Th2-skewed T cells correlate with B cell response to α-Gal and tick antigens in α-Gal syndrome.

Tick bites have been shown to transmit a novel form of severe food allergy, the galactose-α-1,3-galactose (α-Gal) syndrome (AGS). Cellular responses to α-Gal in patients with AGS have, to date, not been thoroughly scrutinized. Therefore, we investigated T and B cell proliferation, activation, and cytokine profiles in response to tick protein extract (TE) and α-Gal-free TE in patients with AGS and in healthy controls. T and B cells from both patients and controls proliferated in response to TE, but significantly more in patients with AGS. B cell proliferation, but not T cell proliferation, in patients with AGS was reduced by removing α-Gal from the TE. In addition, TE induced a clear Th2 cytokine profile in patients with AGS. Expression of CD23 by B cells correlated only to T cell proliferation. However, both B cell proliferation and CD23 expression were reduced when CD40L and IL-4 were blocked. A large portion of the IgG1 and IgE antibodies binding TE in patients with AGS were directed against the α-Gal epitope. We have, for what we believe to be the first time, investigated T and B cell responses to α-Gal carrying tick proteins in patients with AGS, which will be essential for the understanding of the immune response against an allergenic carbohydrate transmitted by ticks.

Intensive weight gain therapy in patients with anorexia nervosa results in improved serum tartrate-resistant acid phosphatase (TRAP) 5a and 5b isoform protein levels.

AIM: Tartrate-resistant acid phosphatase (TRAP) exists as isoforms 5a and 5b. TRAP 5a is a biomarker of chronic inflammation and influences adipose tissue and 5b associates with bone metabolism/pathologies. The aim was to investigate the association of serum TRAP 5a/5b isoforms with fat and bone markers and anthropometric parameters in patients with anorexia nervosa (AN) during weight gain therapy. METHODS: Twenty-five Swedish female AN patients, age 16-24 years, were treated for 12 weeks with a high-energy diet with six meals daily. Serum TRAP 5a/5b, markers of fat/glucose metabolism, markers of bone resorption and formation were measured. Parameters of bone and body composition were assessed by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. RESULTS: BMI increased from median 15.4 kg/m2 to 19.0 kg/m2, p < 0.0001. TRAP 5a and 5a/5b ratio increased but TRAP 5b decreased during the study. TRAP Δ5a and Δ5b correlated with Δinsulin and Δadiponectin, respectively. TRAP 5b correlated with trabecular density at start but not at week 12. At 12 weeks, TRAP 5b correlated with CTX, and Δ decrease in TRAP 5b correlated to Δ increase in bone-specific alkaline phosphatase. CONCLUSIONS: This clinical interventional study resulted in increased BMI in patients with AN. The decreased TRAP 5b protein levels confirm a role for TRAP 5b as a marker of bone resorption, whereas increased TRAP 5a seemed to derive from systemic changes in bone as well as metabolic changes. The combined detection of TRAP 5a and TRAP 5b in serum could be an indicator of improved bone metabolism. LEVEL OF EVIDENCE: Level III, prospective interventional cohort study.

A Novel Sandwich ELISA for Tartrate-Resistant Acid Phosphatase 5a and 5b Protein Reveals that Both Isoforms are Secreted by Differentiating Osteoclasts and Correlate to the Type I Collagen Degradation Marker CTX-I In Vivo and In Vitro.

Tartrate-resistant acid phosphatase type 5 (TRAP) exists as two isoforms, 5a and 5b. 5b is a marker of osteoclast number and 5a of chronic inflammation; however, its association with bone resorption is unknown. In this study, a double-TRAP 5a/5b sandwich ELISA measuring 5a and 5b protein in the same sample was developed. TRAP 5a and 5b protein levels were evaluated as osteoclast differentiation/activity markers in serum and in culture, and their correlation to the resorption marker CTX-I was examined. Serum TRAP 5a and 5b concentrations in healthy men were 4.4 ± 0.6 ng/ml and 1.3 ± 0.2 ng/ml, respectively, and they correlated moderately to each other suggesting that their secretion is coupled under healthy conditions. A correlation was also observed between serum TRAP 5a and 5b with CTX-I, suggesting that both TRAP isoforms associate with osteoclast number. During osteoclast differentiation on plastic/bone, predominantly 5b increased in media/lysate from M-CSF/RANKL-stimulated CD14+ PBMCs. However, substantial levels of 5a were detected at later stages suggesting that both isoforms are secreted from differentiating OCs. More TRAP 5b was released on bone indicating a connection to osteoclast resorptive activity, and a peak in TRAP 5b/5a-ratio coincided with rapid CTX-I release. At the end of the culture period of M-CSF + RANKL-stimulated CD14+ PBMCs, there was a correlation between the secretion of TRAP 5a and 5b proteins with CTX-I. The correlation of not only 5b but also 5a with collagen degradation, both in serum and osteoclast cultures indicates that a considerable proportion of the TRAP 5a originates from osteoclasts and may reflect a hitherto undisclosed regulatory mechanism during bone resorption and bone remodeling.

