Primary Host Response Research Articles

Novel method for detecting complement C3 deposition on Staphylococcus aureus

The primary host response to Staphylococcus aureus infection occurs via complement. Complement is an elegant evolutionarily conserved system, playing essential roles in early defences by working in concert with immune cells to survey, label and destroy microbial intruders and coordinate inflammation. Currently the exact mechanisms employed by S. aureus to manipulate and evade complement is not clear and is hindered by the lack of accurate molecular tools that can report on complement deposition on the bacterial surface. Current gold-standard detection methods employ labelled complement-specific antibodies and flow cytometry to determine complement deposited on bacteria. These methods are restricted by virtue of the expression of the S. aureus immunoglobulin binding proteins, Protein A and Sbi. In this study we describe the use of a novel antibody-independent C3 probe derived from the staphylococcal Sbi protein, specifically Sbi-IV domain. Here we show that biotin-labelled Sbi-IV interacts specifically with deposited C3 products on the staphylococcal surface and thus can be used to measure complement fixation on wild-type cells expressing a full repertoire of immune evasion proteins. Lastly, our data indicates that genetically diverse S. aureus strains restrict complement to different degrees suggesting that complement evasion is a variable virulence trait among S. aureus isolates.

Activation of mucosal immunity and novel prophylactic and therapeutic strategy in combating COVID-19

Coronavirus disease 2019 (COVID-19) emerges as an expeditiously growing pandemic, in the human population caused by the highly transmissible RNA virus severe acute respiratory syndrome of coronavirus 2 (SARS-CoV-2). Prognosis of SARS-CoV-2 infection predominantly occurs at the angiotensin-converting enzyme 2 receptor and transmembrane protease serine type 2 positive (ACE2 + TMPRSS2)+ epithelial cells of the mucosal surface like nasal, oral mucosae, and/or the conjunctival surface of the eye where it has interacted along with the immune system. The primary host response towards the pathogen starts from an immune microenvironment of nasopharynx-associated lymphoid tissue (NALT) and mucosa-associated lymphoid tissue (MALT). The presence of exhausted lymphocytes, lymphopenia, pneumonia and cytokine storm is the hallmark of COVID-19. The multifaceted nature of co-morbidity factors like obesity and type 2 diabetes and its effects on immunity can alter the pathogenesis of SARS-CoV-2 infection. Adipose tissue is a crucial endocrine organ that secretes a plethora of factors like adipokines, cytokines, and chemokines that have a profound impact on metabolism and augments the expression of mucosal pro-inflammatory cytokines, like tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), and the interleukin-12 (IL-12)/IL-23. Mucosal immunization could be a superior approach to activate mucosal and systemic immune responses against pathogenic invasion at mucosal surface entry ports. Mucosal vaccines are also able to generate strong systemic humoral immunity—required to neutralize any virus particle that dodges the primary immune response. To develop an efficient vaccine against mucosal pathogens, considering the designing of the delivery route, immunomodulatory features, and adjuvants are very important. In this article, we further provide evidence to understand the significant role of mucosal immunity, along with secretory and circulating immunoglobulin A (IgA) antibodies in generating a novel mucosal vaccine against COVID-19. Moreover, along with mucosal vaccines, we should look for combination treatment strategies with plant bioactive molecules. Glycan-binding lectins against viral proteins for targeted activation of mucosal immune response are one of such examples. This might play a promising role to halt this emerging virus.

Characterization of innate immune response to Brucella melitensis infection in goats with permissive or restrictive phenotype for Brucella intramacrophagic growth

