Establishment of isotype-switched, antigen-specific B cells in multiple mucosal tissues using non-mucosal immunization

Although most pathogens infect the human body via mucosal surfaces, very few injectable vaccines can specifically target immune cells to these tissues where their effector functions would be most desirable. We have previously shown that certain adjuvants can program vaccine-specific helper T cells to migrate to the gut, even when the vaccine is delivered non-mucosally. It is not known whether this is true for antigen-specific B cell responses. Here we show that a single intradermal vaccination with the adjuvant double mutant heat-labile toxin (dmLT) induces a robust endogenous, vaccine-specific, isotype-switched B cell response. When the vaccine was intradermally boosted, we detected non-circulating vaccine-specific B cell responses in the lamina propria of the large intestines, Peyer's patches, and lungs. When compared to the TLR9 ligand adjuvant CpG, only dmLT was able to drive the establishment of isotype-switched resident B cells in these mucosal tissues, even when the dmLT-adjuvanted vaccine was administered non-mucosally. Further, we found that the transcription factor Batf3 was important for the full germinal center reaction, isotype switching, and Peyer's patch migration of these B cells. Collectively, these data indicate that specific adjuvants can promote mucosal homing and the establishment of activated, antigen-specific B cells in mucosal tissues, even when these adjuvants are delivered by a non-mucosal route. These findings could fundamentally change the way future vaccines are formulated and delivered.

The Adjuvant Combination of dmLT and Monophosphoryl Lipid A Activates the Canonical, Nonpyroptotic NLRP3 Inflammasome in Dendritic Cells and Significantly Interacts to Expand Antigen-Specific CD4 T Cells

Adjuvants are often essential additions to vaccines that enhance the activation of innate immune cells, leading to more potent and protective T and B cell responses. Only a few vaccine adjuvants are currently used in approved vaccine formulations in the United States. Combinations of one or more adjuvants have the potential to increase the efficacy of existing and next-generation vaccines. In this study, we investigated how the nontoxic double mutant Escherichia coli heat-labile toxin R192G/L211A (dmLT), when combined with the TLR4 agonist monophosphoryl lipid A (MPL-A), impacted innate and adaptive immune responses to vaccination in mice. We found that the combination of dmLT and MPL-A induced an expansion of Ag-specific, multifaceted Th1/2/17 CD4 T cells higher than that explained by adding responses to either adjuvant alone. Furthermore, we observed more robust activation of primary mouse bone marrow-derived dendritic cells in the combination adjuvant-treated group via engagement of the canonical NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome complex. This was marked by a multiplicative increase in the secretion of active IL-1β that was independent of classical gasdermin D-mediated pyroptosis. Moreover, the combination adjuvant increased the production of the secondary messengers cAMP and PGE2 in dendritic cells. These results demonstrate how certain adjuvant combinations could be used to potentiate better vaccine responses to combat a variety of pathogens.

Sexual dimorphism in the antigen-specific T cell response in S. Typhimurium infections within extra-lymphoid tissues

Differences in susceptibility to and severity of infectious diseases between the sexes are well established. Females often generate a beneficially stronger immune response when combatting infection but show an increased risk of developing autoimmunity. While the sex-related hormone estradiol is known to affect CD4 T cell cytokine release in vitro, less is known about T cells behavior in vivo. To address this, we intravenously infected male and female mice with attenuated Salmonella Typhimurium (S. Tm). By day 15 post infection (p.i.), male mice showed significantly lower rates of survival. Males also generated a higher number of S. Tm-specific CD4 T cells in the liver but, conversely, displayed higher bacterial burdens. To isolate the role of sex hormones, mice were gonadectomized before reaching sexual maturity and then infected. Ovariectomized mice lost significantly more weight than ovary-intact females by day 15 p.i. Like normal males, ovariectomized females demonstrated a significantly higher number of S. Tm-specific CD4 T cells but also higher liver bacterial burdens. To investigate the role of extra-lymphoid tissues such as the liver, we infected lymphotoxin-alpha (LTa) mice that genetically lack lymphoid tissues. Surprisingly, we found the stark difference in survival and CD4 T cell expansion between the sexes was lost. These differences in T cell expansion, and the commensurate effect on survival, in the presence or absence of endogenous sex hormones or lymphoid tissues indicate that females may have evolved a separate ability to regulate immune responses outside of traditional lymphoid organs. These studies will provide insights into sex-based differences seen in cellular immunity against bacterial pathogens in vivo.

