Digested organs were

further stained with biotinylated-anti-4–1BBL ex vivo, followed by Streptavidin-PE or Streptavidin-allophycocyanin amplification. Biotinylated anti-4–1BBL-treated 4–1BBL-deficient mice were used as a negative staining control for analysis of 4–1BBL expression. The samples were analyzed using FACScalibur, FACSCanto, or LSR II (BD Biosciences) with Cell-Quest or FACSDiva acquisition software. Data analysis was done using FlowJo software (TreeStar Inc., Ashland, OR, USA). Marrow was flushed from the femurs and tibias of 10 C57BL/6 mice and digested for 45 min at 37°C with 0.2 mg/mL Collagenase P (Roche) and 0.2 mg/mL DNase I (Sigma). The single cells were seeded in Petri dishes at a density Ku-0059436 purchase of 1–2 × 106 cells/cm2. One day later, nonadherent cells were washed away and the remaining adherent cells were expanded in medium (see Generation of memory T cells in vitro) for up to 25 days. Half of the medium was replaced with fresh medium once a week. On day 25, adherent cells were removed by trypsinization, stained with anti-CD45.2 (ebioscience), anti-VCAM-1 (ebioscience),

biotinylated anti-4–1BBL (19H3), and secondary streptavidin, and assessed by flow cytometry. In addition, CD45-negative cells were sorted into the VCAM-1+ and VCAM-1− population. Yields of CD45−VCAM-1+ cells were approximately 500,000 in all three experiments, whereas yields of CD45−VCAM-1− cells ranged 13,000- 165,000 cells. Total RNA was extracted and purified using RNeasy Micro kit (Qiagen). Random selleck hexamer primers and purified RNA were used for the reverse transcription reaction (Invitrogen). PCR of the cDNA was done using following primers: 4–1BBL forward: 5′-CTT GAT GTG GAG GAT ACC-3′, 4–1BBL reverse: 5′-GCT TGG

CGA ACA CAG GAG-3′, CCL19 forward: 5′-GCC TCA GAT TAT CTG CCA T-3′, CCL19 reverse: 5′-AGA CAC AGG GCT CCT TCT GGT-3′, IL-7 forward: 5′-TCC TCC ACT GAT CCT TGT TC-3′, IL-7 reverse: 5′-TTG TGT GCC TTG TGA TAC TG-3′, CXCL12 forward: 5′-GTC CTC TTG CTG TCC AGC TC-3′, CXCL12 reverse: 5′-TAA TTT CGG GTC AAT GCA CA-3′, actin forward: 5′-GGG AAT GGG TCA GAA GGA-3′, actin reverse: 5′-AAG AAG GAA GGC TGG AAA-3′, GAPDH forward: 5′-AAC TTT GGC ATT GTG GAA GG-3′, and GAPDH reverse: 5′-GGA Adenosine triphosphate GAC AAC CTG GTC CTC AG-3′. CD8+ memory+ T cells were generated in vitro from OT-I DsRed splenocytes as described [29]. A total of 6 × 106 cells were adoptively transferred into C57BL/6 mice. One day later, femurs were harvested, fixed for 4 h in 4% paraformaldehyde at 4°C, dehydrated in 10, 20, and 30% sucrose solution for 24 h, respectively, and frozen in SCEM embedding medium (Section-Lab Co. Ltd., Yokohama, Japan). Bone cryosections (7 μm) were prepared using Kawamoto’s Film Method [51]. Sections were stained with the following Ab from eBioscience if not indicated otherwise: VCAM-1 (429), CD31 (MEC13.

