Analysis of Cell Immunity for Children Infected with SARS-CoV-2 and Those Vaccinated against SARS-CoV-2 Using T-SPOT®.COVID.

Cellular immunity is critical for the regulation of viral diseases, including coronavirus disease 2019 (COVID-19), and is generally considered immature in childhood. However, the details of cellular immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among children are unclear. We assessed cellular immunity in eight children post-vaccination against SARS-CoV-2 and 11 children after SARS-CoV-2 infection using the T-SPOT®.COVID assay for the spike (S) and nucleocapsid (N) proteins. In the vaccinated group, the T-SPOT®.COVID assay for the S protein yielded positive results in seven children. In the post-infection group, the assay for the N protein was positive for 5 of 11 children, with 3 of these 5 children requiring hospitalization, including 2 who needed mechanical ventilation. The T-SPOT®.COVID assay is thus valuable for assessing cellular immunity against SARS-CoV-2, and most children infected with SARS-CoV-2 may not develop such immunity unless the disease severity is significant.

Single-cell RNA sequencing of human eosinophils from nasal polyps reveals eosinophil heterogeneity in chronic rhinosinusitis tissue.

BACKGROUND: Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by type 2 inflammation in the US, yet the actual roles of eosinophils in CRSwNP are largely unclear. OBJECTIVE: To reveal the roles and heterogeneity of eosinophils in nasal polyp (NP) tissue by single cell RNA-Sequencing (scRNA-Seq) analysis of NP tissue. METHODS: Sinonasal tissues (NP and control sinus tissue) and patient matched peripheral blood (PB) samples were obtained from 5 control patients and 5 patients with CRSwNP. Eosinophils were enriched prior to processing for scRNA-Seq. The gene expression profiles in eosinophils were determined by the microwell-based scRNA-Seq technology (BD Rhapsody platform). We predicted the overall function of NP eosinophils by gene ontology (GO) enrichment and pathway analyses and confirmed expression of selected genes by flow cytometry. RESULTS: After filtering out contaminating cells, we detected 5,542 eosinophils from control PB, 3,883 eosinophils from CRSwNP PB, 101 eosinophils from control sinus tissues (not included in further analyses) and 9,727 eosinophils from NPs by scRNA-Seq. We found that 204 genes were down-regulated, and 354 genes were up-regulated in NP eosinophils, compared to all PB eosinophils (>1.5-fold, Padj<0.05). Up-regulated genes in NP eosinophils were associated with activation, cytokine-mediated signaling, growth factor activity, NF-κB signaling and anti-apoptotic molecules. NP eosinophils displayed 4 clusters revealing potential heterogeneity of eosinophils in NP tissue. CONCLUSIONS: Elevated eosinophils in NP tissue appear to exist in several subtypes that may play important pathogenic roles in CRSwNP, in part via controlling inflammation and hyperproliferation of other cells.

Endotypic heterogeneity and pathogenesis in chronic rhinosinusitis.

PURPOSE OF REVIEW: This review aims to provide updates in realms of endotypic heterogeneity, pathogenesis at the molecular level, potential of biomarkers, and cutting-edge scope of biologics in CRS. RECENT FINDINGS: High-dimensional analyses, such as transcriptomes, and machine learning, have significantly enhanced CRS endotyping, uncovering diverse pathogenetic mechanisms contributing to its heterogeneity. The dynamic process of epithelial remodeling in CRS pathogenesis has gained more clarity and support as exemplified by IL-13 and oncostatin M (OSM) that are shown intricately linked to epithelial barrier dysfunction. Moreover, anti-dsDNA autoantibody, BAFF, periostin, and cystatin SN show promise as potentials biomarkers, offering diagnostic and prognostic value for CRS. SUMMARY: The identification of inflammatory molecules involved in endotype specific signaling pathways provides insights into the underlying mechanisms and verifiable biomarkers for diagnosis and prediction of disease severity. More comprehensive clinical studies should be conducted to facilitate biologics from bench to bedside in treating CRS.

Thioarylation of 6-Amino-2,3,6-trideoxy-d-manno-oct-2-ulosonic Acid (IminoKdo): Access to 3,6-Disubstituted Picolinates and Mechanistic Insights.