Caprine brucellosis is a chronic, world-wide distributed disease which causes reproductive failure in goats and Brucella melitensis, its causative agent, bears a great zoonotic potential. There is evidence suggesting that some cattle and pigs have an innate ability to resist Brucella infection, but this has not yet been investigated in goats. In this study, we compared caprine macrophages that exhibit extreme restriction and permissiveness to B. melitensis’ intracellular growth in vitro. Monocyte derived macrophages (MDMs) from 110 female goats were cultured and challenged in vitro with B. melitensis 16 M. After initial screening, 18 donor goats were selected based on their macrophages ability to restrict or allow bacterial intracellular growth and some elements of humoral and cellular immunity were studied in depth. MDMs that were able to restrict the pathogen’s intracellular growth showed enhanced bacterial internalization, although there were no differences between groups in the production of reactive oxygen and nitrogen intermediates following 48 h treatment with heat-killed B. melitensis. Moreover, there were no differences between groups in the level of antibodies reacting with keyhole limpet hemocyanin (natural antibodies, NAbs) or with Brucella LPS antigens (cross-reacting antibodies, CrAbs), although a strong positive correlation between individual levels of IgM NAbs and IgM CrAbs was detected. Altogether, these results represent an initial step in understanding innate primary host response to B. melitensis, and deciphering which mechanisms may determine a successful outcome of the infection in goats.

STUDY THE EXPRESSION OF TETRASPANIN (CD81) ON B CELLS IN RESPONSE TO INTERFERON THERAPY IN CHRONIC HCV PATIENTS

ABSTRACT Hepatitis C virus (HCV) infection causes life threatening disease due to its persistence in the liver, over time leading to cirrhosis and hepatocellular carcinoma. Therapeutic intervention with interferon (INF) - alpha combined with ribavirin is aimed at viral clearance, Interferon and ribavirin might discontinue the virus induced hepatocytes damage, thus slowing down the progress to end- stage liver disease. It has been demonstrated that HCV virion, via major structure envelop (E) protein 2 or EIE2 complex could specifically bind to human CD81 molecule, thereby altering the cellular activities in B cells, T cells and natural killer (NK) cells. CD81, a surface protein belonging to the tetraspanin family, facilitates B–T cell interaction in the process of antigen presentation Evidence has revealed that CD81 on B and T cells substantially enhanced T helper IL-4 secretion and NK-cell CD81 enabled E2-mediated reduction of the IFN-gamma levels Those data suggest that CD81 might activate the pathway leading to a predominant type-2 immune response, and as such be prone to cause a strong antibody production but weak or insufficient cytotoxic activities to clear the.The aim of this work was to investigate the clinical relevance and the possible mechanism of CD81 down-regulation under IFN-alpha treatment to detect possible role of CD 81in response to INF therapy of chronic HCV patients. Subjects and Methods: The study included: Group I: 10 healthy subjects. And 60 HCV patients classified into 3 groups: Group II: 20 chronic HCV patients have not received treatment Group IIIa: 20 chronic HCV patients have received treatment responsive to treatment Group IIIb: 20 chronic HCV patients have received treatment not responsive to treatment .the patients were subjected to: (CBC) .liver and kidney function tests and special investigation CD 81, CD19, CD 22. Results: TLC and PLT higher in group I while ALT and AST were significantly higher in group II, while T. bilirubin was significantly higher in group IIIb, Direct bilirubin was significantly higher in group II ,and Alb was significantly higher in group I ,ASMA and ANA more higher in group IIIb, AFP and TSH were significantly higher in group IIIb , there was negative correlation between CD81 and TLC positive correlation between ALT, AST and CD81 were positively correlated to T Bilirubin , D Bilirubin and CD81.There was also significant negative correlation between Albumin and CD81. CD81, CD19, CD22 and Lymphocytes were significantly higher in group IIIb. Conclusion: In conclusion, CD81 down-regulation is a primary host response to interferon-alpha-based therapy and an immunophenotype associated with anti-HCV sustained virological response (SVR) Key words:HCV,CD81 ,interferone

Increased Resistance to Intradermal Francisella tularensis LVS Infection by Inactivation of the Sts Phosphatases.

