflammatory cytokines IL-6, IL-8, and TNFalpha.

CONCLUSIONS

The results show for the first time that functional PAR-1 and -2 are present in human cornea. Activation of these receptors results in the production of various corneal epithelial cell proinflammatory cytokines. These observations indicate that PAR-1 and -2 may play an important role in modulating corneal inflammatory and wound-healing responses. These receptors may be useful therapeutic targets in several corneal disease processes.

Alpha-melanocyte stimulating hormone prevents lipopolysaccharide-induced vasculitis by down-regulating endothelial cell adhesion molecule expression

The neuroendocrine hormone alpha-melanocyte stimulating hormone (MSH) has profound antiinflammatory and immunomodulating properties. Here we have examined the possibility that alpha-MSH may interfere with the expression and function of cell adhesion molecules (CAMs) expressed by human dermal microvascular endothelial cells (HDMECs) in response to lipopolysaccharide (LPS) or TNFalpha in vitro and in vivo. In HDMEC, alpha-MSH (10(-8)/10(-12) M) profoundly reduced the mRNA and protein expression of E-selectin, vascular CAM (VCAM)-1, and intercellular CAM (ICAM)-1 induced by LPS or TNFalpha as determined by semiquantitative RT-PCR, ELISA, and fluorescence-activated cell sorter analysis. In addition, alpha-MSH significantly impaired the LPS-induced ICAM-1 and VCAM-1-mediated adhesion of lymphocytes to HDMEC monolayer in a functional adhesion assay. Likewise, alpha-MSH effectively inhibited the transcription factor nuclear factor-kappaB activation in HDMEC, which is required for CAM gene expression. Importantly in vivo, in murine LPS-induced cutaneous vasculitis (local Shwartzman reaction), a single ip injection of alpha-MSH significantly suppressed the deleterious vascular damage and hemorrhage by inhibiting the sustained expression of vascular E-selectin and VCAM-1. This persistent expression has been implicated in the dysregulation of diapedesis and activation of leukocytes, which subsequently leads to hemorrhagic vascular damage. Our findings indicate that alpha-MSH may have an important therapeutical potential for the treatment of vasculitis, sepsis, and inflammatory diseases.

Diminished neuropeptide levels contribute to the impaired cutaneous healing response associated with diabetes mellitus

Background. Patients with diabetic sensory neuropathy have significant risk of chronic ulcers. Insufficient nerve-derived mediators such as substance P (SP) may contribute to the impaired response to injury. Mutant diabetic mice (db/db), which develop neuropathy and have delayed healing, may provide a model to study the role of nerves in cutaneous injury.Methods. Skin from human chronic nonhealing ulcers and age-matched control skin was immunohistochemically evaluated for nerves. Nerve counts were also compared in murine diabetic (C57BL/KsJ-m+/+ Lepr(db); db/db) and nondiabetic (db/-) skin. Excisional wounds on the backs of db/db and db/- mice were grouped as: (a) untreated db/- mice; (b) untreated db/db mice; (c) db/db mice with polyethylene glycol (PEG); (d) db/db mice with PEG and SP 10(-9) M; or (e) db/db mice with PEG and SP 10(-6) M.Results. We demonstrated fewer nerves in the epidermis and papillary dermis of skin from human subjects with diabetes. Likewise, db/db murine skin had significantly fewer epidermal nerves than nondiabetic littermates. We confirmed increased healing times in db/db mice (51.7 days) compared to db/- littermates (19.8 days; P </= 0.001). SP 10(-6) M (44 days; P = 0.02) and SP 10(-9) M (45 days; P = 0.03) shortened time to closure compared to PEG treatment alone (68 days). Since there was no difference in the percentage contraction in these treatment groups, SP may favorably promote wound epithelization.Conclusions. Our data support the use of db/db murine excisional wounds to evaluate the role of nerves in healing. We have demonstrated that exogenous SP improves wound healing kinetics in an animal model.

Neutral endopeptidase inhibition in diabetic wound repair

In response to cutaneous injury, sensory nerves release substance P, a proinflammatory neuropeptide. Substance P stimulates mitogenesis and migration of keratinocytes, fibroblasts, and endothelial cells. Neutral endopeptidase (NEP), a cell surface metallopeptidase, degrades substance P. Chronic nonhealing wounds and skin from patients with diabetes mellitus show increased NEP localization and activity. We hypothesized that increased NEP may retard wound healing and that NEP inhibition would improve closure kinetics in an excisional murine wound model. NEP enzyme activity was measured in skin samples from mutant diabetic mice (db/db) and nondiabetic (db/-) littermates by degradation of glutaryl-ala-ala-phe-4-methoxy-2-naphthylamine. Full-thickness 6-mm dorsal excisional wounds treated with normal saline or the NEP inhibitor thiorphan (10 microM or 25 microM) for 7 days were followed until closure. Histological examination and NEP activity were evaluated in a subset of wounds. NEP activity in unwounded db/db skin (20.6 pmol MNA/hr/ microg) significantly exceeded activity in db/-skin (7.9 pmol MNA/hr/ microg; p = 0.02). In db/db mice, 25 microM thiorphan shortened time to closure (18.0 days; p < 0.05) compared to normal saline (23.5 days). NEP inhibition did not alter closure kinetics in db/-mice. While the inflammatory response appeared enhanced in early wounds treated with thiorphan, blinded histological scoring of healed wounds using a semiquantitative scale showed no difference in inflammation. Unwounded skin from diabetic mice shows increased NEP activity and NEP inhibition improved wound closure kinetics without affecting contraction, suggesting that its principal effect was to augment epithelialization.

Human keratinocytes express functional CD14 and toll-like receptor 4

CD14 and the toll-like receptor 4 have been known to play an important role in lipopolysaccharide-induced cellular responses in bacterial infections. Although CD14 and toll-like receptor 4 expression has been demonstrated in a number of myeloid cells, much less is known about the expression and function of these lipopolysaccharide receptors on nonleukocytes. In this study, we demonstrate that human keratinocytes are capable of expressing functional CD14 and toll-like receptor 4. Keratinocytes were found to constitutively express CD14 and toll-like receptor 4 mRNA that was augmented by exposure to lipopolysaccharide. Cell surface expression of keratinocyte CD14 and toll-like receptor 4 was detected by flow cytometry. Lipopolysaccharide binding to keratinocyte CD14 and toll-like receptor 4 resulted in a rapid intracellular Ca2+ response, nuclear factor-kappaB nuclear translocation, and the secretion of proinflammatory cytokines and chemokines. These results have important implications for our understanding of cutaneous innate immunity to bacterial infections of the skin.

