Perdas embrionárias e alterações gestacionais são frequentemente observadas em prenhezes de embriões bovinos manipulados in vitro. Sabe-se que tais anormalidades são resultantes de alterações epigenéticas ocasionadas pela manipulação dos gametas e/ou do embrião durante as técnicas de reprodução assistida (ARTs), com destaque para as técnicas de fecundação in vitro (FIV) e da clonagem por transferência nuclear de células somáticas (SCNT). Tais alterações resultam em distúrbios no desenvolvimento do concepto em algum momento crítico entre a fertilização e o parto, fornecendo bons modelos de estudos sobre a fisiopatologia de perdas embrionárias e dos distúrbios de desenvolvimento. Caracterizam-se como momentos críticos após a transferência do embrião (TE) o desenvolvimento embrionário no útero, o reconhecimento materno da gestação, a placentação e o desenvolvimento da placenta e do feto, os quais tem de ser transpassados sem nenhuma falha, permitindo um desenvolvimento normal do concepto até o termo. Sendo assim, o presente trabalho abordou três fases distintas do amplo período gestacional em prenhezes por ARTs. O Estudo 1 foi realizado durante o período peri-reconhecimento materno da gestação e objetivou descrever a abundância de expressão de genes estimulados pelo interferon tau (ISGs) de células mononucleares do sangue periférico (PBMCs) maternas em gestações oriundas de ARTs no primeiro mês de gestação; o Estudo 2 compreendeu os primeiros 35 dias de gestação e objetivou descrever as mudanças morfológicas e vasculares do complexo útero-concepto-ovário e o estímulo à expressão de ISGs em PBMCs em gestações de conceptos clonados por SCNT com diferentes fenótipos de desenvolvimento, sendo esses denominados gestação anembrionada e CL persistente; e o Estudo 3 foi conduzido durante o período pré-parto e objetivou descrever as alterações na produção de esteroides sexuais e corticosteroides em gestações produzidas por ARTs. Três hipóteses foram testadas: (1) Gestações de conceptos clonados por SCNT apresentam uma baixa e mais tardia estimulação de ISGs em PBMCs maternas quando comparadas com gestações de conceptos produzidos por FIV e IA; (2) O concepto clonado por SCNT apresenta um menor estímulo sobre mudanças morfológicas e vasculares do complexo útero-ovário e ISGs em PBMCs maternas durante os primeiros 35 dias de gestação, quando comparado com conceptos oriundos de IA; e (3) Gestações de embriões oriundos de ARTs apresentam alterações na dinâmica esteroidogênica no pré-parto quando comparados com gestações de IA. No estudo 1 foram coletadas amostras de sangue de gestações produzidas por inseminação artificial (IA), FIV e clonagem por SCNT, nos dias 15, 18, 20, 22, 24, 26, 28 e 31 pós-ovulação e foi realizada mensuração da abundância de transcritos de ISGs (OAS1 e ISG15) em PBMCs maternas. No estudo 2, gestações produzidas por IA e clonagem por SCNT, foram submetidas a escaneamentos ultrassonográficos dos ovários, útero e concepto a cada 3 dias do dia 14 ao 35 (dia 0 = ovulação) e amostras de sangue foram coletadas nos dias 15, 18, 20, 22, 24, 26, 28 e 31 para mensuração da abundância de transcritos de ISGs (OAS1 e ISG15) em PBMCs maternas. No estudo 3, foram coletadas amostras de sangue no último mês em gestações naturais, oriundas de FIV e de clonagem por SCNT para análise hormonal de 10 esteroides utilizando o método de espectrometria de massas multi-hormonal de alta resolução LC-MS/MS. O primeiro estudo mostrou semelhanças na expressão de genes estimulados pelo IFNT em gestações oriundas de ARTs e produzidas por IA. Entretanto, a estimulação nas gestações oriundas de ARTs aparentou ser quatro dias mais prolongada, sugerindo uma maior funcionalidade do trofectoderma em conceptos oriundos de ARTs. O segundo estudo demonstrou um aumento na expressão de ISGs em PBMCs maternas tanto em gestações de conceptos normais quanto em anormais, justificando a manutenção da função luteal mesmo na ausência de detecção do concepto por ultrasonografia. No terceiro estudo, demonstrou-se alterações na esteroidogênese nas gestações de embriões FIV e clonados no último mês de gestação, sendo essas compatíveis com a hiperativação da enzima aromatase durante todo o último mês de gestações oriundas