The Suppressor of TCR signaling proteins (Sts-1 and Sts-2) are two homologous phosphatases that negatively regulate signaling pathways in a number of hematopoietic lineages, including T lymphocytes. Mice lacking Sts expression are characterized by enhanced T cell responses. Additionally, a recent study demonstrated that Sts-/- mice are profoundly resistant to systemic infection by Candida albicans, with resistance characterized by enhanced survival, more rapid fungal clearance in key peripheral organs, and an altered inflammatory response. To investigate the role of Sts in the primary host response to infection by a bacterial pathogen, we evaluated the response of Sts-/- mice to infection by a Gram-negative bacterial pathogen. Francisella tularensis is a facultative bacterial pathogen that replicates intracellularly within a variety of cell types and is the causative agent of tularemia. Francisella infections are characterized by a delayed immune response, followed by an intense inflammatory reaction that causes widespread tissue damage and septic shock. Herein, we demonstrate that mice lacking Sts expression are significantly resistant to infection by the live vaccine strain (LVS) of F. tularensis Resistance is characterized by reduced lethality following high-dose intradermal infection, an altered cytokine response in the spleen, and enhanced bacterial clearance in multiple peripheral organs. Sts-/- bone marrow-derived monocytes and neutrophils, infected with F. tularensis LVS ex vivo, display enhanced restriction of intracellular bacteria. These observations suggest the Sts proteins play an important regulatory role in the host response to bacterial infection, and they underscore a role for Sts in regulating functionally relevant immune response pathways.

Induction of Macrophage Function in Human THP-1 Cells Is Associated with Rewiring of MAPK Signaling and Activation of MAP3K7 (TAK1) Protein Kinase.

Macrophages represent the primary human host response to pathogen infection and link the immediate defense to the adaptive immune system. Mature tissue macrophages convert from circulating monocyte precursor cells by terminal differentiation in a process that is not fully understood. Here, we analyzed the protein kinases of the human monocytic cell line THP-1 before and after induction of macrophage differentiation by using kinomics and phosphoproteomics. When comparing the macrophage-like state with the monocytic precursor, 50% of the kinome was altered in expression and even 71% of covered kinase phosphorylation sites were affected. Kinome rearrangements are for example characterized by a shift of overrepresented cyclin-dependent kinases associated with cell cycle control in monocytes to calmodulin-dependent kinases and kinases involved in proinflammatory signaling. Eventually, we show that monocyte-to-macrophage differentiation is associated with major rewiring of mitogen-activated protein kinase signaling networks and demonstrate that protein kinase MAP3K7 (TAK1) acts as the key signaling hub in bacterial killing, chemokine production and differentiation. Our study proves the fundamental role of protein kinases and cellular signaling as major drivers of macrophage differentiation and function. The finding that MAP3K7 is central to macrophage function suggests MAP3K7 and its networking partners as promising targets in host-directed therapy for macrophage-associated disease.

Neutrophil activation and periodontal tissue injury.

Neutrophilic polymorphonuclear leukocytes (PMNL) track, engage and eliminate foreign entities, including bacteria, fungi and subcellular particles. PMNL are the major host-cell line involved in the acute response during the early stages of infections, including those in the oral cavity. Rather short lived, they are among the fastest moving cells in the human body and travel great distances only to be immolated after encountering and neutralizing antigens. Although their role as the first line of host defense is well established, their role in chronic granulomatous inflammations, diseases and infections remains poorly understood, and many questions on the activation, motility, bactericidity and termination of PMNL in these conditions remain unanswered. This review aims to summarize our current understanding of the molecular mechanisms of PMNL activation and signaling events. Recent evidence indicates the presence of collateral tissue damage caused by poorly regulated PMNL pursuits of periodontal bacteria. Imbalances between the antigenic challenge and the primary host response may augment periodontal tissue breakdown. Thereafter, orchestrated regulation of the resolution of inflammation fails in the presence of a pathogenic periodontal biofilm.

Identification of Cholesterol 25-Hydroxylase as a Novel Host Restriction Factor and a Part of the Primary Innate Immune Responses against Hepatitis C Virus Infection.