Noscapine alters microtubule dynamics in living cells and inhibits the progression of melanoma

Cellular microtubules, polymers of tubulin, alternate relentlessly between phases of growth and shortening. We now show that noscapine, a tubulin-binding agent, increases the time that cellular microtubules spend idle in a paused state. As a result, most mammalian cell types observed arrest in mitosis in the presence of noscapine. We demonstrate that noscapine-treated murine melanoma B16LS9 cells do not arrest in mitosis but rather become polyploid followed by cell death, whereas primary melanocytes reversibly arrest in mitosis and resume a normal cell cycle after noscapine removal. Furthermore, in a syngeneic murine model of established s.c. melanoma, noscapine treatment resulted in an 85% inhibition of tumor volume on day 17 when delivered by gavage compared with untreated animals (P <or= 0.01), without evidence of toxicity to the spleen, liver, duodenum, bone marrow, or peripheral blood. This inhibition was greater than that seen in vivo by paclitaxel (Taxol) alone and similar to the inhibition of tumor volume observed when noscapine was combined with paclitaxel. Importantly, noscapine also demonstrated the ability to significantly inhibit melanoma progression by 83% on day 18 when delivered in drinking water (P <or= 0.01) and conferred a significant survival advantage (P <or= 0.01). Our results demonstrate that p.o.-administered noscapine significantly inhibits the progression of melanoma cells through alterations in microtubule dynamics, with no detected toxicity to the host. Consequently, noscapine could be a valuable chemotherapeutic agent, alone or in combination, for the treatment of advanced melanoma.

Agonists of proteinase-activated receptor 2 induce cytokine release and activation of nuclear transcription factor kappaB in human dermal microvascular endothelial cells

Proteinase-activated receptor 2 belongs to a new G protein-coupled receptor subfamily activated by various serine proteases. It has been demonstrated to play a role during inflammation of many tissues including the skin. Proteinase-activated receptor 2 is expressed by endothelial cells and regulates cutaneous inflammation in vivo. The underlying mechanisms of proteinase-activated receptor 2 activation in the skin and the effects on human dermal microvascular endothelial cells, however, are still unknown. Agonists of proteinase-activated receptor 2 such as mast cell tryptase induce widespread inflammation in many organs including the skin. Trypsinogen is generated by endothelial cells during inflammation or tumor growth. Therefore we tested whether human dermal microvascular endothelial cells express functional proteinase-activated receptor 2 and whether agonists of proteinase-activated receptor 2 regulate inflammatory responses in these cells. Calcium mobilization studies revealed that proteinase-activated receptor 2 is functional in human dermal microvascular endothelial cells. Interleukin-6 and interleukin-8 were upregulated as detected by reverse transcription polymerase chain reaction or enzyme-linked immunosorbent assay indicating a role of proteinase-activated receptor 2 in stimulating human dermal microvascular endothelial cells. Electromobility shift assays revealed proteinase-activated-receptor-2-induced activation of nuclear transcription factor kappaB with a maximum after 1 h. In conclusion, agonists of proteinase-activated receptor 2 upregulate interleukin-6 and interleukin-8 expression and release in human dermal microvascular endothelial cells. Thus, proteinase-activated receptor 2 may play an important role in cutaneous inflammation by mediating inflammatory responses on dermal microvascular endothelial cells and activation of nuclear transcription factor kappaB.

The cutaneous neurosensory system in skin disease

The cutaneous neurosensory system appears to be involved in a number of skin diseases. Ongoing studies continue to uncover potential new roles for the components of the neurosensory system in skin homeostasis and disease states. There is new evidence that neuropeptides may play a role in melanogenesis with effects on vitiligo. An increase of intraepidermal nerve fibers with a possible pathophysiologic role in photodamaged facial skin has been proposed. As our understanding of the interactions between the cutaneous neurosensory system and the various components of the skin and the immune system in times of health and disease increases, specific treatments modulating the neurocutaneous system will find their way into the armamentarium of daily dermatologic therapy.

The neurosensory tachykinins substance P and neurokinin A directly induce keratinocyte nerve growth factor

Nerve growth factor is an essential neurotrophic factor required for the growth and maintenance of cutaneous sensory nerves. In the skin, keratinocytes are a significant source of nerve growth factor; however, the regulation of cutaneous nerve growth factor production still remains to be fully understood. In this study we tested the hypothesis that neuropeptides released by cutaneous sensory nerves have the capacity to modulate directly the expression of keratinocyte nerve growth factor, which would have important implications for the maintenance and repair of nerves in the skin. In order to address this question experimentally we examined the effect of the neuropeptides, substance P and neurokinin A, on nerve growth factor expression in human keratinocytes and the murine keratinocyte PAM 212 cell line by quantitative reverse transcriptase-polymerase chain reaction, enzyme-linked immunosorbent assay, and the PC-12 nerve growth factor bioassay. The results of these studies indicated that substance P and neurokinin A can directly induce nerve growth factor mRNA expression and the secretion of bioactive nerve growth factor protein in both human and murine keratinocytes. The specificity of these responses was demonstrated using neuropeptide receptor antagonists and nerve growth factor blocking antibodies. Additional studies also demonstrated a significant in vivo upregulation of keratinocyte nerve growth factor expression in murine epidermis after the topical application of the neuropeptide releasing agent capsaicin. This is the first report demonstrating the induction of cutaneous nerve growth factor by sensory nerve-derived neuropeptides such as substance P and neurokinin A. This direct effect of the neurosensory system on keratinocyte nerve growth factor production may have important consequences for the maintenance and regeneration of cutaneous nerves in normal skin and during inflammation and wound healing.

The expression of functional LPS receptor proteins CD14 and toll-like receptor 4 in human corneal cells

PURPOSE

Gram-negative bacterial infections of the eye can lead to corneal bacterial keratitis, visual impairment, and blindness. Many of these pathologic changes may be mediated by bacterially derived products such as lipopolysaccharide (LPS). In this investigation, it has been established for the first time that human corneal cells are capable of expressing the functional LPS receptor complex proteins, CD14 and Toll-like receptor 4 (TLR4).

METHODS

CD14 and TLR4 mRNA expression in human corneal cells was determined by RT-PCR and Northern blot analysis, and cell surface expression of these proteins was measured by flow cytometry. LPS-mediated corneal cell activation was determined by measuring intracellular calcium mobilization. Cellular cytokine and chemokine secretion in response to LPS was measured by ELISA. The expression and localization of CD14 in whole human cornea was determined by immunohistochemistry.

RESULTS

Human corneal epithelial, stromal, and endothelial cells expressed CD14 mRNA and cell surface CD14. LPS binding to cornea CD14 resulted in a rapid intracellular calcium response and the secretion of multiple proinflammatory cytokines and chemokines. CD14 mRNA expression in corneal epithelial cells was upregulated by LPS. In addition to CD14, corneal epithelial cells expressed the functional LPS receptor-signaling protein TLR4, which was also augmented by LPS.

