Ultrastructure of myoepithelial cells as a target cell in sialoadenitis of submandibular glands of lupus-prone female NZBxNZWF1 mice

A closer look into the cellular and molecular biology of myoepithelial cells across various exocrine glands

Myoepithelial cells (MECs) are a unique subset of epithelial cells that possess several smooth muscle cell characteristics, such as a high number of actin-myosin filaments and the ability to contract. These cells are primarily located around the secretory cells of exocrine glands, including the salivary, mammary, lacrimal, and sweat glands. Their primary functions involve the construction of the basement membrane and help with secretion of gland products through contraction. So far, no comparative analysis of MECs in different exocrine glands had ever evaluated their differences. In this review, we took advantage of the various publicly available scRNAseq data from mouse exocrine glands to identify their shared and unique characteristics. The aim of this review is to compare the role of MECs in maintaining healthy glandular function, their involvement in disease states, and their regenerative capacity, with a particular emphasis on the latest research findings in these areas.

The Autoimmune Rheumatic Disease Related Dry Eye and Its Association with Retinopathy

Dry eye disease is a chronic disease of the ocular surface characterized by abnormal tear film composition, tear film instability, and ocular surface inflammation, affecting 5% to 50% of the population worldwide. Autoimmune rheumatic diseases (ARDs) are systemic disorders with multi-organ involvement, including the eye, and play a significant role in dry eye. To date, most studies have focused on Sjögren's syndrome (one of the ARDs) since it manifests as two of the most common symptoms-dry eyes and a dry mouth-and attracts physicians to explore the relationship between dry eye and ARDs. Many patients complained of dry eye related symptoms before they were diagnosed with ARDs, and ocular surface malaise is a sensitive indicator of the severity of ARDs. In addition, ARD related dry eye is also associated with some retinal diseases directly or indirectly, which are described in this review. This review also summarizes the incidence, epidemiological characteristics, pathogenesis, and accompanying ocular lesions of ARD's related dry eye, emphasizing the potential role of dry eye in recognition and monitoring among ARDs patients.

The NZB/W F1 mouse model for Sjögren's syndrome: A historical perspective and lessons learned

Sjögren's syndrome (SS) is a chronic rheumatic autoimmune disorder affecting multiple organ systems. The clinical findings in SS patients show considerable heterogeneity and overlap with other autoimmune diseases. In addition, the autoimmune response in SS initiates several years before the appearance of clinical symptoms. Thus, understanding the pathogenic mechanisms involved in the disease process have been a challenge. Several animal model systems of SS-like disease have been developed to overcome these issues. The New Zealand Black (NZB) x New Zealand White (NZW) F1 (NZB/W F1) mouse represents the first spontaneous mouse model of SS. In this review, we provide a historical perspective and detailed description of this mouse model focusing on exocrine gland histopathology, autoantibody populations, and glandular dysfunction. Considering that NZB/W F1 mice also develop a systemic lupus erythematosus (SLE)-like disease, this mouse model mimics the clinical presentation of polyautoimmunity seen in a sizable subset of SS patients. It is plausible that such patients will require distinct therapeutic interventions necessary to treat both SLE and SS. Therefore, the NZB/W F1 mouse is a powerful tool to decipher pathogenic mechanisms involved in SS related polyautoimmunity and develop appropriate therapeutic strategies.

Myoepithelial cell-driven acini contraction in response to oxytocin receptor stimulation is impaired in lacrimal glands of Sjögren's syndrome animal models

The purpose of the present studies was to investigate the impact of chronic inflammation of the lacrimal gland, as occurs in Sjögren’s syndrome, on the morphology and function of myoepithelial cells (MECs). In spite of the importance of MECs for lacrimal gland function, the effect of inflammation on MECs has not been well defined. We studied changes in MEC structure and function in two animal models of aqueous deficient dry eye, NOD and MRL/lpr mice. We found a statistically significant reduction in the size of MECs in diseased compared to control lacrimal glands. We also found that oxytocin receptor was highly expressed in MECs of mouse and human lacrimal glands and that its expression was strongly reduced in diseased glands. Furthermore, we found a significant decrease in the amount of two MEC contractile proteins, α-smooth muscle actin (SMA) and calponin. Finally, oxytocin-mediated contraction was impaired in lacrimal gland acini from diseased glands. We conclude that chronic inflammation of the lacrimal gland leads to a substantial thinning of MECs, down-regulation of contractile proteins and oxytocin receptor expression, and therefore impaired acini contraction. This is the first study highlighting the role of oxytocin mediated MEC contraction on lacrimal gland function.

