Acute kidney injury (AKI) is a major clinical concern in sickle cell disease (SCD). Clinical evidence suggests that red cell alarmins may cause AKI in SCD however the sterile inflammatory process involved has hitherto not been defined. We discovered that hemopexin deficiency in SCD is associated with a compensatory increase in alpha-1-microglobulin (A1M) resulting in up to 10-fold higher A1M/hemopexin ratio in SCD compared to health controls. The A1M/hemopexin ratio is associated with markers of hemolysis and AKI in both humans and mice with SCD. Studies in mice showed that excess heme is directed to the kidneys in SCD in a process involving A1M causing AKI while excess heme in controls is transported to the liver as expected. Using genetic and bone marrow chimeric tools, we confirmed that hemopexin deficiency promotes AKI in sickle mice under hemolytic stress. However, AKI was blocked when hemopexin deficiency in sickle mice was corrected with infusions of purified hemopexin prior to the induction of hemolytic stress. This study identifies acquired hemopexin deficiency as a risk factor of AKI in SCD and hemopexin replacement as a potential therapy.

Synovial infections (SI) are common in horses of all ages and can be associated with high rates of morbidity and mortality. Identifying factors influencing survival and return to function may be useful for management of affected individuals and determination of prognosis. The objectives of this study were to identify factors associated with survival and return to function of horses and foals with SI presented to an equine hospital. This study is a retrospective case series. Data were collected from medical records of all horses with SI that were presented to a single equine hospital between April 1st, 2008 and May 1st, 2017. Long–term follow up was obtained by a semi-structured telephone questionnaire of clinical outcomes and analysis of online race records. Univariate models were created using generalized linear and linear mixed models to assess factors associated with outcomes. Multivariable models were created using generalized linear and linear mixed models to determine factors significantly associated with outcomes. Of 186 horses presented with SI, 161/186 (86.6%) were treated and 145/161 (90.1%) survived to discharge. The majority of joints were treated with synovial lavage (93.8%). One hundred and twenty horses were included in the return to function analysis and 79 (65%) returned to function. Increasing number of days of treatment with systemic antimicrobials was associated with increased likelihood of survival for each horse (OR 1.15, 95% CI 1.04−1.27, P = 0.025) and when considering each individual synovial structure (OR 1.11, 95% CI 1.04−1.17, P = 0.004). Horses treated with doxycycline were less likely to return to function (OR 0.39, 95% CI 0.19−0.8, P = 0.031). The overall rate of survival of horses treated with SI is good. The likelihood of return to function is lower than for survival. The findings of this study, combined with relevant antimicrobial stewardship practices, can be used as a part of evidence-based decision-making when veterinarians are treating horses with SI.

Background: Grading of equine gastric ulcer syndrome (EGUS) is undertaken in clinical and research settings, but the reliability of EGUS grading systems is poorly understood. Hypothesis/Objectives: Investigate interobserver and intraobserver reliability of an established ordinal grading system and a novel visual analog scale (VAS), and assess the influence of observer experience. Animals: Sixty deidentified gastroscopy videos. Methods: Six observers (3 specialists and 3 residents) graded videos using the EGUS Council (EGUC) system and VAS. Observers graded the videos three 3 for each system, using a cross-over design with at least 1 week between each phase. The order of videos was randomized for each phase. Methods: Interobserver and intraobserver reliability were estimated using Gwet's agreement coefficient with ordinal weights applied (AC2) for the EGUC system and the intraclass correlation coefficient (ICC) for the VAS.

Summary Tumours of vascular origin are uncommon in horses. This report describes the surgical treatment of a large subcutaneous tumour in a Quarter Horse colt. The histopathological appearance of the mass was most consistent with a haemangioma. While these neoplasms of vascular origin are often difficult to characterise, it has been suggested that there is a continuum of types with some cases falling between the categories. Further classification of vascular tumours requires special stains and immunohistochemical techniques.

A 6-month-old female spayed domestic shorthair cat was presented with an acute onset of vomiting and marked lethargy. The cat had undergone elective ovariohysterectomy via a small midline incision 2 weeks prior to presentation. Intestinal strangulation through a mesenteric rent was diagnosed via abdominal ultrasound and exploratory laparotomy. Intestinal resection and anastamosis resulted in a good clinical outcome despite excision of 60% of the small intestine.

