A Comprehensive Review of Neutrophilic Diseases

The Impact of Neutrophil Recruitment to the Skin on the Pathology Induced by Leishmania Infection

Leishmania (L.) are obligate intracellular protozoan parasites that cause the leishmaniases, a spectrum of neglected infectious vector-borne diseases with a broad range of clinical manifestations ranging from local cutaneous, to visceral forms of the diseases. The parasites are deposited in the mammalian skin during the blood meal of an infected female phlebotomine sand fly. The skin is a complex organ acting as the first line of physical and immune defense against pathogens. Insults to skin integrity, such as that occurring during insect feeding, induces the local secretion of pro-inflammatory molecules generating the rapid recruitment of neutrophils. At the site of infection, skin keratinocytes play a first role in host defense contributing to the recruitment of inflammatory cells to the infected dermis, of which neutrophils are the first recruited cells. Although neutrophils efficiently kill various pathogens including Leishmania, several Leishmania species have developed mechanisms to survive in these cells. In addition, through their rapid release of cytokines, neutrophils modulate the skin microenvironment at the site of infection, a process shaping the subsequent development of the adaptive immune response. Neutrophils may also be recruited later on in unhealing forms of cutaneous leishmaniasis and to the spleen and liver in visceral forms of the disease. Here, we will review the mechanisms involved in neutrophil recruitment to the skin following Leishmania infection focusing on the role of keratinocytes in this process. We will also discuss the distinct involvement of neutrophils in the outcome of leishmaniasis.

An extensive pyoderma gangrenosum mimicking necrotizing fasciitis: An unusual case report

Introduction

Pyoderma Gangrenosum (PG) is a rare, benign and inflammatory disease characterized by ulcerative skin lesions. We report the successful management of an unusual case of PG following a caesarean section, with extensive cutaneous skin involvement and mimicking necrotizing fasciitis.

Presentation of case

A 36-year-old woman was admitted with extensive surgical site inflammation after a caesarean section. Despite antibiotic treatment and wound care, the clinical course deteriorated rapidly. Wound debridement following negative pressure closure was performed due to an immediate increase in skin necrosis. A diagnosis of PG was reached based on the absence of a positive wound culture, resistance to wound debridement and the histopathological results. A course of high-dose corticosteroids was started, and a successful clinical course was finally achieved. The patient is now in the 14th month of remission, with no recurrence.

Discussion

PG is often reported after bowel surgery, especially after complicated stoma or diverticulitis, breast surgery and occasionally after C-sections. The diagnosis of pyoderma gangrenosum may be challenging because of a wide variety of macroscopic features and its pronounced similarity to necrotizing fasciitis. Treatment with systemic corticosteroids is the most common management option, while surgical treatment is extremely controversial.

Conclusion

An extensive PG following surgery can mimic necrotizing fasciitis. An interdisciplinary treatment approach provides early diagnosis and effective treatment resulting in less morbidity.

Cranial aseptic osteomyelitis associated with pyoderma gangrenosum

Neutrophilic dermatoses include a heterogeneous group of entities. Uncommonly, they can accumulate aseptic neutrophilic abscesses in other tissues in addition to the skin. A 34-year-old female complained of a headache which was unresponsive to usual drugs. A TAC revealed an osteolytic lesion in the right parietal bone. The biopsy showed osteomyelitis. One year later, pyoderma gangrenosum appeared in the anterior aspect of both legs. The headache and the cutaneous lesions disappeared after treatment with oral prednisone. The bone involvement in the background of neutrophilic dermatoses is exceptional. Usually, it involves children in the context of chronic recurrent multiple osteomyelitis (CRMO). Only two cases have been described in adults. One of them was a 26-year-old woman who had had CRMO since childhood, and the other one in contiguity with the cutaneous lesions of pyoderma gangrenosum.

The neutrophil inflammasome

Since inflammasomes were discovered in the early 21st century, knowledge about their biology has multiplied exponentially. These cytosolic multiprotein complexes alert the immune system about the presence of infection or tissue damage, and regulate the subsequent inflammatory responses. As inflammasome dysregulation is increasingly associated with numerous autoinflammatory disorders, there is an urgent need for further research into the inflammasome's involvement in the pathogenesis of such diseases in order to identify novel therapeutic targets and treatments. The zebrafish has become a widely used animal model to study human diseases in recent years, and has already provided relevant findings in the field of inflammasome biology including the identification of new components and pathways. We provide a detailed analysis of current knowledge on neutrophil inflammasome biology and compare its features with those of the better known macrophage inflammasome, focusing on its contribution to innate immunity and its relevance for human health. Importantly, a large body of evidence points to a link between neutrophil inflammasome dysfunction and many neutrophil-mediated human diseases, but the real contribution of the neutrophil inflammasome to the pathogenesis of these disorders is largely unknown. Although neutrophils have remained in the shadow of macrophages and monocytes in the field of inflammasome research since the discovery of these multiprotein platforms, recent studies strongly suggest that the importance of the neutrophil inflammasome has been underestimated.

A Systematic Review of Promising Therapeutic Targets in Hidradenitis Suppurativa: A Critical Evaluation of Mechanistic and Clinical Relevance

This systematic review identifies and critically evaluates the mechanistic and clinical evidence of new promising therapeutic targets in hidradenitis suppurativa (HS). Evidence for these targets is largely based on observational data with limited ex vivo and translational data from clinical trials. A number of placebo-controlled studies have been completed or are underway utilizing IL-1, IL-23, IL-17, complement, and Jak inhibition, although there is concern regarding elevated placebo response rates and the questionable validity of clinical scores in some participant subsets. Knowledge gaps are identified suggesting a direction for future mechanistic studies in HS, including more comprehensive inflammatory endotype profiling of disease.