100 Three proteins (SP-2, SP-3 and SP-4) were found in higher concentrations in stallions with low fertility scores, while SP-1 was positively correlated with

fertility and was suggested to be homologous to OPN.95 The spermadhesin PSP-I, common in pigs, seems negatively related to fertility58, while other molecules, such as TGF-β, appear unrelated to overall fertility in relation to levels in semen.89 However, as the SP of a boar differs somehow from that of another boar, maybe it is not the amount of the cytokine that selleck products play the major role, but its capacity to differentially induce degrees of maternal tolerance by the female and thus attain differences in embryo survival, leading to variation in fertility. It is hoped that this line of research is followed. Proteins of the seminal plasma are relevant for sperm function particularly

for their interactions with the various environments of the tubular genital tract and the oocyte and its vestments. Moreover, specific peptides and proteins act as signals for the immune system of the female, ultimately modulating sperm rejection MAPK Inhibitor Library or tolerance, perhaps even influencing the relative intrinsic fertility of the male and/or couple. Funding has been provided by The Swedish Research Councils Vetenskapsrådet (VR) and FORMAS, Stockholm, Sweden; and BFU2010-17373, Valencia, Spain. “
“Recent progress achieved by an impressive number of studies focusing upon the ontogenesis and immunobiology of epidermal Langerhans cells (LCs) and other cutaneous dendritic cell (DC) populations as well as DCs at oral mucosal tissue has profoundly revised GPX6 our understanding of the role of DCs in different tissues and microenvironments. By sensing their environment for microbial

signals or allergens and bridging innate and adaptive immunity in a sophisticated manner, subtypes of DCs play a critical role in the maintenance of the immunological homeostasis in the periphery. Thereby, DCs, located directly at the interface to the environment, fulfil opposing tasks as they are key players in both the control and the generation of allergic inflammation. Furthermore, it is under ongoing debate whether DCs attenuate or aggravate allergic inflammation. As a consequence, accumulated knowledge gained in this field within the last few years has provided an excellent basis for innovative therapeutic opportunities which tend to target specifically the multi-faceted properties of DCs at distinct anatomical sites. Since the discovery of the classical epidermal dendritic cells (DCs) by Paul Langerhans in 1863 [1], DCs have fascinated researchers all over the world, but still remained enigmatic due to their complex characteristics and roles in our immune system. However, all DC subtypes display a few common features, such as their localization at the border zones to the environment, which is associated directly with their pivotal role as sentinels of the immune system.

To examine the contribution of transformation, natural transformation

of V. cholerae click here cells in the presence of chitin was performed. A cat was introduced into the T3SS-related gene region of V. cholerae O1 strain ATCC14033 as a selection marker, resulting in 14033VC1758::cat. After overnight incubation of recipient strain V060002 with the chromosomal DNA of 14033VC1758::cat, the culture was plated onto LB agar with or without Cm. Cm-resistant transformants were observed only from the cultures in which shrimp shell was present at frequencies of ∼10−7 (defined as the number of Cm-resistant colonies divided by the number of total viable colonies). Correct insertion of cat and the whole T3SS-related gene region in Cm-resistant transformants was verified by using the respective primer sets as shown in Figure 2. The original recipient strain V060002 with ctxAB did not possess the T3SS-related genes, however, the resultant transformants (V060002ΔVC1760-1772::T3SS)

possessed both T3SS-related genes and ctxAB. The DNA fragments of the estimated size were successfully amplified with two sets of primer pairs for detection Selleck PS 341 of both junctions of the inserted T3SS-related gene cluster, as shown in Figure 2. Additionally, PFGE analysis of NotI-digested profiles obtained from the recipient V060002 and the transformant V060002ΔVC1760-1772::T3SS showed their patterns were similar, differing by only a few bands, which were probably caused by an additional NotI site on the T3SS-related genes (data not shown). These results indicate that uptake of exogenous T3SS-related genes, followed by homologous recombination, occurred exclusively in the VPI-2 region. Furthermore,

