Xanthogranulomatous keratitis in a mixed-breed dog

OBJECTIVE

To evaluate the clinical and histopathological features of a case of xanthogranulomatous keratitis in a mixed-breed dog.

ANIMAL

Mixed-breed dog.

CLINICAL PRESENTATION, PROGRESSION, AND PROCEDURES

An 11-year-old spayed female mixed-breed dog was presented for mild blepharospasm, corneal cloudiness, and increasing conjunctival hyperemia OD. Ophthalmic examination revealed multifocal pink and cream-colored consolidated corneal infiltrative lesions and generalized neovascularization with suspected diagnosis of stromal abscessation. There was no improvement after 1 month of medical management, so a keratectomy was performed, and corneal tissue was sent for histopathological evaluation.

TREATMENT AND OUTCOME

The nonulcerative keratitis was refractive to medical management including topical and systemic antibiotics, topical antifungal, and systemic anti-inflammatory, so keratectomy was performed. Histopathologic diagnosis of xanthogranulomatous keratitis was made 1 week postoperatively. The patient was prescribed 0.05% difluprednate ophthalmic emulsion and 0.2% tacrolimus ophthalmic ointment (initially q 8 h, OD). The difluprednate was tapered and discontinued after 2 months, but the tacrolimus was continued (q 12 h, OD). No lesion recurrence had been documented 1 year postoperatively.

CLINICAL RELEVANCE

There has been little published on canine xanthogranulomas, especially in veterinary ophthalmology. Ocular xanthogranulomas have been reportedly found intraocularly and at the ocular surface. Histologically, they are characterized by well-delineated nodules that contain histiocytes and abundant lipid-laden macrophages. The treatment in this clinical case was surgical excision followed with topical immunosuppression/anti-inflammatory therapy with no recurrence 1 year postoperatively. Xanthogranulomatous keratitis should be an added differential diagnosis when nonulcerative keratitis is found on examination, specifically with consolidated, corneal infiltrate and minimal pain.

TCDD and CH223191 Alter T Cell Balance but Fail to Induce Anti-Inflammatory Response in Adult Lupus Mice

Aryl hydrocarbon receptor (AhR) responds to endogenous and exogenous ligands as a cytosolic receptor, transcription factor, and E3 ubiquitin ligase. Several studies support an anti-inflammatory effect of AhR activation. However, exposure to the AhR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during early stages of development results in an autoimmune phenotype and exacerbates lupus. The effects of TCDD on lupus in adults with pre-existing autoimmunity have not been described. We present novel evidence that AhR stimulation by TCDD alters T cell responses but fails to impact lupus-like disease using an adult mouse model. Interestingly, AhR antagonist CH223191 also changed T cell balance in our model. We next developed a conceptual framework for identifying cellular and molecular factors that contribute to physiological outcomes in lupus and created models that describe cytokine dynamics that were fed into a system of differential equations to predict the kinetics of T follicular helper (Tfh) and regulatory T (Treg) cell populations. The model predicted that Tfh cells expanded to larger values following TCDD exposure compared with vehicle and CH223191. Following the initial elevation, both Tfh and Treg cell populations continuously decayed over time. A function based on the ratio of predicted Treg/Tfh cells showed that Treg cells exceed Tfh cells in all groups, with TCDD and CH223191 showing lower Treg/Tfh cell ratios than the vehicle and that the ratio is relatively constant over time. We conclude that AhR ligands did not induce an anti-inflammatory response to attenuate autoimmunity in adult lupus mice. This study challenges the dogma that TCDD supports an immunosuppressive phenotype.

Tlr5 deficiency exacerbates lupus-like disease in the MRL/lpr mouse model

Introduction

Leaky gut has been linked to autoimmune disorders including lupus. We previously reported upregulation of anti-flagellin antibodies in the blood of lupus patients and lupus-prone mice, which led to our hypothesis that a leaky gut drives lupus through bacterial flagellin-mediated activation of toll-like receptor 5 (TLR5).

Methods

We created MRL/lpr mice with global Tlr5 deletion through CRISPR/Cas9 and investigated lupus-like disease in these mice.

Result

Contrary to our hypothesis that the deletion of Tlr5 would attenuate lupus, our results showed exacerbation of lupus with Tlr5 deficiency in female MRL/lpr mice. Remarkably higher levels of proteinuria were observed in Tlr5 -/- MRL/lpr mice suggesting aggravated glomerulonephritis. Histopathological analysis confirmed this result, and Tlr5 deletion significantly increased the deposition of IgG and complement C3 in the glomeruli. In addition, Tlr5 deficiency significantly increased renal infiltration of Th17 and activated cDC1 cells. Splenomegaly and lymphadenopathy were also aggravated in Tlr5-/- MRL/lpr mice suggesting impact on lymphoproliferation. In the spleen, significant decreased frequencies of regulatory lymphocytes and increased germinal centers were observed with Tlr5 deletion. Notably, Tlr5 deficiency did not change host metabolism or the existing leaky gut; however, it significantly reshaped the fecal microbiota.

Conclusion

Global deletion of Tlr5 exacerbates lupus-like disease in MRL/lpr mice. Future studies will elucidate the underlying mechanisms by which Tlr5 deficiency modulates host-microbiota interactions to exacerbate lupus.

A double-edged sword: interactions of CX3CL1/CX3CR1 and gut microbiota in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a systemic chronic disease initiated by an abnormal immune response to self and can affect multiple organs. SLE is characterized by the production of autoantibodies and the deposition of immune complexes. In regard to the clinical observations assessed by rheumatologists, several chemokines and cytokines also contribute to disease progression. One such chemokine and adhesion molecule is CX3CL1 (otherwise known as fractalkine). CX3CL1 is involved in cell trafficking and inflammation through recognition by its receptor, CX3CR1. The CX3CL1 protein consists of a chemokine domain and a mucin-like stalk that allows it to function both as a chemoattractant and as an adhesion molecule. In inflammation and specifically lupus, the literature displays contradictory evidence for the functions of CX3CL1/CX3CR1 interactions. In addition, the gut microbiota has been shown to play an important role in the pathogenesis of SLE. This review highlights current studies that illustrate the interactions of the gut microbiota and CX3CR1 in SLE.

Egr2 Deletion in Autoimmune-Prone C57BL6/lpr Mice Suppresses the Expression of Methylation-Sensitive Dlk1-Dio3 Cluster MicroRNAs

We previously demonstrated that the upregulation of microRNAs (miRNAs) at the genomic imprinted Dlk1-Dio3 locus in murine lupus is correlated with global DNA hypomethylation. We now report that the Dlk1-Dio3 genomic region in CD4+ T cells of MRL/lpr mice is hypomethylated, linking it to increased Dlk1-Dio3 miRNA expression. We evaluated the gene expression of methylating enzymes, DNA methyltransferases (DNMTs), and demethylating ten-eleven translocation proteins (TETs) to elucidate the molecular basis of DNA hypomethylation in lupus CD4+ T cells. There was a significantly elevated expression of Dnmt1 and Dnmt3b, as well as Tet1 and Tet2, in CD4+ T cells of three different lupus-prone mouse strains compared to controls. These findings suggest that the hypomethylation of murine lupus CD4+ T cells is likely attributed to a TET-mediated active demethylation pathway. Moreover, we found that deletion of early growth response 2 (Egr2), a transcription factor gene in B6/lpr mice markedly reduced maternally expressed miRNA genes but not paternally expressed protein-coding genes at the Dlk1-Dio3 locus in CD4+ T cells. EGR2 has been shown to induce DNA demethylation by recruiting TETs. Surprisingly, we found that deleting Egr2 in B6/lpr mice induced more hypomethylated differentially methylated regions at either the whole-genome level or the Dlk1-Dio3 locus in CD4+ T cells. Although the role of methylation in EGR2-mediated regulation of Dlk1-Dio3 miRNAs is not readily apparent, these are the first data to show that in lupus, Egr2 regulates Dlk1-Dio3 miRNAs, which target major signaling pathways in autoimmunity. These data provide a new perspective on the role of upregulated EGR2 in lupus pathogenesis.

Deficiency of macrophage-derived Dnase1L3 causes lupus-like phenotypes in mice

Systemic lupus erythematosus (SLE) is an autoimmune disease caused by environmental factors and loss of key proteins, including the endonuclease Dnase1L3. Dnase1L3 absence causes pediatric-onset lupus in humans, while reduced activity occurs in adult-onset SLE. The amount of Dnase1L3 that prevents lupus remains unknown. To genetically reduce Dnase1L3 levels, we developed a mouse model lacking Dnase1L3 in macrophages (conditional knockout [cKO]). Serum Dnase1L3 levels were reduced 67%, though Dnase1 activity remained constant. Homogeneous and peripheral antinuclear antibodies were detected in the sera by immunofluorescence, consistent with anti-double-stranded DNA (anti-dsDNA) antibodies. Total immunoglobulin M, total immunoglobulin G, and anti-dsDNA antibody levels increased in cKO mice with age. The cKO mice developed anti-Dnase1L3 antibodies. In contrast to global Dnase1L3-/- mice, anti-dsDNA antibodies were not elevated early in life. The cKO mice had minimal kidney pathology. Therefore, we conclude that an intermediate reduction in serum Dnase1L3 causes mild lupus phenotypes, and macrophage-derived DnaselL3 helps limit lupus.