In this work, we present a metal-free coupling protocol for the regio- and stereoselective C3-thioarylation of 6-amino-2,3,6-trideoxy-d-manno-oct-2-ulosonic acid (iminoKdo). The developed procedure enables the coupling of electron-rich, electron-deficient, and hindered arylthiols, providing a series of C3-modified iminoKdo derivatives in moderate to good yields. Elucidation of active species through controlled experimental studies and time-lapse 31 P NMR analysis provides insights into the reaction mechanism. We demonstrate that, following a tandem Staudinger/aza-Wittig reaction of an azido-containing keto ester, an inseparable equimolar mixture of imine/enamine is formed. The enamine then undergoes a Stork-like nucleophilic attack with the in situ-formed disulfide reagent, resulting in the formation of the coupling products. Additionally, we describe a rarely reported acid-promoted aromatization of the C3-thioarylated iminoKdo skeleton into 3,6-disubstituted picolinates, which are reminiscent of dichotomines.

IL-13 and IL-13-induced periostin levels are specifically decreased in patients following endoscopic sinus surgery for chronic rhinosinusitis.

BACKGROUND: Type 2 (T2) inflammation plays a pathogenic role in chronic rhinosinusitis (CRS). The effects of endoscopic sinus surgery (ESS) on T2 inflammation are unknown. OBJECTIVE: The aim of this study was to compare T2 inflammatory biomarkers from middle meatal (MM) mucus for distinguishing patients with CRS from CRS-free patients, identifying major phenotypes (CRS without nasal polyps [CRSsNP] and CRS with nasal polyps [CRSwNP]), assessing endotypic change, and establishing cross-sectional and longitudinal outcomes in patients undergoing ESS. METHODS: MM mucus samples were collected from patients with CRSsNP and patients with CRSwNP before and 6 to 12 months after ESS and compared with samples from CRS-free control patients. T2 biomarkers were evaluated both continuously and using threshold-based definitions of T2 endotype to identify relationships with patient-reported (based on the 22-Item Sinonasal Outcomes Test and Chronic Rhinosinusitis Patient-Reported Outcomes Measure) and clinician-reported (radiographic and endoscopic) severity. Linear mixed models were developed to analyze clinical variables associated with T2 biomarker levels. RESULTS: A total of 154 patients with CRS (89 with CRSsNP and 65 with CRSwNP) were enrolled, with a mean interval of 9 months between ESS and follow-up. An analysis of pre-ESS MM mucus samples revealed elevated levels of T2 mediators in patients with CRSwNP versus in patients with CRSsNP and CRS-free controls. Temporally stable correlations between levels of IL-13 and IL-5, levels of periostin and complement 5a, and levels of eosinophil cationic protein (ECP) and eotaxin-3 were observed. On this basis and on the basis of pathologic significance, levels of IL-13, periostin and ECP were further analyzed. After ESS, levels of IL-13 and periostin decreased significantly, whereas ECP levels remained unchanged. Across pre- and post-ESS evaluation, the T2 endotype was associated with radiographic severity but did not predict outcomes. CRSwNP status and African American race were associated with higher levels of IL-13 and periostin, whereas ECP level was higher in patients undergoing extensive surgery. CONCLUSION: ESS decreased levels of IL-13 and periostin in the middle meatus. T2 inflammation after ESS was correlated with patient- and clinician-reported severity across phenotypes. Pre-ESS T2 inflammation did not predict post-ESS outcomes.

Epigenetic responses to rhinovirus exposure in airway epithelial cells are correlated with key transcriptional pathways in chronic rhinosinusitis.