expression and secretion of transferred T3SS-related genes was confirmed. Translocon protein VopD2 was detected in the transformant by immunoblotting and samples from the culture supernatant also contained the VopD2 protein (data not shown). The acquisition of foreign DNA via horizontal gene transfer contributes to bacterial evolution, including acquisition of virulence factors. The mechanisms responsible Ribonucleotide reductase for horizontal gene transfer, which can introduce large fragments of DNA into the recipient bacterium, are as follows: conjugation, transduction and transformation,. For example, the ctxAB genes, fundamental virulence factors of V. cholerae, are located on the lysogenic filamentous phage, CTXΦ, which mediates horizontal transfer of genes by transduction [19]. In this study, we found that the T3SS-related genes were similar in diverse V. cholerae strains, which suggests their horizontal transfer and demonstrates that natural transformation could be the mechanism responsible for horizontal gene transfer in the distribution of T3SS-related genes among V. cholerae strains.

We hypothesized that RIG-I signaling drives the HLA-I antigen presentation machinery during hantavirus infection. Indeed, A549 cells pretreated with BX795, a potent inhibitor of TANK-binding kinase 1 (TBK1) and IκB kinase-epsilon (IKKε) [27], did not increase HLA-I expression in response to HTNV (Fig. 8). BX795 interferes with RIG-I as well as see more TRIF-dependent signaling. To analyze the requirement of innate signaling for HLA-I upregulation in more

detail, A549 cells with stable gene knockdowns (KDs) were generated by transfection of plasmids expressing specific small hairpin RNA (shRNA). HTNV-induced HLA-I upregulation was totally abrogated in RIG-I KD A549 cells as compared to parental A549 cells or A549 cells expressing nontarget selleck kinase inhibitor shRNA (Fig. 9A and B), although HTNV replication was clearly increased

(Fig. 9C). In contrast, KD of the double-stranded RNA-activated protein kinase (PKR) [28] did not significantly affect HLA-I surface expression in response to HTNV (Fig. 9A and B) or viral replication (Fig. 9C). Similarly, MyD88-dependent TLR signaling pathways were not important as KD A549 cells increased HLA-I surface expression after HTNV infection (Fig. 9A and B). Intriguingly, A549 cells with stable KD of TRIF completely failed to upregulate HLA-I surface expression upon HTNV infection similar to RIG-I KD A549 cells (Fig. 9A and B). In sum, HTNV-driven HLA-I upregulation requires both RIG-I and a TRIF-dependent viral sensor such as TLR3. In this study, we searched for mechanisms underlying the vigorous responses of HLA-I-restricted T cells in hantavirus-infected patients.

HTNV-induced HLA-I surface expression required live virus and was observed on both actively infected and bystander cells. Our experiments with reporter constructs transfected into A549 cells revealed that HTNV transactivates the promoter elements of all genes encoding classical human HLA-I molecules (HLA-A, -B, -C), which present antigen-derived epitopes to CD8+ T cells. In contrast, regulatory PRKACG elements in the promoter region of genes encoding nonclassical HLA-I proteins did not significantly respond to HTNV infection. Virus-induced upregulation of classical HLA-I molecules in HTNV-infected humans may further increase the frequency of activated T cells, which has been positively correlated with disease severity [10]. It is unclear at the moment which HTNV-induced transcription factors actually bind to the various regulatory elements and cause these locus-specific differences. HLA-I upregulation on HTNV-infected A549 cells was blocked by pretreatment with epoximicin. This suggests that proteasome-independent mechanisms such as increased stability of HLA-I complexes on the cell surface are not involved. Transcriptional enhancement of HLA-I expression requires concomitant upregulation of TAP components to match the increased demand for HLA-I-binding peptides in the ER.

