The effects of diet-induced obesity on B cell function.

B-1 and B-2 B cell subsets carry out a diverse array of functions that range broadly from responding to innate stimuli, antigen presentation, cytokine secretion and antibody production. In this review, we first cover the functional roles of the major murine B cell subsets. We then highlight emerging evidence, primarily in preclinical rodent studies, to show that select B cell subsets are a therapeutic target in obesity and its associated co-morbidities. High fat diets promote accumulation of select murine B cell phenotypes in visceral adipose tissue. As a consequence, B cells exacerbate inflammation and thereby insulin sensitivity through the production of autoantibodies and via cross-talk with select adipose resident macrophages, CD4(+) and CD8(+) T cells. In contrast, interleukin (IL)-10-secreting regulatory B cells counteract the proinflammatory profile and improve glucose sensitivity. We subsequently review data from rodent studies that show pharmacological supplementation of obesogenic diets with long chain n-3 polyunsaturated fatty acids or specialized pro-resolving lipid mediators synthesized from endogenous n-3 polyunsaturated fatty acids boost B cell activation and antibody production. This may have potential benefits for improving inflammation in addition to combating the increased risk of viral infection that is an associated complication of obesity and type II diabetes. Finally, we propose potential underlying mechanisms throughout the review by which B cell activity could be differentially regulated in response to high fat diets.

CD19-CD21 complex regulates an intrinsic Src family kinase amplification loop that links innate immunity with B-lymphocyte intracellular calcium responses.

CD19 is a B-lymphocyte cell surface molecule that functions as a general response regulator or rheostat, which defines intrinsic and B-cell antigen receptor-induced signalling thresholds that are critical for humoral immunity and expansion of the peripheral B-cell pool. In addition, B-cell responses are influenced by signals transduced through a CD19-CD21 cell surface receptor complex, where the binding of complement C3d to CD21 links humoral immune responses with the innate immune system. This review outlines recent biochemical and genetic studies that characterize the signal transduction pathways utilized by this receptor complex to regulate B-cell intracellular calcium responses.

Enhancing effects of anti-CD40 treatment on the immune response of SCID-bovine mice to Trypanosoma congolense infection.

African trypansosomes are tsetse-transmitted parasites of chief importance in causing disease in livestock in regions of sub-Saharan Africa. Previous studies have demonstrated that certain breeds of cattle are relatively resistant to infection with trypanosomes, and others are more susceptible. Because of its extracellular location, the humoral branch of the immune system dominates the response against Trypanosoma congolense. In the following study, we describe the humoral immune response generated against T. congolense in SCID mice reconstituted with a bovine immune system (SCID-bo). SCID-bo mice infected with T. congolense were treated with an agonistic anti-CD40 antibody and monitored for the development of parasitemia and survival. Anti-CD40 antibody administration resulted in enhanced survival compared with mice receiving the isotype control. In addition, we demonstrate that the majority of bovine IgM+ B cells in SCID-bo mice expresses CD5, consistent with a neonatal phenotype. It is interesting that the percentage of bovine CD5+ B cells in the peripheral blood of infected SCID-bo mice was increased following anti-CD40 treatment. Immunohistochemical staining also indicated increased numbers of Ig+ cells in the spleens of anti-CD40-treated mice. Consistent with previous studies demonstrating high IL-10 production during high parasitemia levels in mice and cattle, abundant IL-10 mRNA message was detected in the spleens and peripheral blood of T. congolense-infected SCID-bo mice during periods of high parasitemia. In addition, although detected in plasma when parasites were absent or low in number, bovine antibody was undetectable during high parasitemia. However, Berenil treatment allowed for the detection of VSG-specific IgG 14 days postinfection in T. congolense-infected SCID-bo mice. Overall, the data indicate that survival of trypanosome-infected SCID-bo mice is prolonged when an agonistic antibody against bovine CD40 (ILA156) is administered. Thus, stimulation of B cells and/or other cell types through CD40 afforded SCID-bo mice a slight degree of protection during T. congolense infection.

