A genetic screen identifies a protective type III interferon response to Cryptosporidium that requires TLR3 dependent recognition.

Cryptosporidium is a leading cause of severe diarrhea and diarrheal-related death in children worldwide. As an obligate intracellular parasite, Cryptosporidium relies on intestinal epithelial cells to provide a niche for its growth and survival, but little is known about the contributions that the infected cell makes to this relationship. Here we conducted a genome wide CRISPR/Cas9 knockout screen to discover host genes that influence Cryptosporidium parvum infection and/or host cell survival. Gene enrichment analysis indicated that the host interferon response, glycosaminoglycan (GAG) and glycosylphosphatidylinositol (GPI) anchor biosynthesis are important determinants of susceptibility to C. parvum infection and impact on the viability of host cells in the context of parasite infection. Several of these pathways are linked to parasite attachment and invasion and C-type lectins on the surface of the parasite. Evaluation of transcript and protein induction of innate interferons revealed a pronounced type III interferon response to Cryptosporidium in human cells as well as in mice. Treatment of mice with IFNλ reduced infection burden and protected immunocompromised mice from severe outcomes including death, with effects that required STAT1 signaling in the enterocyte. Initiation of this type III interferon response was dependent on sustained intracellular growth and mediated by the pattern recognition receptor TLR3. We conclude that host cell intrinsic recognition of Cryptosporidium results in IFNλ production critical to early protection against this infection.

The intestinal parasite Cryptosporidium is controlled by an enterocyte intrinsic inflammasome that depends on NLRP6.

The apicomplexan parasite Cryptosporidium infects the intestinal epithelium. While infection is widespread around the world, children in resource-poor settings suffer a disproportionate disease burden. Cryptosporidiosis is a leading cause of diarrheal disease, responsible for mortality and stunted growth in children. CD4 T cells are required to resolve this infection, but powerful innate mechanisms control the parasite prior to the onset of adaptive immunity. Here, we use the natural mouse pathogen Cryptosporidium tyzzeri to demonstrate that the inflammasome plays a critical role in initiating this early response. Mice lacking core inflammasome components, including caspase-1 and apoptosis-associated speck-like protein, show increased parasite burden and caspase 1 deletion solely in enterocytes phenocopies whole-body knockout (KO). This response was fully functional in germfree mice and sufficient to control Cryptosporidium infection. Inflammasome activation leads to the release of IL-18, and mice that lack IL-18 are more susceptible to infection. Treatment of infected caspase 1 KO mice with recombinant IL-18 is remarkably efficient in rescuing parasite control. Notably, NOD-like receptor family pyrin domain containing 6 (NLRP6) was the only NLR required for innate parasite control. Taken together, these data support a model of innate recognition of Cryptosporidium infection through an NLRP6-dependent and enterocyte-intrinsic inflammasome that leads to the release of IL-18 required for parasite control.

Dorsal-to-palmar branch neuroanastomosis in horses undergoing palmar digital neurectomy does not reduce neuroma formation or improve outcome.

OBJECTIVE: Chronic foot pain, a common cause of forelimb lameness, can be treated by palmar digital neurectomy (PDN). Complications include neuroma formation and lameness recurrence. In humans, neuroanastomoses are performed to prevent neuroma formation. The aim of the study was to evaluate the outcome of horses undergoing dorsal-to-palmar branch neuroanastomosis following PDN. STUDY DESIGN: Retrospective case series. ANIMALS: Eighty-five horses with PDN and dorsal-to-palmar branch neuroanastomosis. METHODS: Medical records for horses undergoing this procedure at two hospitals between 2015 and 2020 were reviewed. Palmar and dorsal nerve branches of the PDN were transected and end-to-end neuroanastomosis was performed by apposition of the perineurium. Follow-up was obtained from medical records and telephone interviews. Success was defined as resolution of lameness for at least one year. RESULTS: Lameness resolved following surgery in 81/85 (95%) horses with 57/84 (68%) sound at one year. Postoperative complications occurred in 19/85 (22%) cases. The main limitations of the study were an incomplete data set, inaccurate owner recall, and variations in procedure. CONCLUSION: Compared to previous studies, this technique resulted in similar numbers of horses sound immediately after surgery, a comparable rate of postoperative neuroma formation but a higher recurrence of lameness rate at 1 year postoperatively. CLINICAL SIGNIFICANCE: End-to-end neuroanastomosis of the dorsal and palmar branches of the PDN does not reduce the rate of neuroma formation in horses. Long-term outcome was less favorable compared to previously reported PDN techniques.