Natterin an aerolysin-like fish toxin drives IL-1β-dependent neutrophilic inflammation mediated by caspase-1 and caspase-11 activated by the inflammasome sensor NLRP6

Natterin is an aerolysin-like pore-forming toxin responsible for the toxic effects of the venom of the medically significant fish Thalassophryne nattereri. Using a combination of pharmacologic and genetic loss-of-function approaches we conduct a systematic investigation of the regulatory mechanisms that control Natterin-induced neutrophilic inflammation in the peritonitis model. Our data confirmed the capacity of Natterin to induce a strong and sustained neutrophilic inflammation leading to systemic inflammatory lung infiltration and revealed overlapping regulatory paths in its control. We found that Natterin induced the extracellular release of mature IL-1β and the sustained production of IL-33 by bronchial epithelial cells. We confirmed the dependence of both ST2/IL-33 and IL-17A/IL-17RA signaling on the local and systemic neutrophils migration, as well as the crucial role of IL-1α, caspase-1 and caspase-11 for neutrophilic inflammation. The inflammation triggered by Natterin was a gasdermin-D-dependent inflammasome process, despite the cells did not die by pyroptosis. Finally, neutrophilic inflammation was mediated by non-canonical NLRP6 and NLRC4 adaptors through ASC interaction, independent of NLRP3. Our data highlight that the inflammatory process dependent on non-canonical inflammasome activation can be a target for pharmacological intervention in accidents by T. nattereri, which does not have adequate specific therapy.

Dermatological Manifestations in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBDs) may be associated with extra-intestinal manifestations. Among these, mucocutaneous manifestations are relatively frequent, often difficult to diagnose and treat, and may complicate the course of the underlying disease. In the present review, a summary of the most relevant literature on the dermatologic manifestations occurring in patients with inflammatory bowel diseases has been reviewed. The following dermatological manifestations associated with IBDs have been identified: (i) specific manifestations with the same histological features of the underlying IBD (occurring only in Crohn's disease); (ii) cutaneous disorders associated with IBDs (such as aphthous stomatitis, erythema nodosum, psoriasis, epidermolysis bullosa acquisita); (iii) reactive mucocutaneous manifestations of IBDs (such as pyoderma gangrenosum, Sweet's syndrome, bowel-associated dermatosis-arthritis syndrome, aseptic abscess ulcers, pyodermatitis-pyostomatitis vegetans, etc.); (iv) mucocutaneous conditions secondary to treatment (including injection site reactions, infusion reactions, paradoxical reactions, eczematous and psoriasis-like reactions, cutaneous infections, and cutaneous malignancies); (v) manifestations due to nutritional malabsorption (such as stomatitis, glossitis, angular cheilitis, pellagra, scurvy, purpura, acrodermatitis enteropathica, phrynoderma, seborrheic-type dermatitis, hair and nail abnormalities). An accurate dermatological examination is essential in all IBD patients, especially in candidates to biologic therapies, in whom drug-induced cutaneous reactions may assume marked clinical relevance.

Immune-Mediated Dermatoses in Patients with Haematological Malignancies: A Comprehensive Review

Haematological malignancies induce important alterations of the immune system, which account for the high frequency of autoimmune complications observed in patients. Cutaneous immune-mediated diseases associated with haematological malignancies encompass a heterogeneous group of dermatoses, including, among others, neutrophilic and eosinophilic dermatoses, autoantibody-mediated skin diseases, vasculitis and granulomatous dermatoses. Some of these diseases, such as paraneoplastic pemphigus, are associated with an increased risk of death; others, such as eosinophilic dermatoses of haematological malignancies, run a benign clinical course but portend a significant negative impairment on a patient’s quality of life. In rare cases, the skin eruption reflects immunological alterations associated with an unfavourable prognosis of the associated haematological disorder. Therapeutic management of immune-mediated skin diseases in patients with haematological malignancies is often challenging. Systemic corticosteroids and immunosuppressive drugs are considered frontline therapies but may considerably augment the risk of serious infections. Indeed, developing a specific targeted therapeutic approach is of crucial importance for this particularly fragile patient population. This review provides an up-to-date overview on the immune-mediated skin diseases most frequently encountered by patients with onco-haematological disorders, discussing new pathogenic advances and therapeutic options on the horizon.

Specific Ag-guiding nano-vaccines attenuate neutrophil-dominant allergic asthma

Polymorphonuclear neutrophils (PMN) are one fraction of the major inflammatory cells in allergic asthma (asthma, in short); the role of PMN in the asthma pathogenesis is not fully understood yet. This study aims to investigate the effects of specific Ag-guiding exosomes on suppressing the neutrophil-dominant airway inflammation. In this study, BALB/c mice were immunized with ovalbumin plus complete Freund adjuvant to induce an asthma model featured with neutrophil-dominant lung inflammation. The Ag specific PMN (sPMN)-targeting exosomes (tExo), that were exosomes carrying a complex of specific Ag/anti-CD64 Ab and Fas ligand, were constructed to be used to alleviate neutrophilic asthma in mice. We found that sPMNs were the major cellular component in bronchoalveolar lavage fluid (BALF) in asthma mice, while less than 3% PMNs in naive control mice. The sPMNs expressed higher levels of CD64, which formed complexes with Ag-specific IgG (sIgG). The sIgG/CD64 complex-carrying PMNs could be activated upon exposing to specific Ags. Exposure to tExos induced Ag-specific PMNs apoptosis. Administration of tExos efficiently suppressed experimental asthma. We conclude that a fraction of sPMN was identified in the airway of asthma mice. The sPMNs could be activated upon exposure to specific Ags. tExos could induce sPMNs apoptosis, that show the translational potential in the treatment of asthma.