A comparative quantitative analysis of laminin-5 in the basement membrane of normal, hyperplastic, and malignant oral mucosa by confocal immunofluorescence imaging.

Laminin-5 (Ln-5) is a heterotrimeric basement membrane (BM) molecule (alpha3beta3gamma2). It is a principal protein constituent of the anchoring filaments, which connect the BM with the hemidesmosomes of the basal keratinocytes and possess a crucial function in keratinocyte adhesion. Confocal immunofluorescence imaging is introduced for a quantitative evaluation of the Ln-5 content in the BM of oral squamous epithelium. The BM of normal oral mucosa was used as a reference (100%) for comparative analysis and showed a nearly uniform Ln-5 immunofluorescence intensity (99-100%). In all hyperplastic lesions of oral mucosa, the Ln-5 immunofluorescence intensity was increased (107-141%). The increased Ln-5 content in the BM of hyperplastic lesions suggests an increased keratinocyte-BM adhesion, possibly resulting in a higher stability of the oral mucosa. In contrast, in the oral squamous cell carcinoma (OSCC) invasive front, the remaining BM segments were characterized by a decrease in Ln-5 immunofluorescence intensity (35-74%). A stronger decrease of Ln-5-linked kerationocyte-BM adhesion correlates with a higher tumor grade. Because in central areas of carcinoma BM segments with a normal Ln-5 content could be demonstrated, the fundamental Ln-5 diminution in BM segments of the invasive front should be considered as an invasion-associated phenomenon.

Nitric oxide inhalation and nitric oxide synthase inhibitor supplement for endotoxin-induced hypotension.

BACKGROUND: This study was performed to determine whether a combined therapy of nitric oxide (NO) inhalation and nitric oxide synthase (NOS) inhibitor is effective in experimental animals with endotoxin-induced refractive hypotension accompanied by pulmonary hypertension. METHODS: Escherichia coli lipopolysaccharide (1 mg/kg) was administered to 10 newborn piglets to induce endotoxemia. The experiment then began 60 min later, when the systemic arterial pressure dropped. The inhalation of 20 p.p.m. NO at 60 and 120 min of endotoxemia created a control group. Another group was also administered N w-nitro-L-arginine (L-NNA; 5 mg) after the first NO inhalation at 60 min of endotoxemia (the L-NNA group). Pulmonary arterial pressure, systemic arterial pressure and cardiac output were measured and compared among the groups. RESULTS: Three of the 5 piglets in the control group died of hypotensive shock, while in the L-NNA group the systemic arterial pressure recovered to pre-endotoxin administration levels. The L-NNA group produced a further increase in pulmonary arterial pressure against which NO inhalation was effective. CONCLUSION: Nitric oxide inhalation alone carries a potential risk of further lowering systemic arterial pressure in a piglet with hypotension induced by endotoxin, whereas the combined therapy resulted in the recovery of the blood pressure to pre-endotoxin levels. The combined therapy was simultaneously effective against pulmonary hypertension.

The identification and characterization of a ligand for bovine CD5.

CD5, a type I glycoprotein expressed by T cells and a subset of B cells, is thought to play a significant role in modulating Ag receptor signaling. Previously, our laboratory has shown that bovine B cells are induced to express this key regulatory molecule upon Ag receptor cross-linking. To date, a ligand has not been described for bovine CD5. Given the importance ligand binding presumably plays in the functioning of CD5 on this B cell subset and on T cells, we sought to characterize the ligand for this protein using a bovine CD5-human IgG1 (CD5Ig) fusion protein produced by both mammalian and yeast cells. As determined by CD5Ig binding, expression of this ligand is negative to low on freshly isolated lymphocytes, with low-density expression being limited to activated B cells. Activation with LPS, PMA, and calcium ionophore, or ligation of CD40 alone or in combination with anti-IgM, resulted in B cell-specific expression of this ligand. Interestingly, activation through B cell Ag receptor cross-linking alone, although able to induce CD5 expression, did not result in expression of CD5 ligand (CD5L). In addition, we demonstrate a functional role for CD5L as a costimulatory molecule that augments CD40L-stimulated B cell proliferation. Finally, immunoprecipitation with CD5Ig suggests that the ligand characterized in this study has a molecular mass of approximately 200 kDa. The data reported herein, as well as future studies aimed at further characterizing this newly identified bovine CD5L, will undoubtedly aid in understanding the role that the CD5-CD5L interaction plays in immune responses.