Supported by a grant from the Keck Foundation

Salmonella Biofilm Formation, Chronic Infection, and Immunity Within the Intestine and Hepatobiliary Tract

Within the species of Salmonella enterica, there is significant diversity represented among the numerous subspecies and serovars. Collectively, these account for microbes with variable host ranges, from common plant and animal colonizers to extremely pathogenic and human-specific serovars. Despite these differences, many Salmonella species find commonality in the ability to form biofilms and the ability to cause acute, latent, or chronic disease. The exact outcome of infection depends on many factors such as the growth state of Salmonella, the environmental conditions encountered at the time of infection, as well as the infected host and immune response elicited. Here, we review the numerous biofilm lifestyles of Salmonella (on biotic and abiotic surfaces) and how the production of extracellular polymeric substances not only enhances long-term persistence outside the host but also is an essential function in chronic human infections. Furthermore, careful consideration is made for the events during initial infection that allow for gut transcytosis which, in conjunction with host immune functions, often determine the progression of disease. Both typhoidal and non-typhoidal salmonellae can cause chronic and/or secondary infections, thus the adaptive immune responses to both types of bacteria are discussed with particular attention to the differences between Salmonella Typhi, Salmonella Typhimurium, and invasive non-typhoidal Salmonella that can result in differential immune responses. Finally, while strides have been made in our understanding of immunity to Salmonella in the lymphoid organs, fewer definitive studies exist for intestinal and hepatobiliary immunity. By examining our current knowledge and what remains to be determined, we provide insight into new directions in the field of Salmonella immunity, particularly as it relates to chronic infection.

Identification and characterization of oviductal glycoprotein-binding protein partner on gametes: epitopic similarity to non-muscle myosin IIA, MYH 9

The mammalian estrogen induced oviductal glycoprotein (OGP) has been known to associate with capacitated sperm, oocytes and developing embryos. This study aimed to identify the putative binding partner of OGP on gametes using N-terminal peptide of bonnet monkey (Macaca radiata) OGP, Nmon, as bait. A protein(s) of molecular size approximately 54 kDa was detected by far-western blot analysis of detergent solubilized human sperm proteins. MALDI-TOF mass spectra analysis of approximately 54 kDa tryptic peptides gave a significant hit to non-muscle myosin heavy chain. Biochemical characterization of approximately 54 kDa was done with antibodies specific to non-muscle myosin IIA, MYH9. The approximately 54 kDa protein, possible breakdown product of MYH9, immunoreacted with MYH9 antibody in western blot analysis. OGP binding to approximately 54 kDa could also be demonstrated in far-western blot analysis of detergent solubilized human sperm proteins and nuclear matrix intermediate filament (NM-IF) preparations from human sperm and mouse oocytes. Far-western blot analysis of MYH9 enriched by immunoprecipitation identified the native approximately 220 kDa protein as OGP-binding partner. The identical and characteristic immunogold localization pattern of Nmon and MYH9 on sperm NM-IF preparation substantiated these findings. The results suggest that OGP binds to both gametes through its interaction with MYH9 through the non-glycosylated N-terminal conserved region of OGP, spanning the residues 11-137.

