Interferon-gamma therapy reduces blood leukocyte levels in patients with atopic dermatitis: correlation with clinical improvement

Insights into adult atopic dermatitis heterogeneity derived from circulating biomarker profiling in patients with moderate-to-severe disease

Atopic dermatitis (AD) is a heterogeneous systemic inflammatory skin disease associated with dysregulated immune responses, barrier dysfunction and activated sensory nerves. To characterize circulating inflammatory profiles and underlying systemic disease heterogeneity within AD patients, blood samples from adult patients (N = 123) with moderate‐to‐severe AD in a phase 2 study of baricitinib (JAHG) were analysed. Baseline levels of 131 markers were evaluated using high‐throughput and ultrasensitive proteomic platforms, patient clusters were generated based on these peripheral markers. We implemented a novel cluster reproducibility method to validate cluster outcomes within our study and used publicly available AD biomarker data set (73 markers, N = 58 patients) to validate our findings. Cluster reproducibility analysis demonstrated best consistency for 2 clusters by k‐means, reproducibility of this clustering outcome was validated in an independent patient cohort. These unique JAHG patient subgroups either possessed elevated pro‐inflammatory mediators, notably TNFβ, MCP‐3 and IL‐13, among a variety of immune responses (high inflammatory) or lower levels of inflammatory biomarkers (low inflammatory). The high inflammatory subgroup was associated with greater baseline disease severity, demonstrated by greater EASI, SCORAD Index, Itch NRS and DLQI scores, compared with low inflammatory subgroup. African‐American patients were predominantly associated with the high inflammatory subgroup and increased baseline disease severity. In patients with moderate‐to‐severe AD, heterogeneity was identified by the detection of 2 disease subgroups, differential clustering amongst ethnic groups and elevated pro‐inflammatory mediators extending beyond traditional polarized immune responses. Therapeutic strategies targeting multiple pro‐inflammatory cytokines may be needed to address this heterogeneity.

Recent considerations in the use of recombinant interferon gamma for biological therapy of atopic dermatitis

INTRODUCTION

Atopic dermatitis (AD) is the most common inflammatory skin disease in the general population. There are different endophenotypes of AD that likely have a unique immune and molecular basis, such as those who are predisposed to eczema herpeticum, or Staphylococcus aureus infections.

AREAS COVERED

In this review, we highlight the endophenotypes of AD where reduced interferon gamma expression may be playing a role. Additionally, we review the potential role of recombinant interferon gamma therapy in the treatment of atopic dermatitis and the particular phenotypes that may benefit from this treatment.

EXPERT OPINION

Recombinant interferon gamma treatment will likely benefit the pediatric population with AD, as well as those with susceptibilities for skin infections. Future studies are needed to elucidate whether IFN-γ may reduce the prevalence of skin infection in AD.

Prevention of adverse events of interferon γ gene therapy by gene delivery of interferon γ-heparin-binding domain fusion protein in mice

Sustained gene delivery of interferon (IFN) γ can be an effective treatment, but our previous study showed high levels of IFNγ-induced adverse events, including the loss of body weight. These unwanted events could be reduced by target-specific delivery of IFNγ after in vivo gene transfer. To achieve this, we selected the heparin-binding domain (HBD) of extracellular superoxide dismutase as a molecule to anchor IFNγ to the cell surface. We designed three IFNγ derivatives, IFNγ-HBD₁, IFNγ-HBD₂, and IFNγ-HBD₃, each of which had 1, 2, or 3 HBDs, respectively. Each plasmid-encoding fusion proteins was delivered to the liver, a model target in this study, by hydrodynamic tail vein injection. The serum concentration of IFNγ-HBD₂ and IFNγ-HBD₃ after gene delivery was lower than that of IFNγ or IFNγ-HBD₁. Gene delivery of IFNγ-HBD₂, but not of IFNγ-HBD₃, effectively increased the mRNA expression of IFNγ-inducible genes in the liver, suggesting liver-specific distribution of IFNγ-HBD₂. Gene delivery of IFNγ-HBD₂-suppressed tumor growth in the liver as efficiently as that of IFNγ with much less symptoms of adverse effects. These results indicate that the adverse events of IFNγ gene transfer can be prevented by gene delivery of IFNγ-HBD₂, a fusion protein with high cell surface affinity.