CONCLUSIONS

The cornea expresses functional CD14 and TLR4 LPS receptor proteins. Understanding the function and biology of the corneal LPS receptor complex may lead to novel therapies for the management of ocular Gram-negative bacterial infections.

Management of high-risk melanoma

Improved treatment options for patients with high-risk melanoma are of great importance for clinicians who participate in the care of these patients. There remains an overall lack of response to existing treatment options, which continues to fuel the efforts of basic scientists and clinicians to pursue other approaches for the treatment of melanoma that is no longer limited to the skin. Continued investigation into the innovative and concurrent use of surgery, chemotherapy, immunotherapy, and radiation therapy holds significant promise for improved outcomes in the management of patients with this devastating disease.

Interleukin-18 expression and modulation in human corneal epithelial cells

PURPOSE

The interferon-gamma-inducing factor Interleukin-18 (IL-18) is a recently described cytokine that appears to have multiple important pro-inflammatory effects including the induction of interferon-gamma (IFN-gamma) by activated T-cells. The expression of IL-18 by human cornea has not been previously reported. In the present study, we examine the possibility that human corneal epithelial cells are capable of producing this leukocyte-activating factor which may play an important role in IFN-gamma-dependent inflammation responses in the cornea.

METHODS

Northern blot analysis and ELISA were used to investigate the in vitro expression of IL-18 mRNA and protein respectively in primary (HCEC) and transformed human corneal epithelial cells (HCET). To determine if IL-18 expression was modulated by pro-inflammatory mediators, cells were treated with lipopolysaccharide (LPS), phorbol 12-myristate 13-acetate (PMA) or synthetic double stranded RNA (poly dI : dC). IL-18 bioactivity was determined in a leukocyte interferon-gamma induction assay and IL-18 was immunolocalized in whole human cornea by immunohistochemistry using a specific anti-IL-18 antibody.

RESULTS

IL-18 mRNA and bioactive protein was constitutively expressed by human corneal epithelial cells and upregulated by PMA, LPS and poly dI : dC. The constitutive expression of IL-18 protein immunoreactivity was also demonstrated in the epithelial cells of whole human cornea tissue.

CONCLUSIONS

This is the first study demonstrating that corneal epithelial cells are capable of producing the IFN-gamma inducing factor IL-18. Increased bioactive corneal IL-18 production can be induced by a number of pro-inflammatory agents and may play an important role in initiating gamma-interferon-mediated inflammatory responses in the cornea.

Neutral endopeptidase terminates substance P-induced inflammation in allergic contact dermatitis

Sensory nerve-derived neuropeptides such as substance P demonstrate a number of proinflammatory bioactivities, but less is known about their role in inflammatory skin disease. The cell surface metalloprotease neutral endopeptidase (NEP) is the principal proteolytic substance P-degrading enzyme. This study tests the hypothesis that the absence of NEP results in dysregulated inflammatory skin responses. The effector phase of allergic contact dermatitis (ACD) responses was examined in NEP(-/-) knockout and NEP(+/+) wild-type mice and compared with the irritant contact dermatitis response in these animals. NEP was found to be normally immunolocalized in epidermal keratinocytes and dermal blood vessels. The ACD ear swelling response was 2.5-fold higher in animals lacking NEP and was accompanied by a significant increase in plasma extravasation and infiltration of inflammatory leukocytes. The augmented ACD response in NEP(-/-) animals was abrogated by either administration of a neurokinin receptor 1 antagonist or by repeated pretreatment with topical capsaicin. Similar to NEP(-/-) mice, the acute inhibition of NEP in NEP(+/+) animals resulted in an augmented ACD response. In contrast to the ACD responses, little differences were observed in the irritant contact dermatitis response of NEP(-/-) compared with NEP(+/+) animals after epicutaneous application of the skin irritants croton oil or SDS. Thus, these results indicate that NEP and cutaneous neuropeptides have a significant role in the pathogenesis of ACD.

Neural regulation of endothelial cell-mediated inflammation

There is increasing evidence that the cutaneous neurosensory system can directly modulate inflammatory responses in the skin by the release of neuropeptides such as substance P (SP). Dermal microvascular endothelial cell (DMEC) cellular adhesion molecule (CAM) expression plays a key role in directing leukocyte trafficking during cutaneous inflammatory responses. In recent studies, our laboratory examined the direct effect of SP on DMEC CAM expression and function in vitro and in vivo. Our studies indicate that DMEC express high affinity functional receptors for SP. After exposure to SP, DMEC expressed significant levels of both intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), which was accompanied by increased binding to leukocytes expressing the appropriate integrin counter receptors for these CAM. We then determined the in vivo effect of released neuropeptides on DMEC CAM expression. Our results indicate that the topical cutaneous application of the neuropeptide-releasing agent capsaicin resulted in increased ICAM-1 and VCAM-1 immunostaining of microvascular cells in the skin of human volunteers. Little is known regarding the cellular regulatory events by which SP modulates DMEC CAM expression. Our studies indicate that SP-induced cellular Ca+2 signals led to the activation of the NF-kappaB pathway, resulting in nuclear translocation of p65/p50 heterodimers that bind to high-affinity tandem kappaB sites on the VCAM-1 promoter, whereas SP activation induced NF-AT activation and ICAM-1 DNA binding. Thus, these studies further support the role of the cutaneous neurologic system in modulating inflammatory processes in the skin.

Expression of proopiomelanocortin peptides in human dermal microvascular endothelial cells: evidence for a regulation by ultraviolet light and interleukin-1

