2k). 6 sulphate). A region of strong labelling for aggrecan, dermatan sulphate and chondroitin 6 sulphate immediately surrounded the Meibomian glands. The site of labelling corresponded to a layer of acellular and amorphous matrix seen histologically that we have termed the territorial matrix. The results suggested that this tarsal plate is a specialized connective tissue that is neither purely fibrous nor cartilaginous, yet has an aggrecan content that probably contributes to its stiffness. Its unique character highlights the challenge in choosing an ideal mechanical substitute. As patients with rheumatoid arthritis often have problems relating to tear film deficiency, the ability of aggrecan or COMP to act as autoantigens may be significant. An immune reaction directed against these molecules could alter tarsal gland function by interfering with the interaction between the glands and their territorial matrix. strong class=”kwd-title” Keywords: aggrecan, autoimmune response, extracellular matrix, glycosaminoglycans, proteoglycans, Meibomian glands Introduction The superior tarsus is usually a plate of tissue that stiffens the upper eyelid, gives it support and determines its form (Williams et al. 1995). Its curved shape enables it to maintain close contact with the globe during fast blinking movements. Embedded within the plate are the Meibomian (tarsal) glands. These produce an oily secretion that spreads as a surfactant over Rabbit Polyclonal to TNF Receptor I the globe and contributes to an aqueous barrier that remains functional after blinking (McCulley & Sparkle, 2004). The secretion reduces evaporation by adding a hydrophobic layer to the surface of the tear film (Williams et al. 1995; Lozato et al. 2001). It thus follows that any alteration in tarsal gland secretion will change the composition of the film and this could lead to a variety of symptoms including dry vision, keratonconjunctivitis sicca and even Aliskiren D6 Hydrochloride corneal ulcerations (Shimazaki et al. 1998; Jain et al. 2001). In exocrine glands elsewhere in the body, the connective tissue stroma around the glandular epithelium can modulate the activity of the secretory cells and changes in stromal composition can even be associated with disease (Bissell, 1998; Hagios et al. 1998; Goicovich et al. 2003). It is thus of interest to establish the character of the extracellular matrix (ECM) of the tarsal plate and in particular the ECM that immediately surrounds the Meibomian glands. We have subsequently referred to this ECM as the territorial matrix. The composition of the ECM also Aliskiren D6 Hydrochloride determines the Aliskiren D6 Hydrochloride physical properties of the tarsal plate. These properties are an important surgical concern in reconstructing the upper eyelids of patients with tarsal deficiencies (Jordan et al. 1990; Jordan & Anderson, 1997; Yaqub & Leatherbarrow, 1997; Mullner & Langmann, 1999; Kamiya & Kitajima, 2003). The substitute tissue needs to have a similar consistency to the tarsal plate itself and be grafted together with a mucosa that can functionally replace the conjunctiva and its underlying lamina propria. A mechanically stable, superior tarsus is also essential for the insertion of levator palpebrae superioris (Landolt, 1985). Among the graft tissues that have been most frequently used are various forms of cartilage Aliskiren D6 Hydrochloride C notably from the ear and nasal septum (Jordan et al. 1990; Kamiya & Kitajima, 2003). Mucoperiosteum from the hard palate and aortic wall tissue have also been used (Jordan & Anderson, 1997) and a material called chondroplast that is prepared from irradiated bovine cartilage (Mullner & Langmann, 1999). According to Ito et al. (2001), ear cartilage is too stiff, but fascia lata is not stiff enough. Yet the latter is usually a dense fibrous connective tissue C and this is also how the tarsal plate is commonly classified in modern anatomy texts (Williams et al. 1995). It is of interest, however, that there are several statements in the older histological literature that this plate is usually cartilage-like, fibrocartilaginous or that this eyelid contains lid cartilage (B?hm & von Davidoff, 1895; Szymonowicz, 1924; Wallraff, 1960). Such descriptions seem to be largely based on the mechanical properties of the tissue. The purpose of the present study is to promote a better understanding of the physical characteristics of the superior tarsal plate and its local association with the Meibomian glands. We have done this by analysing the immunohistochemical composition of the plate ECM. In order.