CX3CR1 modulates SLE-associated glomerulonephritis and cardiovascular disease in MRL/lpr mice

OBJECTIVE

Patients with systemic lupus erythematosus (SLE) often develop multi-organ damages including heart and kidney complications. We sought to better define the underlying mechanisms with a focus on the chemokine receptor CX3CR1.

METHODS

We generated Cx3cr1-deficient MRL/lpr lupus-prone mice through backcrossing. We then employed heterozygous intercross to generate MRL/lpr littermates that were either sufficient or deficient of CX3CR1. The mice were also treated with either Lactobacillus spp. or a high-fat diet (HFD) followed by assessments of the kidney and heart, respectively.

RESULTS

Cx3cr1-/- MRL/lpr mice exhibited a distinct phenotype of exacerbated glomerulonephritis compared to Cx3cr1+/+ littermates, which was associated with a decrease of spleen tolerogenic marginal zone macrophages and an increase of double-negative T cells. Interestingly, upon correction of the gut microbiota with Lactobacillus administration, the phenotype of exacerbated glomerulonephritis was reversed, suggesting that CX3CR1 controls glomerulonephritis in MRL/lpr mice through a gut microbiota-dependent mechanism. Upon treatment with HFD, Cx3cr1-/- MRL/lpr mice developed significantly more atherosclerotic plaques that were promoted by Ly6C+ monocytes. Activated monocytes expressed ICOS-L that interacted with ICOS-expressing follicular T-helper cells, which in turn facilitated a germinal center reaction to produce more autoantibodies. Through a positive feedback mechanism, the increased circulatory autoantibodies further promoted the activation of Ly6C+ monocytes and their display of ICOS-L.

CONCLUSIONS

We uncovered novel, Cx3cr1 deficiency-mediated pathogenic mechanisms contributing to SLE-associated glomerulonephritis and cardiovascular disease.

Deficiency of macrophage-derived Dnase1L3 causes lupus-like phenotypes in mice

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease caused by environmental factors and loss of key proteins. One such protein is a serum endonuclease secreted by macrophages and dendritic cells, Dnase1L3. Loss of Dnase1L3 causes pediatric-onset lupus in humans is Dnase1L3. Reduction in Dnase1L3 activity occurs in adult-onset human SLE. However, the amount of Dnase1L3 necessary to prevent lupus onset, if the impact is continuous or requires a threshold, and which phenotypes are most impacted by Dnase1L3 remain unknown. To reduce Dnase1L3 protein levels, we developed a genetic mouse model with reduced Dnase1L3 activity by deleting Dnase1L3 from macrophages (cKO). Serum Dnase1L3 levels were reduced 67%, though Dnase1 activity remained constant. Sera were collected weekly from cKO and littermate controls until 50 weeks of age. Homogeneous and peripheral anti-nuclear antibodies were detected by immunofluorescence, consistent with anti-dsDNA antibodies. Total IgM, total IgG, and anti-dsDNA antibody levels increased in cKO mice with increasing age. In contrast to global Dnase1L3 -/- mice, anti-dsDNA antibodies were not elevated until 30 weeks of age. The cKO mice had minimal kidney pathology, except for deposition of immune complexes and C3. Based on these findings, we conclude that an intermediate reduction in serum Dnase1L3 causes mild lupus phenotypes. This suggest that macrophage-derived DnaselL3 is critical to limiting lupus.

Hypovitaminosis A Drives the Progression of Tubulointerstitial Lupus Nephritis through Potentiating Predisease Cellular Autoreactivity

Vitamin A (VA) deficiency (VAD) is observed in both humans and mice with lupus nephritis. However, whether VAD is a driving factor for accelerated progression of lupus nephritis is unclear. In this study, we investigated the effect of VAD on the progression of lupus nephritis in a lupus-prone mouse model, MRL/lpr. We initiated VAD either during gestation or after weaning to reveal a potential time-dependent effect. We found exacerbated lupus nephritis at ∼15 wk of age with both types of VAD that provoked tubulointerstitial nephritis leading to renal failure. This was concomitant with significantly higher mortality in all VAD mice. Importantly, restoration of VA levels after weaning reversed VAD-induced mortality. These results suggest VAD-driven acceleration of tubulointerstitial lupus nephritis. Mechanistically, at the earlier time point of 7 wk of age and before the onset of clinical lupus nephritis, continued VAD (from gestation until postweaning) enhanced plasma cell activation and augmented their autoantibody production, while also increasing the expansion of T lymphocytes that could promote plasma cell autoreactivity. Moreover, continued VAD increased the renal infiltration of plasmacytoid dendritic cells. VAD initiated after weaning, in contrast, showed modest effects on autoantibodies and renal plasmacytoid dendritic cells that were not statistically significant. Remarkably, analysis of gene expression in human kidney revealed that the retinoic acid pathway was decreased in the tubulointerstitial region of lupus nephritis, supporting our findings in MRL/lpr mice. Future studies will elucidate the underlying mechanisms of how VAD modulates cellular functions to exacerbate tubulointerstitial lupus nephritis.

Lactobacillus spp. act in synergy to attenuate splenomegaly and lymphadenopathy in lupus-prone MRL/lpr mice

Commensal bacteria and the immune system have a close and strong relationship that maintains a balance to control inflammation. Alterations of the microbiota, known as dysbiosis, can direct reactivity to self-antigens not only in the intestinal mucosa but also at the systemic level. Our laboratory previously reported gut dysbiosis, particularly lower abundance of bacteria in the family Lactobacillaceae, in lupus-prone MRL/lpr mice, a model of systemic autoimmunity. Restoring the microbiota with a mix of 5 different Lactobacillus species (spp.), L. reuteri, L. oris, L. johnsonii, L. gasseri and L. rhamnosus, attenuated lupus-liked clinical signs, including splenomegaly and lymphadenopathy. However, our understanding of the mechanism was limited. In this study, we first investigated the effects of individual species. Surprisingly, none of the species individually recapitulated the benefits of the mix. Instead, Lactobacillus spp. acted synergistically to attenuate splenomegaly and renal lymphadenopathy through secreted factors and a CX3CR1-dependent mechanism. Interestingly, oral administration of MRS broth exerted the same benefits likely through increasing the relative abundance of endogenous Lactobacillus spp. Mechanistically, we found increased percentages of FOXP3-negative type 1 regulatory T cells with administration of the mix in both spleen and mesenteric lymph nodes. In addition, oral gavage of Lactobacillus spp. decreased the percentage of central memory T cells while increasing that of effector memory T cells in the lymphoid organs. Furthermore, a decreased percentage of double negative T cells was observed in the spleen with the mix. These results suggest that Lactobacillus spp. might act on T cells to attenuate splenomegaly and lymphadenopathy. Together, this study advances our understanding of how Lactobacillus spp. attenuate lupus in MRL/lpr mice. The synergistic action of these bacteria suggests that multiple probiotic bacteria in combination may dampen systemic autoimmunity and benefit lupus patients.

Deletion of microRNA-183-96-182 Cluster in Lymphocytes Suppresses Anti-DsDNA Autoantibody Production and IgG Deposition in the Kidneys in C57BL/6-Faslpr/lpr Mice

Dysregulated miRNAs have been implicated in the pathogenesis of systemic lupus erythematosus (SLE). Our previous study reported a substantial increase in three miRNAs located at the miR-183-96-182 cluster (miR-183C) in several autoimmune lupus-prone mice, including MRL/lpr and C57BL/6-lpr (B6/lpr). This study reports that in vitro inhibition of miR-182 alone or miR-183C by specific antagomirs in activated splenocytes from autoimmune-prone MRL/lpr and control MRL mice significantly reduced lupus-related inflammatory cytokines, interferon-gamma (IFNγ), and IL-6 production. To further characterize the role of miR-182 and miR-183C cluster in vivo in lupus-like disease and lymphocyte phenotypes, we used hCD2-iCre to generate B6/lpr mice with conditional deletion of miR-182 or miR-183C in CD2+ lymphocytes (miR-182−/−B6/lpr and miR-183C−/-B6/lpr). The miR-182−/−B6/lpr and miR-183C−/−B6/lpr mice had significantly reduced deposition of IgG immunocomplexes in the kidney when compared to their respective littermate controls, although there appeared to be no remarkable changes in renal pathology. Importantly, we observed a significant reduction of serum anti-dsDNA autoantibodies in miR-183C−/−B6/lpr mice after reaching 24 weeks-of age compared to age-matched miR-183Cfl/flB6/lpr controls. In vitro activated splenocytes from miR-182−/−B6/lpr mice and miR-183C−/−B6/lpr mice showed reduced ability to produce lupus-associated IFNγ. Forkhead box O1(Foxo1), a previously validated miR-183C miRNAs target, was increased in the splenic CD4+ cells of miR-182−/−B6/lpr and miR-183C−/−B6/lpr mice. Furthermore, in vitro inhibition of Foxo1 with siRNA in splenocytes from miR-182−/−B6/lpr and miR-183C−/-B6/lpr mice significantly increased IFNγ expression following anti-CD3/CD28 stimulation, suggesting that miR-182 and miR-183C miRNAs regulate the inflammatory IFNγ in splenocytes via targeting Foxo1. The deletion of either miR-182 alone or the whole miR-183C cluster, however, had no marked effect on the composition of T and B cell subsets in the spleens of B6/lpr mice. There were similar percentages of CD4+, CD8+, CD19+, as well as Tregs, follicular helper T (TFH), germinal center B (GCB), and plasma cells in the miR-183C−/−B6/lpr and miR-182−/−B6/lpr mice and their respective littermate controls, miR-183Cfl/flB6/lpr and miR-182fl/flB6/lpr mice. Together, our data demonstrate a role of miR-183C in the regulation of anti-dsDNA autoantibody production in vivo in B6/lpr mice and the induction of IFNγ in in vitro activated splenocytes from B6/lpr mice.