Hepatitis C virus (HCV), a single-stranded positive-sense RNA virus of the Flaviviridae family, causes chronic liver diseases, including hepatitis, cirrhosis, and cancer. HCV infection is critically dependent on host lipid metabolism, which contributes to all stages of the viral life cycle, including virus entry, replication, assembly, and release. 25-Hydroxycholesterol (25HC) plays a critical role in regulating lipid metabolism, modulating immune responses, and suppressing viral pathogens. In this study, we showed that 25HC and its synthesizing enzyme cholesterol 25-hydroxylase (CH25H) efficiently inhibit HCV infection at a postentry stage. CH25H inhibits HCV infection by suppressing the maturation of SREBPs, critical transcription factors for host lipid biosynthesis. Interestingly, CH25H is upregulated upon poly(I · C) treatment or HCV infection in hepatocytes, which triggers type I and III interferon responses, suggesting that the CH25H induction constitutes a part of host innate immune response. To our surprise, in contrast to studies in mice, CH25H is not induced by interferons in human cells and knockdown of STAT-1 has no effect on the induction of CH25H, suggesting CH25H is not an interferon-stimulated gene in humans but rather represents a primary and direct host response to viral infection. Finally, knockdown of CH25H in human hepatocytes significantly increases HCV infection. In summary, our results demonstrate that CH25H constitutes a primary innate response against HCV infection through regulating host lipid metabolism. Manipulation of CH25H expression and function should provide a new strategy for anti-HCV therapeutics. Recent studies have expanded the critical roles of oxysterols in regulating immune response and antagonizing viral pathogens. Here, we showed that one of the oxysterols, 25HC and its synthesizing enzyme CH25H efficiently inhibit HCV infection at a postentry stage via suppressing the maturation of transcription factor SREBPs that regulate lipid biosynthesis. Furthermore, we found that CH25H expression is upregulated upon poly(I·C) stimulation or HCV infection, suggesting CH25H induction constitutes a part of host innate immune response. Interestingly, in contrast to studies in mice showing that ch25h is an interferon-stimulated gene, CH25H cannot be induced by interferons in human cells but rather represents a primary and direct host response to viral infection. Our studies demonstrate that the induction of CH25H represents an important host innate response against virus infection and highlight the role of lipid effectors in host antiviral strategy.

Tristetraprolin Recruits the Herpes Simplex Virion Host Shutoff RNase to AU-Rich Elements in Stress Response mRNAs To Enable Their Cleavage.

Herpes simplex viruses (HSV) package and bring into cells an RNase designated virion host shutoff (VHS) RNase. In infected cells, the VHS RNase targets primarily stress response mRNAs characterized by the presence of AU-rich elements in their 3' untranslated regions (UTRs). In uninfected cells, these RNAs are sequestered in exosomes or P bodies by host proteins that bind to the AU-rich elements. In infected cells, the AU-rich RNAs are deadenylated and cleaved close to the AU-rich elements, leading to long-term persistence of nontranslatable RNAs consisting of the 5' portions of the cleavage products. The host proteins that bind to the AU-rich elements are either resident in cells (e.g., TIA-1) or induced (e.g., tristetraprolin). Earlier, this laboratory reported that tristetraprolin binds VHS RNase. To test the hypothesis that tristetraprolin directs VHS RNase to the AU-rich elements, we mapped the domains of VHS and tristetraprolin required for their interactions. We report that VHS binds to the domain of tristetraprolin that enables its interaction with RNA. A single amino acid substitution in that domain abolished the interaction with RNA but did not block the binding to VHS RNase. In transfected cells, the mutant but not the wild-type tristetraprolin precluded the degradation of the AU-rich RNAs by VHS RNase. We conclude that TTP mediates the cleavage of the 3' UTRs of stress response mRNAs by recruiting the VHS RNase to the AU-rich elements. The primary host response to HSV infection is the synthesis of stress response mRNAs characterized by the presence of AU-rich elements in their 3' UTRs. These mRNAs are the targets of the virion host shutoff (VHS) RNase. The VHS RNase binds both to mRNA cap structure and to tristetraprolin, an inducible host protein that sequesters AU-rich mRNAs in exosomes or P bodies. Here we show that tristetraprolin recruits VHS RNase to the AU-rich elements and enables the degradation of the stress response mRNAs.