[Control of spatiotemporal distribution of interferon γ by genetically fusing functional peptides]

Type II interferon (IFNγ) is a representative Th1 cytokine and it possesses a variety of functions, including immune regulation, antiviral and antitumor activity. Because of its multifunctional nature, IFNγ is expected to be applied to the treatment of autoimmune diseases, cancer and viral infection. Although IFNγ has therapeutic potential for such diseases, the clinical use of IFNγ has been limited due to its short in vivo half-life and serious adverse effects. In contrast, gene delivery of IFNγ is an alternative approach to increasing the retention time of IFNγ. To extend transgene expression after plasmid DNA (pDNA) gene transfer, we designed and developed pDNA with varying numbers of CpG motifs. CpG-reduced pDNA resulted in more durable transgene expression than its CpG replete counterpart in mice. Comparison of the effect of promoter/enhancer elements on transgene expression showed that ROSA26 promoter-mediated IFNγ expression was safe because of the lack of an initial surge after hydrodynamic gene transfer. We also designed an IFNγ-mouse serum albumin (MSA) fusion protein, IFNγ-MSA. Gene transfer of this fusion protein resulted in a sustained concentration of IFNγ fusion protein in mouse serum, and inhibited tumor metastasis in mice. These results provide experimental evidence that IFNγ gene therapy can be a useful treatment for a variety of diseases.

Constant and steady transgene expression of interferon-γ by optimization of plasmid construct for safe and effective interferon-γ gene therapy

BACKGROUND

Hydrodynamic injection of pmCMV(enh) -hEF-1(prom) -muIFN-γ, a plasmid DNA (pDNA) expressing murine interferon (IFN)-γ with a murine cytomegalovirus (mCMV) enhancer and a human elongation factor (EF)-1 promoter, has been proven effective for the treatment of cancer and atopic dermatitis in mice. However, the initial peak of IFN-γ soon after injection was quite high compared to the steady level for subsequent periods, which could cause unwanted adverse effects. Therefore, in the present study, aiming to optimize the efficacy/side-effect ratio of IFN-γ gene transfer, we have developed plasmid vectors encoding murine IFN-γ under the control of different combinations of promoter and enhancer sequences.

METHODS

The promoter and enhancer sequence of pmCMV(enh) -hEF-1(prom) -huIFN-γ, a prototype plasmid expressing human IFN-γ, was replaced or deleted to obtain various pDNAs. To assess the transgene expression profile, each pDNA was delivered to mice by hydrodynamic injection and the serum IFN-γ concentration was measured periodically. On the basis of the results obtained, murine IFN-γ expressing pDNAs were constructed and the body weight change was monitored as an indicator of adverse effects.

RESULTS

The prototype pmCMV(enh) -hEF-1(prom) -huIFN-γ showed a high but declining concentration of IFN-γ. Those containing hROSA26 promoter expressed the transgene in a more constant manner with no initial high concentrations and scarcely reduced the body weight.

CONCLUSIONS

These results indicate that hROSA26 promoter, irrespective of the presence and type of enhancers, is suitable for achieving constant and steady level of transgene expression and effective in avoiding the body weight loss caused by high concentrations of IFN-γ.

Sustained exogenous expression of therapeutic levels of IFN-gamma ameliorates atopic dermatitis in NC/Nga mice via Th1 polarization