A novel adjuvant G3 induces both Th1 and Th2 related immune responses in mice after immunization with a trivalent inactivated split-virion influenza vaccine.

A preferred adjuvant should promote both Th1 and Th2 responses. However, most adjuvants in common use are biased towards a Th2-driven response. Therefore, the ability of a novel saponin-based adjuvant G3 to inducing balanced Th1 and Th2 responses in BALB/c mice immunized with a split trivalent seasonal influenza vaccine was evaluated in comparison to that of the adjuvant Al(OH)3. Clear differences in the IgG profiles induced by G3, Al(OH)3 or non-adjuvanted vaccine were recorded. Both adjuvants enhanced high and similar levels of the Th2 associated IgG1 subtype compared to mice given vaccine alone. Only G3 enhanced the IgG2a subclass reflecting a Th1 response, whereas Al(OH)3 even abrogated the IgG2a production. Accordingly, G3 enhanced the production of IL-2 and IFN-γ and also of IL-2/IFN-γ double secreting cells, emphasizing the strong Th1 driving effect of G3. Only Al(OH)3 increased splenocyte production of IL-17. Taken together, the results indicate a strong propensity for G3 to induce both Th1 and Th2 driven immune responses.

The adipokine tartrate-resistant acid phosphatase 5a in serum correlates to adipose tissue expansion in obesity.

PURPOSE: Tartrate-resistant acid phosphatase (TRAP) exists as two isoforms, 5a and 5b. TRAP 5a is elevated in adipose tissue of obese women, interacts with pre-adipocytes and is linked to insulin-sensitive hyperplastic obesity when overexpressed in mice. The aim of this study was to investigate the relation between serum TRAP 5a, adiposity indices and metabolic syndrome risk markers in lean and obese women, using a newly developed TRAP 5a-specific ELISA. MATERIALS AND METHODS: A TRAP 5a sandwich ELISA was optimized using TRAP 5a-specific monoclonal antibodies and tested in sera of healthy males. TRAP 5a levels were quantitated in sera from healthy males and lean and obese women. RESULTS: Serum TRAP 5a protein levels were lower in obese women in comparison with lean. In obese, but not in lean women, serum TRAP 5a correlated positively to % fat mass, BMI, waist- and hip circumference, waist-to-hip ratio and PAI, while no correlations to serum leptin, HOMA, glucose, insulin, FFA, HDL, TG, APO-A1 and APO-B were observed. CONCLUSIONS: TRAP 5a serum levels correlated positively to anthropometric obesity parameters but not to metabolic syndrome risk factors, indicating that serum TRAP 5a is associated with pathological adipose tissue expansion.

Activation of Neutrophils via IP3 Pathway Following Exposure to Demodex-Associated Bacterial Proteins.

Rosacea is a chronic inflammatory condition that predominantly affects the skin of the face. Sera from rosacea patients display elevated reactivity to proteins from a bacterium (Bacillus oleronius) originally isolated from a Demodex mite from a rosacea patient suggesting a possible role for bacteria in the induction and persistence of this condition. This work investigated the ability of B. oleronius proteins to activate neutrophils and demonstrated activation via the IP3 pathway. Activated neutrophils displayed increased levels of IP1 production, F-actin formation, chemotaxis, and production of the pro-inflammatory cytokines IL-1ß and IL-6 following stimulation by pure and crude B. oleronius protein preparations (2 µg/ml), respectively. In addition, neutrophils exposed to pure and crude B. oleronius proteins (2 µg/ml) demonstrated increased release of internally stored calcium (Ca(2+)), a hallmark of the IP3 pathway of neutrophil activation. Neutrophils play a significant role in the inflammation associated with rosacea, and this work demonstrates how B. oleronius proteins can induce neutrophil recruitment and activation.

