Inflammatory and Immune-Mediated Cutaneous Diseases

Loss of Interleukin-6 Influences Transcriptional Immune Signatures and Alters Bacterial Colonization in the Skin

The skin functions as a protective barrier to inhibit the entry of foreign pathogens, all the while hosting a diverse milieu of microorganisms. Over time, skin cells, immune cells, cytokines, and microbes interact to integrate the processes of maintaining the skin's physical and immune barrier. In the present study, the basal expression of two immunologically divergent mouse strains C57BL/6 and BALB/c, as well as a strain on the C57 background lacking IL-6, was characterized. Additionally, cutaneous antimicrobial gene expression profiles and skin bacterial microbiome were assessed between strains. Total RNA sequencing was performed on untreated C57BL/6 (control), BALB/c, and IL-6-deficient skin samples and found over 3,400 genes differentially modulated between strains. It was found that each strain modulated its own transcriptional "profile" associated with skin homeostasis and also influenced the overall bacterial colonization as indicated by the differential phyla present on each strain. Together, these data not only provide a comprehensive view of the transcriptional changes in homeostatic skin of different mouse strains but also highlight the possible influence of the strain differences (e.g., Th1/Th2 balance) as well as a role for IL-6 in overall skin immunity and resident microbial populations.

Clinical characteristics and predictive factors of erythema nodosum in granulomatous lobular mastitis

BACKGROUND/OBJECTIVES

In recent years, there is a growing incidence of granulomatous lobular mastitis (GLM), but studies about the coexistence of erythema nodosum (EN) and GLM are rare. In this study, we assess the clinical characteristics and predictive factors of EN in GLM.

METHODS

A total of 303 patients diagnosed with GLM were enrolled from January 2012 to October 2018 at the second affiliated Hospital of Guangzhou University of Traditional Chinese Medicine, including 78 patients with EN. Follow-up data included: lesion site, lesion size, therapy approaches, course of GLM, course of EN, the recurrence of disease, possible causes. All patients had pathologic confirmation of GLM based on core needle biopsy (CNB) or surgical excision.

RESULT

Fever in the EN group was significantly more common compared to the non-EN group (44.87% vs 12.89%, P < 0.001). The proportion of lesion range >2 quadrants in the EN group was significantly higher than that in the non-EN group (42.31% vs 16.00%, P < 0.001). The course of the disease was longer in the EN group compared to the non-EN group (10.32 moths vs 8.74 moths, P < 0.001). Patients with EN had a trend towards a higher risk of recurrence (5.13% vs 1.33%, P = 0.055).

CONCLUSION

EN is more likely to be found in GLM patients with breast lesion range >2 quadrants. The presence of EN in GLM indicates that the condition becomes more severe and the course of GLM also becomes longer.

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.

Functional aspects, phenotypic heterogeneity, and tissue immune response of macrophages in infectious diseases

Macrophages are a functionally heterogeneous group of cells with specialized functions depending not only on their subgroup but also on the function of the organ or tissue in which the cells are located. The concept of macrophage phenotypic heterogeneity has been investigated since the 1980s, and more recent studies have identified a diverse spectrum of phenotypic subpopulations. Several types of macrophages play a central role in the response to infectious agents and, along with other components of the immune system, determine the clinical outcome of major infectious diseases. Here, we review the functions of various macrophage phenotypic subpopulations, the concept of macrophage polarization, and the influence of these cells on the evolution of infections. In addition, we emphasize their role in the immune response in vivo and in situ, as well as the molecular effectors and signaling mechanisms used by these cells. Furthermore, we highlight the mechanisms of immune evasion triggered by infectious agents to counter the actions of macrophages and their consequences. Our aim here is to provide an overview of the role of macrophages in the pathogenesis of critical transmissible diseases and discuss how elucidation of this relationship could enhance our understanding of the host-pathogen association in organ-specific immune responses.

The impact of lifestyle factors on evolution of atopic dermatitis: An alternative approach

Atopic dermatitis (AD) is a multifactorial chronic inflammatory disease with an incompletely understood etiopathogenesis. With a significant impact on the quality of life of patients, AD has attracted the interest of many research studies aiming to investigate the complex cellular and molecular mechanisms and to identify new therapeutic pathways. Various studies have focused on psycho-immunology, emphasizing the involvement of stress, defined as a general response of the body to external or internal challenges to the AD pathology. Factors like lifestyle and leisure activities may change the behavior of immune cells in AD with a strong impact on the evolution of the disease. Moreover, the poor adherence of AD patient to standard treatment approach has led to the necessity to combine different therapies in the field of complementary and alternative medicine. Although there are still not enough data to conclude that adjuvant therapies are effective in a conventional sense, there are already promising results suggesting that alternative therapeutic strategies could be a main subject of further research.

The inflammasome in leprosy skin lesions: an immunohistochemical evaluation

Objective

Leprosy is a chronic infectious disease presenting with a spectrum of clinical manifestations that correspond to the type of immune response that develops in the host. Factors that may be involved in this process include inflammasomes, cytosolic proteins responsible for the activation of caspase 1, IL-1β and IL-18 secretion, and induction of a type of death called pyroptosis.

Patients and methods

We evaluated the expression of inflammasome markers (nucleotide-binding oligomerization domain-like receptor containing pyrin domain 1 [NLRP1], nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 [NLRP3], caspase 1, IL-1β, and IL-18) by immunohistochemistry in 43 samples of skin lesions of leprosy patients from the groups indeterminate (I) leprosy (13 patients), tuberculoid (TT) leprosy (15 patients), and lepromatous leprosy (LL; 15 patients).

Results

The evaluated markers were most upregulated in LL lesions, followed by lesions of TT leprosy and I leprosy. Differences were statistically significant between the I leprosy and LL leprosy forms and between the I leprosy and TT leprosy forms. Positive and significant correlations were found between IL-18 and caspase 1 in LL (r=0.7516, P=0.0012) and TT leprosy (r=0.7366, P=0.0017). In I leprosy, correlations were detected between caspase 1 and IL-1β (r=0.6412, P=0.0182), NLRP1 and IL-18 (r=0.5585, P=0.473), NLRP3 and IL-18 (r=0.6873, P=0.0094), and NLRP1 and NLRP3 (r=0.8040, P=0.0009).

Conclusion

The expression of inflammasome markers in LL lesions indicates the ineffectiveness of this protein complex in controlling the infection. Caspase 1 may be involved in the pyroptotic cell death in the lepromatous form of the disease. Inflammasomes may act together in the initial phase of I leprosy; this phenomenon may influence the clinical outcome of the disease.