The short in vivo half-life of IFN-gamma can prevent the cytokine from inducing immunological changes that are favorable for the treatment of Th2-dominant diseases, such as atopic dermatitis. To examine whether a sustained supply of IFN-gamma is effective in regulating the balance of Th lymphocyte subpopulations, plasmid vector encoding mouse IFN-gamma, pCpG-Mugamma, or pCMV-Mugamma was injected into the tail vein of NC/Nga mice, a model for human atopic dermatitis. A single hydrodynamic injection of a CpG motif reduced pCpG-Mugamma at a dose of 0.14 microg/mouse resulted in a sustained concentration of IFN-gamma in the serum, and the concentration was maintained at >300 pg/ml over 80 d. The pCpG-Mugamma-mediated IFN-gamma gene transfer was associated with an increase in the serum concentration of IL-12, reduced production of IgE, and inhibition of mRNA expression of IL-4, -5, -10, -13, and -17 and thymus and activation-regulated chemokine in the spleen. These immunological changes were not clearly observed in mice receiving two injections of 20 microg pCMV-Mugamma, a CpG-replete plasmid DNA, because of the transient nature of the expression from the vector. The mice receiving pCpG-Mugamma showed a significant reduction in the severity of skin lesions and in the intensity of their scratching behavior. Furthermore, high transepidermal water loss, epidermal thickening, and infiltration of lymphocytes and eosinophils, all of which were obvious in the untreated mice, were significantly inhibited. These results indicate that an extraordinary sustained IFN-gamma expression induces favorable immunological changes, leading to a Th1-dominant state in the atopic dermatitis model.

Pneumococcal seroconversion after vaccination for children with atopic dermatitis treated with tacrolimus ointment

OBJECTIVE

We sought to determine the effect of treatment with topical tacrolimus on B- and T-cell immunity including the primary antibody response to pneumococcal polysaccharide vaccine in children with atopic dermatitis.

METHODS

In this open-label, noncomparative study, 23 children aged 2 to 12 years with moderate to severe atopic dermatitis were treated with tacrolimus 0.03% ointment twice daily for 7 weeks, immunized with a 23-valent pneumococcal polysaccharide vaccine after 3 weeks of treatment, and had their antibody response measured (for 12 pneumococcal serotype antigens present in the vaccine) before and 4 weeks after vaccination. None had received pneumococcal vaccine before the study. Patient antibody and cellular immune responses were assessed at each study visit (baseline, week 3, and week 7).

RESULTS

No significant changes in complete blood cell count, lymphocyte subsets, CD4/CD8 ratio, immunoglobulin levels, antibody titers to tetanus and Haemophilus influenzae , or lymphoproliferative responses were noted during the tacrolimus ointment treatment period. Tacrolimus blood levels were 1 ng/mL or less in all 23 children. Protective pneumococcal titers to all 12 serotypes were observed in 2 of 23 (9%) children prevaccination and in 16 of 23 (70%) children postvaccination. All 6 children who had protective titers to 0 to 5 of the 12 serotypes developed protective titers to an additional 5 to 11 serotypes. Of the patients, 91% had a greater than 4-fold increase in titer for at least 4 of 12 pneumococcal serotypes.

CONCLUSION

Topical application of tacrolimus ointment does not affect the serologic response to pneumococcal vaccine or interfere with preexisting T- and B-cell immune responses.

Persistent skin colonization with Staphylococcus aureus in atopic dermatitis: relationship to clinical and immunological parameters

BACKGROUND

Staphylococcus aureus has important implications for the pathogenesis of atopic dermatitis (AD). In some patients S. aureus can be eradicated from the skin during anti-inflammatory treatment, while in others bacterial colonization is persistent. Potential mechanisms and features of these two distinct groups of patients are not known.

OBJECTIVE

Accordingly, we studied relationships between the ability to eliminate S. aureus during an anti-inflammatory treatment and selected clinical and immunological features.

METHODS

Quantitative assessment of S. aureus on the skin, in nasal vestibule and throat, serum IgE levels, CD4/CD8 T-cell ratio, lymphocyte proliferation and phagocyte oxidative burst were determined during the exacerbation and after 4 and 12 weeks of the treatment using topical steroid and oral antihistamine in 34 patients with AD.