Proopiomelanocortin peptides such as alpha-melanocyte-stimulating hormone and adrenocorticotropin are expressed in the epidermal and dermal compartment of the skin after noxious stimuli and are recognized as modulators of immune and inflammatory reactions. Human dermal microvascular endothelial cells mediate leukocyte-endothelial interactions during cutaneous inflammation by the expression of cellular adhesion molecules and cytokines such as interleukin-1. This study addresses the hypothesis that human dermal microvascular endothelial cells express both proopiomelanocortin and prohormone convertases, which are required to generate proopiomelanocortin peptides. Semiquantitative reverse transcriptase polymerase chain reaction and northern blot studies revealed a constitutive expression of proopiomelanocortin mRNA by human dermal microvascular endothelial cells in vitro that was time- and concentration-dependently upregulated by interleukin-1 beta. Furthermore, irradiation of human dermal microvascular endothelial cells with ultraviolet A1 (30J per cm(2)) or ultraviolet B (12.5 mJ per cm(2)) enhanced proopiomelanocortin expression as well as the production and release of the proopiomelanocortin peptides adrenocorticotropin and alpha-melanocyte-stimulating hormone. In addition to proopiomelanocortin, prohormone convertase 1 mRNA expression was detected by reverse transcriptase polymerase chain reaction in unstimulated human dermal microvascular endothelial cells and was augmented after exposure to alpha-melanocyte- stimulating hormone, interleukin-1 beta, or irradiation with ultraviolet. These findings demonstrate that human dermal microvascular endothelial cells express proopiomelanocortin and prohormone convertase 1 required for the generation of adrenocorticotropin. Additionally, human dermal microvascular endothelial cells express mRNA for the prohormone convertase 2 binding protein 7B2. Taken together these findings indicate that human dermal microvascular endothelial cells upon stimulation express both proopiomelanocortin and prohormone convertases required for the generation of alpha-melanocyte-stimulating hormone. As proopiomelanocortin peptides were found to regulate the production of human dermal microvascular endothelial cell cytokines and adhesion molecules and to have a variety of anti-inflammatory properties these peptides may significantly contribute to the modulation of skin inflammation. J Invest Dermatol 115:1021-1028 2000

Substance P induction of murine keratinocyte PAM 212 interleukin 1 production is mediated by the neurokinin 2 receptor (NK-2R)

The neurological system plays an important role in modulating some inflammatory skin diseases. Neuro-cutaneous interactions may be mediated by the release of neuropeptides such as substance P (SP) which activate immunocompetent cells in the skin by binding to high affinity neurokinin receptors (NKR). Since epidermal keratinocytes produce a variety of cytokines and are intimately associated with cutaneous sensory fibers, we tested the ability of these cells to participate in the cutaneous neuroimmune system by the secretion of potent cytokines such as interleukin 1 (IL-1) in response to released SP. RT-PCR studies demonstrated that cultured PAM 212 murine keratinocytes expressed mRNA for NK-2R but not NK-1R. Correspondingly, the addition of SP to these cells resulted in a rapid increase in intracellular Ca2+ levels that could be specifically blocked by an NK-2R antagonist. NK-2R was also shown in normal mouse epidermis by immunohistochemistry. SP augmented the expression of PAM 212 keratinocyte IL-1alpha mRNA in a dose and time dependent manner and this induction was inhibited by an NK-2R antagonist. Secretion of bioactive IL-1alpha by the PAM 212 keratinocytes was likewise stimulated by SP in a dose dependent manner. These data support the hypothesis that SP released from cutaneous sensory nerves contributes to neuroimmune inflammatory responses in the skin by modulating the expression and release of cytokines from epidermal keratinocytes.

Substance P Activates Coincident NF-AT- and NF-κB-Dependent Adhesion Molecule Gene Expression in Microvascular Endothelial Cells Through Intracellular Calcium Mobilization

Upon stimulation, cutaneous sensory nerves release neuropeptides such as substance P (SP), which modulate responses in the skin by activating a number of target cells via neurokinin receptors. We have demonstrated that SP preferentially binds to the NK-1R on human dermal microvascular cells, resulting in increased intracellular Ca2+ and induction of ICAM-1 and VCAM-1 expression. In the current studies, we identify specific elements in the regulatory regions of ICAM-1 and VCAM-1 genes as necessary and sufficient for SP-dependent transcriptional activation. SP treatment of human dermal microvascular endothelial cells leads to coincident activation and binding of the transcription factor NF-AT to the −191/−170 region of the ICAM-1 gene (a region bound by activated p65/p65 homodimers in response to TNF-α), and NF-κB (p65/p50) to tandem NF-κB binding sites at −76/−52 of the VCAM-1 gene. The SP-elicited intracellular Ca2+ signal was required for activation and subsequent binding of both NF-AT and NF-κB. The transacting factor induction by SP was specific, since a selective NK-1R antagonist blocked SP activation and subsequent NF-AT and NF-κB activation and binding. These data demonstrate coincident activation of NF-AT and NF-κB via SP-induced intracellular Ca2+ mobilization and indicate a crucial role for neuropeptides in modulating localized cutaneous inflammatory responses.

Substance P activates coincident NF-AT- and NF-kappa B-dependent adhesion molecule gene expression in microvascular endothelial cells through intracellular calcium mobilization

Upon stimulation, cutaneous sensory nerves release neuropeptides such as substance P (SP), which modulate responses in the skin by activating a number of target cells via neurokinin receptors. We have demonstrated that SP preferentially binds to the NK-1R on human dermal microvascular cells, resulting in increased intracellular Ca2+ and induction of ICAM-1 and VCAM-1 expression. In the current studies, we identify specific elements in the regulatory regions of ICAM-1 and VCAM-1 genes as necessary and sufficient for SP-dependent transcriptional activation. SP treatment of human dermal microvascular endothelial cells leads to coincident activation and binding of the transcription factor NF-AT to the -191/-170 region of the ICAM-1 gene (a region bound by activated p65/p65 homodimers in response to TNF-alpha), and NF-kappa B (p65/p50) to tandem NF-kappa B binding sites at -76/-52 of the VCAM-1 gene. The SP-elicited intracellular Ca2+ signal was required for activation and subsequent binding of both NF-AT and NF-kappa B. The transacting factor induction by SP was specific, since a selective NK-1R antagonist blocked SP activation and subsequent NF-AT and NF-kappa B activation and binding. These data demonstrate coincident activation of NF-AT and NF-kappa B via SP-induced intracellular Ca2+ mobilization and indicate a crucial role for neuropeptides in modulating localized cutaneous inflammatory responses.

Human keratinocytes constitutively express interleukin-18 and secrete biologically active interleukin-18 after treatment with pro-inflammatory mediators and dinitrochlorobenzene

Interleukin-18 is a potent inducer of interferon-gamma by activated T cells, macrophages, and monocytes and is synthesized as an inactive precursor. Pro-interleukin-18 must be cleaved by interleukin-1-beta-converting enzyme for secretion of the biologically active form. We report that among selected non-bone marrow derived skin cells, interleukin-18 mRNA is constitutively expressed by human keratinocytes and not by dermal microvascular endothelial cells, dermal fibroblasts, or melanocytes. Interleukin-18 mRNA and intracellular protein levels are neither changed in human keratinocytes nor induced in human dermal microvascular endothelial cells, dermal fibroblasts, or melanocytes by exposure to pro-inflammatory stimuli. Exposure of human keratinocytes to phorbol 12-myrisate 13-acetate, lipopolysaccharides or the contact sensitizer DNCB results in the secretion of immunoprecipitable interleukin-18 protein. Human keratinocyte-secreted interleukin-18 is biologically active, in that conditioned media from phorbol 12-myrisate 13-acetate, lipopolysaccharide and DNCB-treated human keratinocytes induce interferon-gamma expression by peripheral blood mononuclear cells. This bioactivity is neutralized by anti-interleukin-18, but not anti-interleukin-12 antibodies. By immunohistochemistry, interleukin-18 protein is detected in basal keratinocytes of normal human skin, but its expression is markedly upregulated in suprabasal keratinocytes in psoriasis. These findings indicate that human keratinocytes are a source of biologically functional interleukin-18 and thus are capable of playing an initiating part in the local interferon-gamma-dependent inflammatory processes through expression, activation, and secretion of interleukin-18.