Increased Number of Plasma B Cells Producing Autoantibodies Against Aß42 Protofibrils in Alzheimer's Disease.

The Alzheimer's disease (AD)-related peptide amyloid-ß (Aß) has a propensity to aggregate into various assemblies including toxic soluble Aß protofibrils. Several studies have reported the existence of anti-Aß antibodies in humans. However, it is still debated whether levels of anti-Aß antibodies are altered in AD patients compared to healthy individuals. Formation of immune complexes with plasma Aß makes it difficult to reliably measure the concentration of circulating anti-Aß antibodies with certain immunoassays, potentially leading to an underestimation. Here we have investigated anti-Aß antibody production on a cellular level by measuring the amount of anti-Aß antibody producing cells instead of the plasma level of anti-Aß antibodies. To our knowledge, this is the first time the anti-Aß antibody response in plasma has been compared in AD patients and age-matched healthy individuals using the enzyme-linked immunospot (ELISpot) technique. Both AD patients and healthy individuals had low levels of B cells producing antibodies binding Aß40 monomers, whereas the number of cells producing antibodies toward Aß42 protofibrils was higher overall and significantly higher in AD compared to healthy controls. This study shows, by an alternative and reliable method, that there is a specific immune response to the toxic Aß protofibrils, which is significantly increased in AD patients.

ELISpot and ELISA analyses of human IL-21-secreting cells: Impact of blocking IL-21 interaction with cellular receptors.

Interleukin (IL)-21 is crucial for the regulation of lymphocytes and is implicated in autoimmune and other diseases. The relevance of being able to measure human IL-21 prompted us to develop ELISA and ELISpot assays for analysis of IL-21 levels and IL-21-producing cells, respectively. Monoclonal antibodies (mAbs) to IL-21 were made and ELISA and ELISpot assays were developed. The selected detection mAb also neutralized IL-21-mediated activation of human cells. Peripheral blood mononuclear cells (PBMCs) from healthy donors (n=24) were stimulated polyclonally (phytohemagglutinin; PHA) or with antigen (Candida albicans extract and tetanus toxoid). Using ELISpot, high numbers of IL-21-producing cells were detected after PHA activation; lower but positive responses to antigen were seen in approximately 50% of the donors. In contrast, the ELISA detected IL-21 in supernatants from PHA-activated cells but not from antigen-stimulated cells. When analyzing IL-17A in parallel, PHA and antigens induced detectable responses in ELISpot as well as in ELISA. Hypothesizing that the lack of detectable IL-21 levels after antigenic stimulation was due to a combination of low frequencies of IL-21-secreting cells and consumption of IL-21 by cellular receptors during cell culture, PBMCs (n=18) were stimulated in the presence of the neutralizing detection mAb. When preventing IL-21 from interacting with its receptor, increased IL-21 levels were found by ELISA after PHA activation and IL-21 could also be measured after antigen stimulation. ELISpot results were unaffected by the addition of the neutralizing mAb. In conclusion, IL-21 secreted by low frequencies of antigen-specific ex vivo-stimulated PBMC can be difficult to detect by ELISA but prevention of IL-21 interaction with its receptor leads to detectable IL-21 levels. In ELISpot, where the cytokine is captured by mAbs on a solid phase immediately upon secretion, blocking the receptor interaction does not affect the detection of IL-21-secreting cells.

ApoD mediates binding of HDL to LDL and to growing T24 carcinoma.