Discovery and characterization of a neutralizing pan-ELR+CXC chemokine monoclonal antibody

CXCR1 and CXCR2 signaling play a critical role in neutrophil migration, angiogenesis, and tumorigenesis and are therefore an attractive signaling axis to target in a variety of indications. In human, a total of seven chemokines signal through these receptors and comprise the ELR⁺CXC chemokine family, so named because of the conserved ELRCXC N-terminal motif. To fully antagonize CXCR1 and CXCR2 signaling, an effective therapeutic should block either both receptors or all seven ligands, yet neither approach has been fully realized clinically. In this work, we describe the generation and characterization of LY3041658, a humanized monoclonal antibody that binds and neutralizes all seven human and cynomolgus monkey ELR⁺CXC chemokines and three of five mouse and rat ELR⁺CXC chemokines with high affinity. LY3041658 is able to block ELR⁺CXC chemokine-induced Ca²⁺ mobilization, CXCR2 internalization, and chemotaxis in vitro as well as neutrophil mobilization in vivo without affecting other neutrophil functions. In addition to the in vitro and in vivo activity, we characterized the epitope and structural basis for binding in detail through alanine scanning, crystallography, and mutagenesis. Together, these data provide a robust preclinical characterization of LY3041658 for which the efficacy and safety is being evaluated in human clinical trials for neutrophilic skin diseases.

Prognostic Indicators of Wound Healing in Atypical Wounds: A Case Series

Healing rate is the most accurate method to predict healing; however, there are no data in atypical ulcers. We retrospectively analyzed clinical features, associated comorbidities, and therapies of 159 patients with atypical ulcers. In a subgroup of 59 patients, we analyzed the areas, perimeters, and the healing rate (mm/d) as prognostic indicators of wound healing. Atypical ulcers were more frequent among women (n = 98) with an average age of 76 years. Confirmed by biopsy, the etiologies were as follows: inflammatory diseases (38%), neoplastic ulcers (29%), vasculitis (21%), drug-induced ulcers (7%), and infectious ulcers (4%). Systemic therapies were applied based on the different etiologies. Wound bed preparation principles guided the local treatment. The average reduction of the area during the observation interval was 36%, while the average reduction in the perimeter was 41%. Overall, 51 ulcers showed a reduction in wound size and 8 ulcers showed an increase. Neoplastic ulcers were the group with the fastest healing rate, with an average speed of 0.24 mm/d. The slowest healing occurred in the inflammatory group with an average healing rate of 0.032 mm/d. The initial area and perimeters influenced wound healing; however, ulcer etiology and comorbidities significantly altered the healing rate.

Zebrafish Models to Study Inflammasome-Mediated Regulation of Hematopoiesis

Hematopoiesis is a complex process through which immature bone marrow precursor cells mature into all types of blood cells. Although the association of hematopoietic lineage bias (including anemia and neutrophilia) with chronic inflammatory diseases has long been appreciated, the causes involved are obscure. Recently, cytosolic multiprotein inflammasome complexes were shown to activate inflammatory and immune responses, and directly regulate hematopoiesis in zebrafish models; this was deemed to occur via cleavage and inactivation of the master erythroid transcription factor GATA1. Herein summarized are the zebrafish models that are currently available to study this unappreciated role of inflammasome-mediated regulation of hematopoiesis. Novel putative therapeutic strategies, for the treatment of hematopoietic alterations associated with chronic inflammatory diseases in humans, are also proposed.

Pyoderma gangrenosum

Pyoderma gangrenosum (PG) is a rare neutrophilic dermatosis that presents with rapidly developing, painful skin ulcers hallmarked by undermined borders and peripheral erythema. Epidemiological studies indicate that the average age of PG onset is in the mid-40s, with an incidence of a few cases per million person-years. PG is often associated with a variety of other immune-mediated diseases, most commonly inflammatory bowel disease and rheumatoid arthritis. The cause of PG is not well understood, but PG is generally considered an autoinflammatory disorder. Studies have focused on the role of T cells, especially at the wound margin; these cells may support the destructive autoinflammatory response by the innate immune system. PG is difficult to diagnose as several differential diagnoses are possible; in addition to clinical examination, laboratory tests of biopsied wound tissue are required for an accurate diagnosis, and new validated diagnostic criteria will facilitate the process. Treatment of PG typically starts with fast-acting immunosuppressive drugs (corticosteroids and/or cyclosporine) to reduce inflammation followed by the addition of more slowly acting immunosuppressive drugs with superior adverse event profiles, including biologics (in particular, anti-tumour necrosis factor (TNF) agents). Appropriate wound care is also essential. Future research should focus on PG-specific outcome measures and PG quality-of-life studies.

Phenotypes and Pathophysiology of Syndromic Hidradenitis Suppurativa: Different Faces of the Same Disease? A Systematic Review

<b><i>Background:</i></b> There is growing evidence that (certain) hidradenitis suppurativa (HS) comorbidities comprise syndromes including HS as a key cutaneous manifestation. These apparently autoinflammatory syndromes and their diagnostic delay might have detrimental effects on affected patients. <b><i>Methods:</i></b> A systematic review was performed on the databases MEDLINE, EMBASE, and CENTRAL utilizing a standardized extraction form according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. <b><i>Results:</i></b> Sixty-four eligible articles on syndromic HS were retrieved. The identified syndromes included already described ones (pyoderma gangrenosum-acne-suppurative hidradenitis, pyogenic arthritis-pyoderma gangrenosum-acne-suppurative hidradenitis, psoriatic arthritis-pyoderma gangrenosum-acne-suppurative hidradenitis, pyoderma gangrenosum-acne vulgaris-hidradenitis suppurativa-ankylosing spondylitis, synovitis-acne-pustulosis-hyperostosis-osteitis) and further novel symptom constellations. Cutaneous signs, including HS lesions, usually precede signs from other organs. The cutaneous signs of a considerable proportion of patients appear refractory to conventional treatment, and monotherapy with biologics does not suffice to sustain remission. <b><i>Conclusion:</i></b> The results are subsequently discussed with focus on the pathophysiology and treatment of the detected syndromes. The dermatologist’s role in the precise diagnosis and early treatment administration of HS is pivotal. The purpose of the treatment should be the effective prevention or delay of the autoinflammatory march and its irreversible consequences.

