Target antigens of the SSA/Ro and SSB/La system

The Potential Utility of Salivary and Tear Proteomics to Discriminate Sjögren's Disease from Non-Sjögren's Sicca

Sjögren's Disease (SjD) is an autoimmune disorder associated with decreased saliva and/or tear secretions, resulting in patients reporting dryness in the mouth and eyes. Serum autoantibodies directed against the Ro60/SS-A and La/SS-B autoantigens are a distinctive feature of the disease. Analysis of the saliva and tear proteomes represents one promising alternative method of both classifying and monitoring the condition, and research into salivary and tear proteomics in patients with SjD, with and without sicca, has shown its efficacy and practicality in both clinical and research settings. Studies analyzing the saliva proteomics of SjD patients have generally shown an overexpression of proteins involved in T-cell activation, the immune response, β-2 microglobulin, and the recruitment of pro-inflammatory agents. These studies also show a decrease in or downregulation of proteins involved in salivary secretion. Studies analyzing the tear proteomics of patients with SjD have generally indicated an upregulation of proteins involved with TNF-α signaling, B-cell survival, and the recruitment of pro-inflammatory agents. Studies also note the differential expression of tear protein folding as a hallmark of ocular involvement in this condition. These findings help to elucidate the biochemical relationship between the proteomes of saliva/tear fluids and the general pathophysiology of the gland involved with the pathogenesis of this condition, giving further credence to the potential role of salivary and tear proteomics in the future of diagnosis and treatment for patients with SjD.

Increased Autoantibodies Against Ro/SS-A, CENP-B, and La/SS-B in Patients With Kidney Allograft Antibody-mediated Rejection

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Antibody-mediated rejection (AMR) causes more than 50% of late kidney graft losses. In addition to anti-human leukocyte antigen (HLA) donor-specific antibodies, antibodies against non-HLA antigens are also linked to AMR. Identifying key non-HLA antibodies will improve our understanding of AMR.

Clinical associations of the positive anti Ro52 without Ro60 autoantibodies: undifferentiated connective tissue diseases

Aims

Autoantibodies targeting Ro52 and Ro60 antigens are historically reported as anti SSA/Ro. In general anti SSA/Ro results are either anti Ro52+Ro60+ or anti Ro52−Ro60+ antibodies. Anti Ro52 without anti Ro60 (Ro52+ Ro60−) antibodies are often not reported routinely. This study intends to review the potential significance of these autoantibodies in the management of connective tissue diseases.

Method

A retrospective survey of Ro52+Ro60− was carried out as part of the service evaluation of extractable nuclear antigen antibodies (ENA) reporting from the immunology laboratory, the NHS Greater Glasgow and Clyde (GGC), UK. The clinical documents and laboratory results of 97 patients with Ro52+Ro60− and 100 patients with Ro52+Ro60+ were reviewed.

Results

Seventy-one patients (73%) with anti Ro52+Ro60− antibodies have been diagnosed with autoimmune conditions including undifferentiated connective tissue diseases (n=14, 14%), systemic lupus erythematosus (n=10, 10%), Sjögren’s syndrome (n=10, 10%) and rheumatoid arthritis (n=13, 13%). Twenty-three patients (24%) with anti Ro52+Ro60− antibodies have no autoimmune features but were found to have significant clinical conditions including malignancies. In contrast, 87 patients (87%) with anti Ro52+Ro60+ antibodies have autoimmune conditions including Sjögren’s syndrome (n=34, 34%), systemic lupus erythematosus (SLE; n=23, 23%), undifferentiated connective tissue diseases (n=12, 12%) and rheumatoid arthritis (n=6, 6%).