RESULTS

S. aureus was found on the skin of all 34 patients during exacerbation. Disease severity scoring of atopic dermatitis (SCORAD) correlated with the density of bacteria. Treatment with oral antihistamine and topical steroid resulted in a significant alleviation of symptoms, which correlated with the elimination of S. aureus from the skin in 70% of patients. In the remaining 30% of patients, dense (more than 10(10)/cm2) S. aureus skin colonization, persisted despite the treatment. Patients with persistent S. aureus presented with higher serum IgE levels, lower lymphocyte proliferation in response to staphylococcal enterotoxin B, phytohaemagluttinin and anti-CD3. Persistence of S. aureus was more common in men.

CONCLUSIONS

Patients with AD differ in the ability to clear S. aureus from the skin during anti-inflammatory treatment, which appears to be related to the abnormalities in immunological parameters. Local antibiotic therapy should be considered only in patients with persistent S. aureus colonization.

The effect of a novel, dual function histamine H1 receptor antagonist/5-lipoxygenase enzyme inhibitor on in vivo dermal inflammation and extravasation

Leukotrienes and histamine are thought to play important roles in the development of dermatitis. This study evaluated the in vivo efficacy of 5-{4-[(aminocarbonyl)(hydroxy)amino]but-1-ynyl}-2-(2-{4-[(R)-(4-chlorophenyl)(phenyl)methyl]piperazin-1-yl}ethoxy)benzamide (ucb 35440), a dual function histamine H1 receptor antagonist/5-lipoxygenase enzyme inhibitor, in mouse skin. A single application of phorbol 12-myristate 13-acetate (PMA) was used to induce an acute inflammatory response over a 6-h period. PMA was applied on days 0, 2, 4, 7 and 9 to generate a chronic inflammatory response measured on day 10. ucb 35440 was applied topically at 1 h pre-PMA challenge and 3 h post-PMA challenge in the acute model. In the chronic PMA model, ucb 35440 was applied topically twice a day (AM and PM) on days 7, 8 and 9. Dose-response studies revealed that ucb 35440 inhibited PMA-induced ear weight gain with a 57% inhibition measured using a 3% w/v topical solution in the acute model. The compound appeared less potent in the chronic model with 43% inhibition measured using a 3% w/v topical solution of ucb 35440. Qualitative histologic assessment in PMA challenged ears showed that ucb 35440 produced a moderate reduction of polymorphonuclear cell infiltration in the acute model whereas, a more substantial reduction in polymorphonuclear infiltration was noted in the chronic model. In addition, the oral efficacy of ucb 35440 was evaluated in vivo against histamine-induced extravasation in guinea pig skin. Single oral doses of ucb 35440 (10 mg/kg in 0.5% methylcellulose suspension) at 1, 2, 6 or 24 h pre-histamine challenge produced minimal inhibition of histamine-induced extravasation in the dermis. However, when ucb 35440 (10 mg/kg in a 0.5% methylcellulose suspension) was orally administered 24 and 2 h prior to dermal histamine challenge, significant inhibition of extravasation was observed. Similar inhibition of histamine-induced extravasation was observed when animals were orally dosed twice a day (AM and PM 10 mg/kg in a 0.5% methylcellulose suspension) for 5.5 days prior to dermal histamine challenge. Collectively, these results suggest that ucb 35440 may represent an important therapeutic class for the treatment of dermatologic inflammatory conditions.

Induction of genes mediating interferon-dependent extracellular trap formation during neutrophil differentiation

Interferons (IFNs) are cytokines that possess potent anti-viral and immunoregulatory activities. In contrast, their potential role(s) in anti-bacterial defense and neutrophil activation mechanisms is less well explored. By comparing gene expression patterns between immature and mature human neutrophils, we obtained evidence that intracellular proteases and other anti-bacterial proteins are produced at earlier stages of maturation, whereas the genes for receptors and signaling molecules required for the release of these effector molecules are preferentially induced during terminal differentiation. For instance, mature neutrophils strongly expressed genes that increase their responses to type I and type II IFNs. Interestingly, granulocyte/macrophage colony-stimulating factor was identified as a repressor of IFN signaling components and consequently of IFN-responsive genes. Both IFN-alpha and IFN-gamma induced strong tyrosine phosphorylation of STAT1 in mature but not in immature neutrophils. Functional in vitro studies suggested that IFNs act as priming factors on mature neutrophils, allowing the formation of extracellular traps upon subsequent stimulation with complement factor 5a (C5a). In contrast, both IFN-alpha and IFN-gamma had only little capacity to prime immature cells in this system. Moreover, both IFNs did not have significant anti-proliferative effects on immature neutrophils. These data contribute to our understanding regarding changes of gene expression during neutrophil differentiation and IFN-mediated anti-bacterial defense mechanisms.