Activation of bovine B cells via surface immunoglobulin M cross-linking or CD40 ligation results in different B-cell phenotypes.

Experiments reported herein demonstrate that activation of bovine B cells via surface immunoglobulin M (sIgM) cross-linking, analogous to T-cell independent (TI-2) antigenic stimulation, results in the expression of CD5. Interestingly, in the presence of CD40 ligand, sIgM-mediated induction of CD5 on B cells was inhibited. These findings indicate that activation of bovine B cells via B-cell receptor (BCR) cross-linking results in a CD5+ B-cell phenotype and that CD40 signalling is inhibitory to this process. Analysis of cytokine mRNA indicates that bovine B cells constitutively express tumour necrosis factor-alpha (TNF-alpha) and interleukin (IL)-1beta transcripts in vitro, while IL-10 mRNA expression is induced following sIgM cross-linking. IL-12 p40 transcripts were produced by B cells activated by CD40, but not by BCR, ligation. Analysis of cytokine receptor mRNA indicates that activation through CD40, in the presence or absence of IgM cross-linking, results in increased IL-4 receptor-alpha (IL-4Ralpha), IL-13Ralpha1 and interferon-alpha receptor 1 (IFN-alphaR1) mRNA levels. Overall, these findings suggest that activation of bovine B cells through BCR cross-linking yields an activation phenotype that differs substantially from that of B cells activated through CD40.

Repair of a facial defect with an interpolation skin flap in a cat.

A 9-year-old domestic shorthair cat was referred for removal of a rostrally located fibrosarcoma on the face, which had previously recurred twice following excision. A wide excision was performed, using a neodymium:yttrium-aluminumgarnet (Nd:YAG) laser, resulting in a facial defect that could not be closed by primary suture. An interpolation skin flap was elevated, using skin from the side of the cat's face, and sutured in place over the defect. Recurrence of the tumor at the medial canthus of the left eye, which was observed 4 months after surgery, was treated by laser excision and cryotherapy. Other recurrences of the fibrosarcoma were not noticed for 2.5 years after referral, at which time the cat was euthanatized for other reasons. Necropsy revealed that the fibrosarcoma had not recurred. In this cat, an interpolation skin flap was useful in repairing a large rostral facial defect. Care should be taken when elevating this flap to preserve the palpebral nerve.

Maternal effects influencing DNA endoreduplication in developing endosperm of Zea mays.

A large proportion of the nuclei in developing endosperm of Zea mays L. undergoes endoreduplication. Nuclear preparations of the entire endosperm from maize kernels of inbred lines, their reciprocal hybrids, and in some cases, F2 and F3 endosperm tissue were evaluated using flow cytometry. Data relative to DNA endoreduplication patterns, percentage of nuclei undergoing endoreduplication, and mean DNA content per nucleus were obtained. The patterns of endoreduplication and extent of DNA amplification differ among some inbreds. In all experiments, the endoreduplication patterns show that the F1 endosperm is more similar to the maternal parent than to the paternal parent. F2 endosperms reveal little difference in endoreduplication patterns among individuals within an F2 family and no more variation than the F1 endosperms. In contrast, F3 endosperms showed greater variation among their endoreduplication patterns. These results indicate a maternal effect on endoreduplication; that is, the genotype of the maternal parent's nuclear genome exerts control over the endoreduplication activities of endosperm tissue.