Ca2+ and BMP-6 signaling regulate E2F during epidermal keratinocyte differentiation

The epidermis consists of a squamous epithelium continuously replenished by committed stem cells, which can either self-renew or differentiate. We demonstrated previously that E2F genes are differentially expressed in developing epidermis (Dagnino, L., Fry, C. J., Bartley, S. M., Farnham, P., Gallie, B. L., and Phillips, R. A. (1997) Cell Growth Differ. 8, 553-563). Thus, we hypothesized that various E2F proteins likely play distinct growth regulatory roles in the undifferentiated stem cells and in terminally differentiated keratinocytes. To further understand the function of E2F genes in epidermal morphogenesis, we have examined the expression, regulation, and protein-protein interactions of E2F factors in undifferentiated cultured murine primary keratinocytes or in cells induced to differentiate with Ca(2+) or BMP-6 (bone morphogenetic protein 6). We find similar patterns of E2F regulation with both differentiating agents and demonstrate a switch in expression from E2F-1, -2, and -3 in undifferentiated, proliferating cells to E2F-5 in terminally differentiated keratinocytes. Inhibition of keratinocyte proliferation by transforming growth factor-beta1 did not enhance E2F-5 protein levels, suggesting that this response is specific to differentiation rather than reversible cell cycle withdrawal. E2F-5 up-regulation is also accompanied by formation of heteromeric nuclear complexes containing E2F5, p130, and histone deacetylase (HDAC) 1. Overexpression of E2F5 specifically inhibited DNA synthesis in undifferentiated keratinocytes in an HDAC-dependent manner, suggesting that E2F-5.p130.HDAC1 complexes are likely involved in the permanent withdrawal from the cell cycle of keratinocytes responding to differentiation stimuli.

Apoptosis of rat decidual cells: site specific initiation and related biochemical changes

The artificially induced rat deciduoma serves as a model to study cellular changes associated with implantation in the endometrium. The stromal cells differentiate to form two types of decidual cells and are restricted to specific anatomical sites of the uterus. Programmed cell death starts in the antimesometrial area and expression of glutathione-S-transferase, an antioxidant enzyme, enhances in these cells as the deciduoma enters the regressive phase. The enzyme activity is significantly high compared with that of mesometrial decidual cells. Similarly, lipid peroxide content of antimesometrial decidual cells is high during this phase. DNA fragmentation, a feature of cells undergoing programmed cell death, is initiated in the antimesometrial area during regression of deciduoma.

Topological analysis of NHE1, the ubiquitous Na+/H+ exchanger using chymotryptic cleavage

Proteases, glycosidases, and impermeant biotin derivatives were used in combination with antibodies to analyze the subcellular distribution and transmembrane disposition of the Na+/H+ exchanger NHE1. Both native human NHE1 in platelets and epitope-tagged rat NHE1 transfected into antiport-deficient cells were used for these studies. The results indicated that 1) the entire population of exchangers is present on the surface membrane of unstimulated platelets, ruling out regulation by recruitment of internal stores of NHE1; 2) the putative extracellular loops near the NH2 terminus are exposed to the medium and contain all the N- and O-linked carbohydrates; 3) by contrast, the putative extracellular loops between transmembrane domains 9-10 and 11-12 are not readily accessible from the outside and may be folded within the protein, perhaps contributing to an aqueous ion transport pathway; 4) the extreme COOH terminus of the protein was found to be inaccessible to extracellular proteases, antibodies, and other impermeant reagents, consistent with a cytosolic localization; and 5) detachment of approximately 150 amino acids from the NH2-terminal end of the protein had little effect on the transport activity of NHE1.

Diagnosis and management of stenotic aorto-arteriopathy in childhood

Stenotic aorto-arteriopathy is an uncommon vascular lesion characterized by segmental arterial stenoses. We reviewed the experience with several management algorithms to define the most effective management course. The clinical records of 14 pediatric patients with acquired SAA who presented over a 16-year period were reviewed. Most patients presented with a mid-thoracoabdominal coarctation and were diagnosed with Takayasu arteritis. Differentiating between Takayasu arteritis and fibromuscular dysplasia was difficult on clinical grounds or by angiography. Medical management of the end-organ disease and renovascular hypertension was only palliative. Selective percutaneous transluminal balloon angioplasty of the stenotic renal arteries had only transient benefits; renal autotransplantation had slightly better success. Dilation of stenosed aortic segments with balloon-expandable endovascular stents and subsequent renal autotransplantation proved useful. Distinguishing SAA resulting from fibromuscular dysplasia caused by Takayasu arteritis in the chronic vaso-occlusive phase may be unnecessary for effective treatment. Therapy should focus on interventions to minimize the end-organ damage caused by the vaso-occlusive manifestations of the disorders.