The potential role of allergen-specific sublingual immunotherapy in atopic dermatitis

Atopic dermatitis is a chronic inflammatory skin disease associated with increasing prevalence, morbidity, and cost in developed Western countries. Frequently associated with respiratory allergy during adulthood, atopic dermatitis often represents the first phenotypic appearance of atopy in early childhood when the allergic 'march' starts and progressively moves toward food allergy, asthma, and rhinitis. At present, a consistent body of evidence supports the view that atopic dermatitis may represent the skin compartmentalization of a systemic allergic inflammation. Lymphocytes infiltrating early lesional skin express a T helper (Th) 2 pattern of cytokine secretion (increased levels of interleukin [IL]-4 and/or IL-13 and decreased levels of interferon-gamma) as well as the typical Th2-type chemokine receptor CCR4, specific to the thymus and activation-regulated chemokines. Keratinocytes from patients with atopic dermatitis produce thymic stromal lymphopoietin, a novel cytokine that supports the early lymphocyte development in mouse models, and activates dendritic cells involved in the pathogenesis of allergic diseases in humans. Increased levels of circulating hemopoietic precursor cells have been reported in atopic dermatitis, as in allergic asthma and rhinitis. Furthermore, the recognition of CD34+ hemopoietic precursor cells, and evidence for cellular differentiation/maturational events occurring within atopic dermatitis skin lesion infiltrates, are consistent with the recent reinterpretation of the Th2/Th1 paradigm, where Th2 cells appear to belong to the early stages and Th1 to the ultimate stages of a linear, rather than divergent, pattern of lymphoid differentiation. This more detailed understanding of the immunologic derangements contributing to the atopic dermatitis pathogenesis has led to growing interest in allergen-specific immunotherapy for the disease. Due to the complexity intrinsic to atopic dermatitis and the lack of consensus-based guidelines for standardized outcome measure, only eight studies are available in the literature for a qualitative evaluation of this treatment approach. Two of these studies were double blind and placebo controlled, and six were cohort studies. Immunotherapy was found to be effective in one controlled study and five observational reports. Uncertain results were provided by one low-powered, controlled study, and negative outcomes were raised by a unique study performed with oral immunotherapy, which is not an effective route of mucosal allergen administration. Thus, more efficacy studies are required before immunotherapy could be recommended for the routine treatment of atopic dermatitis. Allergen-specific sublingual immunotherapy, given its excellent safety profile and ability to interfere with the systemic aspects of allergic inflammation, appears a good potential candidate for the pathogenetic treatment of the disease.

