Optineurin deficiency impairs autophagy to cause interferon beta overproduction and increased survival of mice following viral infection.

BACKGROUND: Optineurin (OPTN) is associated with several human diseases, including amyotrophic lateral sclerosis (ALS), and is involved in various cellular processes, including autophagy. Optineurin regulates the expression of interferon beta (IFNß), which plays a central role in the innate immune response to viral infection. However, the role of optineurin in response to viral infection has not been fully clarified. It is known that optineurin-deficient cells produce more IFNß than wild-type cells following viral infection. In this study, we investigate the reasons for, and effects of, IFNß overproduction during optineurin deficiency both in vitro and in vivo. METHODS: To investigate the mechanism of IFNß overproduction, viral nucleic acids in infected cells were quantified by RT-qPCR and the autophagic activity of optineurin-deficient cells was determined to understand the basis for the intracellular accumulation of viral nucleic acids. Moreover, viral infection experiments using optineurin-disrupted (Optn-KO) animals were performed with several viruses. RESULTS: IFNß overproduction following viral infection was observed not only in several types of optineurin-deficient cell lines but also in Optn-KO mice and human ALS patient cells carrying mutations in OPTN. IFNß overproduction in Optn-KO cells was revealed to be caused by excessive accumulation of viral nucleic acids, which was a consequence of reduced autophagic activity caused by the loss of optineurin. Additionally, IFNß overproduction in Optn-KO mice suppressed viral proliferation, resulting in increased mouse survival following viral challenge. CONCLUSION: Our findings indicate that the combination of optineurin deficiency and viral infection leads to IFNß overproduction in vitro and in vivo. The effects of optineurin deficiency are elicited by viral infection, therefore, viral infection may be implicated in the development of optineurin-related diseases.

Staphylococcus aureus in atopic dermatitis: Strain-specific cell wall proteins and skin immunity.

Atopic dermatitis (AD) is a common chronic skin disease. The presence of the bacterium Staphylococcus aureus (S. aureus) is frequently detected on skin affected with AD. In this review, we focused on the characteristics of S. aureus strains isolated from AD skin, particularly the proteins on the cell surface that modulates the interactions between Langerhans cell, keratinocyte, and S. aureus. The skin microbiome plays an important role in maintaining homeostasis of the skin, and colonization of S. aureus in AD is considered to be deeply involved in the clinical manifestation and pathogenesis of skin flares. Colonizing S. aureus strains in AD harbor different surface proteins at the strain level, which are indicated as clonal complexes. Moreover, the cell wall proteins of S. aureus affect skin adhesion and induce altered immune responses. S. aureus from AD skin (AD strain) exhibits internalization into keratinocytes and induces imbalanced Th1/Th2 adaptive immune responses via Langerhans cells. AD strain-derived cell wall proteins and secreted virulence factors are expected to represent therapeutic targets. In addition, the microbiome on the AD skin surface is associated with skin immunity; thus, microbiome-based immunotherapy, whose mechanism of action completely differs from that of typical steroid ointments, are expected to be developed in the future.

Staphylococcus aureus from atopic dermatitis skin accumulates in the lysosomes of keratinocytes with induction of IL-1α secretion via TLR9.

BACKGROUND: Staphylococcus aureus (S. aureus) is frequently detected in the skin of patients with atopic dermatitis (AD), and involved in the flare of AD. There are some evidence-specific strains of S. aureus affect the severity of AD. However, the mechanism of predominant colonization and the aggravation of dermatitis by certain strains of S. aureus in the patients with AD are still unknown. OBJECTIVE: To reveal the characteristics of S. aureus from patients with AD (S. aureus-AD), we analyzed the interaction of S. aureus-AD and keratinocytes in comparison with those of S. aureus laboratory strains (S. aureus-stand.). METHODS: We stimulated HaCaT cells, keratinocyte cell line, and human epidermal keratinocytes by heat-killed S. aureus strains, then evaluated immune response of keratinocytes by ELISA, immunofluorescence staining, and flow cytometry. RESULTS: Upon incubation with keratinocytes, three out of four strains of heat-killed S. aureus-AD were strongly agglutinated inside the cytoplasm. In the cells, they are located in lysosomes and promoted the secretion of interleukin-1α (IL-1α). These reactions were not observed by any of four strains of S. aureus-stand. and S. epidermidis and were abolished by the treatment of S. aureus with proteinase K. Moreover, the IL-1α secretion was diminished by the inhibition of Toll-like receptor 9 (TLR9). CONCLUSION: S. aureus-AD accumulates in lysosome of keratinocytes by means of bacterial cell wall proteins and induces IL-1α via TLR9.

Staphylococcus aureus from atopic dermatitis skin alters cytokine production triggered by monocyte-derived Langerhans cell.

BACKGROUND: Atopic dermatitis (AD) is one of the most common chronic inflammatory skin diseases. The skin of patients with AD presents as a disbalance of the microbiome with a strong colonization by Staphylococcus aureus, which positively correlates with the severity of the disease. However, the effect of colonized S. aureus on the skin immune system has not been fully elucidated. OBJECTIVE: The aim of this study is to explore whether S. aureus isolated from AD skin is able to skew T cell responses via Langerhans cells (LC) as compared to a standard strain of S. aureus and S. epidermidis. METHODS: We prepared monocyte-derived LC (MoLC) from healthy controls and patients with AD, and stimulated MoLC with a standard strain of S. aureus NCTC8325, S. aureus TF3378 isolated from AD skin, or S. epidermidis. Stimulated MoLC were co-cultured with autologous CD4pos T cells and then T cell responses were analyzed by T cell polarization assays, cytokine analysis and real-time PCR. RESULTS: MoLC stimulated by S. aureus TF3378 induced significantly high and rapid proliferation of T cells as compared to those by S. aureus NCTC8325 and S. epidermidis. Cytokine productions from T cells cultured with S. aureus TF3378-stimulated MoLC showed significantly high amounts of IL-2 and less IFN-γ production with imbalanced Th1/Th2 (decreased TBX21/GATA3 ratio) mRNA expression. The T cell proliferation with increased IL-2 production via S. aureus TF3378-stimulated MoLC was diminished by treatment of proteinase K. CONCLUSION: S. aureus TF3378 on AD skin can skew T cell responses via LC toward imbalanced Th1/Th2 skin immunity.