EGR2 Deletion Suppresses Anti-DsDNA Autoantibody and IL-17 Production in Autoimmune-Prone B6/lpr Mice: A Differential Immune Regulatory Role of EGR2 in B6/lpr Versus Normal B6 Mice

Previous studies have reported that deletion of the transcription factor, early growth response protein 2 (EGR2), in normal C57BL/6 (B6) resulted in the development of lupus-like autoimmune disease. However, increased EGR2 expression has been noted in human and murine lupus, which challenges the notion of the autoimmune suppressive role of EGR2 in B6 mice. In this study, we derived both conditional EGR2^-/-B6/lpr and EGR2^-/-B6 mice to elucidate the immune and autoimmune regulatory roles of EGR2 in autoinflammation (B6/lpr) versus physiologically normal (B6) conditions. We found that conditional EGR2 deletion increased spleen weight, enhanced T cell activation and IFNγ production, and promoted germinal center B cells and LAG3⁺ regulatory T cells development in both B6/lpr and B6 mice. Nevertheless, EGR2 deletion also showed strikingly differential effects in these two strains on T lymphocyte subsets profile, Foxp3⁺ Tregs and plasma cell differentiation, anti-dsDNA autoantibodies and immunoglobulins production, and on the induction of IL-17 in in vitro activated splenocytes. Specifically, EGR2 deletion in B6/lpr mice significantly decreased serum levels of anti-dsDNA autoantibodies, total IgG, IgM, IgG1, and IgG2a with reduced plasma cells differentiation. Furthermore, EGR2 deletion in B6/lpr mice had no obvious effect on IgG immunocomplex deposition, medium caliber vessel, and glomeruli inflammation but increased complement C3 immunocomplex deposition and large caliber vessel inflammation in the kidneys. Importantly, we demonstrated that EGR2 deletion in B6/lpr mice significantly reduced pathogenic CD4^-CD8^-CD3⁺B220⁺ double negative T cells, which correlated with the reduced anti-dsDNA autoantibodies in serum and decreased IL-17 production in splenocytes of EGR2^-/-B6/lpr mice. Together, our data strongly suggest that the role of EGR2 is complex. The immunoregulatory role of EGR2 varies at normal or autoinflammation conditions and should not be generalized in differential experimental settings.

EGR2 deletion displays similar and differential effects on immunological development and function in autoinflammation-prone B6/lpr and normal B6 mice

Transcription factor early growth response protein 2 (EGR2) prevents the development of lupus-like autoimmune disease in C57BL/6 (B6) mice by negatively regulating T cell activation, inflammatory cytokine IFNγ and IL-17 production and by suppressing humoral responses. However, increased EGR2 expression has been observed in lupus and also other autoimmune disorders, which contradicts the autoimmune suppressive role of EGR2. Here, we derived conditional EGR2−/−B6/lpr and EGR2−/−B6 mice to investigate and compare the immune regulatory role of EGR2 in autoinflammation (B6/lpr) versus normal physiological (B6) conditions. Significantly, we found that in B6/lpr mice, but not in B6 mice, EGR2 deletion dramatically suppressed serum levels of anti-dsDNA autoantibodies, total IgG, IgG1, IgG2a, and IgM. We further demonstrated that while EGR2 deletion promoted germinal center B (GCB) cell development in both B6 and B6/lpr mice, it significantly reduced the differentiation of plasma and plasmablasts cells in B6/lpr mice. EGR2 deletion promoted splenomegaly and T cell activation in both B6 and B6/lpr mice, but it differentially regulated the profiles of immune cell subpopulations in the spleens of B6 and B6/lpr mice. Especially, EGR2 deletion dramatically suppressed the development of double negative T cells in B6/lpr mice. Moreover, we found that EGR2 had an opposite role in regulating IL-17 production in in vitro activated splenocytes from B6/lpr and B6 mice, although EGR2 had a similar suppressive role for IFNγ production. Together, our data strongly suggest that the immune and autoimmune regulatory roles of EGR2 are context dependent, and should not be generalized in normal physiology and different pathological conditions.

Supported by VMCVM-VCOM Center for One Heath Research Seed Grant Program  

HDAC6 knockout alleviates pristane-induced lupus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by excessive inflammation and production of pathogenic antibodies. Histone deacetylase 6 (HDAC6) is a class IIb histone deacetylase. It has been reported that selective HDAC6 inhibition decreases inflammation in lupus mice models. C57BL/6 mice develop SLE-like symptoms following pristane injection. In this study, sex and age-matched wild type and HDAC6−/− mice on the C57BL/6 background were administered 0.5 ml pristane or PBS intraperitoneally (i.p.) at 8–12 weeks-of-age and were euthanized 10 days later. At sacrifice, body weight and spleen weight were measured, sera were collected, splenocytes and peritoneal cells were harvested for flow cytometry. We found pristane administration increased the spleen weight with no difference between WT mice and HDAC6−/− mice. Flow cytometry results showed that there was no difference in T cell or B cell populations in the spleen. Pristane administration promoted the population of CD11b+ Ly6Chigh inflammatory monocytes and CD11b+Ly6G+ neutrophils. Peritoneal recruitment of these inflammatory monocytes and neutrophils in HDAC6−/− mice was significantly decreased compared to the WT mice. Pristane administration also induced the interferon (IFN) signature genes, like Mx1, Oas1a, Irf7, Irf9, Cxcl10, Isg15. qRT-PCR revealed that these IFN signature genes were decreased in HDAC6−/− mice compared to the WT mice. In summary, our results show that HDAC6 knockout inhibits the recruitment of inflammatory monocytes and neutrophils in the peritoneum in early inflammation response to pristane. HDAC6 deletion also inhibited the expression of IFN signature genes with pristine stimulation.

Importance of microRNAs and gut microbiota in the characterization of a phenotypic drift in lupus-prone MRL/lpr mice

Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease. The cause of SLE is not only genetic; in fact, environmental factors may play a more important role in disease development. The MRL/lpr mouse model lupus-like symptoms due to multiple SLE susceptible loci in the MRL background, and offers an accelerated model compared to the MRL parent strain due to the Faslpr mutation. Recently, our laboratory witnessed a loss of disease phenotype in our in-house colony of MRL/lpr mice. We thus compared mice newly obtained from The Jackson Laboratory (JAX; Stock Number 000485) to our in-house mice. The single-nucleotide polymorphism (SNP) analysis showed no genetic drift, suggesting that environmental factors could be triggering a phenotypic drift. Surprisingly, the newly purchased JAX mice also had attenuation of glomerulonephritis. Even though JAX mice manifested similar attenuation of lupus nephritis, our in-house colony showed differences in organ weights. Furthermore, males showed a significantly higher level of anti-double stranded DNA auto-IgG consistent with germinal center maturation. In addition, in-house males had significantly higher levels of microRNA-21 and microRNA-183 explaining spleen size difference. Moreover, the composition of gut microbiota was different between in-house and new JAX mice at early age, with many groups of bacteria differing at later time points, which might explain some of the phenotypic differences. These results suggest that microRNAs and gut microbiota might be responsible for the phenotypic differences of MRL/lpr mice in JAX and our colonies as they were genetically identical. On the other hand, the attenuation of nephritis in both groups requires further investigation.

Supported by R01AR073240

Phenotypic Drift in Lupus-Prone MRL/lpr Mice: Potential Roles of MicroRNAs and Gut Microbiota

MRL/lpr mice have been extensively used as a murine model of lupus. Disease progression in MRL/lpr mice can differ among animal facilities, suggesting a role for environmental factors. We noted a phenotypic drift of our in-house colony, which was the progeny of mice obtained from The Jackson Laboratory (JAX; stocking number 000485), that involved attenuated glomerulonephritis, increased splenomegaly, and reduced lymphadenopathy. To validate our in-house mice as a model of lupus, we compared these mice with those newly obtained from JAX, which were confirmed to be genetically identical to our in-house mice. Surprisingly, the new JAX mice exhibited a similar phenotypic drift, most notably the attenuation of glomerulonephritis. Interestingly, our in-house colony differed from JAX mice in body weight and kidney size (both sexes), as well as in splenic size, germinal center formation, and level of anti-dsDNA auto-IgG in the circulation (male only). In addition, we noted differential expression of microRNA (miR)-21 and miR-183 that might explain the splenic differences in males. Furthermore, the composition of gut microbiota was different between in-house and new JAX mice at early time points, which might explain some of the renal differences (e.g., kidney size). However, we could not identify the reason for attenuated glomerulonephritis, a shared phenotypic drift between the two colonies. It is likely that this was due to certain changes of environmental factors present in both JAX and our facilities. Taken together, these results suggest a significant phenotypic drift in MRL/lpr mice in both colonies that may require strain recovery from cryopreservation.

