Platelet dysfunction in Chediak-Higashi syndrome-affected cattle

Induced pluripotent stem cells from domesticated ruminants and their potential for enhancing livestock production

Ruminant livestock, including cattle, sheep, goat, and buffalo, are essential for global food security and serve valuable roles in sustainable agricultural systems. With the limited availability of embryonic stem cells (ESCs) from these species, ruminant induced pluripotent stem cells (iPSCs) and iPSC-like cells provide a valuable research tool for agricultural, veterinary, biomedical, and pharmaceutical applications, as well as for the prospect of translation to human medicine. iPSCs are generated by reprogramming of adult or fetal cells to an ESC-like state by ectopic expression of defined transcription factors. Despite the slow pace the field has evolved in livestock species compared to mice and humans, significant progress has been made over the past 15 years in using different cell sources and reprogramming protocols to generate iPSCs/iPSC-like cells from ruminants. This mini review summarizes the current literature related to the derivation of iPSCs/iPSC-like cells from domesticated ruminants with a focus on reprogramming protocols, characterization, associated limitations, and potential applications in ruminant basic science research and production.

Gastrointestinal Bleeding in Congenital Bleeding Disorders

Gastrointestinal bleeding (GIB) is serious, intractable, and potentially life-threatening condition. There is considerable heterogeneity in GIB phenotypes among congenital bleeding disorders (CBDs), making GIB difficult to manage. Although GIB is rarely encountered in CBDs, its severity in some patients makes the need for a comprehensive and precise assessment of underlying factors and management approaches imperative. Initial evaluation of GIB begins with assessment of hematological status; GIB should be ruled out in patients with chronic anemia, and in presentations that include hematemesis, hematochezia, or melena. High-risk patients with recurrent GIB require urgent interventions such as replacement therapy for treatment of coagulation factor deficiency (CFD). However, the best management strategy for CFD-related bleeding remains controversial. While several investigations have identified CBDs as potential risk factors for GIB, research has focused on assessing the risks for individual factor deficiencies and other CBDs. This review highlights recent findings on the prevalence, management strategies, and alternative therapies of GIB related to CFDs, and platelet disorders.

A genome-wide association study reveals a locus for bilateral iridal hypopigmentation in Holstein Friesian cattle

BACKGROUND

Eye pigmentation abnormalities in cattle are often related to albinism, Chediak-Higashi or Tietz like syndrome. However, mutations only affecting pigmentation of coat color and eye have also been described. Herein 18 Holstein Friesian cattle affected by bicolored and hypopigmented irises have been investigated.

RESULTS

Affected animals did not reveal any ophthalmological or neurological abnormalities besides the specific iris color differences. Coat color of affected cattle did not differ from controls. Histological examination revealed a reduction of melanin pigment in the iridal anterior border layer and stroma in cases as cause of iris hypopigmentation. To analyze the genetics of the iris pigmentation differences, a genome-wide association study was performed using Illumina BovineSNP50 BeadChip genotypes of the 18 cases and 172 randomly chosen control animals. A significant association on bovine chromosome 8 (BTA8) was identified at position 60,990,733 with a -log₁₀(p) = 9.17. Analysis of genotypic and allelic dependences between cases of iridal hypopigmentation and an additional set of 316 randomly selected Holstein Friesian cattle controls showed that allele A at position 60,990,733 on BTA8 (P = 4.0e-08, odds ratio = 6.3, 95% confidence interval 3.02-13.17) significantly increased the chance of iridal hypopigmentation.

CONCLUSIONS

The clinical appearance of the iridal hypopigmentation differed from previously reported cases of pigmentation abnormalities in syndromes like Chediak-Higashi or Tietz and seems to be mainly of cosmetic character. Iridal hypopigmentation is caused by a reduced content of melanin pigment in the anterior border layer and iridal stroma. A single genomic position on BTA8 was detected to be significantly associated with iridal hypopigmentation in examined cattle. To our knowledge this is the first report about this phenotype in Holstein Friesian cattle.