BACKGROUND: Viruses may drive immune mechanisms responsible for chronic rhinosinusitis with nasal polyposis (CRSwNP), but little is known about the underlying molecular mechanisms. OBJECTIVES: To identify epigenetic and transcriptional responses to a common upper respiratory pathogen, rhinovirus (RV), that are specific to patients with CRSwNP using a primary sinonasal epithelial cell culture model. METHODS: Airway epithelial cells were collected at surgery from patients with CRSwNP (cases) and from controls without sinus disease, cultured, and then exposed to RV or vehicle for 48 h. Differential gene expression and DNA methylation (DNAm) between cases and controls in response to RV were determined using linear mixed models. Weighted gene co-expression analysis (WGCNA) was used to identify (a) co-regulated gene expression and DNAm signatures, and (b) genes, pathways, and regulatory mechanisms specific to CRSwNP. RESULTS: We identified 5585 differential transcriptional and 261 DNAm responses (FDR <0.10) to RV between CRSwNP cases and controls. These differential responses formed three co-expression/co-methylation modules that were related to CRSwNP and three that were related to RV (Bonferroni corrected p < .01). Most (95%) of the differentially methylated CpGs (DMCs) were in modules related to CRSwNP, whereas the differentially expressed genes (DEGs) were more equally distributed between the CRSwNP- and RV-related modules. Genes in the CRSwNP-related modules were enriched in known CRS and/or viral response immune pathways. CONCLUSION: RV activates specific epigenetic programs and correlated transcriptional networks in the sinonasal epithelium of individuals with CRSwNP. These novel observations suggest epigenetic signatures specific to patients with CRSwNP modulate response to viral pathogens at the mucosal environmental interface. Determining how viral response pathways are involved in epithelial inflammation in CRSwNP could lead to therapeutic targets for this burdensome airway disorder.

Insights from managing clinical issues in distal pancreatectomy with en bloc coeliac axis resection: experiences from 626 patients.

BACKGROUND: Distal pancreatectomy with en bloc coeliac axis resection (DP-CAR) for pancreatic body cancer has been reported increasingly. However, its large-scale outcomes remain undocumented. This study aimed to evaluate DP-CAR volume and mortality, preoperative arterial embolization for ischaemic gastropathy, the oncological benefit for resectable tumours close to the bifurcation of the splenic artery and coeliac artery using propensity score matching, and prognostic factors in DP-CAR. METHODS: In a multi-institutional analysis, 626 DP-CARs were analysed retrospectively and compared with 1325 distal pancreatectomies undertaken in the same interval. RESULTS: Ninety-day mortality was observed in 7 of 21 high-volume centres (1 or more DP-CARs per year) and 1 of 41 low-volume centres (OR 20.00, 95 per cent c.i. 2.26 to 177.26). The incidence of ischaemic gastropathy was 19.2 per cent in the embolization group and 7.9 per cent in the no-embolization group (OR 2.77, 1.48 to 5.19). Propensity score matching analysis showed that median overall survival was 33.5 (95 per cent c.i. 27.4 to 42.0) months in the DP-CAR and 37.9 (32.8 to 53.3) months in the DP group. Multivariable analysis identified age at least 67 years (HR 1.40, 95 per cent c.i. 1.12 to 1.75), preoperative tumour size 30 mm or more (HR 1.42, 1.12 to 1.80), and preoperative carbohydrate antigen 19-9 level over 37 units/ml (HR 1.43, 1.11 to 1.83) as adverse prognostic factors. CONCLUSION: DP-CAR can be performed safely in centres for general pancreatic surgery regardless of DP-CAR volume, and preoperative embolization may not be required. This procedure has no oncological advantage for resectable tumour close to the bifurcation of the splenic artery, and should be performed after appropriate patient selection.

Evaluation of nonnatural L-iminosugar C,C-glycosides, a new class of C-branched iminosugars, as glycosidase inhibitors.

Capitalizing on a previously developed Staudinger/azaWittig/Grignard (SAWG)-ring contraction sequence that furnished protected six-membered L-iminosugar C,C-glycosides bearing an allyl group and various substituents at the pseudoanomeric position, the synthesis and glycosidase inhibition of a small library of six- and seven-membered L-iminosugar C,C-glycosides is reported. Their hydrogenolysis or cyclization by RCM followed by deprotection afforded eleven L-iminosugars including spirocyclic derivatives. All compounds adopt a 1C4 conformation in solution according to NMR data. Compared to previously reported branched L-iminosugars, the L-iminosugar C,C-glycosides reported herein were less potent glycosidase inhibitors. However, some of these compounds showed micromolar inhibition of human lysosome ß-glucocerebrosidase suggesting that such iminosugars could be useful to access potent CGase inhibitors by adjusting the structure/length of the pseudoanomeric substituents.

Design and Pharmacological Chaperone Effects of N-(4'-Phenylbutyl)-DAB Derivatives Targeting the Lipophilic Pocket of Lysosomal Acid α-Glucosidase.