Expression of functional melanocortin receptors and proopiomelanocortin peptides by human dermal microvascular endothelial cells

Human dermal microvascular endothelial cells (HDMEC) are capable of mediating leukocyte-endothelial interactions by the expression of cellular adhesion molecules and the release of proinflammatory cytokines and chemokines during cutaneous inflammation. Recent studies support the important role for proopiomelanocortin (POMC) peptides, such as alpha-melanocyte stimulating hormone (alpha-MSH), as immunomodulators in the cutaneous immune system. The purpose of the studies described here was to determine whether HDMEC serves as both target and source for POMC peptides. RT-PCR and Northern blot studies demonstrated the constitutive expression of mRNA for the adrenocorticotropin (ACTH) and alpha-MSH-specific melanocortin receptor 1 (MC-1R) in HDMEC, and the microvascular endothelial cell line HMEC-1 that could be upregulated by stimulation with IL-1 beta and alpha-MSH. HDMEC responded to stimulation by alpha-MSH with a dose- and time-dependent synthesis and release of the CXC chemokines, IL-8 and GRO alpha. Likewise, alpha-MSH augmented HDMEC chemokine release induced by TNF or IL-1. HD-MEC were found to constitutively express POMC and prohormone convertase 1 (PC-1); the latter being required to generate ACTH from the POMC prohormone. POMC and PC-1 mRNA expression are increased as a result of stimulation with UVB and UVA1 radiation, IL-1, and alpha-MSH. In addition, UV-radiation is capable of inducing the release of HDMEC, ACTH, and alpha-MSH in a time- and dose-dependent fashion. Thus, these data provide evidence that HDMEC are capable of expressing functional MC-1R, POMC, and PC-1 mRNA; and of releasing POMC peptides with UV light, IL-1, and alpha-MSH as regulatory factors. The expression and regulation of these peptides may be of importance, not only for the autocrine or paracrine regulation of physiologic functions of dermal endothelial cells, but also for the regulation of certain microvascular-mediated cutaneous or systemic inflammatory responses.

Effect of ultraviolet light on the release of neuropeptides and neuroendocrine hormones in the skin: mediators of photodermatitis and cutaneous inflammation

Ultraviolet (UV) irradiation of the skin causes both inflammation and alterations in the skin immune system. There is increasing experimental evidence that UV-induced skin inflammation is influenced by the sensory nervous system and the neuroendocrine system in the skin. The resulting complex network of cytokines, chemokines, neuropeptides, neuropeptide-degrading enzymes, neurohormones, and other inflammatory mediators mediate photodermatitis and cutaneous inflammation. Neuropeptides such as substance P (SP) and calcitonin gene-related peptide (CGRP) are released from sensory nerves innervating the skin upon UV exposure. In addition, a variety of cells in the skin produce increased neuroendocrine hormones such as proopiomelanocortin (POMC) peptides and their receptors as well as neurotrophins after UV exposure. Neuropeptides and neurohormones are capable of directly or indirectly mediating UV-induced cutaneous neurogenic inflammation by the induction of vasodilatation, plasma extravasation, and augmentation of UV-induced cytokine, chemokine, or cellular adhesion molecule expression required for activation and trafficking of inflammatory cells into the inflamed tissue. Neuropeptides and neurotrophins may also play a role in the repair of cutaneous UV injury. In addition to proinflammatory effects, UV-induced neuropeptides and neurohormones such as CGRP and alpha-melanocyte-stimulating hormone may have immunosuppressive effects in the skin. This review will focus on the role that SP, CGRP, POMC peptides, and their receptors may play in modulating UV-induced inflammation in the skin.

Proteinase-activated receptor-2 in human skin: tissue distribution and activation of keratinocytes by mast cell tryptase

Proteinase-activated receptor-2 (PAR-2) is a G-protein coupled receptor. Tryptic proteases cleave PAR-2 exposing a tethered ligand (SLIGKV), which binds and activates the receptor. Although PAR-2 is highly expressed by cultured keratinocytes and is an inflammatory mediator, its precise localization in the normal and inflamed human skin is unknown, and the proteases that activate PAR-2 in the skin have not been identified. We localized PAR-2 in human skin by immunohistochemistry, examined PAR-2 expression by RT-PCR and RNA blotting, and investigated PAR-2 activation by mast cell tryptase. PAR-2 was localized to keratinocytes, especially in the granular layer, to endothelial cells, hair follicles, myoepithelial cells of sweat glands, and dermal dendritic-like cells. PAR-2 was also highly expressed in keratinocytes and endothelial cells of inflamed skin. PAR-2 mRNA was detected in normal human skin by RT-PCR, and in cultured human keratinocytes and dermal microvascular endothelial cells by Northern hybridization. Trypsin, tryptase and a peptide corresponding to the tethered ligand (SLIGKVNH2) increased [Ca2+]i in keratinocytes, measured using Fura-2/AM. Although tryptase-containing mast cells were sparsely scattered in the normal dermis, they were numerous in the dermis in atopic dermatitis, and in the dermis, dermal-epidermal border, and occasionally within the lower epidermis in psoriasis. Tryptase may activate PAR-2 on keratinocytes and endothelial cells during inflammation.