Atopic dermatitis: the role of recombinant interferon-gamma therapy

Atopic dermatitis is a common, chronic, relapsing cutaneous disease with typical cellular and humoral immunologic abnormalities that can result in significant physical and psychological morbidity to the patient. Atopic dermatitis typically begins in childhood and can often persist through adolescence into adulthood. Although there are a variety of treatments for atopic dermatitis, many patients' symptoms do not improve or they have adverse reactions to medications, requiring the search for other, effective therapeutic agents. A number of inflammatory and immunological abnormalities have long been noted in patients with atopic dermatitis. Although great strides have been made in understanding the causes, the complex pathophysiology of atopic dermatitis is still not completely understood. Most notably, patients with atopic dermatitis often have an elevation of serum immunoglobulin (Ig) E levels, depressed cellular immunity, elevated blood eosinophilia, and increased interleukin (IL)-4 production. In addition, peripheral blood mononuclear cells of patients with atopic dermatitis produce reduced levels of interferon-gamma spontaneously and in response to stimuli. Due to this constellation of features, atopic dermatitis was initially viewed as a prototypical type 2 helper T lymphocyte (T(h2)) disease. These immunological findings led to a number of clinical trials with recombinant interferon-gamma in patients who had severe, unremitting atopic dermatitis. Treatment with recombinant interferon-gamma was postulated to be able to correct the immunological imbalances in patients with atopic dermatitis by decreasing serum IgE levels, IL-4 levels, restoring immune balance, and thereby leading to clinical improvement. Initial open-label studies, a double-blind placebo trial, and long-term open-label studies have demonstrated the clinical efficacy and tolerability of recombinant interferon-gamma in a subset of patients with severe, unremitting atopic dermatitis. Patients receiving treatment often had marked decreases in severity of clinical parameters: erythema, edema/indurations, pruritus, excoriations, dryness, lichenification and associated reduction in total body surface area involvement. Surprisingly, treatment with recombinant interferon-gamma did not lower serum IgE levels refuting the hypothesized mechanism by which interferon-gamma would bring about clinical improvement in patients with atopic dermatitis. Instead, decreases were noted in absolute white blood cell and eosinophil counts that tended to correlate with clinical improvement. Although the exact mechanism by which recombinant interferon-gamma brings about clinical changes in patients with atopic dermatitis is unknown, recombinant interferon-gamma should be considered a possible therapy for patients with atopic dermatitis.

What are the most promising strategies for the therapeutic immunomodulation of allergic diseases?

Specific immunotherapy and other immunomodulatory strategies have long been a stronghold in the management of allergic diseases. In particular, "immunodeviation-therapy" or "vaccination for allergies", i.e. the redirection of Th2-type immune responses towards a Th1-response pattern, has become an ever more popular concept. The present feature of CONTROVERSIES complements our previous discussion of atopy (Röcken et al., Exp Dermatol 7: 97--104, 1998), and is dedicated to a critical analysis of the general problems and limitations one faces with the main immunomodulatory strategies traditionally considered in this context. We also explore alternative approaches that appear promising in order to achieve both a more effective and/or a more specific immunotherapy of allergic diseases. Given that the mast cell remains a key protagonist in the pathogenesis of allergic diseases finally, this feature examines how innovative, more selectively mast cell-targeted strategies may be developed for the management of allergic diseases.

Immunotherapy in atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory disease involving the skin and often other organs and systems, mainly respiratory. A definitive general consensus on the AD pathogenesis has not yet been established, however several lines of evidence suggest that T-cells play a crucial role in priming AD early-stage lesions. Main topics involved in the disease pathogenesis have been reviewed, which considered the concept of local and systemic haemopoietic events as important contributors to allergic inflammation, a concept now achieving great acceptance. The recently recognised atopic nature of the skin inflammation in AD has raised increasing interest for treatment with allergen-specific immunotherapy. However, we only found eight studies using specific immunotherapy (SIT) in AD, two double-blind, placebo-controlled (DBPC) and six observational. One controlled and five observational reported favourable outcomes. The one unique study providing negative results was flawed by the ineffective oral route of extract administration. Despite being encouraging, the reported results do not allow definitive conclusions based on meta-analytic techniques because the amount and quality of information in the literature is not sufficient. The highly promising sub-lingual immunotherapy (SLIT) is discussed with its potential capability of controlling not only the skin lesion severity but also its capability of preventing the development of atopic dermatitis into asthma.

Atopic dermatitis: new insights and opportunities for therapeutic intervention

Atopic dermatitis (AD) is a chronic inflammatory skin disease that frequently predates the development of allergic rhinitis or asthma. It is an important skin condition with significant costs and morbidity to patients and their families; the disease affects more than 10% of children. Recent studies have demonstrated the complex interrelationship of genetic, environmental, skin barrier, pharmacologic, psychologic, and immunologic factors that contribute to the development and severity of AD. The current review will examine the cellular and molecular mechanisms that contribute to AD as well as the immunologic triggers involved in its pathogenesis. These insights provide new opportunities for therapeutic intervention in this common skin condition.