This study provides the first example of a strategy to design a practical ligand toward lysosomal acid α-glucosidase (GAA) focusing on N-alkyl derivatives of 1,4-dideoxy-1,4-imino-d-arabinitol (DAB). The optimized N-4'-(p-trifluoromethylphenyl)butyl-DAB (5g) showed a Ki value of 0.73 µM, which was 353-fold higher affinity than N-butyl-DAB (3f) without a terminal phenyl group. Docking analysis showed that the phenyl part of 5g was accommodated in a lipophilic pocket. Furthermore, the p-trifluoromethyl group effectively suppresses the fluctuation of the phenyl group, allowing it to produce a stable bonding form with GAA. 5g increased the midpoint of the protein's protein denaturation temperature (Tm) by 6.6 °C above that in the absence of the ligand and acted as a "thermodynamic stabilizer" to improve the thermal stability of rhGAA. 5g dose-dependently increased intracellular GAA activities in Pompe patient's fibroblasts with the M519V mutation; its effect was comparable to that of DNJ, which is under clinical trials.

Synthesis of the Purported Structure of Glyphaeaside C and Proposed Revisions to the Structures of the Glyphaeaside Alkaloids.

The 10 glyphaeaside alkaloids isolated from the roots of Glyphaea brevis were originally purported as piperidine-based 1-C-alkylated iminosugars, with the A-, B-, and C-type glyphaeasides bearing l-DFJ, DGJ, and DNJ ring configurations, respectively. Subsequent investigations have revealed glyphaeaside C as being a pyrrolidine-based iminosugar with a DMDP ring configuration via total synthesis of the revised structure. In this work, side chain diastereomers of the originally purported structure of glyphaeaside C (10) and two related α-1-C-alkylated DNJ derivatives were synthesized from a common precursor, which was prepared in turn via stereoselective Grignard addition to a protected d-glycosylamine, followed by a reductive amination-cyclization sequence. Glycosidase inhibitory activity studies revealed general structure 10 as having potent inhibition against various α-glucosidases and weak inhibition against almond ß-glucosidase in agreement with similar DNJ-based iminosugars and in contrast to natural glyphaeaside C, suggesting that the (1,2-dihydroxy-3-phenyl)propyl moiety does not play a particularly vital role in the inhibitory modes of action of either compound. Furthermore, the absolute configuration of natural glyphaeaside C was proposed as that of d-DMDP, and the structures of the A- and B-type glyphaeasides were revised as 1-deoxy-DALDP and DALDP derivatives, respectively, based on interpretation of their reported NMR spectroscopic data.

Sinus inflammation and chronic rhinosinusitis are associated with a diagnosis of new onset asthma in the following year.

BACKGROUND: Chronic rhinosinusitis (CRS) and asthma commonly co-occur. No studies have leveraged large samples needed to formally address whether preexisting CRS is associated with new onset asthma over time. METHODS: We evaluated whether prevalent CRS [identified in two ways: validated text algorithm applied to sinus computerized tomography (CT) scan or two diagnoses] was associated with new onset adult asthma in the following year. We used electronic health record data from Geisinger from 2008 to 2019. For each year we removed persons with any evidence of asthma through the end of the year, then identified those with new diagnosis of asthma in the following year. Complementary log-log regression was used to adjust for confounding variables (e.g., sociodemographic, contact with the health system, comorbidities), and hazard ratios (HRs) and 95% confidence intervals (CI) were calculated. RESULTS: A total of 35,441 persons were diagnosed with new onset asthma and were compared to 890,956 persons who did not develop asthma. Persons with new onset asthma tended to be female (69.6%) and younger (mean [SD] age 45.9 [17.0] years). Both CRS definitions were associated (HR, 95% CI) with new onset asthma, with 2.21 (1.93, 2.54) and 1.48 (1.38, 1.59) for CRS based on sinus CT scan and two diagnoses, respectively. New onset asthma was uncommonly observed in persons with a history of sinus surgery. CONCLUSION: Prevalent CRS identified with two complementary approaches was associated with a diagnosis of new onset asthma in the following year. The findings may have clinical implications for the prevention of asthma.

Design and synthesis of iso-allo-DNJ and L-isoDALDP derivatives: pursuit of potent and selective inhibitors of α-glucosidase.