5B). Thus, NKT cells in the lungs of mice immunized by the intranasal route using α-GalCer as adjuvant exhibit no changes in the PD-1 expression on day one post-immunization and no signs of functional anergy, in terms of cytokine production and expansion. These results support the hypothesis that mucosal, as opposed to systemic administration of α-GalCer, (i.e. intranasal versus intravenous route) may lead to different consequences for NKT cells in terms of induction of anergy or functional BIBW2992 mouse competence in response to repeated α-GalCer delivery. The results from this investigation

strongly support mucosal delivery as an efficient approach to harness the adjuvant potential of α-GalCer for priming as Palbociclib molecular weight well as boosting cellular immune responses to co-administered immunogens. This is due to the repeated activation of NKT cells and DCs achieved after intranasal immunization with α-GalCer as an adjuvant. Meanwhile, systemic immunization by the intravenous route resulted in the unresponsiveness of the NKT cells to booster doses of α-GalCer, a phenomenon known as NKT cell anergy. These results are consistent with our earlier published studies which demonstrated the effectiveness and necessity of α-GalCer for repeated immunization by mucosal routes for the induction of strong cellular immune responses to the co-administered antigen 7. Our studies

comparing the intravenous and intranasal routes for delivering α-GalCer revealed similar kinetics of activation of NKT cells and DCs in terms of peak levels of IFN-γ production by NKT cells and DC activation at one day after a single immunization and are consistent with literature reports 5, 8,

14. The key finding from our investigation is that 4-Aminobutyrate aminotransferase a booster immunization employing α-GalCer as an adjuvant by the intravenous and intranasal routes revealed vastly different effects on NKT cells and DCs. While a single intravenous administration of α-GalCer, as demonstrated in this manuscript and reported in the literature, leads NKT cells to become unresponsive in terms of inability to produce cytokines in response to a booster dose of α-GalCer and also an inability to proliferate 5, 6, 8, our data demonstrates that after booster intranasal administration of α-GalCer, a potent activation of the NKT cells is observed for a second time in the lung, including IFN-γ production and expansion as well as DC activation. This repeated activation of NKT cells and DCs occurs regardless of the timing for the administration of the booster dose (i.e. day 5 or 23), suggesting that immunization by the intranasal route is a potential means to allow repeated dosing of the α-GalCer adjuvant without the induction of NKT cell anergy. A recent report published during the preparation of this manuscript showed delivery of α-GalCer by the intradermal route to be effective in avoiding NKT cell anergy, but mechanistic details are not described 15.

After this, horseradish peroxidase-conjugated antibody against rabbit, mouse or goat IgG was added (Bethyl Laboratories, Inc., Montgomery, TX), diluted 1 : 2000 in 5% skim milk TBST for 1 hr at room temperature. Chemiluminescence was detected on an X-ray film after treating with enhanced chemiluminescence solution. Expression

vectors for GATA-3 and MTA-2 were constructed AZD4547 cost from the CMV-base expression vector (pCMV-SPORT6). Cell transfection to EL4, a mouse thymoma cell line, and measurement of dual luciferase was performed as previously described with minor modifications.9 Five million EL4 cells were resuspended in 400 μl Opti-MEM (Invitrogen) and transferred to a 0·4-cm cuvette (Bio-Rad); expression vectors, reporter plasmids and Renilla luciferase reporter plasmid were added to the cuvette. Cells were electroporated using a Bio-Rad Gene Pulse set at 950 μF and 280 V. Transfected cells were allowed to recover overnight in complete medium, and were then stimulated with 0·5 ng/ml PMA and

1 μm/ml ionomycin for 4 hr. Cells were then harvested and cell extracts were made. Luciferase assay was performed using the Dual-Luciferase Reporter Assay System (Promega, Madison, WI) according to the manufacturer’s instructions. Transfection efficiency was normalized by dividing firefly luciferase activity by Renilla luciferase activity. EL4 cells were transfected Mdm2 antagonist by electroporation as described