Apolipoprotein (Apo) D is an important protein produced in many parts of the body. It is necessary for the development and repair of the brain and protection from oxidative stress. The purpose of this study was to investigate the extent to which apoD interacts with lipoproteins in human plasma. By using detergent-free ELISA, we show that immobilized monoclonal antibodies against apoD very efficiently bind to low density lipoprotein (LDL) from plasma; this binding is as equally efficient as binding to an anti-apoB monoclonal antibody. Adding detergent to the plasma inhibited the binding, suggesting that the binding is dependent on the presence of intact lipoprotein particles. Reversing the system by using immobilized anti-apoB revealed that the affinity of apoD for LDL is rather low, suggesting that multiple bindings are needed for a durable connection. Biosensor experiments using purified lipoproteins also showed that purified apoD and high density lipoprotein 3 (HDL3), a lipoprotein fraction rich in apoD, were both able to bind LDL very efficiently, indicating that the HDL3-LDL interaction may be a physiological consequence of the affinity of apoD for LDL. Furthermore, we found that apoD increases the binding of HDL to actively growing T24 bladder carcinoma cells but not to quiescent, contact-inhibited, confluent T24 cells. This result is especially intriguing given that the T24 supernatant only contained detectable levels of apoD after growth inhibition, raising the possibility that alternating the expression of apoD and a putative apoD-receptor could give direction to the flow of lipids. In the current paper, we conclude that apoD mediates binding of HDL to LDL and to growing T24 carcinomas, thereby highlighting the importance of apoD in lipid metabolism.

Caveolae-mediated endocytosis of the glucosaminoglycan-interacting adipokine tartrate resistant acid phosphatase 5a in adipocyte progenitor lineage cells.

Adipogenesis depends on growth factors controlling proliferation/differentiation of mesenchymal stem cells (MSCs). Membrane binding and endocytosis of growth factors are often coupled to receptor activation and downstream signaling leading to specific cellular responses. The novel adipokine tartrate-resistant acid phosphatase (TRAP) 5a exhibits a growth factor-like effect on MSCs and pre-adipocytes and induces hyperplastic obesity in vivo. However its molecular interaction with pre-adipocytes remains unknown. Therefore, this study aimed to investigate membrane interaction of TRAP and its endocytosis routes in pre-adipocytes. Confocal and/or electron microscopy were used to detect TRAP in untreated or TRAP 5a/b treated pre-adipocytes under conditions that allow or inhibit endocytosis in combination with co-staining of endocytotic vesicles. TRAP interaction with heparin/heparan sulfate was verified by gel filtration. It could be shown that TRAP 5a, but not 5b, binds to the membrane of pre-adipocytes where it co-localizes with heparin-sulfate proteoglycan glypican-4. Also in vitro, TRAP 5a exhibited affinity for both heparin and heparan sulfate with heparin inhibiting its enzyme activity. Upon caveolae-mediated endocytosis of saturating levels of TRAP 5a, TRAP 5a co-localized intracellularly with glypican-4 and late endosomal marker Rab-7 positive vesicles. The protein was also located in multivesicular bodies (MVBs) but did not co-localize with lysosomal marker LAMP-1. TRAP 5a endocytosis was also detectable in pre-osteoblasts, but not fibroblasts, embryonic MSCs or mature adipocytes. These results indicate that TRAP 5a exhibits binding to cell surface, endocytosis and affinity to glucosaminoglycans (GAGs) in pre-adipocyte and pre-osteoblast lineage cells in a manner similar to other heparin-binding growth factors.

Clinical validation of IFNγ/IL-10 and IFNγ/IL-2 FluoroSpot assays for the detection of Tr1 T cells and influenza vaccine monitoring in humans.

The type of T cell polarization and simultaneous production of multiple cytokines have been correlated with vaccine efficacy. ELISpot is a T cell detection technique optimized for the measurement of a secreted cytokine at the single cell level. The FluoroSpot assay differs from ELISpot by the use of multiple fluorescent-labeled anticytokine detection antibodies, allowing optimal measurement of multiple cytokines. In the present study, we show that an IFNγ/IL-10 FluoroSpot assay is more sensitive than flow cytometry to detect Tr1 regulatory T cells, an immunosuppressive T cell population characterized by the production of IL-10 and IFNγ. As many tolerogenic vaccines are designed to induce these Tr1 cells, this FluoroSpot test could represent a standard method for the detection of these cells in the future. The use of an IFNγ/IL-2 FluoroSpot assay during influenza vaccine monitoring showed that the influenza-specific IL-2-producing T-cell response was the dominant response both before and after vaccine administration. This study therefore questions the rationale of using the single-color IFNγ ELISpot as the standard technique to monitor vaccine-specific T-cell response. Using this same test, a trend was also observed between baseline levels of IFNγ T cell response and T cell vaccine response. In addition, a lower IFNγ+IL-2+ T-cell response after vaccine was observed in the group of patients treated with TNFα inhibitors (P=0.08). This study therefore supports the use of the FluoroSpot assay due to its robustness, versatility and the complementary information that it provides compared with ELISpot or flow cytometry to monitor vaccine-specific T-cell responses.