Neutral endopeptidase expression and distribution in human skin and wounds

Cutaneous sensory nerves mediate inflammation and wound healing by the release of neuropeptides such as substance P. Neutral endopeptidase is a cell surface enzyme that degrades substance P and thereby terminates its biologic actions. The distribution of neutral endopeptidase in normal skin and wounded human skin, however, has not been examined. The objectives of this study were to evaluate neutral endopeptidase expression in wounded and unwounded skin as well as in cells derived from human skin. Neutral endopeptidase was strikingly localized in normal skin by immunohistochemistry to keratinocytes of the epidermal basal layer, to hair follicles, eccrine and sebaceous glands as well as to endothelium of blood vessels and to large nerves. Standard incisional human wounds were studied at several time points between 1 h and 28 d after wounding. Staining for neutral endopeptidase was noted in the wound bed 6 h after wounding. In contrast to normal skin, staining of all the epidermal cell layers was noted in the migrating tongue of epithelium in l d wounds. Similar full-thickness staining was noted in 3 d and 7 d wounds in all layers of the new wound epithelium and in a "transition epithelium" near the wound edge. By 28 d post wounding neutral endopeptidase staining again was detected only in the basal layer of the epidermis. Neutral endopeptidase mRNA was detected in normal skin and wounds as well as cultured keratinocytes, fibroblasts and endothelial cells. Neutral endopeptidase enzymatic bioactivity was demonstrated in cultured keratinocytes. While it is known that several metalloproteinases important to tissue repair are produced by keratinocytes, this is the first evidence that keratinocytes produce neutral endopeptidase. Neutral endopeptidase may terminate the proinflammatory and mitogenic actions of neuropeptides in normal skin and wounds.

VCAM-1 Expression on Human Dermal Microvascular Endothelial Cells Is Directly and Specifically Up-Regulated by Substance P

Sensory nerves in skin are capable of releasing multiple neuropeptides, which modulate inflammatory responses by activating specific cutaneous target cells. Extravasation of particular subsets of leukocytes depends upon the regulated expression of cellular adhesion molecules such as VCAM-1 on microvascular endothelial cells. We examined the direct effect of cutaneous neuropeptides on the expression and function of human dermal microvascular endothelial cell (HDMEC) VCAM-1. A significant increase in VCAM-1 immunostaining of microvascular endothelium was observed in vivo following capsaicin application to human skin. Multiple cutaneous sensory C-fiber-released neuropeptides were evaluated for their ability to induce VCAM-1 cell surface expression on HDMEC. Only substance P (SP) was found to be capable of inducing HDMEC VCAM-1 expression. This SP-mediated VCAM-1 induction appeared to be a direct effect that did not require the release of other HDMEC-derived soluble factors. Increased HDMEC VCAM-1 mRNA expression was detected 1 h after the addition of SP, with peak mRNA increase at 6–9 h postinduction. FACS studies demonstrated a 6.5-fold increase in endothelial cell surface VCAM-1 expression detectable 16 h after addition of SP, which was specifically blocked by a neurokinin-1 receptor antagonist. Increased VCAM-1 cell surface expression on SP-treated HDMEC resulted in a 4-fold increase in the functional binding of 51Cr-labeled MOLT-4 T cells. These data indicate that SP is capable of directly and specifically up-regulating functional endothelial VCAM-1 expression and thus may play a key role in modulating certain inflammatory responses in the skin.

VCAM-1 expression on human dermal microvascular endothelial cells is directly and specifically up-regulated by substance P

Sensory nerves in skin are capable of releasing multiple neuropeptides, which modulate inflammatory responses by activating specific cutaneous target cells. Extravasation of particular subsets of leukocytes depends upon the regulated expression of cellular adhesion molecules such as VCAM-1 on microvascular endothelial cells. We examined the direct effect of cutaneous neuropeptides on the expression and function of human dermal microvascular endothelial cell (HDMEC) VCAM-1. A significant increase in VCAM-1 immunostaining of microvascular endothelium was observed in vivo following capsaicin application to human skin. Multiple cutaneous sensory C-fiber-released neuropeptides were evaluated for their ability to induce VCAM-1 cell surface expression on HDMEC. Only substance P (SP) was found to be capable of inducing HDMEC VCAM-1 expression. This SP-mediated VCAM-1 induction appeared to be a direct effect that did not require the release of other HDMEC-derived soluble factors. Increased HDMEC VCAM-1 mRNA expression was detected 1 h after the addition of SP, with peak mRNA increase at 6-9 h postinduction. FACS studies demonstrated a 6.5-fold increase in endothelial cell surface VCAM-1 expression detectable 16 h after addition of SP, which was specifically blocked by a neurokinin-1 receptor antagonist. Increased VCAM-1 cell surface expression on SP-treated HDMEC resulted in a 4-fold increase in the functional binding of 51Cr-labeled MOLT-4 T cells. These data indicate that SP is capable of directly and specifically up-regulating functional endothelial VCAM-1 expression and thus may play a key role in modulating certain inflammatory responses in the skin.

A 15-year follow-up of AJCC stage III malignant melanoma patients treated postsurgically with Newcastle disease virus (NDV) oncolysate and determination of alterations in the CD8 T cell repertoire

BACKGROUND

The development of effective adjuvant therapies for the treatment of high-risk melanoma patients is critical for the prevention of metastatic disease and improvement of patient survival. Active specific immunotherapy has been tested as an adjuvant treatment in numerous clinical trials with overall limited, but occasionally promising, success rates. Newcastle disease virus (NDV) oncolysate has been utilized as an adjunctive immunotherapeutic agent in the postsurgical management of these patients. A phase II study initiated in 1975 using adjuvant vaccine therapy composed of allogeneic and autologous human melanoma cells infected with live NDV (NDV oncolysate) in patients with AJCC stage III melanoma following therapeutic lymph node dissection has shown >60% survival rate at 10 years with no adverse effects. Continued long-term analysis of trials with promising early results as well as assessment of immunologic responses generated in these patients may result in improved therapeutic decisions for clinical trials in the future.

MATERIALS AND METHODS

We analyzed the 15-year survival of patients treated postsurgically with NDV oncolysate in the phase II study described above. In an attempt to understand the immunological effects of this treatment, we have also carried out a comprehensive analysis of the peripheral blood T cell repertoire in these patients.

RESULTS

The overall 15-year survival of this group of patients is 55%. Previous studies have suggested that improved outcome in patients undergoing immunotherapy is correlated with increased numbers of CD8(+)CD57(+) cells. In surviving patients, we observed a striking oligoclonality in the CD8(+) T cell population in peripheral blood, which reflects clonal expansions in the CD8(+)CD57(+) subset.

CONCLUSIONS

The data suggest that adjuvant vaccination with NDV oncolysates is associated with prolonged survival of patients with lymph node-positive malignant melanoma and that CD8(+) T cells may be an important component of therapeutic efficacy.