A series of iso-allo-DNJ and L-isoDALDP derivatives were synthesized from dithioacetal 16 with sequential and highly diastereoselective Ho and Henry reactions, and aziridinium intermediate-mediated ring rearrangement as key steps. Glycosidase inhibition assay found four of them as selective α-glucosidase inhibitors, and the less substituted compound 30 showed more potent α-glucosidase inhibition (IC50 = 9.3 µM) than the others. Molecular docking study revealed different docking modes of the iso-allo-DNJ and L-isoDALDP derivatives from their parent compounds, and also the similarity of compound 30 to isofagomine.

Design, synthesis and glycosidase inhibition of DAB derivatives with C-4 peptide and dipeptide branches.

A series of DAB-peptide and DAB-dipeptide derivatives were synthesized from D-tartrate-derived nitrone 18. The DAB peptides 16 are derivatives of trans,trans-3,4-dihydroxy-L-proline. Glycosidase inhibition assay found four of them to be weak and selective bovine liver ß-galactosidase inhibitors, and the C-2' methyl substituted compound 23b showed the most potent ß-galactosidase inhibition (IC50 = 0.66 µM). Molecular docking studies revealed different docking modes of compound 23b compared to those of other DAB-peptides, and partial similarity of compound 23b to DGJ.

Genetics and epigenetics of chronic rhinosinusitis.

Discerning the genetics and epigenetics of chronic rhinosinusitis (CRS) may optimize outcomes through early diagnostics, personalized and novel therapeutics, and early prognostication. CRS associated with cystic fibrosis and primary ciliary dyskinesia has well-characterized genetic mutations. Most CRS subjects, however, do not exhibit identifiable monogenic alterations. Clustering in related individuals is seen in CRS with nasal polyps. Spouses of subjects with CRS without nasal polyps also may be at increased risk of the same disease. These observations generate questions on genetic and environmental influences in CRS. Genome-wide association studies have identified variations and polymorphisms between CRS and control subjects in genes related to innate and adaptive immunity. Candidate gene and transcriptomics studies have investigated and identified genetic variations related to immunity, inflammation, epithelial barrier function, stress-response, antigen processing, T-cell regulation, and cytokines in CRS. Epigenetic studies have identified mechanisms through which environmental factors may affect these gene functions. However, causality is not determined for most variations. Inferences drawn from these data must be measured because most investigations report unreplicated results from small study populations. Large, replicated studies in tight cohorts across diverse populations remain a pressing need in studying CRS genetics.

Evidence that oncostatin M synergizes with IL-4 signaling to induce TSLP expression in chronic rhinosinusitis with nasal polyps.

BACKGROUND: Oncostatin M (OSM) may promote type 2 inflammation in chronic rhinosinusitis with nasal polyps (CRSwNP) by inducing thymic stromal lymphopoietin (TSLP). OBJECTIVE: We sought to study the impact of OSM on TSLP synthesis and release from nasal epithelial cells (NECs). METHODS: OSM receptors, IL-4 receptors (IL-4R), and TSLP were evaluated in mucosal tissue and primary NECs from patients with CRSwNP by quantitative PCR and immunofluorescence. Air-liquid interface-cultured NECs were stimulated with cytokines, including OSM, and quantitative PCR, ELISA, Western blot, and flow cytometry were used to assess the expression of OSM receptors, IL-4R, and TSLP. RESULTS: Increased levels of OSM receptor ß chain (OSMRß), IL-4Rα, and TSLP were observed in nasal polyp tissues and primary epithelial cells from nasal polyps of patients with CRSwNP compared with control tissues or cells from control subjects. The level of expression of OSMRß in tissue was correlated with levels of both IL-4Rα and TSLP. OSM stimulation of NECs increased the expression of OSMRß and IL-4Rα. Stimulation with IL-4 plus OSM augmented the production of TSLP; the response was suppressed by a signal transducer and activator of transcription 6 inhibitor. Stimulation of NECs with IL-4 plus OSM increased the expression of proprotein convertase subtilisin/kexin 3, an enzyme that truncates and activates TSLP. CONCLUSIONS: OSM increases the expression of IL-4Rα and synergizes with IL-4 to induce the synthesis and release of TSLP in NECs. Because the combination of IL-4 and OSM also augmented the expression of proprotein convertase subtilisin/kexin 3, these results suggest that OSM can induce both synthesis and posttranslational processing/activation of TSLP, promoting type 2 inflammation.