Hepatitis C virus NS3/4A protease blocks IL-28 production.

Type I interferons (IFNs), including IFN-α, -β, and -ω, play a critical role in innate immune responses against viral infection. IFN-λ, including IL-29, IL-28A, and IL-28B, recently identified as a new subfamily of IFN named type III IFN, has also been demonstrated to suppress virus replication in vitro and in vivo. However, the molecular mechanisms that regulate the induction of type III IFNs during viral infection remain elusive. Here, we demonstrate that IL-28 (IFN-λ 2/3) IFN production, similar to type I IFN, represents a primary and direct host response to HCV genomic RNA transfection. IL-28 (IFN-λ2/3) induction by HCV genomic RNA was dependent upon the activation of NF-κB and IRF3. We identified a minimal IL-28 promoter region consisting of putative NF-κB and IRF3-binding sites. Furthermore, we showed that HCV infection can inhibit HCV genomic RNA-induced IL-28 expression, and that the viral NS3/4A protease activity was responsible for this inhibitory effect. Our results present important evidence for the control of type III IFN response by HCV, and shed more light on the molecular mechanisms underlying the persistence of HCV infection.

Microflora associated with primary endodontic infections: Correlations among sem evaluation, clinical features, and radiographic findings

The aim of the present study was to characterize, by means of SEM, primary endodontic infections and to correlate with clinical and radiographic findings. Twelve (12) human extracted teeth (19 roots) presenting primary endodontic infection were examined. SEM qualitative observations of bacterial and defense cells, their features and distribution within the root canal lumen and root dentine were recorded for association with clinical and radiographic tabled data. Although a direct correlation between biofilm composition and clinical/radiographic findings was not established, structural organization and distribution of the biofilm, as well as the characteristics of host response, could be easily related to those features. Bacterial biofilm was predominant at the apical third. Symptomatic apical periodontitis was related to presence of bacterial biofilm all thirds. Defense cells could be seen in the apical third of some samples. These cells were present in all thirds in some of the cases with open cavities. The correlations performed in this study allowed a better understanding of the picture of primary endodontic infection, host response and relevant clinical features. The combined use of scanning electron microscopy with clinical and radiographic evaluation has the potential to overcome some limits of the current knowledge related to pulpal and periapical diseases, providing important insights for improving treatment strategies.

CD81 down-regulation on B cells is associated with the response to interferon-alpha-based treatment for chronic hepatitis C virus infection

The lymphocytic CD81 molecule, capable of modulating type-1/-2 T-helper responses and serving as a putative receptor for hepatitis C virus (HCV), might influence the outcome of anti-HCV treatment. This study characterized the interferon-alpha-induced alteration of lymphocytic CD81. The CD81 levels in healthy subjects and naïve chronic HCV patients were compared, with the results showing that the two groups had comparable surface CD81 levels for total peripheral blood lymphocytes, subpopulation-B, -T, and -NK cells. In vitro interferon-alpha treatment could suppress the CD81 expression from both groups. Subsequently, we compared the in vitro interferon-alpha modulatory effects on lymphocytic CD81 from patients having received anti-HCV therapy with either sustained virological response (SVR) or without SVR. There was a significant down-regulation of the B-cell's CD81 only in the SVR group. The CD81 modulation was further investigated using Daudi lymphoid cell line, showing declined surface CD81 levels following treatment with interferon-alpha, interferon-beta or polyI:C. Thus, interferons could directly decrease CD81 expression. The interferon-alpha effect could be restored by 2-aminopurine, suggesting that double-stranded RNA activated kinase might be involved in the suppression of CD81. In conclusion, CD81 down-regulation is a primary host response to interferon-alpha-based therapy and an immunophenotype associated with anti-HCV SVR.