Gross, histopathologic, microbiologic, and radiologic characterization of lesions associated with clinical lameness in a cohort of group-housed sows euthanized for lameness.

Lameness in sows is reported as the most frequent cause of early culling from commercial farms and results in reduced productivity, economic losses, and a negative impact on animal welfare. Osteochondrosis was reported as the leading cause of lameness in North American sows and, although more recent European studies report infectious arthritis as the leading cause, lameness in US production facilities using group housing for gestating sows has not yet been evaluated. This study's aim was to characterize lesions associated with lameness in the appendicular musculoskeletal system of 26 sows euthanized for lameness using pathologic, radiologic, and microbiologic analyses. Of 178 total lesions, infectious lesions were most common (54%), predominated in distal limb segments (ie, at or distal to carpi and tarsi) and more often correlated with the clinically lame limb, whereas osteochondrosis and degenerative osteoarthritis predominated in proximal limb segments (ie, at or proximal to cubital and stifle joints) and rarely correlated with the clinically lame limb. The location and characteristics of infectious lesions, including mixed bacterial growth isolated from 22/22 orthopedic sites representing 19 sows with Trueperella pyogenes isolated in 16/22 (73%) of samples, suggest an etiologic component involving trauma. Radiography had a 70.6% sensitivity and 93.9% specificity for detecting infectious lesions affecting tarsocrural, antebrachiocarpal, and digital (ie, claw) regions combined. The frequency, type, and location of infectious lesions identified in this cohort of sows euthanized for lameness differ from previous reports, indicating the need for further investigation of the etiopathogenesis, earlier detection methods, and prevention.

The clinical and histopathologic effects of potentiated chlorhexidine in the upper respiratory tract of horses.

OBJECTIVE: To describe the bactericidal and fungicidal properties of a 0.0005% chlorhexidine (CHD) solution potentiated with EDTA-Tris buffers (CHD-EDTA-Tris) and evaluate the safety of 0.0005% CHD-EDTA-Tris in the upper respiratory tract (URT) of normal horses. STUDY DESIGN: Clinical, prospective study. ANIMALS: Eight healthy, skeletally mature horses. METHODS: In vitro-serial dilutions of CHD-EDTA-Tris and EDTA-Tris alone were evaluated for bactericidal and fungicidal activity against Aspergillus fumigatus, Escherichia coli, Staphylococcus aureus, Streptococcus equi subspecies ssp. equi, Streptococcus equi ssp. zooepidemicus, and Pseudomonas aeruginosa. In vivo-eight healthy horses were topically treated twice with 30 ml of 0.0005% CHD-EDTA-Tris. Mucosal samples from each location were evaluated for the presence of inflammation or pathologic lesions. RESULTS: Solutions containing CHD were superior in fungal and bacterial killing to those without. In vitro-a 0.005% CHD-EDTA-Tris was 100% effective against all bacterial and fungal species evaluated, while a 0.0005% CHD-EDTA-Tris was less efficacious against A. fumigatus and S. equi ssp. equi. In vivo-a 0.0005% CHD-EDTA-Tris did not cause any clinical, gross, or histologic abnormalities when topically applied to the equine URT. CONCLUSIONS: A 0.0005% CHD-EDTA-Tris was highly effective for killing of common bacterial and fungal isolates in the equine upper respiratory tract. Short-term topical treatment of the equine URT with dilute CHD did not cause gross or histological inflammation in the tissue. CLINICAL SIGNIFICANCE: A 0.0005% CHD solution with EDTA-Tris should be considered for treatment of clinically relevant inflammatory or infectious conditions or in the URT of the horse.