Nanomolar ß-glucosidase and ß-galactosidase inhibition by enantiomeric α-1-C-alkyl-1,4-dideoxy-1,4-imino-arabinitol derivatives.

A series of α-1-C-alkyl DAB (1,4-dideoxy-1,4-imino-d-arabinitol) and LAB (1,4-dideoxy-1,4-imino-l-arabinitol) derivatives with aryl substituents have been designed as analogues of broussonetine W (12), and assayed as glycosidase inhibitors. While the inhibition spectrum of α-1-C-alkyl DAB derivative 16 showed a good correlation to that of broussonetine W (12), introduction of substituents on the terminal aryl (17a-f) or hydroxyl groups at C-1' position of the alkyl chains (18a-e) decreased their α-glucosidase inhibitions but greatly improved their inhibitions of bovine liver ß-glucosidase and ß-galactosidase. Furthermore, epimerization of C-1' configurations of compounds 18a-e clearly lowered their inhibition potency of bovine liver ß-glucosidase and ß-galactosidase. Notably, some of the α-1-C-alkyl DAB derivatives were also found to have potent human lysosome ß-glucosidase inhibitions. In contrast, enantiomers of compounds 18a-e and 1'-epi-18a-e generally showed increased α-glucosidase inhibitions, but sharply decreased bovine liver ß-glucosidase and ß-galactosidase inhibitions. Molecular docking calculations unveiled the novel two set of binding modes for each series of compounds; introduction of C-1' hydroxyl altered the conformations of the pyrrolidine rings and orientation of their long chains, resulting in improved accommodation in the hydrophobic grooves. The compounds reported herein are very potent ß-glucosidase and ß-galactosidase inhibitions with novel binding mode; and the structure-activity relationship provides guidance for design and development of more pyrrolidine pharmacological chaperones for lysosomal storage diseases.

Persistent discharge or edema after endoscopic sinus surgery in patients with chronic rhinosinusitis is associated with a type 1 or 3 endotype.

BACKGROUND: Patients with chronic rhinosinusitis (CRS) may have persistence of polyps, discharge, or edema after endoscopic sinus surgery (ESS). Inflammation in CRS can be classified into three endotypes, with the presence of polyps associated with the type 2 endotype. Here, we evaluate the endotypic underpinnings of discharge or edema without polyps after ESS. METHODS: At a visit 6-12 months post ESS, patients underwent endoscopy and completed the CRS-PRO and SNOT-22. Luminex analysis of middle meatal mucus obtained at that visit was performed for IFN-γ, ECP, and IL-17a. Type 1, 2, and 3 endotypes were defined as greater than the 90th percentile expression of each marker, respectively, in controls. Wilcoxon rank-sum and chi-squared tests were used to compare cytokine levels and endotype prevalence between those with and without endoscopic findings. RESULTS: A total of 122 CRS patients completed a clinical exam (median: 8.2 months post ESS). Of the 122 patients, 107 did not have polyps on endoscopy. Of these 107 patients, 48 had discharge, 44 had edema, and 46 had neither discharge nor edema. Compared with those patients without any findings, patients with discharge or edema reported significantly worse severity as measured by CRS-PRO (10.5 vs. 7.0, p = 0.009; 12.0 vs. 7.0, p < 0.001; respectively), and had higher post-ESS IFN-γ, ECP, and IL-17a. Patients with discharge had higher prevalence of only T1 and T3 endotypes, while patients with edema had higher prevalence of only the T3 endotype. CONCLUSIONS: Post-ESS discharge or edema in the absence of polyps was associated with higher patient-reported outcome severity and was more strongly associated with type 1 or 3 inflammation.

Regional antibiotic perfusion through the lateral saphenous vein in two horses with septic calcaneal osteitis.

In this case report, two horses with chronic refractory infections in the tuber calcanei were successfully managed via intravenous antibiotic regional limb perfusion through the lateral saphenous vein after failure of conventional treatment approaches, including surgery and intravenous regional limb perfusion using the cranial branch of the medial saphenous vein. Surgical delay in these cases may have allowed the development of chronic infection, which prevented the conventional regional perfusion from working effectively. The spatial difference of the vessels relative to the tuber calcanei possibly contributed to the treatment outcome in these horses. This report describes a novel approach for regional antimicrobial perfusion to the equine plantar hock region using the lateral saphenous vein.