above. After 2 days, cells were stimulated with 0·5 ng/ml PMA and 1 μm/ml ionomycin for 4 hr. Total RNA was isolated from the cells using TRIzol reagent (Invitrogen). Complementary DNA was synthesized using SuperScript II reverse transcriptase and oligo-dT (Invitrogen) according to the manufacturer’s protocol. Quantitative PCRs were performed with real-time fluorogenic 5′-nuclease PCR using the 7500 Real Time PCR System (Applied Biosystems, Foster City, CA) according to the manufacturer’s instructions. Sequences used for quantitative PCR were as follows: il4 sense: 5′-AGATCATCGGCATTTTGAACG-3′, il4 anti-sense: 5′-TTTGGCACATCCATCTCCG-3′, il4 probe: Suplatast tosilate (FAM)-5′-TCACAGGAGAAGGGACGCCATGC-3′-(Tamra); ifng sense: 5′-GGATGCATTCATGAGTATTGC-3′, ifng anti-sense: 5′-CCTTTTCCGCTTCCTGAGG-3′, ifng probe: (FAM)-5′-TTTGAGGTCAACAACCCACAGGTCCA-3′-(Tamra); hprt sense: 5′-CTGGTGAAAAGGACCTCTCG-3′, hprt anti-sense: 5′-TGAAGTACTCATTATAG-TCAAGGGCA-3′, hprt probe: (FAM)-5′-TGTTGGATA-CAGGCCAGACTTTGTTGGAT-3′-(Tamra). Exponentially growing EL4 cells (1 × 107) were resuspended in 400 μl Opti-MEM (Invitrogen) and transferred to a 0·4-cm cuvette (Bio-Rad). Thirty microlitres of control or gata3 small interfering RNA (siRNA; stock concentration 100 μm) (Bioneer, Daejeon, Korea) was added to the cuvette. Cells were electroporated using a Bio-Rad Gene Pulse set at 950 μF and 250 V.

coli) were dissolved in sterile, endotoxin-free water to obtain concentrations of from 0.1 mg/mL

to 10 pg/mL, and mixed with an equal amount of LAL (E-Toxate, Sigma). After 1 hr of incubation at 37°C (in a water bath), gelation was determined by inverting the test tubes once. The human myelomonocytic cell line THP-1 (from the European Collection of Cell Cultures, Cat No. 88081201) was cultured in RPMI 1640 medium Selleckchem Rucaparib supplemented with 2 mM L-glutamine, 10% FBS (Sigma), and 1% antibiotic-antimycotic solution (Sigma). The culture was maintained at 37°C in a humidified atmosphere containing 5% CO2. A mature macrophage-like state was induced by treating the THP-1 cells with PMA (Sigma). Release of NO, measured as its end product, nitrite, was assessed using Griess reagent (35). Briefly, THP-1 cells were stimulated with the LPS preparations (0.01 μg/mL) for 24 hr. The culture supernatant (100 μL) was mixed with 100 μL of Griess reagent for 10 min, then the absorbance at 570 nm was measured using a microplate reader

(Molecular Devices, Sunnyvale, CA, USA) and computer software (Softmax). THP-1 cells were plated on 24-well tissue culture plates (Nunc, Roskilde, Denmark) at a density of 5 × 105 cells/mL (1 mL in each well) and cultured in RPMI 1640 cell culture medium supplemented with 2mM L-glutamine, 10% FBS, antibiotics, and 50 ng/mL PMA for 72 hr. Differentiated, plastic-adherent cells were washed twice with cold Dulbecco’s PBS (Sigma) this website Bortezomib molecular weight and incubated with a fresh culture medium without PMA. The medium was then changed every 24 hr for another 3 days. Cytokine induction was performed on the fourth day after removal of PMA. The medium was replaced by fresh RPMI 1640 medium supplemented with 2% FBS and LPSs from the examined strains or standard LPS from Salmonella enterica sv. Typhimurium. The LPSs were diluted in RPMI 1640 cell