Comparison of one-layer Utrecht pattern with two-layer (simple continuous/Cushing) pattern for jejunojejunostomy in healthy horses in vivo.

OBJECTIVE: To compare end-to-end jejunal anastomoses with a one-layer (Utrecht) and two-layer (simple continuous/Cushing) patterns. STUDY DESIGN: Experimental study. ANIMALS: Eight healthy adult horses. METHODS: Jejunal end-to-end anastomoses were performed in randomly assigned one-layer or two-layer patterns. Horses were recovered from surgery and monitored for complications. At 14 days, the opposite pattern was performed (cross-over design) prior to euthanasia. Duration of closures was compared between patterns. Serosal width was measured before harvesting anastomotic sites from the first procedure. Luminal diameter was measured, and sections were collected for histological evaluation of heating after routine and immunohistochemical staining. RESULTS: One-layer closure was faster (716 ± 86 s) than two-layer closures (1136 ± 111 s). Postoperative complications were minimal. No difference was detected in lumen size between groups. The lumen was reduced by 18% after one-layer and 15% after two-layer closures (p = .34). Serosal adhesions to the mesentery without clinical evidence of obstruction were observed in two horses with two-layer closure. Histopathological scores for inflammation, infection, and healing did not differ between groups. CONCLUSION: Jejunal anastomosis with one-layer Utrecht technique was about 7 min faster and led to similar luminal reduction and histological healing scores as two-layer jejunojejunostomies. CLINICAL SIGNIFICANCE: The outcomes of one-layer Utrecht jejunojejunostomies in healthy horses justify clinical evaluation of this technique.

Use of polyamide cable ties during experimental omentectomy in adult horses with histopathological assessment.

OBJECTIVE: To report the use of nylon cable ties (NCT) for omentectomy in the horse. STUDY DESIGN: Experimental study. ANIMALS: Eight healthy adult horses. METHODS: Horses underwent nylon cable tie (NCT) ligation of the greater omentum after ventral midline celiotomy. The time required to complete the omentectomy was recorded. Horses were recovered for 14 days before repeat celiotomy, adhesions assessment, and histological examination of the omentectomy site using a proposed histologic grading scheme. The total time for omentectomy procedure and histologic score was assessed for normality. Data are expressed as mean ± standard deviation. RESULTS: NCT ligation provided sufficient hemostasis to complete the omentectomy (28 ± 15 s), without rescue ligation. No gross evidence of intra-abdominal adhesion or morbidity was associated with the omentectomy site 14 days after surgery. NCT were intact at the site of application, covered with smooth fibrous connective tissue. Adiponecrosis with minimal inflammation and fibrovascular occlusion of omental vessels was present at the surgical site. Mild inflammation was present at the NCT-tissue interface. CONCLUSION: The use of NCT resulted in fast and effective omentectomy in healthy horses without short-term evidence of inflammatory reaction or intra-abdominal adhesion. CLINICAL SIGNIFICANCE: The described technique provides an alternative for omentectomy in healthy adult horses.

Ocular disease in horses with confirmed ocular or central nervous system Borrelia infection: Case series and review of literature.