Conclusion

Anti Ro52 without anti Ro60 (Ro52+Ro60−) antibodies should be reported. In the majority of patients these autoantibodies were associated with various autoimmune diseases. Anti Ro52+Ro60− antibodies were also found in patients with significant clinical conditions including malignancies even though there was no suggestion of autoimmunity at the time of testing.

mRNA knockdown by single strand RNA is improved by chemical modifications

While RNAi has traditionally relied on RNA duplexes, early evaluation of siRNAs demonstrated activity of the guide strand in the absence of the passenger strand. However, these single strands lacked the activity of duplex RNAs. Here, we report the systematic use of chemical modifications to optimize single-strand RNA (ssRNA)-mediated mRNA knockdown. We identify that 2′F ribose modifications coupled with 5′-end phosphorylation vastly improves ssRNA activity both in vitro and in vivo. The impact of specific chemical modifications on ssRNA activity implies an Ago-mediated mechanism but the hallmark mRNA cleavage sites were not observed which suggests ssRNA may operate through a mechanism beyond conventional Ago2 slicer activity. While currently less potent than duplex siRNAs, with additional chemical optimization and alternative routes of delivery, chemically modified ssRNAs could represent a powerful RNAi platform.

Effective siRNA delivery and target mRNA degradation using an amphipathic peptide to facilitate pH-dependent endosomal escape

Effective delivery of siRNA (small interfering RNA) into the cells requires the translocation of siRNA into the cytosol. One potential delivery strategy uses cell-delivery peptides that facilitate this step. In the present paper, we describe the characterization of an amphipathic peptide that mediates the uptake of non-covalently bound siRNA into cells and its subsequent release into the cytosol. Biophysical characterization of peptide and peptide/siRNA mixtures at neutral and lysosomal (acidic) pH suggested the formation of α-helical structure only in endosomes and lysosomes. Surprisingly, even though the peptide enhanced the uptake of siRNA into cells, no direct interaction between siRNA and peptide was observed at neutral pH by isothermal titration calorimetry. Importantly, we show that peptide-mediated siRNA uptake occurred through endocytosis and, by applying novel endosomal-escape assays and cell-fractionation techniques, we demonstrated a pH-dependent alteration in endosome and lysosome integrity and subsequent release of siRNA and other cargo into the cytosol. These results indicate a peptide-mediated siRNA delivery through a pH-dependent and conformation-specific interaction with cellular membranes and not with the cargo.

Evaluation of efficacy, biodistribution, and inflammation for a potent siRNA nanoparticle: effect of dexamethasone co-treatment

Despite recent progress, systemic delivery remains the major hurdle for development of safe and effective small inhibitory RNA (siRNA)-based therapeutics. Encapsulation of siRNA into liposomes is a promising option to overcome obstacles such as low stability in serum and inefficient internalization by target cells. However, a major liability of liposomes is the potential to induce an acute inflammatory response, thereby increasing the risk of numerous adverse effects. In this study, we characterized a liposomal siRNA delivery vehicle, LNP201, which is capable of silencing an mRNA target in mouse liver by over 80%. The biodistribution profile, efficacy after single and multiple doses, mechanism of action, and inflammatory toxicity are characterized for LNP201. Furthermore, we demonstrate that the glucocorticoid receptor (GR) agonist dexamethasone (Dex) inhibits LNP201-induced cytokine release, inflammatory gene induction, and mitogen-activated protein kinase (MAPK) phosphorylation in multiple tissues. These data present a possible clinical strategy for increasing the safety profile of siRNA-based drugs while maintaining the potency of gene silencing.

Direct and indirect immunofluorescence as a diagnostic adjunct in the interpretation of nonneoplastic medical lung disease