Altered Germinal-Center Metabolism in B Cells in Autoimmunity

B lymphocytes play an important role in the pathophysiology of many autoimmune disorders by producing autoantibodies, secreting cytokines, and presenting antigens. B cells undergo extreme physiological changes as they develop and differentiate. Aberrant function in tolerogenic checkpoints and the metabolic state of B cells might be the contributing factors to the dysfunctionality of autoimmune B cells. Understanding B-cell metabolism in autoimmunity is important as it can give rise to new treatments. Recent investigations have revealed that alterations in metabolism occur in the activation of B cells. Several reports have suggested that germinal center (GC) B cells of individuals with systemic lupus erythematosus (SLE) have altered metabolic function. GCs are unique microenvironments in which the delicate and complex process of B-cell affinity maturation occurs through somatic hypermutation (SHM) and class switching recombination (CSR) and where Bcl6 tightly regulates B-cell differentiation into memory B-cells or plasma cells. GC B cells rely heavily on glucose, fatty acids, and oxidative phosphorylation (OXPHOS) for their energy requirements. However, the complicated association between GC B cells and their metabolism is still not clearly understood. Here, we review several studies of B-cell metabolism, highlighting the significant transformations that occur in GC progression, and suggest possible approaches that may be investigated to more precisely target aberrant B-cell metabolism in SLE.

Changing the Wound: Covalent Immobilization of the Epidermal Growth Factor

Re-epithelialization of wounds is a critical element of wound closure. Growth factors have been used in combination with conventional wound management to promote closure, but the method of delivery has been limited to the topical application of ointment formulations. Cytoactive factors delivered in this way have short resident times in wounds and have met with limited success. Here, we demonstrate that methods used to covalently immobilize proteins on synthetic materials can be extended to immobilize cytoactive factors such as the epidermal growth factor (EGF) onto the wound beds of genetically diabetic mice that exhibit impaired healing. Full-thickness splinted excisional wounds were created in diabetic (db/db) mice with a well-defined silicone splint to limit wound contracture. Wound surfaces were treated with a reducing agent to expose sulfhydryl groups and subsequently treated with EGF modified with a heterobifunctional crosslinker. This allowed for the covalent immobilization of the EGF to the wound surface. The conjugation chemistry was validated in vitro and in vivo. In a separate group of mice, wounds were topically treated twice daily with soluble EGF. The mice were evaluated over 11 days for wound closure. This covalent immobilization strategy resulted in EGF being retained on the wound surface for 2 days and significantly increased epithelial wound closure by 20% compared to wounds treated with topical EGF or topical vehicle. Covalent immobilization was not only therapeutically effective but also delivered a markedly reduced load of growth factor to the wound surface compared to topical application (when only 180 ng of EGF was immobilized onto the wound surface in comparison with 7200 ng of topically applied EGF over a period of 11 days). No adverse effects were observed in treated wounds. Results obtained provide proof of concept for the effectiveness of covalent immobilization in the treatment of dysregulated wounds. The covalent immobilization of cytoactive factors represents a potentially transformative approach to the management of difficult chronic wounds.

Vitamin A Deficiency Deteriorates Lupus Nephritis

Vitamin A deficiency (VAD) is observed in both human and mice with lupus nephritis (LN). However, whether VAD is a driving factor for LN progression is unclear. Here, we investigated the effect of VAD on the progression of LN in a lupus-prone mouse model, MRL/lpr. In these mice, while LN is not apparent before 8 weeks of age, the inflammation of lymphoid tissues suggesting initiation of lupus is evident at weaning. Thus, we initiated VAD either before or after weaning to reveal a potential time-dependent effect. At around 15 weeks of age with both types of VAD, we found exacerbated LN that was characterized by deteriorated kidney inflammation, impaired renal epithelial integrity, and dramatic squamous metaplasia of the renal pelvic urothelium. Both types of VAD provoked severe neutrophilic tubulointerstitial nephritis and accelerated renal failure. This was concomitant with significantly higher mortality in all VAD mice. Looking at an earlier time point of 7 weeks of age and before the onset of clinical LN, both types of VAD increased splenomegaly, lymphadenopathy, and circulating autoantibodies; three additional hallmarks of lupus, as well as renal infiltration of conventional and plasmacytoid dendritic cells. These results suggest VAD-driven deterioration of LN regardless of the time of VAD initiation. Our findings raise significant public health concerns that concurrent lupus and VAD may lead to more severe SLE. Future studies will elucidate the underlying mechanisms of how VAD modulates myeloid cells to accelerate the initiation of LN.

Depletion of microRNA-183-96-182 miRNA cluster in lymphocytes suppresses anti-dsDNA autoantibody production and IgG deposition in kidney in C57BL/6-Faslpr/lpr mice

The miR-183-96-182 (miR-183C) is a highly conserved miRNA cluster among species. Our previous work found a significant upregulation of miR-183C in the splenic cells of three different murine models of systemic lupus erythematosus (SLE). Current studies revealed that miR-183C miRNAs are critically involved in immunity and autoimmunity.

In this study, we found that inhibition of miR-182 alone or miR-183C in vitro with antagomirs significantly reduced lupus-related inflammatory cytokine IFN-γ and IL-6 in activated splenocytes from MRL or MRL/lpr mice. To further characterize the pathogenic role of miR-182 and miR-183C in lupus in vivo, we developed B6-lpr mice with conditional depletion of miR-182 or miR-183C in CD2+ lymphocyte. We found that depletion of either miR-182 or miR-183C in the lymphocytes of B6/lpr mice had no obvious effect on T and B cell development as similar percentage of CD4+. CD8+, CD19+, as well as Tregs, follicular helper T (TFH), germinal center B (GCB), and plasma cells were observed in the miR-182−/− and miR-183C−/− and their respective control. Importantly, we observed a significant reduction of serum anti-dsDNA autoantibodies in miR-183C−/− mice when compared to age-matched controls and the B6/lpr mice with miR-182 or miR-183C deficiency have significantly reduced IgG deposition in the kidneys. Meanwhile, there was reduced IFN production in ex vivo activated splenocytes from the knockout mice. Furthermore, we demonstrated that miR-182 and miR-183C regulated the inflammatory response in splenocytes via targeting forkhead box O1 (Foxo1). Together, our data suggest a potential therapeutic effect of targeting miR-183C in lupus.

EGR2 plays a differential immune regulatory role in normal C57BL/6 mice and autoimmune-prone B6/lpr mice

Early growth response protein 2 (EGR2) is a zinc-finger transcription factor that belongs to the early growth response (Egr) gene family. Recent studies have shown that EGR2 is required to induce T cell anergy, and it plays an important role in T cell immunity and autoimmunity. Conditional depletion of EGR2 in T lymphocytes in C57BL/6 (B6) mice (EGR2−/−B6) was able to break immune tolerance and induce T cell-driven, a lupus-like autoimmune disease. In EGR2−/−B6 mice, there was also enhanced GC response and humoral responses. However, increased EGR2 expression has been observed in lupus and autoimmune disorder systemic sclerosis. These observations seem to contradict the autoimmune suppressive role of EGR2 in B6 mice. To investigate further the immune regulatory role of EGR2 in an autoimmune context, we derived EGR2−/−B6/lpr mice with EGR2 deficiency in both T and B cells. We found that EGR2 depletion promoted splenomegaly and increased IFNγ, IL-10, IL-2 in both B6 and B6/lpr mice. Significantly, we found that in B6/lpr mice, EGR2 depletion reduced serum levels of anti-dsDNA autoantibodies, total IgG, IgG1, IgG2a, and IgM. Furthermore, in B6/lpr mice, depletion of EGR2 promoted germinal center B (GCB) cell development, but suppressed plasma cell (PC) differentiation. However, in wild-type B6 mice, EGR2 depletion significantly increased anti-dsDNA autoantibodies, accompanied by a significant increase of GCB cell development and a trend of increase in PC differentiation. Together, we demonstrated that EGR2 has a differential role in the normal and autoimmune state, particularly in regulating GCB transition into plasma cell during late B cell development.