OBJECTIVE: To describe the clinical presentation, treatment, and clinical outcome of horses with ocular disease and evidence of systemic or ocular Lyme disease. ANIMALS STUDIED: Five horses met the inclusion criteria of ocular disease with evidence of B burgdorferi present in ocular or CNS tissues. PROCEDURE: The goal of this study was to describe the clinical presentation and progression of ocular disease when associated with ocular or CNS B burgdorferi infection in horses. A retrospective review of medical records was performed on horses admitted for ocular disease with evidence of B burgdorferi infection between 1998 and 2015. The diagnosis of B burgdorferi-associated uveitis was based on histopathologic lesions of lymphohistiocytic and suppurative uveitis/endophthalmitis and intralesional argyrophilic spirochetes in either ocular or CNS tissue consistent with Borrelia. Leptospiral uveitis was ruled out by PCR. RESULTS: All five horses in the current study had intraocular inflammation at the time of presentation. Medical management with anti-inflammatories was successful in controlling uveitis in the two horses in which treatment of uveitis was attempted. Systemic treatment with oral tetracyclines was unsuccessful in a single case in which treatment of Borrelia was attempted. Four horses were euthanized due to progression of neurologic disease. The surviving horse had an enucleation performed and did not show systemic signs. CONCLUSIONS: Infection with Borrelia burgdorferi should be considered in endemic areas as a differential for horses with ocular disease, in particular, uveitis. The prognosis for uveitis and neurologic disease associated with Lyme disease was poor in the current study.

Detection of endoplasmic reticulum stress and the unfolded protein response in naturally-occurring endocrinopathic equine laminitis.

BACKGROUND: Laminitis is often associated with endocrinopathies that cause hyperinsulinemia and is also induced experimentally by hyperinsulinemia, suggesting that insulin initiates laminitis pathogenesis. Hyperinsulinemia is expected to activate pro-growth and anabolic signaling pathways. We hypothesize that chronic over-stimulation of these pathways in lamellar tissue results in endoplasmic reticulum stress, contributing to tissue pathology, as it does in human metabolic diseases. We tested this hypothesis by asking whether lamellar tissue from horses with naturally-occurring endocrinopathic laminitis showed expression of protein markers of endoplasmic reticulum stress. RESULTS: Three markers of endoplasmic reticulum stress, spliced XBP1, Grp78/BiP and Grp94, were upregulated 2.5-9.5 fold in lamellar tissues of moderately to severely laminitic front limbs (n = 12) compared to levels in controls (n = 6-7) measured by immunoblotting and densitometry. Comparing expression levels between laminitic front limbs and less affected hind limbs from the same horses (paired samples from 7 to 8 individual horses) demonstrated significantly higher expression for both spliced XBP1 and Grp78/BiP in the laminitic front limbs, and a similar trend for Grp94. Expression levels of the 3 markers were minimal in all samples of the control (n = 6-7) or hind limb groups (n = 7-8). Immunofluorescent localizations were used to identify cell types expressing high levels of Grp78/BiP, as an indicator of endoplasmic reticulum stress. Grp78/BiP expression was highly elevated in suprabasal epidermal keratinocytes and only observed in laminitic front limbs (10/12 laminitic samples, compared to 0/7 in sections from the hind limbs and 0/5 of controls). CONCLUSIONS: These data demonstrate that the endoplasmic reticulum stress pathway is active in naturally occurring cases of laminitis and is most active within a subset of epidermal keratinocytes. These data provide the rationale for further study of endoplasmic reticulum stress in experimental models of laminitis and the links between laminitis and human diseases sharing activation of this stress pathway. Pharmacological options to manipulate the endoplasmic reticulum stress pathway under investigation for human disease could be applicable to laminitis treatment and prevention should this pathway prove to be a driver of disease progression.

Identification of the Identical Human Mutation in ACVR1 in 2 Cats With Fibrodysplasia Ossificans Progressiva.

Two domestic shorthair cats, 1 intact female and 1 intact male, presented with progressive limb lameness and digital deformities at 4 and 6 months of age. Stiffness and swelling of the distal thoracic and pelvic limb joints progressed to involve hip and shoulder joints, resulting in reduced mobility. Radiographs in both cats and computed tomography of the male cat revealed ankylosing, polyarticular deposits of extracortical heterotopic bone spanning multiple axial and appendicular joints, extending into adjacent musculotendinous tissues. All findings supported fibrodysplasia ossificans progressiva (FOP), a disorder characterized by toe malformations and progressive heterotopic ossification in humans. In both cats, molecular analyses revealed the same heterozygous mutation in the activin A receptor type I (ACVR1) gene that occurs in humans with FOP. Several reports of heterotopic ossification in cats exist, but this is the first one to identify clinical FOP in 2 cats with the identical mutation that occurs in >95% of humans with FOP.