Trichuris suis excretory secretory products (ESP) elicit interleukin-6 (IL-6) and IL-10 secretion from intestinal epithelial cells (IPEC-1)

Immune responses to gastrointestinal helminth infections have received increasing attention due to similarities to allergen-induced responses. In fact, the whipworm parasite of swine, Trichuris suis, has been used in beginning clinical trials as an antidote to inflammatory bowel disease. This strategy was based on this similarity and the recognition that other worms have been documented to induce anti-inflammatory responses in the host. In an effort to understand the basis for this response, we hypothesized that the proteins and peptides secreted by T. suis stimulate local intestinal epithelial cells to produce anti-inflammatory cytokines. To test this hypothesis in a correlate system of the natural swine host, T. suis excretory secretory products (ESP) were used to treat both differentiated and undifferentiated intestinal pig epithelial cells (IPEC-1) in vitro as a model for the effect on villus tip and crypt epithelial cells in the vicinity of the worms. IPEC-1 were exposed to low-level doses (0.3 mg/ml) of T. suis ESP, and IL-4, IL-6 and IL-10 cytokine responses were measured by an enzyme-linked immunosorbant assay (ELISA). IL-6 was the predominant cytokine produced, accompanied by moderate IL-10 secretion from both differentiated and undifferentiated cells. As expected, IL-4 was not produced by IPEC-1. Additionally, IL-6 and IL-10 cytokines were produced within 24 h, suggesting that these two cytokines form part of the primary host response to T. suis infections. These data suggest that T. suis ESP could enhance host immune responses and modulation through the induction of enteric IL-6 and IL-10.

Periodontitis, a marker of risk in pregnancy for preterm birth

Why chronic periodontitis may induce an inflammatory response with premature pregnancy termination is unclear. (1) To assess if periodontitis predicts premature gestation; (2) to study amniotic fluid cytokines and periodontitis variables in early-stage pregnancy. A periodontal examination and collection of amniotic fluid was performed (weeks 15-20) of pregnancy in 36 women at risk for pregnancy complications. Amniotic fluid (bacteria), vaginal smears and intra-oral plaque samples were studied. Cytokine levels in amniotic fluid were studied in relation to other study variables. Periodontitis was diagnosed in 20% of normal and in 83% of preterm birth cases (p<0.01). Bacteria were never found in the amniotic fluids studied. Sub-gingival plaque samples including bacteria in the orange and red complexes were found in 18% of full-term 100% of preterm cases (p<0.001) and total colony-forming units (CFUs) were higher in preterm birth (p<0.01). Amniotic levels of interleukin (IL)-6 and prostaglandin-E2 (PGE2) were higher in preterm cases (p<0.001). Amniotic IL-6 (r=0.56, p<0.01) and PGE2 (r=0.50, p<0.01) cytokine levels were correlated with CFU from sub-gingival plaque samples (r2=0.44). The odds ratio of preterm delivery and having periodontitis was 20.0 (95% confidence interval (CI): 2.0-201.7, p<0.01). The odds of >60 CFU in sub-gingival plaque and preterm birth was 32.5:1 (95% CI: 3.0-335.1, p<01). Pregnant women with findings of elevated amniotic fluid levels of PGE2, IL-6 and IL-8 in the 15-20 weeks of pregnancy and with periodontitis are at high risk for premature birth. The implication of this is that periodontitis can induce a primary host response in the chorioamnion leading to preterm birth.

Ultrastructure of Mycobacterium marinum granuloma in striped bass Morone saxatilis