Roles of CX3CR1 and probiotic lactobacilli on the development of autoimmunity in MRL/lpr mice

Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease with no known cure. Gut microbiota and the immune system have a close relationship that controls inflammation. Alterations in the gut microbiota, known as dysbiosis, can trigger SLE in both human and mouse. We previously published differences between the gut microbiota in lupus-prone MRL/Mp-Faslpr (lpr) mice compared to healthy controls, with lower Lactobacillaceae abundance in lpr mice. Restoring the gut microbiota with a mix of 5 different strains of this family significantly attenuated lupus-liked disease in lpr mice. In this study, we sought to understand the potential benefit of this mix in lpr mice with Cx3cr1 deficiency (KO). KO mice on C57BL/6 background display increased translocation of commensal bacteria into the mesenteric lymph node (MLN) and increased susceptibility to intestinal inflammation. However, whether CX3CR1+ macrophages play a role in controlling systemic inflammation was unclear. After backcrossing the KO allele to lpr mice, we found that KO lpr mice exhibited exacerbated splenomegaly and lymphadenopathy, as well as increased proteinuria. Interestingly, treating the KO lpr mice with the 5 Lactobacillus strains attenuated the enlargement of MLN and abrogated the increase of proteinuria. Furthermore, the effects of the probiotic bacteria were accompanied by downregulation of serum endotoxin, suggesting the reversal of a leaky gut that may explain their benefits on KO lpr mice. Together, our results show an important role of CX3CR1+ macrophages in controlling systemic inflammation in lupus, and that probiotic Lactobacillus spp. may be an effective treatment against SLE through preventing bacterial translocation.

Choroidal neuroendocrine neoplasia in a dog

OBJECTIVE

To report onset and progression of clinical signs of a neuroendocrine neoplasm (NEN) presumed metastatic to the choroid in a dog.

ANIMALS STUDIED

A 7.5-year-old female spayed German shepherd dog mix referred for advanced imaging and evaluation of a subretinal mass in the right eye.

PROCEDURES

Procedures performed included general physical and ophthalmic examinations; ocular, orbital, and abdominal ultrasonography; thoracic radiographs; cranial magnetic resonance imaging; serologic testing for infectious agents; analysis of hematologic as well as serum and urine biochemical parameters; echocardiography; electrocardiography; cytologic assessment of lymph nodes; and histopathology and immunohistochemistry of the enucleated globe.

RESULTS

Examination and imaging identified a pigmented mass within and expanding the superior choroid. Following enucleation, a choroidal NEN with tumor emboli in scleral blood vessels was diagnosed by histopathologic assessment and confirmed by immunohistochemical labelling. Despite extensive and repeated diagnostic testing over many months, a putative primary site was not identified until 19 months after the initial ocular signs were noted. At that time, a heart-base mass and congestive heart failure were highly suggestive of a chemodectoma.

CONCLUSION

This comprehensive report of a NEN presumed metastatic to the choroid in a dog suggests that ocular disease can be a very early and solitary sign of NEN in the dog.

Differential effects of Hsp90 inhibition on corneal cells in vitro and in vivo

The transformation of quiescent keratocytes to activated fibroblasts and myofibroblasts (KFM transformation) largely depends on transforming growth factor beta (TGFβ) signaling. Initiation of the TGFβ signaling cascade results from binding of TGFβ to the labile type I TGFβ receptor (TGFβRI), which is stabilized by the 90 kDa heat shock protein (Hsp90). Since myofibroblast persistence within the corneal stroma can result in stromal haze and corneal fibrosis in patients undergoing keratorefractive therapy, modulation of TGFβ signaling through Hsp90 inhibition would represent a novel approach to prevent myofibroblast persistence. In vitro, rabbit corneal fibroblasts (RCFs) or stratified immortalized human corneal epithelial cells (hTCEpi) were treated with a Hsp90 inhibitor (17AAG) in the presence/absence of TGFβ1. RCFs were cultured either on tissue culture plastic, anisotropically patterned substrates, and hydrogels of varying stiffness. Cellular responses to both cytoactive and variable substrates were assessed by morphologic changes to the cells, and alterations in expression patterns of key keratocyte and myofibroblast proteins using PCR, Western blotting and immunocytochemistry. Transepithelial electrical resistance (TEER) measurements were performed to establish epithelial barrier integrity. In vivo, the corneas of New Zealand White rabbits were wounded by phototherapeutic keratectomy (PTK) and treated with 17AAG (3× or 6× daily) either immediately or 7 days after wounding for 28 days. Rabbits underwent clinical ophthalmic examinations, SPOTS scoring and advanced imaging on days 0, 1, 3, 7, 10, 14, 21 and 28. On day 28, rabbits were euthanized and histopathology/immunohistochemistry was performed. In vitro data demonstrated that 17AAG inhibited KFM transformation with the de-differentiation of spindle shaped myofibroblasts to dendritic keratocyte-like cells accompanied by significant upregulation of corneal crystallins and suppression of myofibroblast markers regardless of TGFβ1 treatment. RCFs cultured on soft hydrogels or patterned substrates exhibited elevated expression of α-smooth muscle actin (αSMA) in the presence of 17AAG. Treatment of hTCEpi cells disrupted zonula occludens 1 (ZO-1) adherens junction formation. In vivo, there were no differences detected in nearly all clinical parameters assessed between treatment groups. However, rabbits treated with 17AAG developed greater stromal haze formation compared with controls, irrespective of frequency of administration. Lastly, there was increased αSMA positive myofibroblasts in the stroma of 17AAG treated animals when compared with controls. Hsp90 inhibition promoted reversion of the myofibroblast to keratocyte phenotype, although this only occurred on rigid substrates. By contrast, in vivo Hsp90 inhibition was detrimental to corneal wound healing likely due to impairment in corneal epithelial closure and barrier function restoration. Collectively, our data demonstrated a strong interplay in vitro between biophysical cues and soluble signaling molecules in determining corneal stromal cell phenotype.

Gut Microbiota and Bacterial DNA Suppress Autoimmunity by Stimulating Regulatory B Cells in a Murine Model of Lupus

Autoimmune diseases, such as systemic lupus erythematosus, are characterized by excessive inflammation in response to self-antigens. Loss of appropriate immunoregulatory mechanisms contribute to disease exacerbation. We previously showed the suppressive effect of vancomycin treatment during the "active-disease" stage of lupus. In this study, we sought to understand the effect of the same treatment given before disease onset. To develop a model in which to test the regulatory role of the gut microbiota in modifying autoimmunity, we treated lupus-prone mice with vancomycin in the period before disease development (3-8 weeks of age). We found that administration of vancomycin to female MRL/lpr mice early, only during the pre-disease period but not from 3 to 15 weeks of age, led to disease exacerbation. Early vancomycin administration also reduced splenic regulatory B (Breg) cell numbers, as well as reduced circulating IL-10 and IL-35 in 8-week old mice. Further, we found that during the pre-disease period, administration of activated IL-10 producing Breg cells to mice treated with vancomycin suppressed lupus initiation, and that bacterial DNA from the gut microbiota was an inducer of Breg function. Oral gavage of bacterial DNA to mice treated with vancomycin increased Breg cells in the spleen and mesenteric lymph node at 8 weeks of age and reduced autoimmune disease severity at 15 weeks. This work suggests that a form of oral tolerance induced by bacterial DNA-mediated expansion of Breg cells suppress disease onset in the autoimmune-prone MRL/lpr mouse model. Future studies are warranted to further define the mechanism behind bacterial DNA promoting Breg cells.

Brain-Machine Interfaces as Commodities: Exchanging Mind for Matter

Brain-machine interfaces (BMIs), which enable a two-way flow of signals, information, and directions between human neurons and computerized machines, offer spectacular opportunities for therapeutic and consumer applications, but they also present unique dangers to the safety, privacy, psychological health, and spiritual well-being of their users. The sale of these devices as commodities for profit exacerbates such issues and may subject the user to an unequal exchange with corporations. Catholic healthcare professionals and bioethicists should be especially concerned about the implications for the essential dignity of the persons using the new BMIs.

Summary

The commercial sale of brain-machine interfaces (BMIs) generates and exacerbates problems for end-users' safety, psychological health, and spiritual well-being.

EGR2 is elevated and positively regulates inflammatory IFNγ production in lupus CD4+ T cells

Background

Recent studies have shown that early growth response 2 (EGR2) is highly induced in activated T cells and regulates T cell functions. In normal C57BL/6 (B6) mice, deletion of EGR2 in lymphocytes results in the development of lupus-like systemic autoimmune disease, which implies indirectly an autoimmune protective role of EGR2. Conversely, increased EGR2 gene expression is suggested to link with high risk of human lupus. In the present studies we sought to clarify the expression and inflammation regulatory role of EGR2 in murine lupus T cells directly.

Results

We performed RT-qPCR analysis and found a significant increase of EGR2 mRNA expression in human lupus PBMCs and in CD4⁺ T cells from three different murine lupus models including MRL-lpr, B6-lpr, and B6.sle123 mice at diseased stage when compared to age-matched control MRL or B6 mice. By performing intracellular flow cytometry analysis, we found that EGR2 protein expression was significantly increased in resting lupus (either MRL-lpr or B6.sle123) CD4⁺ T cells when compared to CD4⁺ T cells from their respective non-autoimmune controls. However, there was no difference of EGR2 protein expression in anti-CD3 and anti-CD28 stimulated control and lupus CD4⁺ T cells since there was a stronger induction of EGR2 in activated control CD4⁺ T cells. EGR2 expression was significantly increased in MRL-lpr mice at an age when lupus is manifested. To understand further the function of elevated EGR2 in lupus CD4⁺ T cells, we inhibited EGR2 with a specific siRNA in vitro in splenocytes from MRL-lpr and control MRL mice at 15 weeks-of-age. We found that EGR2 inhibition significantly reduced IFNγ production in PMA and ionomycin activated MRL-lpr lupus CD4⁺ T cells, but not control MRL CD4⁺ T cells. We also found that inhibition of EGR2 in vitro suppressed the Th1 differentiation in both MRL and MRL-lpr naïve CD4⁺ T cells.