Infection-induced changes in hematopoiesis.

The bone marrow (BM) is an important site for the interrelated processes of hematopoiesis, granulopoiesis, erythropoiesis, and lymphopoiesis. A wide variety of microbial challenges are associated with profound changes in this compartment that impact on hematopoietic differentiation and mobilization of a variety of cell types. This article reviews some of the key pathways that control BM homeostasis, the infectious and inflammatory processes that affect the BM, and how addressing the knowledge gaps in this area has the potential to widen our comprehension of immune homeostasis.

Single injection of intra-articular autologous protein solution in horses with acute interleukin-1B-induced synovitis decreases joint pathology scores.

BACKGROUND: Autologous protein solution (APS) has been shown to decrease lameness in horses with osteoarthritis (OA). Synovitis is an early driver of OA, providing an opportunity to intervene in the progression of disease via intra-articular (IA) therapeutics. OBJECTIVES: The objective of this study was to investigate the effects of a single IA APS injection in horses with interleukin-1ß (IL-1ß)-induced synovitis. We hypothesised that APS would decrease joint swelling and lameness, improve synovial fluid parameters and improve joint pathology scores in horses compared with untreated controls. STUDY DESIGN: Randomised controlled in vivo experiment. METHODS: Synovitis was induced with IL-1ß (65 ng) in one randomly selected tarsocrural joint. Twenty-four hours later, joints were treated with APS (Pro-Stride®) (n = 12) or left as untreated controls (n = 6). Lameness examinations and joint circumference measurements were performed on Days 0 (prior to IL-1ß), 1 (prior to APS), 2, 4, 7 and 14. Synovial fluid, obtained on the same days, was analysed for protein concentration, nucleated cell count, and cytokine (IL-1ß, TNF-α, IFN-γ, IL-6, IL-10) and prostaglandin E2 (PGE2) concentrations. Gross pathology and synovial membrane histopathology scoring was performed on APS-treated (n = 5), untreated control (n = 4) and normal (n = 9) tarsocrural joints. RESULTS: APS did not decrease lameness or joint circumference compared with untreated controls. Synovial fluid parameters were not different between treatment groups. APS treatment did significantly decrease gross and histopathology scores. MAIN LIMITATIONS: Main limitations included the use of an induced model of the synovitis, inter-horse variability in the response to IL-1ß and likely variability in the constituents of APS from individual horses. CONCLUSIONS: APS treatment of tarsocrural joints with synovitis did not significantly improve lameness or alter synovial fluid parameters. APS did lead to significant improvement in gross joint appearance and synovial membrane histology suggesting that APS may have disease-modifying effects.

Targeted transcriptomic analysis of synovial tissues from horses with septic arthritis treated with immune-activated mesenchymal stromal cells reveals induction of T-cell response pathways.