An emerging epizootic of mycobacteriosis currently threatens striped bass Morone saxatilis populations in Chesapeake Bay, USA. Several species of mycobacteria, including Mycobacterium marinum, species resembling M. avium, M. gordonae, M. peregrinum, M. scrofulaceum and M. terrae, and the new species M. shottsii have been isolated from diseased and healthy bass. In this study, we describe the ultrastructure of developing M. marinum granulomas in experimentally infected bass over a period of 45 wk. The primary host response to injected mycobacteria was formation of large macrophage aggregations containing phagocytosed bacilli. M. marinum were always contained within phagosomes. Close association of lysosomes with mycobacterial phagosomes, as well as the presence of electron-opaque material within phagosomes, suggested phagolysosomal fusion. Development of granulomas involved epithelioid transformation of macrophages, followed by appearance of central necrosis. Desmosomes were present between mature epithelioid cells. The necrotic core region of M. marinum granulomas was separated from overlying epithelioid cells by several layers of flattened, electron-opaque spindle-shaped cells. These cells appeared to be formed by compression of epithelioid cells and, aside from a flattened nucleus, did not possess recognizable organelles. Following the development of well-defined, paucibacillary granulomas, secondary disease was observed. Recrudescence was marked by bacterial replication followed by disruption of granuloma architecture, including loss of epithelioid and spindle cell layers. In advanced recrudescent lesions, normal tissue was replaced by macrophages, fibroblasts, and other inflammatory leukocytes. Large numbers of mycobacteria were observed, both intracellular and suspended in cellular debris.

The Role of Antigen in the Localization of Naive, Acutely Activated, and Memory CD8+ T Cells to the Lung During Influenza Pneumonia

The role of Ag in the recruitment and localization of naive, acutely activated, and memory CD8(+) T cells to the lung during influenza infection was explored using TCR-transgenic (Tg) mice. Naive, Thy1.2(+)CD8(+) OT-I TCR-Tg cells were primed and recruited to the lung after transfer into congenic Thy1.1(+) recipients challenged with a genetically engineered influenza virus (influenza A/WSN/33 (WSN)-OVA(I)) containing the K(b) restricted OVA(257-264) epitope (siinfekl) in the viral neuraminidase stalk. However, if the transferred animals were infected with a similar influenza virus that expressed an irrelevant K(b) epitope (WSN-PEPII), no TCR-Tg T cells were detectable in the lung, although they were easily visible in the lymphoid organs. Conversely, there were substantial numbers of OT-I cells found in the lungs of WSN-PEPII-infected mice when the animals had been previously, or were concurrently, infected with a recombinant vaccinia virus expressing OVA. Similar results were obtained with nontransgenic populations of memory CD8(+) T cells reactive to a murine gamma-herpesvirus-68 Ag. Interestingly, the primary host response to the immunodominant influenza nucleoprotein epitope was not affected by the presence of memory or recently activated OT-I T cells. Thus, although Ag is required to activate the T cells, the subsequent localization of T cells to the lung during a virus infection is a property of recently activated and memory T cells and is not necessarily driven by Ag in the lung.

Granulocyte Colony-Stimulating Factor to Prevent the Progression of Systemic Nonresponsiveness in Systemic Inflammatory Response Syndrome and Sepsis

T HE SYSTEMIC inflammatory response syndrome (SIRS) constitutes the primary host response to a variety of severe clinical insults, such as trauma, burns, pancreatitis, or major surgical interventions.[1][1] Distinct from SIRS, the term sepsis is applied to the clinical state when bacterial

Host response to initial and challenge infections, following treatment, of Gyrodactylus bullatarudis and G. turnbulli (Monogenea) on the guppy (Poecilia reticulata).

The host response of Poecilia reticulata Peters against two species of Gyrodactylus (G. bullatarudis Turnbull, 1956 and G. turnbulli Harris, 1986) was investigated by comparing the dynamics of infrapopulations arising from initial infections, challenge infections begun 1 day after formalin treatment of 3-day-old initial infections and challenge control infections. The primary host response of P. reticulata to Gyrodactylus was shown to be non-(Gyrodactylus)-species-specific. Observations of differences in host-site specificities of initial and challenge infection infrapopulations indicated that the host response is largely localised to areas of heavy infection. The exact nature of the response remains unknown.