Conclusions

EGR2 is highly upregulated in human and murine lupus cells. Our in vitro data suggest a positive role of EGR2 in the regulation of Th1 differentiation and IFNγ production in lupus effector CD4⁺ T cells.

A Virtuous Appraisal of Heritable Genome Editing

The ethics of heritable genome editing (HGE), or germline engineering, are currently being debated vigorously among scientists and bioethicists, and the Catholic Church has declared the procedure to be morally illicit. While these judgments are based mostly on the justice and consequences of the act, a fruitful approach is to consider HGE from the perspective of the virtuous Christian. This article examines participation in HGE according to the virtues of charity, justice, hope, faith, fortitude, temperance, and prudence. HGE does not appear to be consonant with the virtuous life of a Christian person.

Summary

The article evaluates heritable genome editing (HGE or genetic engineering of embryos) according to the Christian virtues of charity, justice, hope, faith, fortitude, temperance, and prudence. HGE does not seem to be consonant with the virtuous life of a Christian person.

Characterizing the role of Lactobacillus spp. in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease with no known cure. The role of gut microbiota and its interaction with the immune system can direct tolerance induction to self-antigens not only in the intestinal mucosa but also at the systemic level. Our lab previously showed differences between the gut microbiota in lupus-prone MRL/Mp-Faslpr (lpr) mice compared to healthy controls, with lower Lactobacillaceae levels in lpr mice. Restoring the microbiota with a mix of 5 different Lactobacillus strains, L. reuteri, L. oris, L. johnsonii, L. gasseri, and L. rhamnosus significantly attenuated lupus-liked disease in lpr mice, by increasing regulatory T cells and balancing T helper-17 cells. Interestingly, we found L. reuteri and an uncultured Lactobacillus spp. were present based on 16S rRNA sequencing. To evaluate the effect of the main candidate L. reuteri in attenuating lupus, we treated lpr mice with the single bacterial strain. Surprisingly, L. reuteri did not reproduce the same results as the Lactobacillus mixture. Thus, we tested the remaining strains individually but none was able to recapitulate the effect of the 5 strains. Additionally, we treated lpr mice with the supernatant of the 5 strains containing secreted metabolites, which did not significantly attenuate lupus. These results suggest that communications among different strains of lactobacilli may be required in ameliorating the disease. Probiotic Lactobacillus spp. may be an alternative treatment against SLE, but further investigations are warranted to delineate the mechanisms of how multiple strains of lactobacilli can exert a beneficial effect as a community.

Retinoic acid exerts disease stage-dependent and tissue-specific effects on pristane-induced lupus

We previously showed that all-trans-retinoic acid (tRA) exacerbated pre-existing autoimmunity in lupus; however, its effects before disease onset are unknown. Here, using a pristane-induced model, we show that tRA exerts tissue-specific effects when given at the initiation vs. continuation phase of lupus. Pre-pristane treatment with tRA aggravated glomerulonephritis through increasing renal expression of pro-fibrotic protein laminin β1, activating bone marrow CD11b- conventional dendritic cells, increasing the splenic CD4:CD8 ratio, and upregulating the interaction of ICAM-1 and LFA-1 that led to the infiltration of inflammatory cells to the spleen. Transcriptomic analysis revealed that prior to lupus induction, tRA significantly upregulated genes associated with cell differentiation, activation, and migration. Moreover, compared to pristane alone, tRA pre-treatment potentiated, whereas tRA post-treatment significantly suppressed, the renal expression of proinflammatory TNF-α, IL-1β, CCL2, and CCL3. While it may benefit the kidney, post-pristane treatment with tRA worsened the onset and severity of pristane-induced arthritis through promoting neutrophil and mononuclear cell infiltration into the joints. Together, these findings suggest that tRA supplementation regardless of the time of administration promotes chemokine-driven migration and tissue-specific infiltration of inflammatory cells, thereby exacerbating lupus-associated kidney or joint inflammation. Interestingly, both pre- and post-treatments with tRA modulated the gut microbiota in a similar fashion, suggesting a gut microbiota-independent mechanism by which tRA affects the initiation vs. continuation phase of lupus.

TLR9 stimulation by the gut microbiota promotes tissue-specific immunosuppression in autoimmune-prone MRL/lpr mice

To investigate the ability of gut microbiota to modify immune regulation in autoimmune disease, we treated lupus-prone mice with oral vancomycin prior to disease development, and subsequently administered bacterial DNA isolated from commensal bacteria. Vancomycin given prior to disease initiation promotes exacerbation of autoimmune disease, likely due to a decrease in the frequency of B regulatory (Breg) cells, whereas vancomycin given after autoimmune disease onset has suppressive effects on disease phenotype in MRL/lpr mice. Bacterial DNA administration during the pre-disease stage promoted Breg cell production and suppressed autoimmune disease parameters in MRL/lpr mice. Further, we showed that activation of toll-like receptor 9 (TLR9) on B cells was involved in the suppressive effects of bacterial DNA seen in the MRL/lpr mouse model. We found that during the pre-disease period, joint treatment with vancomycin and oral administration of a TLR9 specific agonist, ODN 1826, promoted Breg cells in the lamina propria, increased total CD8+ T cells and effector memory CD44 expressingCD8+ T cells in the spleen, and suppressed Th17 and IFNγ producing CD4+ T cells in the mesenteric lymph nodes. Oral ODN 1826 administration also increased the Treg/Th17 ratio in the mesenteric lymph nodes. The alterations in suppressive vs. proinflammatory cell phenotypes by oral exposure to ODN 1826 suggests that the suppressive effects of bacterial DNA from the gut microbiota are modulated through TLR9 activation in a tissue-specific manner.

The Effect of Dietary Fiber Intake on Systemic Lupus Erythematosus (SLE) Disease in NZB/W Lupus Mice

Dysbiosis in the gut microbiota has been observed in a various autoimmune disease, including SLE, which could cause a leaky gut, triggering an immune response, and thus worsening autoimmune disease expression. In our current studies, we hypothesized that increasing dietary fiber would create a healthy microbiota environment in the gut, leading to decreased leakiness of the gut and to decreased disease expression in and NZB/NZW female mice. NZB/NZW mice were placed on standardized high fiber (HF 30%) or low fiber (LF 0.4%) for 12 weeks beginning at 10 weeks of age. Mice were assessed as they aged for various parameters of disease including proteinuria and anti-dsDNA antibody production. Alteration of the microbiota and short chain fatty acid levels were also assessed. At 36 weeks-of-age, the mice were euthanized and we assessed occlusion protein expression, splenocyte profiles, and kidney tissue. We found as the mice aged, their body weights, anti-dsDNA antibody levels, and proteinuria were not significantly different between the groups. Similarly, there were no differences in SCFA levels. In regard to the microbiota, Chlostridiales bacteria were consistently increased in the HF treated mice compared to the LF treated mice. In regard to disease progression, spleen weight, immune cell profiles, proteinuria, dsDNA levels, and kidney pathology, there was no difference between the HF and LF treated groups. Taken together, these results indicate that in the NZB/W female mouse, a HF diet may alter the microbiota but does not influence disease progression.

Surgical excision of iridociliary tumors using a postero-anterior cyclo-iridectomy and thermocautery in two dogs

OBJECTIVE

To report the surgical excision of an iridociliary adenoma and iridal melanocytoma using a postero-anterior cyclo-iridectomy in two dogs.

PROCEDURE

A 7 year old neutered male English springer spaniel (case 1) and a 7 year old neutered male Labrador mix (case 2) were presented for evaluation of an intrairidal mass OS.

RESULTS

Complete ophthalmic examination revealed a large, dorsonasal, well-demarcated, intrairidal mass OS. A tan to pink intrairidal mass extending into the iridocorneal angle (case 1) and a pigmented intrairidal mass (case 2) were present. B-mode ultrasonography showed a focal, soft tissue, homogenous mass within the uvea adjacent to and contacting the lens. Neither pars plana involvement nor vitreal extension was present. A postero-anterior cyclo-iridectomy was performed through a polyhedral scleral flap. Thermocautery was used to complete the cyclo-iridectomy (case 1) and partial iridectomy (case 2) to excise the mass en bloc. Histopathology revealed a completely excised iridociliary adenoma (case 1) and iris melanocytoma (case 2). The surgery sites healed without complication. Mild uveitis (cases 1 and 2), scant vitreal hemorrhage (case 1), and mild hyphema (case 2) were present three days postoperatively but had resolved ten days postoperatively. The patients remain visual twenty-two months (case 1) and seven months (case 2) postoperatively with a normal intraocular examination other than an iridal defect and mild dorsonasal lens capsular opacities.

CONCLUSIONS

The surgical approach described in these cases is utilized in physician-based medicine. This approach and the use of thermocautery provide a viable surgical option for excision of large iridociliary tumors in dogs.