OBJECTIVE: To investigate mechanistically the reported beneficial effects of immune-activated mesenchymal stromal cell (MSC) therapy to treat equine septic arthritis, leveraging Nanostring technology. ANIMALS: 8 Quarter Horses with induced tibiotarsal Staphylococcus aureus septic arthritis treated IA with either Toll-like receptor-3 agonist polyinosinic:polycytidylic acid-activated MSCs + vancomycin antimicrobials (TLR-MSC-VAN; n = 4) or antimicrobials (VAN; 4). METHODS: Synovial tissues were collected and fixed in neutral-buffered 10% formalin, and formalin-fixed paraffin-embedded synovial and osteochondral tissues were sequenced using a custom-designed 200-gene equine Nanostring nCounter immune panel to directly quantify expression of key immune and cartilage-related genes. Immunohistochemistry to detect CD3+ T cells was performed on synovial tissues to further quantify T-cell infiltration in TLR-MSC-VAN- versus VAN-treated joints. RESULTS: Comparison of synovial transcriptomes between groups revealed moderate changes in differential gene expression, with upregulated expression of 9 genes and downregulated expression of 17 genes with fold change ≥ 2 or ≤ -2 and a significant false discovery rate-adjusted P value of ≤ .05. The most upregulated genes in TLR-MSC-VAN-treated horses included those related to T-lymphocyte recruitment and function, while pathways related to innate immune activation and inflammation were significantly downregulated. Immunohistochemistry and quantitation of CD3+ T-cell infiltrates revealed a numerically greater infiltrate in synovial tissues of TLR-MSC-VAN-treated horses, which did not reach statistical significance in this small sample set (P = .20). CLINICAL RELEVANCE: Targeted transcriptomic analyses using an equine Nanostring immune and cartilage health panel provided new mechanistic insights into how innate and adaptive immune cells within synovial tissues respond to TLR-activated MSC treatment when used to treat septic arthritis.

Plasma and synovial fluid extracellular vesicles display altered microRNA profiles in horses with naturally occurring post-traumatic osteoarthritis: an exploratory study.

OBJECTIVE: The objective of this study was to characterize extracellular vesicles (EVs) in plasma and synovial fluid obtained from horses with and without naturally occurring post-traumatic osteoarthritis (PTOA). ANIMALS: EVs were isolated from plasma and synovial fluid from horses with (n = 6) and without (n = 6) PTOA. METHODS: Plasma and synovial fluid EVs were characterized with respect to quantity, size, and surface markers. Small RNA sequencing was performed, and differentially expressed microRNAs (miRNAs) underwent bioinformatic analysis to identify putative targets and to explore potential associations with specific biological processes. RESULTS: Plasma and synovial fluid samples from horses with PTOA had a significantly higher proportion of exosomes and a lower proportion of microvesicles compared to horses without PTOA. Small RNA sequencing revealed several differentially expressed miRNAs, including miR-144, miR-219-3p, and miR-199a-3l in plasma and miR-199a-3p, miR-214, and miR-9094 in synovial fluid EVs. Bioinformatics analysis of the differentially expressed miRNAs highlighted their potential role in fibrosis, differentiation of chondrocytes, apoptosis, and inflammation pathways in PTOA. CLINICAL RELEVANCE: We have identified dynamic molecular changes in the small noncoding signatures of plasma and synovial fluid EVs in horses with naturally occurring PTOA. These findings could serve to identify promising biomarkers in the pathogenesis of PTOA, to facilitate the development of targeted therapies, and to aid in establishing appropriate translational models of PTOA.

Prevalence, association with stifle conditions, and histopathologic characteristics of tibial tuberosity radiolucencies in dogs.

A tibial tuberosity radiolucency is sometimes identified on lateral radiographs of canine stifle joints, however little is known about the cause or significance. The purpose of this study was to describe the prevalence, association with other stifle conditions, and histopathologic characteristics of tibial tuberosity radiolucencies in a group of dogs. Radiographs of all canine stifle joints over 5 years were evaluated. Presence or absence of a tibial tuberosity radiolucency was recorded by an observer who was unaware of clinical status. Patient signalment and presence of other stifle joint conditions were recorded from medical records. A tibial tuberosity radiolucency was found in 145/675 dogs (prevalence = 21.5%). Statistically significant associations were identified between tibial tuberosity radiolucency and stifle condition (P < 0.0001), breed size (P = 0.011), and younger age of presentation (P = 0.001), but not with gender (P = 0.513). Dogs with a tibial tuberosity radiolucency had higher odds of having a medial patellar luxation than dogs without (OR = 9.854, P < 0.0001, 95% CI 6.422-15.120). Dogs with a tibial tuberosity radiolucency had lower odds of having a cranial cruciate ligament rupture than dogs without (OR = 0.418, P < 0.0001, 95% CI 0.287-0.609). Four canine cadavers, two with normal stifles and two with tibial tuberosity radiolucencies, underwent radiographic, computed tomographic, and histologic examination of the stifles. Computed tomography revealed a hypoattenuating cortical defect in the lateral aspect of the proximal tibial tuberosity that corresponded histopathologically to a hyaline cartilage core. Findings indicated that the tibial tuberosity radiolucency may be due to a retained cartilage core and associated with medial patellar luxation in dogs.