No abstract

Chronic kidney disease (CKD), widespread among the individuals with sickle cell disease (SCD), is a major contributor to early death in this patient population. The progressive deterioration of renal health in SCD is associated with chronic persistent intravascular hemolysis leading to anemia. We have previously reported that extracellular heme, released during acute intravascular hemolysis triggers clinically relevant acute kidney injury (AKI) in SCD mice (SS) (Blood (2020) 135 (13): 1044-1048). Although AKI is reversible, it is considered as a risk factor for CKD. The mechanistic approach elucidating the hemolysis driven pathogenesis of AKI-to-CKD transition in SCD is unknown. We found that CKD develops in the SS mice by progressive (1-10 months of age) increase in albuminuria (urinary albumin and creatinine ratio, uACR) and decrease in glomerular filtration rate (GFR) (n=5; p<0.001). Histopathology of the kidney showed age-dependent deterioration in renal peritubular vascular congestion in SS mice compared to that of the AA mice. Alongside, Evan's blue extravasation experiments showed that the SS mice are susceptible to vascular leakage that is correlated positively with age (Pearson r=0.98, p<0.001) and negatively with anemia (Pearson r= -0.46, p<0.05). We hypothesized that multiple acute hemolytic events may instigate persistent endothelial damage that ensues CKD development in SCD. To test this hypothesis, we intravenously infused vehicle or heme (14 μmoles/kg body weight; 5 times on alternate days) to 1-month old SS mice and monitored for 3 weeks following first heme injection. These mice developed severe albuminuria (n=5; p<0.01) with substantial loss of GFR (n=5; p<0.001), indicating heme induced CKD development. Next, we used ultrasound super-resolution (USR) imaging technology to determine renal microvascular changes in older SS mice (6-months) without heme challenge and in young SS mice (1-month) challenged with heme. Analysis of the USR data showed reduced renal blood volume (rBV) and substantial loss of vessel density in renal cortex as well as in corticomedullary areas of the older SS mice compared to the age-matched AA mice. Accordingly, multiple heme challenge reduced rBV and vessel density extensively in young SS mice comparable to the older SS mice without heme challenge. Since endothelial protein C receptor (EPCR) maintains vascular barrier integrity by activating protease activated receptor-1 (PAR1) signaling in the endothelium, we tested whether alterations in EPCR expression contribute to progressive endothelial damage in SS mice during CKD development. Using immunofluorescence microscopy, we determined that renal endothelium lacks expression of EPCR in older SS mice while younger SS mice retains EPCR cellular expression. In corroboration, infusion of heme in younger SS mice results in loss of renal endothelial EPCR. Shedding of EPCR from endothelium often results in a soluble form of EPCR (sEPCR). We found that SS mice had higher plasma levels of soluble EPCR (sEPCR) compared to their AA counterparts. While age dependent increase in plasma and urinary sEPCR were evident in SS mice (n=6; p<0.01), infusion of heme in younger SS mice results in significant increase in plasma sEPCR (n=6; p<0.01). In consistent with the mouse data, we discovered that the plasma sEPCR was significantly elevated in SCD patients compared to normal individuals (n=8-16; p<0.05). Moreover, the plasma sEPCR was significantly associated with the baseline albuminuria in a cohort of SCD patients (n=16; Pearson r=0.64; p<0.01). This study supports the conclusion that multiple hemolytic events may trigger CKD development in SCD by gradual loss of renal microvascular EPCR expression. Clinically, the sEPCR can be developed as risk factor for sickle CKD. Finally, our data suggest that restoration of EPCR function may protect SCD patients from CKD. Disclosures No relevant conflicts of interest to declare.

Acute kidney injury (AKI) is a major clinical concern during episodes of acute chest syndrome and vaso-occlusive crisis in sickle cell disease (SCD). AKI increases the risk of chronic kidney disease (CKD) and end stage renal disease (ESRD). We previously showed that alpha-1-microglobulin (A1M), a low affinity heme-binding protein that carries heme for renal clearance is elevated in patients and mice with homozygous SCD (SS). Hemopexin (Hx), which primarily scavenges circulating heme to the liver, is exhausted in SCD. In this study, we explored the idea that acquired Hx deficiency in SCD is a risk factor for AKI development in SCD. We studied mice with a global knockout of Hx with no detectable plasma Hx at baseline. Plasma A1M was significantly elevated in the Hx-/-mice compared to control (Hx+/+) mice (n=5; p<0.01). We then transplanted whole bone marrow cells from SS mice into Hx+/+and Hx-/-mice to create bone marrow chimeric SSHx+/+and SSHx-/-mice with SCD phenotype. The chimeras had elevated plasma A1M compared to recipient littermates (Hx+/+and Hx-/-) and low baseline glomerular filtration rate (GFR). Modest elevation of circulating heme with infusion of hemin (20 μmoles/kg bw) worsened GFR and caused severe AKI. Next, to determine whether hemin induced AKI is attenuated by elevation of circulating Hx, we infused SS mice with purified Hx, and control SS mice with either purified A1M or vehicle immediately prior to the hemin challenge. We observed improved GFR in the Hx-treated SS mice, while vehicle and A1M-treated mice suffered 23% and 39% loss of GFR respectively compared to their baseline. In agreement with the GFR data, the levels of several AKI diagnostic markers, plasma creatinine (plasma Cr), urinary albumin-creatinine ratio (uACR) and kidney injury molecule (uKIM-1) were elevated significantly in vehicle and A1M treated mice following hemin challenge. In Hx-treated mice, these biomarkers remained unaltered. Importantly, Hx infusions re-directed excess heme in SS mice to the liver, while A1M infusion significantly increased total heme content in the kidneys. Two-way ANOVA analysis of GFR (p<0.01) and plasma Cr (p<0.001) revealed significant exacerbation of kidney injury in A1M treated SS mice compared to vehicle treated mice. Histopathology of renal tissue showed considerable tissue damage in vehicle and A1M infused SS mice, while Hx treated SS mice kidneys appeared relatively normal. This study provides genetic evidence that hemopexin deficiency promotes AKI development in SCD, and we provide proof-of-principle for hemopexin replacement therapy to treat AKI in SCD. Disclosures Ofori-Acquah: Shire Human Genetic Therapies Inc: Other: Financial Relationship.