Retinoic Acid Exerts Disease Stage-Dependent Effects on Pristane-Induced Lupus

We previously showed that all-trans-retinoic acid (tRA), an active metabolite of vitamin A, exacerbated pre-existing autoimmunity in lupus; however, its effects before the development of autoimmunity are unknown. Here, using a pristane-induced model, we show that tRA exerts differential effects when given at the initiation vs. continuation phase of lupus. Unlike tRA treatment during active disease, pre-pristane treatment with tRA aggravated glomerulonephritis through increasing renal expression of pro-fibrotic protein laminin β1, activating bone marrow conventional dendritic cells (cDCs), and upregulating the interaction of ICAM-1 and LFA-1 in the spleen, indicating an active process of leukocyte activation and trafficking. Transcriptomic analysis revealed that prior to lupus induction, tRA significantly upregulated the expression of genes associated with cDC activation and migration. Post-pristane tRA treatment, on the other hand, did not significantly alter the severity of glomerulonephritis; rather, it exerted immunosuppressive functions of decreasing circulatory and renal deposition of autoantibodies as well as suppressing the renal expression of proinflammatory cytokines and chemokines. Together, these findings suggest that tRA differentially modulate lupus-associated kidney inflammation depending on the time of administration. Interestingly, both pre- and post-pristane treatments with tRA reversed pristane-induced leaky gut and modulated the gut microbiota in a similar fashion, suggesting a gut microbiota-independent mechanism by which tRA affects the initiation vs. continuation phase of lupus.

Effects of chronic low-dose radiation on cataract prevalence and characterization in wild boar (Sus scrofa) from Fukushima, Japan

This study evaluated cataracts in wild boar exposed to chronic low-dose radiation. We examined wild boar from within and outside the Fukushima Exclusion Zone for nuclear, cortical, and posterior subcapsular (PSC) cataracts in vivo and photographically. Plausible upper-bound, lifetime radiation dose for each boar was estimated from radioactivity levels in each animal's home range combined with tissue concentrations of 134+137Cesium. Fifteen exposed and twenty control boar were evaluated. There were no significant differences in overall prevalence or score for cortical or PSC cataracts between exposed and control animals. Nuclear (centrally located) cataracts were significantly more prevalent in exposed boar (p < 0.05) and had statistically higher median scores. Plausible upper-bound, lifetime radiation dose ranged from 1 to 1,600 mGy in exposed animals, with no correlation between dose and cortical or PSC score. While radiation dose and nuclear score were positively associated, the impact of age could not be completely separated from the relationship. Additionally, the clinical significance of even the highest scoring nuclear cataract was negligible. Based on the population sampled, wild boar in the Fukushima Exclusion Zone do not have a significantly higher prevalence or risk of cortical or PSC cataracts compared to control animals.

Selective Histone Deacetylase 6 Inhibition Normalizes B Cell Activation and Germinal Center Formation in a Model of Systemic Lupus Erythematosus

Autoantibody production by plasma cells (PCs) plays a pivotal role in the pathogenesis of systemic lupus erythematosus (SLE). The molecular pathways by which B cells become pathogenic PC secreting autoantibodies in SLE are incompletely characterized. Histone deactylase 6 (HDAC6) is a unique cytoplasmic HDAC that modifies the interaction of a number of tubulin- associated proteins; inhibition of HDAC6 has been shown to be beneficial in murine models of SLE, but the downstream pathways accounting for the therapeutic benefit have not been clearly delineated. In the current study, we sought to determine whether selective HDAC6 inhibition would abrogate abnormal B cell activation in SLE. We treated NZB/W lupus mice with the selective HDAC6 inhibitor, ACY-738, for 4 weeks beginning at 20 weeks-of age. After only 4 weeks of treatment, manifestation of lupus nephritis (LN) were greatly reduced in these animals. We then used RNAseq to determine the genomic signatures of splenocytes from treated and untreated mice and applied computational cellular and pathway analysis to reveal multiple signaling events associated with B cell activation and differentiation in SLE that were modulated by HDAC6 inhibition. PC development was abrogated and germinal center (GC) formation was greatly reduced. When the HDAC6 inhibitor-treated lupus mouse gene signatures were compared to human lupus patient gene signatures, the results showed numerous immune, and inflammatory pathways increased in active human lupus were significantly decreased in the HDAC6 inhibitor treated animals. Pathway analysis suggested alterations in cellular metabolism might contribute to the normalization of lupus mouse spleen genomic signatures, and this was confirmed by direct measurement of the impact of the HDAC6 inhibitor on metabolic activities of murine spleen cells. Taken together, these studies show HDAC6 inhibition decreases B cell activation signaling pathways and reduces PC differentiation in SLE and suggest that a critical event might be modulation of cellular metabolism.

Pregnancy and lactation interfere with the response of autoimmunity to modulation of gut microbiota

BACKGROUND

Dysbiosis of gut microbiota exists in the pathogenesis of many autoimmune diseases, including systemic lupus erythematosus (lupus). Lupus patients who experienced pregnancy usually had more severe disease flares post-delivery. However, the possible role of gut microbiota in the link between pregnancy and exacerbation of lupus remains to be explored.

RESULTS

In the classical lupus mouse model MRL/lpr, we compared the structures of gut microbiota in pregnant and lactating individuals vs. age-matched naïve mice. Consistent with studies on non-lupus mice, both pregnancy and lactation significantly changed the composition and diversity of gut microbiota. Strikingly, modulation of gut microbiota using the same strategy resulted in different disease outcomes in postpartum (abbreviated as "PP," meaning that the mice had undergone pregnancy and lactation) vs. control (naïve; i.e., without pregnancy or lactation) MRL/lpr females; while vancomycin treatment attenuated lupus in naïve mice, it did not do so, or even exacerbated lupus, in PP mice. Lactobacillus animalis flourished in the gut upon vancomycin treatment, and direct administration of L. animalis via oral gavage recapitulated the differential effects of vancomycin in PP vs. control mice. An enzyme called indoleamine 2,3-dioxygenase was significantly inhibited by L. animalis; however, this inhibition was only apparent in PP mice, which explained, at least partially, the lack of beneficial response to vancomycin in these mice. The differential production of immunosuppressive IL-10 and proinflammatory IFNγ in PP vs. control mice further explained why the disease phenotypes varied between the two types of mice bearing the same gut microbiota remodeling strategy.

CONCLUSIONS

These results suggest that pregnancy and lactation interfere with the response of autoimmunity to modulation of gut microbiota. Further studies are necessary to better understand the complex relationship between pregnancy and lupus.

Pregnancy and lactation interfere with the response of autoimmunity to modulation of gut microbiota

Dysbiosis of gut microbiota exists in the pathogenesis of many autoimmune diseases, including lupus. Currently, women with lupus are recommended to avoid pregnancy, as lupus patients who experienced pregnancy usually had more severe disease flares. However, the possible role of gut microbiota in the link between pregnancy and exacerbation of lupus remains to be explored. In the present study, in the classical lupus mouse model MRL/lpr, we compared the structures of gut microbiota in pregnant and lactating individuals vs. age-matched naïve mice. Consistent with studies on non-lupus mice, both pregnancy and lactation significantly changed the composition and diversity of gut microbiota. Strikingly, modulation of gut microbiota using the same strategy resulted in different disease outcomes in experienced (which had undergone pregnancy and lactation) vs. control (naïve) MRL/lpr females: while vancomycin treatment attenuated lupus in naïve mice, it even exacerbated lupus in experienced mice. L. animalis flourished in the gut upon vancomycin treatment, and direct administration of the bacteria recapitulated the differential effects of vancomycin in experienced vs. control mice. A pregnancy-related enzyme, DHNA, was significantly inhibited by L. animalis; however, this inhibition was only apparent in experienced mice, which explained, at least partially, the lack of beneficial response to vancomycin in these mice. The differential production of IL-10 and IFNγ in experienced vs. control mice further explained why the disease phenotypes varied between the two types of mice bearing the same treatment. These results suggest that pregnancy and lactation interfere with the response of autoimmunity to modulation of gut microbiota.

A missense mutation in damage-specific DNA binding protein 2 is a genetic risk factor for ocular squamous cell carcinoma in Belgian horses

BACKGROUND

Belgian horses are commonly affected with ocular squamous cell carcinoma (SCC), the most common cancer of the equine eye. A missense mutation in damage-specific DNA binding protein 2 (DDB2 c.1013C>T, p.Thr338Met) has been established as a recessive genetic risk factor for ocular SCC in the Haflinger breed. A sample of Belgian horses with unknown SCC phenotype was shown to possess this variant at a similar frequency to the Haflinger breed. Retrospective studies indicate that chestnut coat colour may predispose to the development of SCC.

OBJECTIVES

To determine if DDB2 c.1013C>T is a risk factor for ocular SCC in a strictly phenotyped sample of Belgian horses. To investigate associations between coat colour loci genotypes and ocular SCC.

STUDY DESIGN

Retrospective and prospective case identification, genetic investigation.

METHODS

Genomic DNA was isolated from blood, hair or formalin-fixed paraffin-embedded tissue from 25 Belgian horses with histologically confirmed ocular SCC and 18 unaffected Belgian horses. Association testing of 34 single nucleotide variants from 11 genomic loci and genotyping for DDB2 c.1013C>T and coat colour alleles were performed. Exons of DDB2 were sequenced in four cases and two controls. Associations were analysed by Chi-square or Fisher's exact tests and relative risk was calculated.