A potentially fatal cranial pathology in a specimen of Tarchia.

Skulls of the Mongolian ankylosaurids Shamosaurus, Tarchia, and Saichania were scanned for information about their internal anatomy. Computed tomography (CT) imaging of the Tarchia skull revealed substantial internal anatomical differences from known Campanian North American taxa, particularly in the morphology of the airway. In addition, unexpected anomalies were detected within the airway and sinuses. The anomalies include multiple bilaterally distributed, variably sized hyperdense (mineralized) concretions within the airway and sinuses, the largest of which, positioned in the right nasal cavity medial to the supraorbitals, has an asymmetric ovoid shape that tapers caudally and which is partially encased within a hemispherical trabeculated osseous proliferation (sinus exostosis). Immediately adjacent to the exostosis is a subcircular transosseous defect in the prefrontal region of the skull roof that is partially filled with trabeculated ossified material with similar architectural features as the larger exostosis. Irregularities along the internal and external surfaces of the cranial vault may be associated. The radiologic features of the hemicircumferential exostosis suggest a chronic reactive osteoproliferation, possibly in response to an ongoing inflammatory reaction to primary sinus infection or, in combination with the unilateral transosseous defect, traumatically introduced infection with potentially fatal consequences. This report underscores the value of CT scanning of fossil vertebrate specimens, which in this case revealed large internal lesions of the skull that, at the time the scan was performed, were otherwise indiscernible.

Evaluation of locking compression plate fixation of the distal phalanx to the hoof wall as a potential therapy for laminitis.

BACKGROUND: Surgical stabilisation of the distal phalanx (DP) is a potential therapeutic strategy for severe acute laminitis. OBJECTIVE: To evaluate the effects of locking compression plate (LCP) fixation of the DP to the dorsal hoof wall. STUDY DESIGN: Ex vivo and in vivo experiments. METHODS: A T-shaped LCP was applied to one limb per pair in six pairs of cadaver forelimbs subjected to a combination of thermally induced lamellar failure and vertical load to simulate severe acute laminitis. Standard radiographic measurements were used to compare DP displacement. The LCP was then applied to one forefoot in 12 healthy Standardbred horses either standing (n = 6) or under general anaesthesia (n = 6). Lameness was evaluated daily, then horses were euthanised (day 8) and lamellar tissue analysed using light microscopy, histomorphometery and molecular markers of apoptosis. RESULTS: In the cadaver limb model, LCP fixation prevented the significant changes in hoof-distal phalanx distance, coronary extensor process distance and sole depth that characterised DP displacement in untreated limbs (p < 0.05). Application of the construct in vivo was well tolerated with minimal lameness (10/12 horses were sound at the trot on day 8); however, histology revealed dorsal lamellar pathology consistent with laminitis, but with extensive keratinocyte apoptosis. Adjacent to the LCP, caspase-3 positive cell counts were approximately 20-fold higher than control (p < 0.001). MAIN LIMITATIONS: Pathology was evaluated at a single time point. Microvascular perfusion was not evaluated. CONCLUSIONS: Rigid fixation of the DP to the hoof capsule was achieved with the LCP construct in a cadaver limb laminitis model. In live horses, LCP fixation caused regional lamellar pathology with extensive apoptosis, likely due to disturbed lamellar microvascular perfusion and/or mechanostasis. Understanding these mechanisms is critical for refinement of the technique in order to avoid iatrogenic lamellar damage.