A new method for rapid detection of the mutant allele for Chediak-Higashi syndrome in Japanese black cattle

Chediak-Higashi syndrome (CHS) is an autosomal recessive hereditary disorder in Japanese Black cattle, caused by a mutation of the Lyst gene. So far, the mutation has been detected by PCR-restriction fragment length polymorphism (PCR-RFLP) analysis. However, this method is disadvantaged by its low-throughput performance. Here, we report an alternative method involving real-time PCR with TaqMan minor groove binder probes, which shortens the total assay time by more than 120 min, analyzing 10 samples in a duplicated manner. Using this method, we examined 102 Japanese Black cattle and found that 8.8% of the cattle were CHS-carriers. These data indicate that our technique is useful for routine diagnostic testing for CHS in Japanese Black cattle.

Case control study to investigate risk factors for bovine neonatal pancytopenia (BNP) in young calves in southern Germany

A case control study on farm level was conducted at the Clinic for Ruminants, LMU Munich, to identify possible risk factors associated with the observed increase in numbers of calves showing clinical signs of Bovine Neonatal Pancytopenia (BNP) since 2006 in southern Germany. Interviews were conducted between August 2008 and June 2010.

The characteristics of 56 dairy farms with at least one confirmed case of BNP (thrombocytopenia and leukocytopenia and/or typical findings in post-mortem examination and bone marrow histology) were compared with those of two sets of 50 control dairy farms each, with no history of BNP. The first set of 50 control farms was selected randomly from veterinary practices which had never observed a BNP case on the farms they serviced. The second set of 50 control farms was matched by the veterinary practices which had provided case farms. Two separate analyses were conducted: (1) case farms (n = 56) vs. randomly selected control farms (n = 50) and (2) case farms (n = 56) vs. a matched set of control farms (n = 50). All variables with p < 0.2 in the univariable analysis were included in stepwise logistic regression models. In the first analysis, only the use of PregSure^® BVD vaccine was positively associated with BNP with an odds ratio of 1292 (95% CI: 114–14707). In the second analysis, conditional logistic regression models did not converge, therefore non-conditional logistic regression models were conducted. In the non-conditional analysis five variables remained in the model, three of which were negatively associated with BNP: the use of vitamin E and selenium, the frequent use of mastitis tubes, and the use of stem growth regulators in grain production. The use of prophylactic measures (such as control of parasites or vaccination of calves against respiratory disease) was positively associated with BNP with an odds ratio of 14.3 as well as the use of PregSure^® BVD vaccine with an odds ratio of 426 (95% CI: 20–9095).

Neutrophil function in small animals

Neutrophils are highly mobile phagocytes that serve as the initial effectors against pathogens and are actively recruited to sites of inflammation. Chemoattractants guide them toward the inflammation, and their interaction with endothelial cells directs them through postcapillary venules and into the tissues. Once they have reached their destination, they can efficiently kill many microbes via phagocytosis, extracellular release of granule contents, and the formation of NETs. They also actively produce cytokines and other mediators to promote or suppress inflammation, repair tissues, and modulate the immune response. The importance of neutrophil function in host health is emphasized through discussion of inherited disorders of neutrophil function such as leukocyte adhesion deficiency and cyclic hematopoiesis.

Potential large animal models for gene therapy of human genetic diseases of immune and blood cell systems

Genetic mutations involving the cellular components of the hematopoietic system--red blood cells, white blood cells, and platelets--manifest clinically as anemia, infection, and bleeding. Although gene targeting has recapitulated many of these diseases in mice, these murine homologues are limited as translational models by their small size and brief life span as well as the fact that mutations induced by gene targeting do not always faithfully reflect the clinical manifestations of such mutations in humans. Many of these limitations can be overcome by identifying large animals with genetic diseases of the hematopoietic system corresponding to their human disease counterparts. In this article, we describe human diseases of the cellular components of the hematopoietic system that have counterparts in large animal species, in most cases carrying mutations in the same gene (CD18 in leukocyte adhesion deficiency) or genes in interacting proteins (DNA cross-link repair 1C protein and protein kinase, DNA-activated catalytic polypeptide in radiation-sensitive severe combined immunodeficiency). Furthermore, we describe the potential of these animal models to serve as disease-specific preclinical models for testing the efficacy and safety of clinical interventions such as hematopoietic stem cell transplantation or gene therapy before their use in humans with the corresponding disease.