RESULTS

Homozygosity for DDB2 c.1013C>T was significantly associated with ocular SCC (P = 7.4 × 10^-7 ). Seventy-six per cent of affected horses were homozygous for the variant. Relative risk for homozygous horses developing SCC was 4.0 (P = 1.0 × 10^-4 ). Sequencing DDB2 did not identify a variant more concordant with disease phenotype. An association between disease and coat colour loci was not identified.

MAIN LIMITATIONS

Phenotyping was determined at a single timepoint. Each included horse genotyped as chestnut, so association with this MC1R variant could not be investigated.

CONCLUSIONS

A missense variant, DDB2 c.1013C>T, p.Thr338Met, is a risk factor for ocular SCC in Belgian horses. A genetic risk test is commercially available.

Diagnosis, treatment, and outcome of and risk factors for ophthalmic disease in leopard geckos (Eublepharis macularius) at a veterinary teaching hospital: 52 cases (1985-2013)

OBJECTIVE To describe diagnosis, treatment, and outcome of and risk factors for ophthalmic disease in leopard geckos (Eublepharis macularius) evaluated at a veterinary teaching hospital. DESIGN Retrospective case series. ANIMALS 112 of 144 (78%) leopard geckos that were evaluated at a veterinary teaching hospital in January 1985 through October 2013 and for which sufficient medical record information was available. PROCEDURES Information from medical records was used to identify leopard geckos with ophthalmic disease, characterize cases, and determine risk factors for the presence of ophthalmic disease. RESULTS Of the 112 leopard geckos, 52 (46%) had ophthalmic disease (mainly corneal or conjunctival disease). Female geckos were less likely to have ophthalmic disease, and there was a positive association between increasing age and ophthalmic disease. Use of a paper towel substrate, absence of any heat source, and lack of vitamin A supplementation were positively associated with a diagnosis of ophthalmic disease. Head dysecdysis was the only concurrent disorder significantly associated with ophthalmic disease. At necropsy, 5 affected leopard geckos had squamous metaplasia of the conjunctivae. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that ophthalmic disease is a common finding in leopard geckos. The cause of ocular surface disease in leopard geckos may be multifactorial, and hypovitaminosis A may be an important risk factor. Although animals receiving supplemental vitamin A were less likely to have ophthalmic disease, further understanding is required regarding the metabolism of and nutritional requirements for vitamin A in leopard geckos.

Equine idiopathic hemorrhagic cystitis: Clinical features and comparison with bladder neoplasia

BACKGROUND

A new syndrome of hematuria in horses has been documented.

HYPOTHESIS/OBJECTIVES

Hemorrhagic cystitis is a novel cause of stranguria and hematuria in horses. This syndrome may be difficult to differentiate from bladder neoplasia because they share several clinical features.

ANIMALS

Eleven horses with idiopathic hemorrhagic cystitis and 7 horses with bladder neoplasia.

METHODS

Retrospective cohort study.

RESULTS

Hemorrhagic cystitis was detected on cystoscopy of affected horses, with hemorrhagic and thickened apical bladder mucosa. Clinical signs and endoscopic appearance of the bladder resolved within 3-8 weeks. Histopathology of bladder mucosal biopsy specimens featured neutrophilic and hemorrhagic cystitis. Histopathology was suggestive of dysplasia or neoplasia in 3 horses with hemorrhagic cystitis, yet the horses experienced complete resolution, suggesting that small biopsy specimens obtained by endoscopy can be difficult to interpret. Horses with bladder neoplasia had lower hematocrits, were older, more likely to be female, and more likely to have a mass detected on ultrasonographic examination of the bladder than horses with hemorrhagic cystitis syndrome.

CONCLUSIONS AND CLINICAL IMPORTANCE

Hemorrhagic cystitis represents a novel differential diagnosis for horses with hematuria, and is associated with a favorable prognosis. Although histopathology may suggest a neoplastic process, affected horses should be monitored cystoscopically, because complete resolution of hemorrhagic cystitis occurs. The cause of this disease is unknown, and warrants investigation.

Multiple ocular developmental defects in four closely related alpacas

OBJECTIVE

To describe the clinical, gross pathologic, and histopathologic findings for a visually impaired 5.8-year-old female alpaca with multiple ocular abnormalities, as well as the clinical findings for three closely related alpacas.

ANIMALS STUDIED

Four alpacas.

PROCEDURES

Ophthalmic examination was performed on a 16-month-old female alpaca following observation of visual impairment while hospitalized for an unrelated illness. Following acute systemic decline and death 4.5 years later, the alpaca's brain, optic nerves, and eyes were examined grossly and histologically. Ophthalmic examination of three closely related alpacas was subsequently performed.

RESULTS

The 16-month-old female alpaca (Alpaca 1) had ophthalmoscopic findings suggestive of a coloboma or hypoplasia of the retinal pigment epithelium (RPE) and choroid, and suspected optic nerve hypoplasia OU. Histopathology performed 4.5 years later revealed moderate to severe choroidal, RPE, and retinal hypoplasia with multifocal retinal detachments OU. However, the optic nerves were normal in size and histologic appearance when compared to an age-matched control. Clinical evaluation of the 2-year-old son of Alpaca 1 revealed iris colobomata OU and choroidal dysplasia/hypoplasia OD in addition to nonpathologic variations in melanin density including heterochromia iridis and a subalbinotic fundus OU. Clinical evaluation of the 13-year-old mother of Alpaca 1 revealed heterochromia iridis, cataracts, and a subalbinotic fundus OU. A 2-year-old half-brother of Alpaca 1 had an RPE and choroidal coloboma OS.

CONCLUSION

The developmental ocular abnormalities diagnosed in these closely related alpacas are likely hereditary.

Gut Microbiota in Human Systemic Lupus Erythematosus and a Mouse Model of Lupus

Gut microbiota dysbiosis has been observed in a number of autoimmune diseases. However, the role of the gut microbiota in systemic lupus erythematosus (SLE), a prototypical autoimmune disease characterized by persistent inflammation in multiple organs of the body, remains elusive. Here we report the dynamics of the gut microbiota in a murine lupus model, NZB/W F1, as well as intestinal dysbiosis in a small group of SLE patients with active disease. The composition of the gut microbiota changed markedly before and after the onset of lupus disease in NZB/W F1 mice, with greater diversity and increased representation of several bacterial species as lupus progressed from the predisease stage to the diseased stage. However, we did not control for age and the cage effect. Using dexamethasone as an intervention to treat SLE-like signs, we also found that a greater abundance of a group of lactobacilli (for which a species assignment could not be made) in the gut microbiota might be correlated with more severe disease in NZB/W F1 mice. Results of the human study suggest that, compared to control subjects without immune-mediated diseases, SLE patients with active lupus disease possessed an altered gut microbiota that differed in several particular bacterial species (within the genera Odoribacter and Blautia and an unnamed genus in the family Rikenellaceae) and was less diverse, with increased representation of Gram-negative bacteria. The Firmicutes/Bacteroidetes ratios did not differ between the SLE microbiota and the non-SLE microbiota in our human cohort.IMPORTANCE SLE is a complex autoimmune disease with no known cure. Dysbiosis of the gut microbiota has been reported for both mice and humans with SLE. In this emerging field, however, more studies are required to delineate the roles of the gut microbiota in different lupus-prone mouse models and people with diverse manifestations of SLE. Here, we report changes in the gut microbiota in NZB/W F1 lupus-prone mice and a group of SLE patients with active disease.

Feline dry eye syndrome of presumed neurogenic origin: a case report

Case summary

A 14-year-old female spayed Abyssinian cat, which about 1 year previously underwent thoracic limb amputation, radiotherapy and chemotherapy for an incompletely excised vaccine-related fibrosarcoma, was presented for evaluation of corneal opacity in the left eye (OS). The ocular surface of both eyes (OU) had a lackluster appearance and there was a stromal corneal ulcer OS. Results of corneal aesthesiometry, Schirmer tear test-1 (STT-1) and tear film breakup time revealed corneal hypoesthesia, and quantitative and qualitative tear film deficiency OU. Noxious olfactory stimulation caused increased lacrimation relative to standard STT-1 values suggesting an intact nasolacrimal reflex. Various lacrimostimulants were administered in succession; namely, 1% pilocarpine administered topically (15 days) or orally (19 days), and topically applied 0.03% tacrolimus (47 days). Pilocarpine, especially when given orally, was associated with notable increases in STT-1 values, but corneal ulceration remained/recurred regardless of administration route, and oral pilocarpine resulted in gastrointestinal upset. Tacrolimus was not effective. After 93 days, the cat became weak and lame and a low thyroxine concentration was detected in serum. The cat was euthanized and a necropsy performed. Both lacrimal glands were histologically normal, but chronic neutrophilic keratitis and reduced conjunctival goblet cell density were noted OU.

Relevance and novel information

The final diagnosis was dry eye syndrome (DES) of presumed neurogenic origin, associated with corneal hypoesthesia. This report reinforces the importance of conducting tearfilm testing in cats with ocular surface disease, as clinical signs of DES were different from those described in dogs.