Myeloperoxidase Modulates Inflammation in Generalized Pustular Psoriasis and Additional Rare Pustular Skin Diseases

Generalized pustular psoriasis (GPP) is a severe multi-systemic inflammatory disease characterized by neutrophilic pustulosis and triggered by pro-inflammatory IL-36 cytokines in skin. While 19%–41% of affected individuals harbor bi-allelic mutations in IL36RN, the genetic cause is not known in most cases. To identify and characterize new pathways involved in the pathogenesis of GPP, we performed whole-exome sequencing in 31 individuals with GPP and demonstrated effects of mutations in MPO encoding the neutrophilic enzyme myeloperoxidase (MPO). We discovered eight MPO mutations resulting in MPO -deficiency in neutrophils and monocytes. MPO mutations, primarily those resulting in complete MPO deficiency, cumulatively associated with GPP (p = 1.85E−08; OR = 6.47). The number of mutant MPO alleles significantly differed between 82 affected individuals and >4,900 control subjects (p = 1.04E−09); this effect was stronger when including IL36RN mutations (1.48E−13) and correlated with a younger age of onset (p = 0.0018). The activity of four proteases, previously implicated as activating enzymes of IL-36 precursors, correlated with MPO deficiency. Phorbol-myristate-acetate-induced formation of neutrophil extracellular traps (NETs) was reduced in affected cells (p = 0.015), and phagocytosis assays in MPO-deficient mice and human cells revealed altered neutrophil function and impaired clearance of neutrophils by monocytes (efferocytosis) allowing prolonged neutrophil persistence in inflammatory skin. MPO mutations contribute significantly to GPP’s pathogenesis. We implicate MPO as an inflammatory modulator in humans that regulates protease activity and NET formation and modifies efferocytosis. Our findings indicate possible implications for the application of MPO inhibitors in cardiovascular diseases. MPO and affected pathways represent attractive targets for inducing resolution of inflammation in neutrophil-mediated skin diseases.

The great imitator with no diagnostic test: pyoderma gangrenosum

Pyoderma gangrenosum is a rare, neutrophil-mediated, auto-inflammatory dermatosis that wound care specialists must be prepared to recognise. This condition has clinical features analogous to infectious processes. There is no specific diagnostic test and the diagnosis is usually obtained from exclusion. Its early recognition and proper management with prompt initiation of immunosuppressive therapy are essential to improve the quality of life and the prognosis of patients.

PAPA spectrum disorders

Pyogenic arthritis, pyoderma gangrenosum (PG) and acne (PAPA) syndrome is an autosomal dominant autoinflammatory syndrome due to mutations in proline-serine-threonine phosphatase interacting protein 1 (PSTPIP1) gene and presenting with cutaneous and articular manifestations. Other autoinflammatory syndromes caused by mutations in PSTPIP1 gene or characterized by clinical findings overlapping with those found in PAPA syndrome have been recently included in the group of PAPA spectrum disorders. These disorders are PASH (PG, acne and hidradenitis suppurativa [HS]), PAPASH (PASH associated with pyogenic sterile arthritis), PsAPASH (PASH combined with psoriatic arthritis [PsA], PASS (PG, acne, ankylosing spondylitis, with or without HS), PAC (PG, acne and ulcerative colitis [UC]) and PAMI syndrome (PSTPIP1-associated myeloid-related-proteinemia inflammatory syndrome). Except for PAPA and PAMI, no specific pathogenetic mutations have been identified in these syndromes. Dermatologists should be aware that PG, acne and HS may represent cutaneous signs hiding the presence of these rare entities. Systemic corticosteroids, a number of immunosuppressants and biologics, such as interleukin (IL)-1 antagonists and tumour necrosis factor (TNF) α inhibitors, are nowadays therapy for these diseases. A pathogenesis-driven treatment is the near future in the management of these conditions.

Improved mouse models and advanced genetic and genomic technologies for the study of neutrophils

Mice have been excellent surrogates for studying neutrophil biology and, furthermore, murine models of human disease have provided fundamental insights into the roles of human neutrophils in innate immunity. The emergence of novel humanized mice and high-diversity mouse populations offers the research community innovative and powerful platforms for better understanding, respectively, the mechanisms by which human neutrophils drive pathogenicity, and how genetic differences underpin the variation in neutrophil biology observed among humans. Here, we review key examples of these new resources. Additionally, we provide an overview of advanced genetic engineering tools available to further improve such murine model systems, of sophisticated neutrophil-profiling technologies, and of multifunctional nanoparticle (NP)-based neutrophil-targeting strategies.

Pseudo-wound infection after a caesarean section: Case report of unrecognized Pyoderma Gangrenosum

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Pyoderma Gangrenosum (PG) is a rare auto-inflammatory disease.

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It can develop after surgery due to the pathergy phenomena.

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Consider PG in the differential diagnosis of a suspected surgical wound infection.

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Avoid surgical treatment as long as the disease is active to reduce morbidity.

Background

Pyoderma Gangrenosum (PG) is a rare auto-inflammatory disease, characterized by painful ulcerative skin-lesions often developing at sites of injury or surgery because of the typical pathergy phenomena. We describe an unusual case of PG after a caesarean section with excessive extra-cutaneous manifestation within internal organs.