In vivo human melanoma cytokine production: inverse correlation of GM-CSF production with tumor depth

Melanomas produce multiple cytokines which may influence their growth in vivo. Experimental evidence suggests that granulocyte macrophage-colony stimulating factor (GM-CSF) can induce a potent anti-melanoma response. whereas interleukin-8 (IL-8) may act as a growth factor in human melanoma. Little is currently known regarding the production of these cytokines by human melanoma in vivo. In this study we tested the hypothesis that endogenous production of GM-CSF and IL-8 can be correlated with the depth of human malignant melanoma surgical specimens. We examined 45 melanocytic human tissue samples consisting of 27 primary cutaneous melanomas, 9 metastatic melanomas, and 9 dysplastic nevi for in vivo GM-CSF and IL-8 production using immunohistochemistry. The majority of thin melanomas (< or = 0.76 mm) stained highly positive for GM-CSF with little or no staining for IL-8 whereas the medium (>0.76- < or = 4.0 mm) and thick (>4.0 mm) melanoma specimens showed little or no staining for GM-CSF and significant amounts of IL-8 staining. Metastatic melanoma as well as dysplastic nevi specimens had little or no GM-CSF and IL-8 staining. These results support the hypothesis that endogenous melanoma cytokines such as GM-CSF and IL-8 with opposing effects on tumor progression play an important role in melanoma growth and regulation.

Neuropeptide regulation of human dermal microvascular endothelial cell ICAM-1 expression and function

There is increasing evidence that sensory nerves may participate in cutaneous inflammatory responses by the release of neuropeptides such as substance P (SP). We examined the direct effect of SP on human dermal microvascular endothelial cell (HDMEC) intercellular adhesion molecule 1 (ICAM-1) expression and function. Our results indicated that, although cultured HDMEC expressed mRNA for neurokinin receptors 1, 2, and 3 (NK-1R, NK-2R, and NK-3R), SP initiated a rapid increase in HDMEC intracellular Ca2+ levels, primarily by the activation of NK-1R. Immunohistochemistry studies likewise demonstrated that HDMEC predominantly expressed NK-1R. The addition of SP to HDMEC resulted in a rapid increase in cellular ICAM-1 mRNA levels, followed by a fivefold increase in ICAM-1 cell surface expression. This functionally resulted in a threefold increase in 51Cr-labeled binding of J-Y lymphoblastoid cells to HDMEC. In vivo studies demonstrated a marked increase in microvascular ICAM-1 immunostaining 24 and 48 h after application of capsaicin to the skin. These results indicate that neuropeptides such as SP are capable of directly activating HDMEC to express increased levels of functional ICAM-1 and further support the role of the cutaneous neurological system in modulating inflammatory processes in the skin.

Protein gene product 9.5 is expressed by fibroblasts in human cutaneous wounds

In a study initially designed to evaluate reinnervation of human cutaneous wounds using an antibody to the neuroneal marker protein gene product (PGP) 9.5, we observed marked immunostaining of cells with morphologic features of fibroblasts in the wounds. PGP 9.5 has recently been shown to be an important enzyme in the highly conserved ubiquitin system of proteolysis. Because the ubiquitin system is known to play an important role in regulating the cell cycle, the presence of PGP 9.5 in cells at a wound site was of considerable interest. Our objectives were to clarify the time frame for the appearance of PGP 9.5 and ubiquitin in wounds, to verify that PGP 9.5 is produced by wound fibroblasts, and to evaluate a potential role for these proteins in the tissue repair process. Standard incisional human wounds were stained with antibodies specific for PGP 9.5 and ubiquitin. At 7 d, stellate cells with morphologic features of fibroblasts stained for PGP 9.5, whereas earlier wounds were generally negative. In 14 and 21 d incised wounds and in chronic granulation tissue from nonhealing ulcers there was strong cellular staining for PGP 9.5 and for ubiquitin. These stellate cells also showed expression of mRNA for PGP 9.5 by reverse transcriptase-polymerase chain reaction in situ hybridization. PGP 9.5 was detected in cultured fibroblasts both by reverse transcriptase-polymerase chain reaction and by northern blot analysis. Confocal microscopy showed colocalization of antibodies to PGP 9.5 and prolyl-4-hydroxylase (a fibroblast marker) as well as colocalization of PGP 9.5 and the platelet derived growth factor beta receptor. We conclude that ubiquitin and PGP 9.5 were expressed by fibroblasts during the granulation tissue and remodeling phases wound healing. The mRNA for PGP 9.5 was demonstrated in stellate cells in chronic wounds and in fibroblasts in culture. The appearance of these degradative proteins in later wounds suggests a downregulation function in the wound healing response.

Inhibition of murine melanoma growth by granulocyte-macrophage colony stimulating factor gene transfection is not haplotype specific

Granulocyte-macrophage colony stimulating factor (GM-CSF) has been shown to inhibit the growth and progression of murine melanoma cells in syngeneic C57BL/6 (H-2b) recipient animals. We now demonstrate that this effect is not specific to melanomas derived from a single strain of mice by examining the subcutaneous growth of K1735 murine melanoma cells (H-2k) transfected with GM-CSF in a syngeneic mouse model. Non-GM-CSF-secreting melanoma cells (parental K1735 and K1735 cells transfected with the GM-CSF gene in antisense orientation) generated tumours that reached a mean volume of 4000 mm3 30-40 days, with a mean survival of 40 days after tumour cell injection. In contrast, 90% of the mice injected with three different clones of GM-CSF-producing K1735 melanomas developed no measurable tumours and were healthy and tumour-free when followed for over 300 days post-inoculation. Additionally, mice injected with GM-CSF-secreting K1735 cells developed long-lasting immunity to the parental melanoma cell line challenge in vivo. A dense neutrophilic and lymphocytic inflammatory infiltrate as well as large numbers of dendritic cells were detected only at the inoculation sites of the GM-CSF-producing melanoma cells. Thus, these studies demonstrate for the first time that GM-CSF inhibits melanoma growth in a second genetically distinct MHC tumour-host model system and further support the use of GM-CSF in clinical trials in the treatment of advanced malignant melanoma in humans.

Neuropeptides in the skin: interactions between the neuroendocrine and the skin immune systems

The interaction between components of the nervous system and multiple target cells in the cutaneous immune system has been receiving increasing attention. It has been observed that certain skin diseases such as psoriasis and atopic dermatitis have a neurogenic component. Neuropeptides released by sensory nerves that innervate the skin and often contact epidermal and dermal cells can directly modulate functions of keratinocytes, Langerhans cells (LC), mast cells, dermal microvascular endothelial cells and infiltrating immune cells. Among these neuropeptides the tachykinins substance P (SP) and neurokinin A (NKA), calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP) and somatostatin (SOM) have been reported to effectively modulate skin and immune cell functions such as cell proliferation, cytokine production or antigen presentation under physiological or pathophysiological conditions. Expression and regulation of their corresponding receptors that are expressed on a variety of skin cells as well as the presence of neuropeptide-specific peptidases such as neutral endopeptidase (NEP) or angiotensin-converting enzyme (ACE) determine the final biological response mediated by these peptides on the target cell or tissue. Likewise, skin cells like keratinocytes or fibroblasts are a source for neurotrophins such as nerve growth factor that are required not only for survival and regeneration of sensory neurons but also to control responsiveness of these neurons to external stimuli. Therefore, neuropeptides, neuropeptide receptors, neuropeptide-degrading enzymes and neurotrophins participate in a complex, interdependent network of mediators that modulate skin inflammation, wound healing and the skin immune system. This review will focus on recent studies demonstrating the role of tachykinins, CGRP, SOM and VIP and their receptors and neuropeptide-degrading enzymes in mediating neurogenic inflammation in the skin.

