<p> Allogeneic bone marrow-derived mesenchymal stem cells (MSCs) are a promising cell therapy for effective and efficient treatment of various inflammatory and immunemediated diseases. While the prevailing dogma has been that MSCs are immune privileged, very few studies have controlled for MHC haplotype or adequately measured MSC immunogenicity in vitro or in vivo. Controlled studies have found that major histocompatibility complex (MHC)-mismatched MSCs evoke both cell-mediated and humoral immune responses in vivo. Microcytotoxicity assays were used to show that horses injected with MHC-mismatched MSCs generate cytotoxic alloantibodies capable of killing MSCs as early as 7-days post-transplantation. Rejection of MSCs likely leads to reduced therapeutic efficacy and the development of strategies to avoid allorecognition and rejection are necessary to provide safe and efficacious allogeneic therapy.</p><p> Downregulation of MHC expression allows cells to avoid immune surveillance and may enhance the ability of MSCs to avoid allorecognition and rejection. Transforming growth factor-&beta;2 (TGF-&beta;2) has been shown to downregulate MHC surface expression in various cell types. In agreement with what has been demonstrated in other cell types, TGF-&beta;2 treatment significantly reduced constitutive MHC I and MHC II surface expression and partially blocked IFN-&gamma;-induced MHC expression on equine MSCs. TGF-&beta;2 treatment did not significantly affect the morphology, cell surface markers, viability, or secretion of TGF- &beta;1 and TGF-&beta;2, but did increase the cell yield from cultures. This data indicates that TGF-&beta;2 may reduce MSC immunogenicity without altering the immunomodulatory properties of the cells.</p><p> The immunomodulatory capabilities of TGF-&beta;2-treated MSCs were analyzed in modified one-way mixed leukocyte reactions and ELISAs. Naive and TGF-&beta;2-treated MSCs both significantly reduced T cell proliferation as measured by the relative division index and relative CFSE geometric mean fluorescent intensity attenuation. Similar amounts of PGE2 and TGF-&beta;2 were also measured in the supernatant of MLRs with naive and TGF-&beta;2-treated MSCs. This supports that TGF-&beta;2 treatment does not negatively affect the immunomodulatory properties of equine MSCs, which are critical for therapeutic function and evading immune responses in vivo.</p><p> In conclusion, although MHC-mismatched equine MSCs are immunogenic in vivo, MHC I and MHC II surface expression can be manipulated by treating cells with TGF-&beta;2 in vitro. Downregulate of MHC surface expression is a promising strategy for enhancing the ability of MSCs to evade immune responses allowing for allogenic use clinically without the risk of immune rejection. The ability of TGF-&beta;2-treated MSCs to avoid immune rejection should continue to be investigated in vitro and in vivo along with the mechanism by which TGF-&beta;2 downregulates MHC expression.</p><p>

<p> Research has shown that direct-fed microbials (DFM) and enzyme supplementation can impact the dry matter intake (DMI), milk production, and milk composition. However, limited research has evaluated the impact of DFM and enzyme supplementation on colostrum quality and the uptake of the Immunoglobulins A and G (IgA and IgG) by calves. In this study, 36 multiparous Holstein cows were blocked by expected calving date and randomly assigned to 1 of 3 treatments 3 weeks prior to calving and remained on these treatments until week 8 postpartum. These treatments were: 1) 0 g of DFM and enzyme (control), 2) 45.40 g/d of Tri-Lution&reg; (Tri), or 3) 45.40 g/d of Tri-Lution&reg; and 18.16 g/d of Zy-mend&reg; (Tri + Zy). The amount of total mixed ration (TMR) fed and orts refused were measured each day to determine DMI. Blood samples were taken on the cows every Monday, Wednesday, and Friday at 1100 h from the coccygeal veins and arteries to be analyzed for &beta;-hydroxybutyrate (BHBA), glucose, and nonesterified fatty acids (NEFA). Cows were also weighed once a week throughout the course of the study. Colostrum was harvested and weighed at parturition and later analyzed for IgA and IgG concentration via radial immunoassay. Calves were fed 4 L of maternal colostrum within 2 h after calving. Blood samples were also taken from the calves at 0 and 24 h in order to be analyzed for IgA and IgGconcentrations and to determine apparent efficiency of absorption of IgA and IgG. Finally, milk yields were taken daily for 8 wk postpartum and samples were taken once a week and sent to DairyOne (Ithaca, NY) to be analyzed for quality. Prepartum body weight (BW), BW, efficiency of gain, DMI, BHBA, NEFA, and glucose concentrations were not impacted by treatment. There was also no impact of treatment on colostrum yield, IgA and IgG content, and composition with the exception of IgA yield and ash percentage. The ash percentage of colostrum tended (<i>P</i> = 0.07) to increase with the Tri and Tri + Zy treatments while the IgA yield (<i>P</i> = 0.05) decreased with the Tri treatment. Treatments did not impact BW, serum IgA and IgG concentrations or apparent efficiency of absorption of IgA and IgG of the calves. Postpartum BW, DMI, blood metabolites, milk production and composition, with the exception of BW gain and somatic cell score (SCS), of the cows were not impacted by treatment. Cows on the Tri treatment gained more BW (<i>P</i> =0.03) and tended to have a greater efficiency of gain (<i>P</i> = 0.09) in comparison to those on the Tri + Zy treatment, but both treatments did not differ from the control. This suggests that there is a negative effect of applying the Tri-Lution&reg; and Zy-mend&reg; together which might be due to negative interactions among ingredients and microorganisms. An increase in SCS (<i>P</i> = 0.04) was also observed with the Tri treatment. All these results indicate that the supplementation of DFM and enzymes is not beneficial in improving the health and performance of dairy cattle during the transition period and early lactation.</p>