ApoE production in human monocytes and its regulation by inflammatory cytokines.

The apoE production by tissue macrophages is crucial for the prevention of atherosclerosis and the aim of this study was to further elucidate how this apolipoprotein is regulated by cytokines present during inflammation. Here we studied apoE production in peripheral blood mononuclear cells (PBMC) and analysis was made with a newly developed apoE ELISpot assay. In PBMC, apoE secretion was restricted to monocytes with classical (CD14(++)CD16(-)) and intermediate (CD14(+)CD16(+)) monocytes being the main producers. As earlier described for macrophages, production was strongly upregulated by TGF-ß and downregulated by bacterial lipopolysaccharide (LPS) and the inflammatory cytokines IFN-γ, TNF-α and IL-1ß. We could here show that a similar down-regulatory effect was also observed with the type I interferon, IFN-α, while IL-6, often regarded as one of the more prominent inflammatory cytokines, did not affect TGF-ß-induced apoE production. The TNF-α inhibitor Enbrel could partly block the down-regulatory effect of IFN-γ, IFN-α and IL-1ß, indicating that inhibition of apoE by these cytokines may be dependent on or synergize with TNF-α. Other cytokines tested, IL-2, IL-4, IL-12, IL-13, IL-17A and IL-23, had no inhibitory effect on apoE production. In contrast to the effect on monocytes, apoE production by primary hepatocytes and the hepatoma cell line HepG2 was more or less unaffected by treatment with cytokines or LPS.

Circulating monocytes are not the major source of plasma cytokines in patients with sepsis.

In sepsis, large quantities of inflammatory cytokines are released into the bloodstream. The cellular source of these cytokines is unclear, and we have here investigated to what extent circulating cells in blood contributed to this production. We used the enzyme-linked immunospot technique to study the spontaneous as well as the lipopolysaccharide (LPS)-induced secretion of the proinflammatory cytokines interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), granulocyte-macrophage colony-stimulating factor, IL-1ß, IL-12p40, and the anti-inflammatory cytokine IL-10 from whole-blood cells. The study comprised 32 septic patients (24 with septic shock) and 30 healthy controls. Despite significantly increased plasma cytokine levels in the septic patients, the number of spontaneous cytokine-secreting cells was small or nonexistent and did not differ between the two groups. Lipopolysaccharide stimulation of cells from the same samples triggered substantially increased numbers of cytokine-producing cells in both patients and controls. However, although the numbers of IL-6- and tumor necrosis factor α-secreting monocytes were very similar in both groups, significantly fewer IL-1ß-, IL-10-, IL-12p40-, and granulocyte-macrophage colony-stimulating factor-secreting monocytes were seen in samples from septic patients as compared with healthy controls. The reduced number of cytokine-secreting cells in response to LPS stimulation correlated with disease severity, as expressed by Sequential Organ Failure Assessment score and the stage of sepsis. In summary, circulating leukocytes did not appear to be responsible for the increased plasma levels of cytokines observed in sepsis. A selective sepsis-induced downregulation of cytokine secretion in response to LPS underscores the complexity of cytokine regulation in sepsis.

Adjuvant properties of mesoporous silica particles tune the development of effector T cells.

Alum is the most frequently used adjuvant today, primarily inducing Th2 responses. However, Th1-type responses are often desirable within immune therapy, and therefore the development of new adjuvants is greatly needed. Mesoporous silica particles with a highly ordered pore structure have properties that make them very interesting for future controlled drug delivery systems, such as controllable particle and pore size; they also have the ability to induce minor immune modulatory effects, as previously demonstrated on human-monocyte-derived dendritic cells (MDDCs). In this study, mesoporous silica particles are shown to be efficiently engulfed by MDDCs within 2 h, probably by phagocytic uptake, as seen by confocal microscopy and transmission electron microscopy. A co-culture protocol is developed to evaluate the capability of MDDCs to stimulate the development of naïve CD4(+) T cells in different directions. The method, involving ELISpot as a readout system, demonstrates that MDDCs, after exposure to mesoporous silica particles (AMS-6 and SBA-15), are capable of tuning autologous naïve T cells into different effector cells. Depending on the size and functionalization of the particles added to the cells, different cytokine patterns are detected. This suggests that mesoporous silica particles can be used as delivery vehicles with tunable adjuvant properties, which may be of importance for several medical applications, such as immune therapy and vaccination.