Intestinal coccidiosis: using targeted mutagenesis to examine the role of αβ and γδ T-cells in the primary and secondary host response to Eimeria

The crypt epithelial cells of the routine small intestine are targets for infection by Emeria vermiformis. Other species of this genus of protozoan parasites target many vertebrates including birds and reptiles. In fact, Eimeria infection of poultry is of considerable commercial importance. Eimeria infection induces crypt hyperplasia, munosal inflammation, and villous atrophy. However, the mechanism by which animals become immune to Eimeria is poorly understood. To approach this issue, we have studied the immune response to Eimeria in immunocompetent mice, and in mice rendered deficient in cO o r T-cells or B cells by targeted gene disruption. The duration and severity of infection was monitored by counting the number of infectious oocysts shed in the feces. We can conclude from our studies that infection elicits increases in both the cO and ~ T-cell repertoires in the local lymph nodes, and within the epithelium itself. However, attenuation of primary infection and the development of parasite-specific immunity are dependent entirely on cO T cells, und not on either T-cells or B-cells. We are currently studying the contribution of ~6 T-cells to the regulation of epithelial celi turnover and the control of inflammation during the infection. Recent data will be presented. • EFFECT OF PLA2 INHIBITORS UPON THE INFLAMMATORY RESPONSE IN AN IN VIVO MODEL OF NECROTIZING ENTEROCOLITIS. JK Roche. L VanHoru, RL Guerrant. Department of Internal Medicine, University o f Virginia Health Sciences Center, Charlottesville, VA. Neerotizing enterocolitis (NEe) is the most serious gastroenterological disorder affecting premature infants. It is characterized by segmental bowel inflammation and sometimes perforation, biliary pneumatosis, and failure to gain weight. We chose to study how local mucosal substances might modify pathophysiological mechanisms responsible for the intestinal lesions, through pharmacological blocking of requisite pro-inflammatory mediators. The model system, adapted from that of Clark et a/. (Ped. Res. 19:919), used ligated rat intestinal segments exposed to acidified casein injected intraluminslly (small bowel and colon), where inflammatory lesions are quantitated as an enhanced volume/length (V/L) ratio (indicating a secretory response) as Well as by macroscopic appearance and histology of the intestinal mucosa. Quinacrine was found to reduce the inflammatory secretion by > 50%, when injected intraluminally with the inciting agent (acidified casein) (Fig. 1). This result was found in both colon and small bowel, at several points after lesion induction (3 and 6 hours), and did not rely on systemic absorption of the quinecrine, e.g., lesions developed in intestinal loops adjacent to ,o

Endotoxin Enhances EEG Alpha and Beta Power in Human Sleep

Endotoxin, a lipopolysaccharide (0.4 or 0.8 ng/kg body weight), was injected at 1900 hours in 17 healthy men in a single-blind, placebo-controlled experiment. The administration was followed by a 4-hour period of quiet wakefulness in bed (light intensity < 200 lux). Unlimited sleep was allowed after 2300 hours (lights off) until the next morning. The electroencephalogram (EEG), electromyogram, electrooculogram, electrocardiogram and rectal temperature were recorded throughout the experimental session. Standard sleep stages were assessed, and the EEG was submitted to a state-specific, serial spectral analysis. Endotoxin administration induced a rise of body temperature and heart rate, which started approximately 2 hours after the injection and persisted through most of the sleep period. Sleep latency remained unchanged, whereas rapid eye movement (REM) sleep latency increased from 60.3 to 89.0 minutes (paired t test; p = 0.06) compared to control values. Stage 2 sleep was elevated from 45.5 to 49.0% of time in bed (p < 0.05), and total nonrapid eye movement (NREM) sleep from 64.2 to 69.1% (p < 0.05). No significant change could be observed in slow-wave sleep (SWS, stages 3 and 4). During the first 4 hours of the sleep period, NREM sleep EEG spectral power was distinctly and markedly increased between 8 and 12 Hz (alpha) and 15 and 20 Hz (beta) (p < 0.05), whereas at the same time EEG power between 1 and 8 Hz (delta, theta) was not significantly changed. We conclude that in humans the primary host response induced by endotoxin initially suppresses REM sleep and increases stage 2 NREM sleep, but does not affect SWS. No clear modification of sleep EEG delta activity could be observed after endotoxin injection, despite marked endocrinological and physiological changes such as the elevation of body temperature. Numerous factors related to the human primary host response may be responsible for the EEG intensification of the alpha and beta range.