Destruction of salivary and lacrimal glands by Th1-polarized reaction in a model of secondary Sjögren's syndrome in lupus-prone female NZB × NZWF(1) mice

T helper (Th)1/Th2 balance determines the direction of some kinds of autoimmune diseases. The involvement of acini areas by CD4(+) helper T(Th) cell subset in submandibular and lacrimal glands are largely unknown in secondary Sjögren's syndrome (sSjS) with systemic lupus erythematosus (SLE). Submandibular and lacrimal glands were examined immunopathologically in lupus-prone female NZB × NZW(B/W)F(1) mice, model for human sSjS with SLE. Dacryoadenitis and sialoadenitis with renal failure developed with age. Infiltration of lymphoid cells (lymphocytes and plasma cells) expanded from the periductal areas in striated ducts to the acini, and the isolated foci in the acini were observed in those organs. The destruction of duct and acini epithelium, including the myoepithelium, was induced by interferon (IFN)-γ(+) and IgG2a(+) lymphoid cells, but not by interleukin(IL)-4(+), IL-5(+), IL-13(+), and IgG1(+) lymphoid cells. Compared with IL-5 and IL-13, high values of IFN-γ were produced systemically at various ages. Also local expression of IFN-γ mRNA was higher than that of IL-4 mRNA. The result suggests that the acini destruction in submandibular and lacrimal glands may be induced by systemic and local Th1 cell dominant reactions in lupus-prone B/WF(1) mice with sSjS.

Dysfunction of lacrimal and salivary glands in Sjögren's syndrome: nonimmunologic injury in preinflammatory phase and mouse model

Sjögren's syndrome (SjS) is a chronic autoimmune disorder characterized by dry eyes and dry mouth due to dacryoadenitis and sialoadenitis with SS-A/Ro and/or SS-B/La autoantibodies in genetically predisposed individuals. Destruction of lacrimal and salivary glands by autoimmune reactions may lead to clinical manifestation. However, the mechanisms behind the decreased volume of secretions in tears and saliva are complex and are not fully understood. Exocrine gland dysfunction may precede autoimmunity (acquired immunity) or represent a process independent from inflammation in the pathogenesis of SjS. The preceded functional and morphologic changes of those tissues by nonimmunologic injury before the development of inflammation at the sites of target organs have been implicated. This paper focuses on the several factors and components relating to glandular dysfunction and morphologic changes by nonimmunologic injury during the preinflammatory phase in mouse model, including the factors which link between innate immunity and adaptive immunity.

Therapeutic strategies for SLE involving cytokines: mechanism-oriented therapies especially IFN-gamma targeting gene therapy

Systemic lupus erythematosus (SLE: lupus) is a chronic complicated autoimmune disease and pathogenesis is still unclear. However, key cytokines have been recognized. Interferon (IFN)-γ and also IFNalpha/beta are of particular importance. Depending on the concept that lupus is a helper T(Th)1 disease and that dendritic cells (DCs) determine the direction of lupus, balance shift of Th1/Th2 and immunogenic/tolerogenic DCs is reviewed for therapy. (IFN)-gamma- and IFN-alpha/beta-targeted (gene) therapies are introduced. These consist of Th1/Th2 balance shift and elimination of IFN-gamma and IFN-gamma-related cytokines such as (interleukin)IL-12 and IL-18. Other approaches include suppression of immunocompetent cells, normalization of abnormal T-cell function, costimulation blockade, B lymphocyte stimulator (Blys) blockade, and suppression of nephritic kidney inflammation. Moreover, balance shift of IFN-alpha/beta and tumor necrosis factor (TNF)-alpha together with regulatory T(Treg) cells are briefly introduced. Clinical application will be discussed.

Systemic treatment of anti-CD4CD25 T cell monoclonal antibody exacerbates sialoadenitis in submandibular glands during the early life in lupus-prone female NZB x NZWF mice

BACKGROUND

The maintenance mechanisms of peripheral tolerance by CD4(+)CD25(+) T cells before the development of sialoadenitis in secondary Sjögren's syndrome (sSS) are not well understood. The aim of the present study is to examine the effect of reduction of CD4(+)CD25(+) T cells on the development of sialoadenitis during the early life in female NZB x NZWF(1) (B/WF(1)) mice, a model for human sSS.

METHODS

Female B/WF(1) mice at 3 days after birth were treated with either anti-mouse CD4(+)CD25(+) T cells rat IgG(1) monoclonal antibody (mAb) or Rat IgG(1)(control). At 25 weeks of age, autoantibodies against nucleus and cytoplasm of ductal epithelial and myoepithelial cells, and histpathology of submandibular glands were examined in the mAb-treated and control groups. Also the development of anti-Ro/SS-A antibodies was examined until 25 weeks of age in both groups.

RESULTS

The mAb-treated group showed severe lesions with the development of autoantibodies compared to the control group.

CONCLUSIONS

The present results suggest that peripheral CD4(+)CD25(+) T cells may, at least in part, contribute to down-regulate the development of sialoadenitis in submandibular glands of lupus-prone female B/WF(1) mice during their early life.