Heavy-chain complementarity-determining regions determine conformation selectivity of anti-aß antibodies.

BACKGROUND/AIMS: Amyloid-ß (Aß) protofibrils are neurotoxic soluble intermediates in the Aß aggregation process eventually forming senile plaques in Alzheimer's disease. This Aß species is a potential biomarker for Alzheimer's disease and also a promising target for immunotherapy. In this study, we investigated the characteristics of conformation-dependent Aß antibodies specific for Aß protofibrils. METHODS: Mice were immunized with Aß protofibrils to generate hybridomas producing Aß-specific monoclonal antibodies. Binding of antibodies to different Aß conformations was investigated with inhibition ELISA. The antibodies' complementarity-determining region (CDR) sequences were determined and compared. RESULTS: A majority of the antibodies were of the IgM class, all selectively binding to aggregated Aß. Two IgG antibodies were generated: one with selective affinity for Aß protofibrils and the other bound Aß in all conformations. A high degree of similarity between the heavy-chain CDRs of the conformation-dependent antibodies was found, and all high-affinity Aß antibodies displayed a high degree of sequence similarity in the light-chain CDRs. CONCLUSION: Sequence similarity in the heavy-chain CDRs is associated with conformation selectivity of the antibodies, while sequence similarity in the light-chain CDRs correlates with the affinity for Aß.

Interference from heterophilic antibodies in amyloid-ß oligomer ELISAs.

Amyloid-ß (Aß) oligomers of different sizes and forms have recently been the focus formany Alzheimer's disease (AD) researchers. Various immunoassays have been used to detect low concentrations of these elusive Aß species in different forms of human samples using little or no sample dilutions. However, the possibility that positive results may be caused by interference from heterophilic antibodies (HA) is often overlooked. HA, which recognize immunoglobulins from other species, are present in human plasma and cerebrospinal fluid (CSF) and may cause interference in sandwich immunoassays like enzyme-linked immunosorbent assays (ELISAs) by cross-binding the capture and detection antibodies of the assay. They thus may generate a false positive signal. Here we show that when assessing the Aß oligomer content in plasma samples from 44 individuals with a sandwich ELISA, none of the 21 positive signals remained when the assay was repeated in the presence of factors blocking HA. Similarly, in CSF samples from 104 individuals, the signals from the 22 positive samples were strongly reduced when analyzed after anti-HA treatment. Taken together, HA interference is a problem that needs to be addressed when measuring low levels of an antigen in human plasma and CSF samples.

Selective expansion of HIV-1 envelope glycoprotein-specific B cell subsets recognizing distinct structural elements following immunization.

The HIV-1 envelope glycoprotein (Env) functional spike has evolved multiple immune evasion strategies, and only a few broadly neutralizing determinants on the assembled spike are accessible to Abs. Serological studies, based upon Ab binding and neutralization activity in vitro, suggest that vaccination with current Env-based immunogens predominantly elicits Abs that bind nonneutralizing or strain-restricted neutralizing epitopes. However, the fractional specificities of the polyclonal mixture of Abs present in serum, especially those directed to conformational Env epitopes, are often difficult to determine. Furthermore, serological analyses do not provide information regarding how repeated Ag inoculation impacts the expansion and maintenance of Env-specific B cell subpopulations. Therefore, we developed a highly sensitive Env-specific B cell ELISPOT system, which allows the enumeration of Ab-secreting cells (ASC) from diverse anatomical compartments directed against different structural determinants of Env. In this study, we use this system to examine the evolution of B cell responses in mice immunized with engineered Env trimers in adjuvant. We demonstrate that the relative proportion of ASC specific for defined structural elements of Env is altered significantly by homologous booster immunizations. This results in the selective expansion of ASC directed against the variable regions of Env. We suggest that the B cell specificity and compartment analysis described in this study are important complements to serological mapping studies for the examination of B cell responses against subspecificities of a variety of immunogens.