culture medium and added at concentrations of 0.01 μg/mL and 1 μg/mL. After 24 hr of incubation at 37°C in a humidified atmosphere containing 5% CO2, supernatants were collected, centrifuged, and stored at −80°C until cytokine assay. The concentrations of IL-1β, IL-6, and TNF in the supernatants were measured by ELISA using kits from Bender MedSystems, GmbH (Vienna, Austria) according to the manufacturer’s protocols. The detection limits were 0.32 pg/mL for IL-1β, 0.92 pg/mL for IL-6, and 3.83 pg/mL for TNF. For each experiment, the mean of three wells ± SD was expressed. Analyses were performed with GraphPad Prism 5 software. Statistical significances were determined by Student’s t-test and set at P < 0.05 or P < 0.01. The LPS preparations were isolated using standard hot phenol/water extraction. The majority of LPSs from B. sp. (Lupinus), B. japonicum, B. yuanmingense, M. huakuii, and A. lipoferum strains were found in the water phase, whereas LPSs from B. elkanii and B. liaoningense were extracted into the phenol phase. SDS-PAGE analysis revealed a high degree of heterogeneity for all the examined LPSs (Fig.

This then remixes with a known electrolyte concentrate for representation to the dialyser. As the same small water volume can recirculate, at least until column exhaustion, water source independence is assured. Many current technological developments find more in dialysis equipment are now focusing on sorbent-based dialysate circuitry. Although possibly déjà vu for some, it is timely for a brief review of sorbent chemistry and its application to dialysis systems. The single pass proportioning dialysis system has been the dominant

haemodialysis configuration since it was commercially introduced in the early 1960s.1,2 Only one other delivery system ever emerged to significantly challenge this method – sorbent dialysis.3,4 However, the cost differential soon heavily biased in favour of single pass delivery paired with reverse osmosis (R/O) water purification. Consequently, by the early 1990s, sorbent dialysis had disappeared from clinical use. Single pass systems are inherently water hungry and, despite solid-state electronics, require regular and costly fluid pathway maintenance. Further, to provide ‘dialysis-grade’

water for the proportioning system, an expensive, complex and power-hungry R/O plant is needed. Even then, the water quality provided by an R/O and single pass system often remains questionable. Late in the Adenosine triphosphate 1990s, interest was rekindled in sorbent-based systems, ACP-196 order particularly by those seeking system miniaturization, portability and wearability.5 Meanwhile, the range, capacity and manufacturing costs of dialysis-suited sorbents had also improved. By 2010, although still largely developmental, sorbent dialysis has again emerged as a viable technological alternative.6,7 The search for smaller, portable, water-sparing, low maintenance and user-friendly machines, equally suited to home or to facility, has inevitably led

back towards sorbent technology. A range of new haemodialysis and peritoneal dialysis delivery systems are now basing their independence from continuous-flow water supply on the reconstitution of the dialysate through sorbent cartridges.6–9 This paper seeks to introduce – or reacquaint prior users with – the basic concepts of sorbent-based dialysate regeneration. A sorbent is a material that, either as a solid or a liquid, can bind another substance or compound by adsorption to or absorption into its structure. This bonding may be physical or chemical and, primarily, involves chemical or ionic bonding, or the formation of molecular complexes. The larger the sorbent surface area, the greater the binding efficiency.

BM macrophages induced by M-CSF express Jmjd3 more than cells induced by GM-CSF, suggesting that the Jmjd3 expression level is critical for M2 polarization. However, it is also possible that the enzymatic activity of Jmjd3 is regulated by posttranslational modification. Jmjd3-deficient mice show neonatal death with defects in lung cell wall development. Given that Jmjd3 has been implicated in the control of development by the regulation of Hox, and oncogenesis by promoting the expression of Ink4a42, 43, Jmjd3 may regulate different target genes for expression depending on the cell type. Furthermore, selleckchem Jmjd3 and another H3K27-specific demethylase

UTX might function redundantly with regard to controlling the proper development of the body. Although