Presentation of case

A 21-year-old Dutch primigravida developed signs of sepsis after a caesarean section. Despite antibiotic treatment, fast clinical deterioration occurred. Exploration of the wound showed necrosis of the uterus and surrounding tissues. Due to the progression of necrosis, consecutive debridement procedures were executed resulting in a substantial abdominal wall defect. The progressive clinical course of the necrosis combined with absence of positive wound cultures and histology of prominent interstitial neutrophilic infiltration, led to the diagnosis ‘Pyoderma Gangrenosum’. Treatment with high dose corticosteroids led to rapid regression of the disease. After several weeks, the abdominal wall defect was surgically corrected under systemic corticosteroid therapy.

Discussion

This case of PG is unique due to the excessive extra-cutaneous presentation, which contributed to delayed diagnosis. Several surgical interventions in the active stage of disease resulted in expansion of PG and substantial morbidity for the patient.

Conclusion

Post-operative PG can mimic infectious diseases, but treatment is substantially different. This case of extensive PG highlights the importance of timely recognition and treatment of the disease to reduce iatrogenic morbidity.

A man with recurrent fever, arthritis, and rashes-brucellosis? A case report

Background

We report a rare case of chronic brucellosis accompanied with myelodysplastic syndrome and neutrophilic dermatosis, which to the best of our knowledge, has never been reported.

Case presentation

A young man was admitted to our hospital complaining of recurrent fever, arthritis, rashes and anemia. He had been diagnosed with brucellosis 6 years prior and treated with multiple courses of antibiotics. He was diagnosed with myelodysplastic syndrome and neutrophilic dermatosis following bone marrow puncture and skin biopsy. After anti-brucellosis treatment and glucocorticoid therapy, the symptoms improved.

Conclusions

Clinicians should consider noninfectious diseases when a patient who has been diagnosed with an infectious disease exhibits changing symptoms.

Cutaneous manifestations in inflammatory bowel disease (Review)

Inflammatory bowel disease (IBD) is defined as a chronic condition characterized by unpredictable relapsing episodes of gastrointestinal inflammation. IBD is not limited to the gastrointestinal tract and should be considered a systemic disease which can involve any organ. Cutaneous manifestations in IBD are frequent and comprise a broad spectrum of diseases, ranging from mild to severe and sometimes debilitating lesions. Some of the cutaneous manifestations can present signs of an underlying intestinal disease, leading to the screening for non-detected IBD even in the absence of symptoms. Cutaneous EIMs are divided into 4 categories: i) Disease-specific lesions that show the same histopathologic findings as the underlying gastrointestinal disease, ii) reactive lesions which are inflammatory lesions that share a common pathogenetic mechanism but do not share the same pathology with the gastrointestinal disease, iii) associated conditions are more frequently observed in the context of IBD, without sharing the pathogenetic mechanism or the histopathological findings with the underlying disease and iv) drug-related skin reactions.

Pyoderma gangrenosum: a review with special emphasis on Latin America literature

Pyoderma gangrenosum is a neutrophilic dermatosis characterized by chronic ulcers due to an abnormal immune response. Despite the existence of diagnostic criteria, there is no gold standard for diagnosis or treatment. In Latin America, recognizing and treating pyoderma gangrenosum is even more challenging since skin and soft tissue bacterial and non-bacterial infections are common mimickers. Therefore, this review aims to characterize reported cases of pyoderma gangrenosum in this region in order to assist in the assessment and management of this condition. Brazil, Mexico, Argentina, and Chile are the countries in Latin America that have reported the largest cohort of patients with this disease. The most frequent clinical presentation is the ulcerative form and the most frequently associated conditions are inflammatory bowel diseases, inflammatory arthropaties, and hematologic malignancies. The most common treatment modalities include systemic corticosteroids and cyclosporine. Other reported treatments are methotrexate, dapsone, and cyclophosphamide. Finally, the use of biological therapy is still limited in this region.

Organization of the Skin Immune System and Compartmentalized Immune Responses in Infectious Diseases

The skin is an organ harboring several types of immune cells that participate in innate and adaptive immune responses. The immune system of the skin comprises both skin cells and professional immune cells that together constitute what is designated skin-associated lymphoid tissue (SALT). In this review, I extensively discuss the organization of SALT and the mechanisms involved in its responses to infectious diseases of the skin and mucosa. The nature of these SALT responses, and the cellular mediators involved, often determines the clinical course of such infections. I list and describe the components of innate immunity, such as the roles of the keratinocyte barrier and of inflammatory and natural killer cells. I also examine the mechanisms involved in adaptive immune responses, with emphasis on new cytokine profiles, and the role of cell death phenomena in host-pathogen interactions and control of the immune responses to infectious agents. Finally, I highlight the importance of studying SALT in order to better understand host-pathogen relationships involving the skin and detail future directions in the immunological investigation of this organ, especially in light of recent findings regarding the skin immune system.

[Pyoderma gangrenosum and systemic lupus erythematosus: A rare association]

INTRODUCTION

Pyoderma gangrenosum (PG) is a neutrophilic dermatosis that is traditionally associated with systemic disorders such as chronic inflammatory bowel diseases, rheumatoid arthritis and malignant hematologic disorders. Its association with systemic lupus erythematosus (SLE) is rare and not well known. We report a case of this association with a review of the literature.

CASE REPORT

A 43-year-old female patient, followed for 4 years for SLE, presented a deep ulceration of the anterior face of the left thigh with inflammatory borders, an ulcerated nodule of the right shoulder and four small ulcerations of the back of the right hand. The biopsy of the ulceration of the left thigh concluded to PG. The patient was treated by corticosteroids with complete healing of lesions.

CONCLUSION

The prognosis of lupus does not seem to be aggravated by PG and the treatments of a SLE flare are usually enough for treating associated PG.