Biogenesis of L-glyceric aciduria, oxalosis and renal injury in rats simulating type II primary hyperoxaluria

Tracer experiments in rats mimicking type II primary hyperoxaluria, with an expanded intracellular pool of hydroxypyruvate, showed that the excess formation of oxalate did not originate from its immediate precursor glyoxylate. In these animals, the hepatic and kidney activities of oxalate synthesising enzymes such as lactate dehydrogenase and glycolate oxidase were normal, but tissue lipid peroxidation was significantly higher. In vitro experiments established that in a mild alkaline solution, hydroxypyruvate underwent auto-oxidation to form oxalate and H2O2 and also inhibited lactate dehydrogenase and glycolate oxidase from oxidising glyoxylate to oxalate. On the basis of the experimental evidence, we suggest that in type II primary hyperoxaluria, the accumulating hydroxypyruvate could reduce the intracellular pool of glyoxylate and on ageing, give rise to excess oxalate and H2O2, to cause oxalosis in the former and free radical mediated-cell injuries in the latter.

Investigation with chitosan-oxalate oxidase-catalase conjugate for degrading oxalate from hyperoxaluric rat chyme

Enteric hyperoxaluria manifests due to hyperabsorption of dietary oxalate, secondary to a variety of chronic gastrointestinal disorders. The potential use of chitosan immobilized oxalate oxidase-catalase conjugate to deplete the oxalate content of food materials, while they are in the digestive tract has been evaluated by treating rat stomach chyme with such an enzyme preparation. Oxalate oxidase, obtained from beet stem, was adsorbed on chitosan along with catalase and then cross linked with glutaraldehyde to stabilize the derivative. This chemical modification of oxalate oxidase brought about a shift in its optimal pH from 4.2 to 3.8 with a marginal increase in its K(m). Compared to native enzyme, the modified oxalate oxidase exhibited increased storage stability, higher thermal stability and enhanced resistance to proteolytic digestion and heavy metal inactivation. These improved properties of the immobilized oxalate oxidase possibly render it suitable for oral administration under hyperoxaluric conditions.

Pulmonary function abnormalities in childhood sickle cell disease

Pulmonary function tests in adults with sickle cell disease have shown a restrictive pattern that has been attributed to the sequelae of acute chest syndrome (ACS). We compared pulmonary function test results in 37 children with sickle cell anemia (20 with SS hemoglobin (HbSS), 14 with SC hemoglobin, and 3 with S beta hemoglobin) with those in 22 control subjects matched for sex, race, and height and compared pulmonary function in patients with and without a history of ACS. Of the 10 patients with a history of ACS, all but one had HbSS. Pulmonary function tests measured forced vital capacity (FVC), the diffusion capacity of carbon monoxide, and the plethysmographic determination of lung volumes. The FVC and forced expiratory volume in 1 second (FEV1), expressed as the percentage of the predicted value, were significantly less for those with HbSS with or without a history of ACS than for control subjects (p < 0.05), but the FEV1/FVC ratio, an index of airway obstruction, was normal in all groups. Total lung capacity was also significantly lower in patients with HbSS with or without a history of ACS than in control subjects (p < 0.05), but the ratio of residual volume to total lung capacity, another index of airway obstruction, was normal. We conclude that children with sickle cell disease, particularly those with HbSS, may have abnormally small lungs that function normally relative to their size; clustering of ACS episodes is not specifically associated with the observed abnormality.