Ultraviolet irradiation induces the production of multiple cytokines by human corneal cells

PURPOSE

Ultraviolet (UV) irradiation exposure represents a significant environmental and occupational hazard that can cause acute and chronic inflammatory changes in the exposed cornea. Acute exposure to solar UV irradiation or to UV irradiation from such artificial sources as tanning lamps can result in severe pain and inflammation in the cornea. Chronic exposure to solar UV irradiation is associated with several external eye diseases including pterygium and squamous metaplasia or carcinoma. In the skin, inflammatory responses to UV exposure appear to be mediated by the release of inflammatory cytokines. The role of corneal-derived cytokines in UV-mediated corneal inflammation has not been established. In this study, the effect of UV exposure on the production of proinflammatory cytokines by corneal cells was examined.

METHODS

Cultured human corneal stroma cells and whole human corneas received UV irradiation (10 to 100 mJ/cm2), and the production of the proinflammatory cytokines interleukin (IL)-1, IL-6, IL-8, and tumor necrosis factor alpha (TNF alpha) was measured by Northern blot analysis, enzyme-linked immunosorbent assay, cytokine bioassays, and immunohistochemical analysis.

RESULTS

The results indicate that acute UV exposure leads to a significant increase in the production of IL-1, IL-6, IL-8, and TNF alpha in human corneal stroma cells. Similarly, acute UV irradiation of whole human corneas ex vivo induces a significant increase in the production of IL-1, IL-6, IL-8, and TNF alpha.

CONCLUSIONS

Acute UV irradiation exposure results in the induction of cornea-derived proinflammatory cytokines. The local release of these proinflammatory cytokines by cells in the irradiated cornea may be responsible for UV-mediated corneal inflammation.

Interactions of the skin and nervous system

There is increasing experimental evidence that the neurologic system can directly participate in cutaneous inflammation and wound healing. Recent studies indicate that neuropeptides released by cutaneous nerves such as c-fibers can activate a number of target cells including keratinocytes, Langerhans cells, mast cells, and endothelial cells. One such neuropeptide, substance P (SP), is able to specifically bind to murine and human keratinocytes and induce the release of cytokines such as interleukin 1 (IL-1). Other studies demonstrate that SP can also activate mast cells to produce the potent pro-inflammatory cytokine tumor necrosis factor alpha (TNF alpha). More recently, we examined the effect of cutaneous neuropeptides on human dermal microvascular endothelial cell (HDMEC) activities. Our studies indicate that the c-fiber-derived calcitonin gene-related peptide (CGRP) is capable of stimulating HDMEC to secrete the neutrophil chemotactic factor interleukin 8 (IL-8). In addition, SP is able to directly activate HDMEC to express high levels of the important cellular adhesion molecule vascular cellular adhesion molecule 1 (VCAM-1). Thus, these studies support the role that the neurologic system may play in mediating the biologic processes that occur during inflammation and wound healing in the skin.

Trauma and alkali burns induce distinct patterns of cytokine gene expression in the rat cornea

Cytokines such as the interleukins (IL) and tumor necrosis factor alpha (TNF alpha) have traditionally been associated with paracrine regulation of immune reactions. These proteins also have properties suggestive of functional roles in the inflammatory and reparative responses to tissue injury. In this study, mRNA levels for IL-1 alpha, IL-1 beta, IL-6, TNF alpha, interferon gamma, transforming growth factor beta 1, and CD4 were monitored in rat corneas at times from 1 hour through 2 weeks after incisional trauma or alkali burns. Transcripts for IL-1 alpha, TNF alpha, and TGF beta 1 were present in most corneal samples; whereas those for IFN gamma and CD4 were not detected. As early as 1 hour following either of these non-immunologic forms of injury, expression of IL-6 mRNA levels was induced. Only in corneas with alkali burns did IL-6 induction persist from days 1 through 7. The alkali-injured corneas also had markedly increased IL-1 beta mRNA levels from days 1 through 7. These observations indicate that cytokine mRNA is induced in the cornea by trauma without an apparent immunologic stimulus. Our data are consistent with the hypothesis that corneal tissues respond to different types of injury with different patterns of cytokine gene expression.

Antitumor effects of granulocyte-macrophage colony-stimulating factor production by melanoma cells

The use of immunomodulating gene therapy in the treatment of malignant disease is under intensive investigation. In this study, we examined the potential of melanoma-derived granulocyte-macrophage colony-stimulating factor (GM-CSF) to inhibit melanoma progression in a murine model. The HGH18 murine melanoma cell line was transfected with the murine GM-CSF gene in a SV40 expression vector that resulted in melanoma clones that produced varying amounts of GM-CSF. Syngeneic mice inoculated s.c. with HFH18 parental melanoma cells or HFH18 cells transfected with the GM-CSF gene n the noncoding 3'-5' orientation [HFH18/GM-CSF(-) cells] develop large tumors that reach a mean tumor volume of 3300 mm3 by day 30. In contrast, animals inoculated with two melanoma clones producing high levels of GM-CSF [HFH18/GM-CSF(++) and HFH18/GM-CSF(+ + +)] either completely reject the tumor cells or develop tumors with a mean volume of only 40 mm3. In comparison, animals inoculated with a melanoma clone producing low levels of GM-CSF [HFH18/GM-CSF(+)] develop large tumors averaging 2000 mm3, thus demonstrating a dose-response effect of tumor inhibition by melanoma-derived GM-CSF. Additionally, vaccination with irradiated GM-CSF-producing melanoma cells conferred optimal immunogenicity against a subsequent challenge with HFH18 cells. Tissue sections from excised GM-CSF-producing tumor cell inoculation sites but not from HFH18 parental or HFH18/GM-CSF(-) inoculation sites demonstrate a dense inflammatory infiltrate composed of neutrophils, tissue macrophages, and numerous CD4- and CD8-positive lymphocytes but few melanoma cells. Large numbers of dendritic cells and cells expressing the B7-2 costimulatory molecule are detected only within HFH18/GM-CSF(+ + +) melanoma inoculation sites. Our results lend further support to clinical trials of GM-CSF gene therapy in the treatment of advanced malignant melanoma, possibly by the recruitment of dendritic antigen-presenting cells.