Fresh open lung biopsy material from 57 patients was incubated with fluoresceinated complement and immunoglobulin antisera. An indirect immunofluorescent assay using neonatal lung as substrate was conducted as well. Direct immunofluorescent patterns could be categorized into interalveolar septal capillary deposition, large vessel wall localization, alveolar basement membrane localization, or a pauci-immune immunofluorescence pattern. With respect to the septal capillary pattern, endothelial cell decoration was seen with scleroderma, mixed connective tissue disease, anti-Ro-associated lupus erythematosus, dermatomyositis, humoral allograft rejection, and patients with isolated pulmonary fibrosis in whom autoantibodies were established, including antiphospholipid antibodies. A similar pattern of endothelial cell staining was seen in these cases via the indirect assay. Granular mural septal capillary deposition was seen in the aforesaid settings along with rheumatoid factor-positive rheumatoid arthritis, type II cryofibrinogenemia, and mixed cryoglobulinemia and, in some cases, light microscopically corresponded to a neutrophilic capillaritis. Isolated vascular IgA corresponded with rheumatoid arthritis corresponding to IgA-specific antiendothelial cell antibodies, celiac disease-associated pulmonary hemorrhage, Schönlein-Henoch purpura and with IgA antiphospholipid antibodies. Alveolar wall deposition was seen with anti-glomerular basement membrane disease.

Cytokine-induced injury of the lacrimal and salivary glands

Damages to the lacrimal and salivary glands that accompany various autoimmune diseases are categorized as secondary Sjögren syndrome. Cytokines and free radicals are thought to be responsible for the pathologic changes, but the precise mechanisms are not clear. We evaluated whether cytokines alone can cause the damages in these exocrine tissues, and whether gaseous molecules such as nitric oxide (NO) play a role in these injuries. Various knockout (KO) mice as well as wild-type mice were injected intraperitoneally (i.p.) with the proinflammatory cytokines, IL-12 and IL-18, singly or in combination. Concurrent administration of IL-12 and IL-18 to mice caused serious atrophy in the lacrimal and salivary glands, which was spared when each cytokine was singly administered. Microscopically, there were apparently no infiltrating cells; nonetheless, numerous apoptotic cells were observed in the epithelium, which was confirmed by DNA ladder formation on gel electrophoresis. Serum levels of IFN-gamma and NO2/NO3 were markedly elevated. Combined injections of IL-12 and IL-18 caused the same changes in Fas-deficient and Fas-ligand deficient mice, as well as in perforin-KO mice, but the same changes were not detected in inducible NO synthase-KO mice or IFN-gamma KO mice. Thus, the synergistic effect of IL-12 and IL-18 was dependent on production of IFN-gamma and NO, but independent of Fas/Fas ligand system and perforin-dependent cytotoxic T cells. IL-18 together with IL-12 caused destructive changes in the glandular tissues without apparent lymphocyte infiltration. It is suggested that these cytokines can mediate apoptosis in glandular epithelial cells and that the elevated NO production is responsible for the change.

Role of HLA in congenital heart block: susceptibility alleles in mothers

In congenital heart block (CHB), abnormal maternal immunisation leads to autoantibody production against SS-A/Ro and SS-B/La antigens. These maternal antibodies are transferred across the placenta to the unborn child and are believed to transmit irreversible immunological injury in developing foetal heart tissue, thus causing 3rd-degree atrioventricular block. The mothers may suffer from systemic lupus erythematosus (SLE) or primary Sjögren's syndrome (SS), but they may be asymptomatic. Women with primary SS show a typical autoimmune HLA antigen pattern, namely higher frequency of HLA B8 and DR3 than in the normal population. The HLA pattern may affect individual ability to resist infecting bacteria and viruses and to response in various ways to autoantigens. It is probable that other factors such as genetic regulation of immune response are involved in CHB. We compared the HLA class I and class II alleles of mothers having CHB children with those of women suffering from primary SS and having healthy children, and with those of healthy Finns. Antibodies against 52-kD and 60-kD SS-A/Ro and 48-kD SS-B/La antigens were compared between the two groups of mothers. Our results show that anti-SS-A/Ro antibody-positive mothers all show a strong association with known autoimmune-predisposing HLA alleles, however, the mothers of CHB children differ in some HLA class I alleles, and especially in HLA haplotypes, from mothers of healthy children. Mothers with HLA A1, Cw7, B8 and without B15 are at particularly high-risk of having CHB children.