The crystal structure of the platelet activator aggretin reveals a novel (alphabeta)2 dimeric structure

Aggretin is a C-type lectin purified from Calloselasma rhodostoma snake venom. It is a potent activator of platelets, resulting in a collagen-like response by binding and clustering platelet receptor CLEC-2. We present here the crystal structure of aggretin at 1.7 A which reveals a unique tetrameric quaternary structure. The two alphabeta heterodimers are arranged through 2-fold rotational symmetry, resulting in an antiparallel side-by-side arrangement. Aggretin thus presents two ligand binding sites on one surface and can therefore cluster ligands in a manner reminiscent of convulxin and flavocetin. To examine the molecular basis of the interaction with CLEC-2, we used a molecular modeling approach of docking the aggretin alphabeta structure with the CLEC-2 N-terminal domain (CLEC-2N). This model positions the CLEC-2N structure face down in the "saddle"-shaped binding site which lies between the aggretin alpha and beta lectin-like domains. A 2-fold rotation of this complex to generate the aggretin tetramer reveals dimer contacts for CLEC-2N which bring the N- and C-termini into the proximity of each other, and a series of contacts involving two interlocking beta-strands close to the N-terminus are described. A comparison with homologous lectin-like domains from the immunoreceptor family reveals a similar but not identical dimerization mode, suggesting this structure may represent the clustered form of CLEC-2 capable of signaling across the platelet membrane.

Alteration of release and role of adenosine diphosphate and thromboxane A2 during collagen-induced aggregation of platelets from cattle with Chediak-Higashi syndrome

OBJECTIVE

To compare the interaction of endogenous ADP with collagen and thromboxane A(2) (TXA(2)) during collagen-induced platelet aggregation between platelets from healthy cattle and those with Chediak-Higashi syndrome (CHS). POPULATION SAMPLE: Platelets harvested from blood samples from healthy Japanese Black cattle and those with CHS.

PROCEDURES

Aggregation of gel-filtered platelets; release of ATP-ADP; and generation of thromboxane B(2) (TXB(2)), a metabolite of TXA(2), were measured.

RESULTS

The potency of collagen to induce aggregation in platelets of cattle with CHS (ie, CHS platelets) was less than a tenth of that in platelets of healthy cattle (ie, control platelets). Platelet aggregation induced by collagen at an intermediate concentration depended on the coexistence of ADP and TXA(2), suggesting that released ADP cannot cause platelet aggregation by itself. Collagen-induced ADP release was markedly decreased, whereas TXB(2) production was slightly low in CHS platelets, compared with that in control platelets. A combination of subthreshold amounts of ADP and 9,11-dideoxy-9alpha, 11alpha-methano-epoxy-prostaglandin F(2) (U46619), a TXA(2) analogue, caused platelet aggregation. Similarly, a combination of subthreshold amounts of collagen and ADP caused platelet aggregation, whereas collagen and U46619 were not synergistic.

CONCLUSIONS AND CLINICAL RELEVANCE

Deficient ADP release ensuing from the delta-storage pool deficiency in platelets from cattle with CHS resulted in reduction of collagen-induced platelet aggregation, through attenuation of synergism between TXA(2) and ADP and between ADP and collagen. Furthermore, results of the study reported here indicated that TXA(2) was important for aggregation of bovine platelets.

Molecular diversity and accelerated evolution of C-type lectin-like proteins from snake venom

A number of C-type lectin-like proteins that affect thrombosis and hemostasis by inhibiting or activating specific platelet membrane receptors or blood coagulation factors have been isolated from the venom of various snake species and characterized and more than 80 have been sequenced. Recent data on the primary sequences and 3D structures of C-type lectins and C-type lectin-like proteins from snake venoms have enabled us to analyze their molecular evolution. Statistical analysis of their cDNA sequences shows that C-type lectin-like proteins, with some exceptions, have evolved in an accelerated manner to acquire their diverse functions. Phylogenetic analysis shows that the A and B chains of C-type lectin-like proteins are clearly separated from C-type lectins and that the A and B chains are further divided into a group of platelet receptor-binding proteins and a group of coagulation factor-binding proteins. Elucidation of the tertiary structures of several C-type lectin-like proteins led to the discovery of a unique domain-swapping interaction between heterodimeric subunits, which creates a concave surface for ligand binding.