Pathergy testing: prospective comparison of dermatoscopic evaluation and naked eye examination

Pathergy phenomenon is a non-specific tissue hyperreactivity reaction due to trauma and is a minor diagnostic criterion of Behcet's disease. In this study, 100 patients with a suspicion of Behcet's disease who were referred to Cerrahpasa Medical Faculty Dermatology department between 01.11.2014 and 31.01.2015 are included. Skin pathergy tests were applied to all the patients and results were evaluated by two dermatologists separately at 48th hour, each with naked eye and with dermatoscopy. Test results were scored on a scale of 0-6. At the end of the study, score results of naked eye and dermatoscopy for doctor number 1 were statistically similar. Same results applied for doctor number 2. However, naked eye results of doctor number 1 and 2 for the same patients were significantly different from each other (p 0.0372) and with dermatoscopy examination this difference was eliminated (p > 0.05). This study revealed that naked eye evaluation of pathergy test results can yield different results among different interpreters. Use of dermatoscopy during the evaluation process decreases interobserver variation and subjectivity of the test.

Autoinflammatory Disorders: A Review and Update on Pathogenesis and Treatment

The autoinflammatory diseases comprise a broad spectrum of disorders characterized by unchecked activation of the innate immune system. Whereas aberrations in adaptive immunity have long been identified in 'autoimmune' disorders, the concept of 'autoinflammation' emerged relatively recently, first describing a group of clinical disorders characterized by spontaneous episodes of systemic inflammation without manifestations typical of autoimmune disorders. Improved knowledge of innate immune mechanisms, coupled with remarkable progress in genomics and an expanding number of clinical cases, has since led to an increasing number of disorders classified as autoinflammatory or containing an autoinflammatory component. Biologic therapies targeting specific components of the innate immune system have provided immense clinical benefit, and have further elucidated the role of innate immunity in autoinflammatory disorders. This article reviews the basic mechanisms of autoinflammation, followed by an update on the pathophysiology and treatment of the monogenic and multifactorial autoinflammatory diseases, and the common dermatologic conditions in which autoinflammation plays a major role.

Pulmonary type-2 innate lymphoid cells in paediatric severe asthma: phenotype and response to steroids

Children with severe therapy-resistant asthma (STRA) have poor control despite maximal treatment, while those with difficult asthma (DA) have poor control from failure to implement basic management, including adherence to therapy. Although recognised as clinically distinct, the airway molecular phenotype, including the role of innate lymphoid cells (ILCs) and their response to steroids in DA and STRA is unknown.Immunophenotyping of sputum and blood ILCs and T-cells from STRA, DA and non-asthmatic controls was undertaken. Leukocytes were analysed longitudinally pre- and post-intramuscular triamcinolone in children with STRA. Cultured ILCs were evaluated to assess steroid responsiveness in vitroAirway eosinophils, type 2 T-helper (Th2) cells and ILC2s were significantly higher in STRA patients compared to DA and disease controls, while IL-17+ lymphoid cells were similar. ILC2s and Th2 cells were significantly reduced in vivo following intramuscular triamcinolone and in vitro with steroids. Furthermore, asthma attacks and symptoms reduced after systemic steroids despite persistence of steroid-resistant IL-17+ cells and eosinophils.Paediatric STRA and DA have distinct airway molecular phenotypes with STRA characterised by elevated type-2 cells. Systemic corticosteroids, but not maintenance inhaled steroids resulted in improved symptom control and exacerbations concomitant with a reduction in functional ILC2s despite persistently elevated IL-17+ lymphoid cells.

A novel topical therapy for resistant and early peristomal pyoderma gangrenosum

Peristomal pyoderma gangrenosum (PPG) is an under-recognised and difficult condition to treat. We describe a case series using a novel topical combination therapy that promotes wound healing and allows for adhesion of the stoma appliance. A crushed oral prednisolone tablet mixed with Stomahesive Protective Powder (ConvaTec) was applied topically to seven patients with PPG and resulted in pain relief and wound healing in six of seven patients. Only one patient experienced recurrence. The novel topical therapy we describe is cost-effective, readily available, and easily applied in any inpatient or outpatient setting.

Inflammasome Regulates Hematopoiesis through Cleavage of the Master Erythroid Transcription Factor GATA1

Chronic inflammatory diseases are associated with altered hematopoiesis that could result in neutrophilia and anemia. Here we report that genetic or chemical manipulation of different inflammasome components altered the differentiation of hematopoietic stem and progenitor cells (HSPC) in zebrafish. Although the inflammasome was dispensable for the emergence of HSPC, it was intrinsically required for their myeloid differentiation. In addition, Gata1 transcript and protein amounts increased in inflammasome-deficient larvae, enforcing erythropoiesis and inhibiting myelopoiesis. This mechanism is evolutionarily conserved, since pharmacological inhibition of the inflammasome altered erythroid differentiation of human erythroleukemic K562 cells. In addition, caspase-1 inhibition rapidly upregulated GATA1 protein in mouse HSPC promoting their erythroid differentiation. Importantly, pharmacological inhibition of the inflammasome rescued zebrafish disease models of neutrophilic inflammation and anemia. These results indicate that the inflammasome plays a major role in the pathogenesis of neutrophilia and anemia of chronic diseases and reveal druggable targets for therapeutic interventions.

Idiopathic, Refractory Sweet's Syndrome Associated with Common Variable Immunodeficiency: a Case Report and Literature Review

PURPOSE OF REVIEW

Sweet's syndrome (SS) is classically considered a hypersensitivity reaction often associated with autoimmune disorders and malignancy. SS has also been increasingly reported to occur with immunodeficiencies. We present a case of treatment-refractory, systemic SS as the initial manifestation in a young child with common variable immunodeficiency (CVID). We also review current literature about SS and concurrent immunodeficiencies and autoimmunity in CVID patients.

