Megan Casady

Homologous RXLR effectors from Hyaloperonospora arabidopsidis and Phytophthora sojae suppress immunity in distantly related plants

Diverse pathogens secrete effector proteins into plant cells to manipulate host cellular processes. Oomycete pathogens contain large complements of predicted effector genes defined by an RXLR host cell entry motif. The genome of Hyaloperonospora arabidopsidis (Hpa, downy mildew of Arabidopsis) contains at least 134 candidate RXLR effector genes. Only a small subset of these genes is conserved in related oomycetes from the Phytophthora genus. Here, we describe a comparative functional characterization of the Hpa RXLR effector gene HaRxL96 and a homologous gene, PsAvh163, from the Glycine max (soybean) pathogen Phytophthora sojae. HaRxL96 and PsAvh163 are induced during the early stages of infection and carry a functional RXLR motif that is sufficient for protein uptake into plant cells. Both effectors can suppress immune responses in soybean. HaRxL96 suppresses immunity in Nicotiana benthamiana, whereas PsAvh163 induces an HR-like cell death response in Nicotiana that is dependent on RAR1 and Hsp90.1. Transgenic Arabidopsis plants expressing HaRxL96 or PsAvh163 exhibit elevated susceptibility to virulent and avirulent Hpa, as well as decreased callose deposition in response to non-pathogenic Pseudomonas syringae. Both effectors interfere with defense marker gene induction, but do not affect salicylic acid biosynthesis. Together, these experiments demonstrate that evolutionarily conserved effectors from different oomycete species can suppress immunity in plant species that are divergent from the source pathogens host.

CD14++CD16+ monocytes are enriched by glucocorticoid treatment and are functionally attenuated in driving effector T cell responses

Human peripheral monocytes have been categorized into three subsets based on differential expression levels of CD14 and CD16. However, the factors that influence the distribution of monocyte subsets and the roles that each subset plays in autoimmunity are not well studied. In this study, we show that circulating monocytes from patients with autoimmune uveitis exhibit a skewed phenotype toward intermediate CD14++CD16+ cells, and that this is associated with glucocorticoid therapy. We further demonstrate that CD14++CD16+ monocytes from patients and healthy control donors share a similar cell-surface marker and gene expression profile. Comparison of the effects of intermediate CD14++CD16+ monocytes with classical CD14++CD16− and nonclassical CD14+CD16++ monocytes revealed that the intermediate CD14++CD16+ subset had an attenuated capacity to promote both naive CD4+ T cell proliferation and polarization into a Th1 phenotype, and memory CD4+ T cell proliferation and IL-17 expression. Furthermore, CD14++CD16+ cells inhibit CD4+ T cell proliferation induced by other monocyte subsets and enhance CD4+ T regulatory cell IL-10 expression. These data demonstrate the impact of glucocorticoids on monocyte phenotype in the context of autoimmune disease and the differential effects of monocyte subsets on effector T cell responses.

Fundus Autofluorescence Patterns in Primary Intraocular Lymphoma

Purpose: To evaluate fundus autofluorescence (FAF) patterns in patients with primary intraocular (vitreoretinal) lymphoma. Methods: Records of all patients with primary intraocular lymphoma who underwent FAF imaging at the National Eye Institute were reviewed. Fundus autofluorescence patterns were evaluated with respect to clinical disease status and the findings on fluorescein angiography and spectral-domain optical coherence tomography. Results: There were 18 eyes (10 patients) with primary intraocular lymphoma that underwent FAF imaging. Abnormal autofluorescence in the form of granular hyperautofluorescence and hypoautofluorescence was seen in 11 eyes (61%), and blockage by mass lesion was seen in 2 eyes (11%). All eyes with granular pattern on FAF had active primary intraocular lymphoma at the time of imaging, but there were 5 eyes with unremarkable FAF, which were found to have active lymphoma. The most common pattern on fluorescein angiography was hypofluorescent round spots with a “leopard spot” appearance (43%). These hypofluorescent spots on fluorescein angiography correlated with hyperautofluorescent spots on FAF in 5 eyes (36%) (inversion of FAF). Nodular hyperreflective spots at the level of retinal pigment epithelium on optical coherence tomography were noted in 43% of eyes. The hyperautofluorescent spots on FAF correlated with nodular hyperreflective spots on optical coherence tomography in 6 eyes (43%). Conclusion: Granularity on FAF was associated with active lymphoma in majority of the cases. An inversion of FAF (hyperautofluorescent spots on FAF corresponding to hypofluorescent spots on fluorescein angiography) was observed in less than half of the eyes.

Diagnostic Procedures in Vitreoretinal Lymphoma

Abstract Purpose: To evaluate the type and number of diagnostic interventions needed to confirm the presence of vitreoretinal lymphoma. Method: Chart review of interventions performed for diagnosis of vitreoretinal lymphoma. Results: Of the 27 cases, diagnosis was made by pars plana vitrectomy in 13 (48.1%), vitreous tap in 2 (7.4%), anterior chamber tap in 1 (3.7%), chorioretinal biopsy in 2 (7.4%), brain biopsy in 5 (18.5%), and cerebrospinal fluid cytology via lumbar puncture in 4 (14.8%). Ten (37%) had definitive results on the first procedure, and 17 (63%) had at least one false negative. Vitrectomy was the most common procedure performed. Patients required a mean of 2.1 procedures. Average time from onset of symptoms to confirmed histopathologic diagnosis was 13.9 months. Conclusion: Vitreoretinal lymphoma is difficult to recognize and requires a high degree of clinical suspicion. It often takes more than one invasive procedure to make the diagnosis.

Chemotherapy‐induced eccrine squamous syringometaplasia in an infant

There are few reports of chemotherapy‐induced eccrine squamous syringometaplasia in children. We report the first case of an infant developing this condition after treatment with busulfan, fludarabine, and antithymocyte globulin in preparation for bone marrow transplantation. Twenty‐eight days after transplantation, the infant developed faintly erythematous papules and plaques on the bilateral axillae, inguinal folds, and sites of adhesives. Punch biopsy revealed eccrine glands with dyskeratotic cells and focal squamous metaplasia consistent with chemotherapy‐induced eccrine squamous syringometaplasia.