Jmjd3-deficient macrophages show defects in M-CSF-derived and chitin-induced M2 macrophages, their responses against IL-4 stimulation were not impaired. Thus, it seems that M2 macrophages can be further subclassified and Metformin in vivo each of these classes should be examined for its epigenetic status. For instance, “regulatory macrophages”, induced by immune complex together with TLR ligands produce vast amounts of IL-10, and are proposed to function in immunosuppression (this Viewpoint series 44). Recent studies have identified numerous histone-modifying enzymes, such as methyltransferases, demethylases, acetyltransferases and deacetylases, although the functional roles of most of these in vivo

are yet to be clarified. Thus, it is not clear to date if other histone-modifying enzymes have any specific roles in macrophage differentiation and polarization. It has been shown that naïve CD4+ T cells undergo dynamic changes in histone modification on different lysine and arginine residues while differentiating into different helper T-cell subtypes 27, 45. Future studies in the global changes in histone modifications and DNA methylations in different macrophage subtypes will further reveal the dynamics of histone modification in macrophages. The authors thank all the colleagues Carnitine dehydrogenase in our laboratory, E. Kamada and M. Kageyama for secretarial assistance. This work was supported by the Special Coordination Funds of the Japanese Ministry of Education, Culture, Sports, Science and Technology, and grants from the Ministry of Health, Labour and Welfare in Japan, and the Japan Society for the Promotion of Science (JSPS) through the Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST Program). Conflict of interest: The authors declare no financial or commercial conflict of interest. See accompanying Viewpoint:http://dx.doi.org/10.1002/eji.201141706 The complete Macrophage Viewpoint series is available at: http://onlinelibrary.wiley.com/doi/10.1002/eji.v41.9/issuetoc “
“Helmholtz Center Munich, Institute of Molecular Immunology, Munich, Germany F.

This threshold could be numerical or physiological, Staurosporine or a combination of both. It therefore takes a “team effort” to cause periodontitis in that the disease requires cooperative

interactions among bacteria with different roles. A recently formulated model that accommodates these concepts is called the polymicrobial synergy and dysbiosis (PSD) model [2]. This model holds that physiologically compatible organisms assemble into heterotypic communities, which exist in a controlled immunoinflammatory state. While they are pro-inflammatory and can produce toxic products such as proteases, overgrowth and overt pathogenicity are controlled by the host response. The microbial constituents of the communities can vary among individuals, among sites, and over time. Colonization by keystone pathogens such as P.

gingivalis elevates the virulence of the entire community following interactive communication with accessory pathogens. Initially, host immune surveillance is impaired and the dysbiotic community increases in number. Subsequently, the community proactively induces inflammation to sustain itself with derived nutrients, which will also shape a modified “inflammophilic” community. The action of pathobionts in the community, in addition to overt pathogens, eventually leads to destruction of periodontal tissues. The PSD model reconciles a number of features of periodontal Doxorubicin disease that were discordant with earlier concepts of pathogenicity. These include: the variable microbiota at disease sites, even within the same patient; the presence of pathogens

in the absence of disease; the episodic nature of the disease; and the failure of P. gingivalis to cause periodontitis in the absence of the commensal microbiota [13]. Bacteria on human mucosal surfaces tend to accumulate into complex multispecies communities, a process controlled by a sophisticated series of interbacterial signaling and host response interactions. Within these communities, bacteria have specialized roles, such as provision of an essential enzyme for progressive nutrient metabolism. Bacteria Lck that influence the pathogenicity of the entire community are keystone pathogens, the best-documented example of which is P. gingivalis. While P. gingivalis can affect gene and protein expression in other community members, the major keystone-related influence of the organism is likely through interference with host immunity. This is accomplished by a multipronged approach that compromises immune function on a number of levels (Fig. 1 and 3). It is important to bear in mind, however, that periodontitis is an inflammatory disease, and thus the timing, location, and context of immune suppression by P. gingivalis will have major significance for the ultimate progression of disease.