Monthly Archives: April 2023
To determine if endogenous TCR expression enhanced positive selection of CD4+ KRN T cells about I-Ab, we bred TCR/deficient KRN
To determine if endogenous TCR expression enhanced positive selection of CD4+ KRN T cells about I-Ab, we bred TCR/deficient KRN.H-2b mice. no apparent gene-dosage effect (data not demonstrated). The TCR/-deficient KRN.H-2b/g7 mice had a significant reduction in the frequency and complete quantity of CD4 SP thymocytes and CD4+ splenic T cells relative to mice able to express endogenous TCR and/or TCR chains, as well as a reduction in the level of arthritogenic PR52B anti-GPI IgG autoantibodies (Figure 3 and Supplemental Figure 1 (S1)). Open in a separate window Number 2 Both endogenous TCR and TCR chains can facilitate spontaneous autoimmune arthritis(A) Arthritis development expressed as ankle thickening over time in mice of ELQ-300 the indicated genotypes (all KRN.H-2b/g7). The + denotes the endogenous and alleles are present either in heterozygosity or homozygosity; ? denotes homozygosity of the knockout allele. Each collection represents one mouse (= 5C6 mice per group). (B) Representative ankle sections from 8-week-old mice of the indicated genotypes. H&E staining; level bar in remaining panel represents 500 microns and all images are at the same magnification. Open in a separate window Number 3 Endogenous TCR/ manifestation allows autoreactive CD4+ T cells to escape clonal deletionFlow cytometry of thymocytes (top) and CD3+ splenocytes (bottom) from mice of the indicated genotypes (all KRN.H-2b/g7) and stained with anti-CD4 and anti-CD8 monoclonal antibodies. Figures show the percentage of cells in each of the boxed gates. The plots are representative of 6 experiments with a total of 5C6 mice/group. The mice were 8C10 weeks of age. Because the development of arthritis with this model depends on autoantibody production, we wanted to verify that the lack of arthritis development in the TCR/-deficient KRN.H-2b/g7 mice was not due to an unanticipated B cell defect. Adoptive transfer of CD4+ splenic T cells from KRN.H-2b mice to the TCR/-deficient KRN.H-2b/g7 mice provoked the quick onset of arthritis (Supplemental Table I), demonstrating the failure of the TCR/-deficient KRN.H-2b/g7 mice to develop arthritis was because of the lack of CD4+ KRN T cells. Taken together, these findings show that incomplete TCR (or TCR) allelic exclusion facilitates the thymic maturation of CD4+ T cells expressing the autoreactive KRN TCR, allowing ELQ-300 them to provoke autoantibody-mediated arthritis. Dual TCR manifestation is readily recognized among CD4 SP thymocytes To determine how dual TCR manifestation enhances thymic maturation of autoreactive KRN T cells, we performed further analyses to determine at what stage of T cell differentiation dual TCR manifestation was first detectable. Manifestation of endogenously-encoded TCR and TCR chains was readily recognized among CD4+ splenic T cells (Supplemental Number 2) and CD4 SP thymocytes (Supplemental Number 3). Among splenocytes, the rate of recurrence of cells expressing dual TCR chains was higher in mice lacking endogenous TCR chains relative to the endogenous TCR/-adequate mice ELQ-300 (34.7% versus 18.3%); similarly the rate of recurrence of cells expressing dual TCR chains was higher in mice lacking endogenous TCR chains relative to the endogenous TCR/-adequate mice (41.7% versus 32.4%), further demonstrating that allelic inclusion can occur readily in the KRN system. Cells co-expressing an endogenously-encoded TCR chain plus an endogenously-encoded TCR chain in addition to the KRN-encoded TCR chain were detectable, but not common. Manifestation of dual TCR chains was associated with decreased manifestation of the KRN transgene-encoded V6 ELQ-300 chain in the presence of I-Ag7 (Numbers 1, S2) (23). ELQ-300 We did not detect significant endogenous TCR or TCR manifestation at the earlier CD4+ CD8+ double-positive (DP) and CD4? CD8? double-negative (DN) phases of thymic development (Number S4 and data not shown). The simplest interpretation of these findings is definitely that dual TCR manifestation is rare through the DP stage, but that dual TCR-expressing DP thymocytes.