Cardiac output and oxygen delivery during exercise in sickle cell anemia

Desaturation in patients with sickle cell anemia (SCA) can lead to intravascular sickling and vascular occlusion. The increased metabolic demands of exercise tend to increase oxygen extraction, giving rise to a fall in saturation in the capillary bed that may predispose to sickling. This could be minimized with an increase in cardiac output. The aims of this study were to assess the role of increased stroke volume (SV) in augmenting cardiac output (Q) and to estimate the role of enlarged arteriovenous O2 content difference in maintaining O2 transport in children with SCA. A group of 30 children with SCA (Hb 65 to 133 g/L) and 16 healthy controls of the same racial group and of similar height and weight performed incremental and steady-state exercise at 50% Wmax. Cardiac output (Q) was measured by the indirect (CO2) Fick method during steady state. The slope of delta HR/delta VO2 during incremental exercise was higher in SCA subjects compared with controls (4.01 +/- 1.73 versus 2.80 +/- 0.61 bpm per ml/min/kg VO2, p = 0.001). Q for VO2 was abnormally high in patients, particularly older ones with lower Hb levels. HR (% predicted) was higher in patients than in controls (106 +/- 11 versus 92 +/- 8% predicted, p less than 0.0001), as was SV (113 +/- 16 versus 98 +/- 14% predicted, p = 0.002). Multiple linear regression of Q % predicted and SV % predicted on Hb and age showed a positive correlation with age and a negative correlation with Hb (r = 0.84 for Q and r = 0.76 for SV).(ABSTRACT TRUNCATED AT 250 WORDS)

Ventilation and gas exchange during exercise in sickle cell anemia

Adults with sickle cell anemia (SCA) have restrictive lung impairment, increased alveolar dead space, and hypoxemia. These factors, together with increased anaerobic metabolism, are thought to cause exercise hyperventilation. To assess the role of each of these in children, 34 patients with SCA and 16 control subjects performed pulmonary function and exercise tests. Twenty-eight patients with SCA had spirometric values and lung volumes, and all but two patients with SCA had arterial saturation greater than 91% during exercise. Despite a low VO2max (30.07 +/- 6.55 ml/min/kg), the ventilatory anaerobic threshold (VAT) in the patients occurred at a similar %VO2max as in the control subjects (69 +/- 9% versus 63 +/- 12%). The slope of the delta VE/delta VCO2 relationship for sub-VAT work was steeper in the patients (29.4 +/- 6.5 versus 24.7 +/- 5.2, p = 0.01), and the ventilatory equivalent for CO2 (VE/VCO2) in steady-state exercise was greater in the patients than in the control subjects (33.2 +/- 3.5 versus 30.8 +/- 3.5, p = 0.03). End-tidal PCO2 did not differ (38.3 +/- 3.0 versus 39.2 +/- 3.1), indicating equivalent alveolar ventilation. The patients had a higher dead space:tidal volume ratio (VD/VT) than did the control subjects (0.204 +/- 0.033 versus 0.173 +/- 0.024, p = 0.0005). The PaCO2 was significantly lower in those with lower Hb, but there was no difference in pH. In conclusion, children with SCA have an increased exercise ventilatory response caused in part by increased physiologic dead space, and in part by their low Hb. The greater dead space may be the result of sickle cells impairing capillary perfusion to ventilated alveoli.

Aspirin, indomethacin, and tartrazine increase carotid-sinus-nerve activity and arterial blood pressure in guinea pigs

Acetylsalicylic acid (ASA; 0.1-10 mg/kg), indomethacin (IND; 0.1-1.0 mg/kg), and tartrazine (TZ; 0.1-2.0 mg/kg), given intravenously induced dose-dependent increases in carotid-sinus nerve (CSN) activity, accompanied by increases in mean arterial blood pressure (MABP), but only the IND-induced MABP increases were dose-dependent. The MABP and CSN activity responses to all three drugs were not correlated, suggesting a direct action on CSN afferents that is unrelated to the pressor effects of the drugs. Sodium cromoglycate (10 mg/kg) selectively reduced the increases in CSN response to ASA and IND. Phentolamine (0.2 mg/kg) inhibited the increased CSN activity induced by ASA, IND, and TZ. These findings indicate that ASA, IND, and TZ act directly on carotid baroreceptors to increase their activity.