Efficient internalization of mesoporous silica particles of different sizes by primary human macrophages without impairment of macrophage clearance of apoptotic or antibody-opsonized target cells.

Macrophage recognition and ingestion of apoptotic cell corpses, a process referred to as programmed cell clearance, is of considerable importance for the maintenance of tissue homeostasis and in the resolution of inflammation. Moreover, macrophages are the first line of defense against microorganisms and other foreign materials including particles. However, there is sparse information on the mode of uptake of engineered nanomaterials by primary macrophages. In this study, mesoporous silica particles with cubic pore geometries and covalently fluorescein-grafted particles were synthesized through a novel route, and their interactions with primary human monocyte-derived macrophages were assessed. Efficient and active internalization of mesoporous silica particles of different sizes was observed by transmission electron microscopic and flow cytometric analysis and studies using pharmacological inhibitors suggested that uptake occurred through a process of endocytosis. Moreover, uptake of silica particles was independent of serum factors. The silica particles with very high surface areas due to their porous structure did not impair cell viability or function of macrophages, including the ingestion of different classes of apoptotic or opsonized target cells. The current findings are relevant to the development of mesoporous materials for drug delivery and other biomedical applications.

ELISpot analysis of LPS-stimulated leukocytes: human granulocytes selectively secrete IL-8, MIP-1beta and TNF-alpha.

Granulocytes and monocytes/macrophages represent key effector cells of the innate immune system. While human monocytes have been recognized as capable of secreting a broad spectrum of cytokines, the situation has been less clear in granulocytes with studies often showing conflicting results. In this study, lipopolysaccharide (LPS)-induced cytokine secretion from polymorphonuclear cells (PMN) and peripheral blood mononuclear cells (PBMC) was analyzed at the single cell level with the enzyme-linked immunospot (ELISpot) assay. This method allowed us to establish the cytokine profiles for both PBMC and PMN based on the frequency and pattern of cytokine secreting cells, rather than on the amount of produced cytokine detectable in solution by ELISA. As a result, low levels of contaminating mononuclear cells present in our PMN preparations could be discriminated from granulocytes. Using this technique, neutrophils were found to secrete the two chemokines, IL-8 and MIP-1beta in response to LPS. Also TNF-alpha was secreted but in lower amounts and by significantly fewer cells. However, and as opposed to several other reports, we were unable to detect secretion of IL-1beta, IL-6, IL-10, IL-12 and GM-CSF. In contrast to the limited cytokine production by PMN, PBMC secreted considerably larger amounts of the investigated cytokines with CD14(+) monocytes being the primary source of production. Finally, we believe that the cytokine ELISpot technique may provide a powerful tool by which cells of the innate immune system can be studied from a functional perspective at the single cell level.

Sensitive ELISA detection of amyloid-beta protofibrils in biological samples.

Amyloid-beta (Abeta) protofibrils are known intermediates of the in vitro Abeta aggregation process and the protofibrillogenic Arctic mutation (APPE693G) provides clinical support for a pathogenic role of Abeta protofibrils in Alzheimer's disease (AD). To verify their in vivo relevance and to establish a quantitative Abeta protofibril immunoassay, Abeta conformation dependent monoclonal antibodies were generated. One of these antibodies, mAb158 (IgG2a), was used in a sandwich ELISA to specifically detect picomolar concentrations of Abeta protofibrils without interference from Abeta monomers or the amyloid precursor protein (APP). The specificity and biological significance of this ELISA was demonstrated using cell cultures and transgenic mouse models expressing human APP containing the Swedish mutation (APPKN670/671ML), or the Swedish and Arctic mutation in combination. The mAb158 sandwich ELISA analysis revealed presence of Abeta protofibrils in both cell and animal models, proving that Abeta protofibrils are formed not only in vitro, but also in vivo. Furthermore, elevated Abeta protofibril levels in the Arctic-Swedish samples emphasize the usefulness of the Arctic mutation as a model of enhanced protofibril formation. This assay provides a novel tool for investigating the role of Abeta protofibrils in AD and has the potential of becoming an important diagnostic assay.