Little Brown Bats (Myotis lucifugus) Support the Binding of SARS-CoV-2 Spike and Are Likely Susceptible to SARS-CoV-2 Infection.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), believed to have originated from a bat species, can infect a wide range of non-human hosts. Bats are known to harbor hundreds of coronaviruses capable of spillover into human populations. Recent studies have shown a significant variation in the susceptibility among bat species to SARS-CoV-2 infection. We show that little brown bats (LBB) express angiotensin-converting enzyme 2 receptor and the transmembrane serine protease 2, which are accessible to and support SARS-CoV-2 binding. All-atom molecular dynamics (MD) simulations revealed that LBB ACE2 formed strong electrostatic interactions with the RBD similar to human and cat ACE2 proteins. In summary, LBBs, a widely distributed North American bat species, could be at risk of SARS-CoV-2 infection and potentially serve as a natural reservoir. Finally, our framework, combining in vitro and in silico methods, is a useful tool to assess the SARS-CoV-2 susceptibility of bats and other animal species.

Tension-activated nanofiber patches delivering an anti-inflammatory drug improve repair in a goat intervertebral disc herniation model.

Conventional microdiscectomy treatment for intervertebral disc herniation alleviates pain but does not repair the annulus fibrosus, resulting in a high incidence of recurrent herniation and persistent dysfunction. The lack of repair and the acute inflammation that arise after injury can further compromise the disc and result in disc-wide degeneration in the long term. To address this clinical need, we developed tension-activated repair patches (TARPs) for annulus fibrosus repair and local delivery of the anti-inflammatory factor anakinra (a recombinant interleukin-1 receptor antagonist). TARPs transmit physiologic strain to mechanically activated microcapsules embedded within the patch, which release encapsulated bioactive molecules in direct response to spinal loading. Mechanically activated microcapsules carrying anakinra were loaded into TARPs, and the effects of TARP-mediated annular repair and anakinra delivery were evaluated in a goat model of annular injury in the cervical spine. TARPs integrated with native tissue and provided structural reinforcement at the injury site that prevented aberrant disc-wide remodeling resulting from detensioning of the annular fibrosus. The delivery of anakinra by TARP implantation increased matrix deposition and retention at the injury site and improved maintenance of disc extracellular matrix. Anakinra delivery additionally attenuated the inflammatory response associated with TARP implantation, decreasing osteolysis in adjacent vertebrae and preserving disc cellularity and matrix organization throughout the annulus fibrosus. These results demonstrate the therapeutic potential of TARPs for the treatment of intervertebral disc herniation.

Comparison of the zip skin closure system with conventional suture for skin closure of ventral midline incisions in horses.

OBJECTIVE: To compare the application and healing of the zip skin closure system (ZSCS) with sutured closure by use of a split-scar model of ventral midline incisions in horses in a prospective, randomized experimental study. ANIMALS: 8 adult horses. PROCEDURES: All horses underwent an exploratory ventral midline celiotomy with a standardized 30-cm skin incision. Each horse was randomized to have either the cranial 15 cm closed with suture and caudal 15 cm with the ZSCS or vice versa (split-scar model). Skin closure time was recorded and compared. Photography and skin biopsies were taken preoperatively and 14 days postoperatively. Cosmetic appearance was assessed by use of a proposed equine celiotomy incision score. Healing at 14 days was assessed by histopathology. RESULTS: Skin closure times were faster with the ZSCS compared to sutured incisions. At 14 days postoperatively, the cosmetic appearance (equine celiotomy incision scores) for ZSCS incisions were better than sutured closure and histologic healing scores were not different between methods of closure. Subcuticular sutures were associated with deep dermal inflammation and necrosis independent of epidermal closure methods. CLINICAL RELEVANCE: While limitations to the utility of the ZSCS are recognized, the potential benefits of expedient closure, good cosmetic outcome, and satisfactory healing make this method viable for closure of linear wounds or incisions in horses.