RECENT FINDINGS

Few case reports exist regarding the co-occurrence of Sweet's syndrome and primary immunodeficiencies. SS is characterized by a pro-inflammatory state with a neutrophil predominance resulting in a spectrum of clinical manifestations. CVID is a multifactorial antibody deficiency that can be associated with autoimmunity, which some studies have proposed to be secondary to altered CD21 expression. SS occurring in patients with CVID has been infrequently reported, and one case study demonstrated improvement of Sweet's associated skin lesions with immunoglobulin replacement. In our case, the patient had multi-system SS refractory to multiple immunomodulatory therapies. To our knowledge, this is the first report of the effective and safe use of intravenous tocilizumab and oral lenalidomide to treat SS in a child with CVID. Immunoglobulin replacement reduced the frequency of infections and may have contributed to the opportunity to wean the immunosuppressive therapies for Sweet's syndrome. Sweet's syndrome as an initial manifestation of co-occurring immunodeficiencies is rare, and providers need a high index of suspicion. In addition, treatment of SS associated with an immunodeficiency can be a challenge. Treatment with immunoglobulin replacement reduces the frequency of infections, and in some patients with concurrent SS may improve skin lesions and reduce the need for immunomodulator therapy. Further study is necessary to better understand the pathogenesis of CVID in patients with SS and to identify possible biomarkers that predict who with SS are at risk for developing hypogammaglobulinemia.

Mechanisms of Inflammation in Neutrophil-Mediated Skin Diseases

Neutrophil-mediated skin diseases, originally named neutrophilic dermatoses (NDs), are a group of conditions due to an altered neutrophil recruitment and activation, characterized by polymorphic cutaneous manifestations with possible internal organ involvement. Although a number of diseases are included in this setting, the two prototypic forms are pyoderma gangrenosum (PG) and Sweet's syndrome (SS) which usually present with skin ulcers and plaque-type lesions, respectively. They have central features significantly overlapping with autoinflammatory conditions which manifest as repeated episodes of tissue inflammation. However, in contrast to appropriate inflammatory responses to insults or to autoimmune disease, there is an absence of identifiable pathogens, autoantibodies, or autoreactive lymphocytes. The recognition of monogenic autoinflammatory diseases which can present with NDs has led to study several genes involved in autoinflammation in NDs. Based on discovering of a number of mutations involving different autoinflammatory genes, neutrophil-mediated skin diseases are nowadays regarded as a spectrum of polygenic autoinflammatory conditions. Although disease mechanisms have not yet been completely elucidated, NDs are recognized as diseases involving dysfunctional cellular signaling mediated by pathways mainly related to inflammasome and IL-1 with the contributory role of IL-17 and other effector molecules. The precise elucidation of the above-mentioned pathologic mechanisms may pave the way to tailored treatments for patients with different neutrophil-mediated skin diseases.

Extracutaneous involvement of pyoderma gangrenosum

Pyoderma Gangrenosum (PG) is an inflammatory neutrophilic dermatosis (ND) associated with underlying chronic inflammation and/or malignancy. Diagnosis remains to be challenging as a gold standard diagnostic test is lacking. Initial manifestations may include papules, vesicles, or pustules that subsequently develop into ulceration with features of undermining and violaceous borders. Timely recognition of pyoderma gangrenosum is impeded by clinical findings shared with other etiologies, such as granulomatosis with polyangiitis, polyarteritis nodosa, and antiphospholipid syndrome. As with any other ND, extracutaneous involvement may also occur preceding, during, or following the appearance of skin lesions. Sterile neutrophilic infiltrates have been found to affect internal organs supporting the concept of PG being a systemic disease, with lung being the most common extracutaneous manifestation followed by ocular and visceral compromise. Therefore, in this review, we describe the current knowledge of extracutaneous involvement of PG and its respective clinical manifestations to aid dermatologists in diagnosis, management, and determining prognosis.

Paradoxical Skin Reactions to Biologics in Patients With Rheumatologic Disorders

Targeted immune-modulating treatment with biological agents has revolutionized the management of immune-mediated inflammatory diseases, including rheumatologic conditions. The efficacy and tolerability of biological agents, from the initial tumour necrosis factor (TNF)-α inhibitors to the new anti-cytokine monoclonal antibodies, have dramatically changed the natural history of debilitating conditions such as rheumatoid arthritis and seronegative spondyloarthropathies. The widening use of biologics across several rheumatologic diseases has been associated with a new class of adverse events, the so-called paradoxical reactions. These events are inflammatory immune-mediated tissue reactions, developing paradoxically during treatment of rheumatologic conditions with targeted biologics that are commonly used for treating the idiopathic counterparts of these drug-induced reactions. The skin is frequently involved, and, even if considered rare to uncommon, these cutaneous manifestations are an important cause of biologic agent discontinuation. TNF-α antagonist-induced psoriasis, which can manifest de novo or as exacerbation of a pre-existing form, is the prototypic and most frequent paradoxical skin reaction to biologics while other reactions, such as eczematous and lichenoid eruptions, hidradenitis suppurativa, pyoderma gangrenosum, Sweet’s syndrome and granulomatous skin diseases, occur much more rarely. Management of these reactions consists of topical or systemic skin-directed therapies, depending on the severity and extension of the cutaneous picture, and it is generally associated with switching over to other disease-modifying regimens for treating the underlying rheumatologic condition. Here, we review in detail the current concepts and controversies on classification, pathogenesis and clinical management of this new class of cutaneous adverse events induced by biologics in rheumatologic patients.

Post-surgical Thyroid Bed Pyoderma Gangrenosum Mimicking Recurrent Papillary Thyroid Carcinoma

Background: Pyoderma gangrenosum (PG) is a rare inflammatory disease presenting with chronic-recurrent cutaneous ulcers histopathologically hallmarked by neutrophilic infiltrates, which may occur more frequently at sites of surgical traumas. The disease is habitually limited to the skin, but it can virtually involve any organ. Nevertheless, no prior cases of PG involving the thyroid bed have ever been reported. Case Report: A bilateral PG of the breast was diagnosed in a 51-year-old woman and treated with intravenous methylprednisolone pulse-therapy and cyclosporine, with partial improvement. During the hospitalization, cytological examination of two hypoechoic thyroid nodules by fine-needle aspiration (FNA) was consistent with thyroid carcinoma. After total thyroidectomy, histopathology confirmed a papillary thyroid cancer (PTC), and radioactive iodine ablation was performed. At 12-month ultrasonographic follow-up, two hypoechoic avascular areas localized in the empty thyroid bed raised the suspect of PTC recurrence. However, (i) undetectable levels of thyroglobulin without anti-thyroglobulin antibodies, (ii) neutrophilia and increased inflammatory marker levels, and (iii) cytological examination of FNA showing numerous neutrophils induced to suspect thyroid bed PG infiltration. An ex juvantibus approach with high-dose methylprednisolone led to dimensional reduction of the hypoechoic areas on ultrasonography, thus confirming the hypothesis of thyroid bed PG. Conclusion: This case of thyroid bed PG supports the idea that PG reflects a cutaneous phenotype encompassed in the spectrum of systemic neutrophilic diseases. Endocrinologists should be aware that thyroid bed PG involvement is an albeit rare differential diagnosis to consider in patients who had undergone thyroid surgery, especially with a history of PG.

Erosive pustular dermatosis of the scalp: A neutrophilic folliculitis within the spectrum of neutrophilic dermatoses: A clinicopathologic study of 30 cases

BACKGROUND

It is general opinion that histopathology is nonspecific and of little value in diagnosing erosive pustular dermatosis of the scalp (EPDS).

OBJECTIVES

Clinicopathologic correlation of erosive pustular dermatosis of the scalp.

METHODS

We reviewed the clinical and pathologic records of patients with a clinicopathologic diagnosis of EPDS between 2011 and 2016 at the Dermatopathology Unit of Turin University.

RESULTS

Thirty elderly patients with EPDS were identified (22 men and 8 women). Androgenetic alopecia was present in 19 of 30 patients. Triggering factors included mechanical trauma in 10 of 30 cases, surgical procedures in 4 of 30 cases, and herpes zoster in 1 of 30 cases. Three patients were affected by autoimmune disorders. The vertex was the most common location. Disease presentation varied markedly from tiny, erosive, scaly lesions to crusted and hemorrhagic plaques, mimicking pustular pyoderma gangrenosum. The pathologic changes differed according to lesion type and disease duration. Interestingly, a spongiotic and suppurative infundibulo-folliculitis was observed in 8 of 30 cases.

LIMITATIONS

This was a retrospective study.

CONCLUSIONS

We believe that the primary lesion of erosive pustular dermatosis of the scalp is a spongiotic, pustular superficial folliculitis. The clinicopathologic similarities with other neutrophilic dermatoses, such as pustular pyoderma gangrenosum, suggest this condition should be included in this spectrum, where pathergy plays a pathogenetic role.

Two case reports of pyoderma gangrenosum and systemic lupus erythematosus: A rare but nonfortuitous association?

RATIONALE

Pyoderma gangrenosum (PG), like other neutrophilic dermatosis, may be associated with a variety of systemic disorders including inflammatory bowel diseases, rheumatoid arthritis, and hematologic disorders. Conversely, the association between PG and systemic lupus erythematosus (SLE) has rarely been reported.

PATIENT CONCERNS

We report here 2 cases of this association.

DIAGNOSES

The first case involves a 32-year-old woman who developed, 1 year after SLE diagnosis, 3 painful nodular lesions of PG on her face, and cervical area. The second case was observed in a 37-year-old woman referred for ulcerative nodular papules of PG on her legs, whereas she had been diagnosed with SLE 10 years before. SLE was inactive in the first case, whereas PG occurred during a lupus flare up in the second one.

INTERVENTIONS

We found 23 previous cases of SLE and PG in the literature with most cases (12/20) occurring during a lupus flare.

OUTCOMES

Although rare, this association may be supported by common innate immunity dysregulation and abnormal neutrophil activation.

LESSONS

PG and other neutrophilic diseases reported in patients with SLE may be added to the large clinical spectrum of cutaneous lesions observed in SLE.

Pyoderma gangrenosum-like ulcerations in granulomatosis with polyangiitis: two cases and literature review

Granulomatosis with polyangiitis (GPA) is a systemic necrotizing small vessel vasculitis associated with circulating anti-neutrophil cytoplasmic antibodies (ANCAs). Skin manifestations, mostly represented by palpable purpura, papulonodular lesions and livedo reticularis, are present in up to 50% of the cases. Ulcerations with undermined, raised erythematous-violaceous border resembling pyoderma gangrenosum (PG) have rarely been reported as skin involvement in GPA. The presence of circulating ANCAs with a cytoplasmic labelling pattern, the involvement of internal organs, particularly of the lung, and the absence on histology of a mainly neutrophilic infiltrate in early phases of the cutaneous lesions may be regarded as clues to rule out true PG and confirm the diagnosis of GPA skin ulcerations simulating PG. Herein, we describe two paradigmatic cases of such a unique presentation of GPA and a literature review focusing on clinicopathological features of GPA presenting with PG-like ulcerations in the skin has been provided. Moreover, referring to the scenario observed in these two cases, an easy-to-use working approach for the differential diagnosis between the two conditions has also been proposed.