de FIV e hiperativação das enzimas P450C11 e P450C21 trinta dias antes do parto em gestações oriundas de clonagem por SCNT. O presente estudo concluiu que conceptos oriundos de FIV e clonagem por SCNT apresentam um prolongamento no estímulo de ISGs pelo IFNT, conceptos clonados anormalos apresentam estímulo de ISGs, o que justifica a manutenção da função luteal, e, por fim, a cascata esteroidonênica que culmina com o parto apresenta-se alterada em gestações oriundas de FIV e clonagem por SCNT. / Pregnancy losses and gestational abnormalities are frequently observed in pregnancies from in vitro produced embryos in bovines. It is known that these abnormalities are due to epigenetic changes from the manipulation of gametes and/or embryo during the use of assisted reproduction techniques (ARTs), especially for the in vitro fertilization (IFV) and cloning by somatic cells nuclear transfer (SCNT). These changes results in disturbances of conceptus development in any critical stage between the fertilization and parturition, which provides good models for the study of physiopathology of embryo losses and disturbances of development. Critical stages after the embryo transfer (ET) to the uterus are characterized as the maternal recognition of pregnancy, placentation, and fetal-placental development, which needs to be surpassed without failures, in order to develop a normal conceptus until term. Therefore, the present work approached three distinct phases of the wide gestational period in pregnancies from ARTs. The Study 1 was conducted during the maternal peri-recongnition of pregnancy period and aimed to describe the expression of interferon stimulated genes (ISGs) in maternal peripheral blood mononuclear cells (PBMCs) in pregnancies derived of ARTs; the Study 2 comprise the first 35 days of pregnancy and aimed to describe morphological and vascular changes of the complex uterus-ovaries-conceptus, as well as the expression of ISGs in maternal PBMCs in pregnancies of conceptus cloned by SCNT with different phenotypes of development, denominated as anembryonic gestation and persistent CL; the Study 3 was conducted during the pre-partum period and aimed to describe changes in the production of sexual steroids and corticosteroids during the last month of pregnancies derived of ARTs. Three hypothesis were tested: (1) Pregnancies of conceptus cloned by SCNT presented a decrease and delay in the stimulation of ISGs in maternal PBMCs when compared with conceptuses produced by IFV and AI; (2) Stimulus from the conceptus for changes in the morphology and vasculature of the the uterus-ovarian complex, detected by ultrasonography in B and Doppler modes, and the stimulation of ISGs in maternal PBMCs during the first 35 days of pregnancy of conceptus cloned by SCNT are less intense when compared with conceptus derived from AI; and (3) Pregnancies derived of ARTs present changes in the steroidogenic dynamics in the pre-partum, when compared with pregnancies derived from AI. In Study 1 blood samples were collected from pregnancies produced by AI, IVF, and cloning by SCNT, at days 15, 18, 20, 22, 24, 26, 28, and 31 post-ovulation for the measurement of abundance of transcripts of ISGs (OAS1 and ISG15) in maternal PBMCs. In Study 2, pregnancies derived of AI and cloning by SCNT, were submitted to ultrasonographic scans for the evaluation and description of morphological and vascular changes in ovaries, uterus, and conceptus every 3 days from day 14 to 35 (day 0 = ovulation) and blood samples were collected on days 15, 18, 20, 22, 24, 26, 28 e 31 for the measurement of the abundance of transcripts of ISGs (OAS1 and ISG15) in maternal PBMCs. In Study 3, blood samples were collected during the last month of pregnancies naturally conceived, derived of IVF, and cloned by SCNT for the analysis of 10 steroids using the method of mass spectrometry high resolution LC-MS/MS. The first study showed similarities in the ISGs expression stimulation in pregnancies derived of ARTs and AI. However, the stimulation in the ART derived pregnancies was apparently 4 days longer, suggesting a greater placental function in conceptus derived of ARTs. The second study showed an increase in ISG expression in both normal and abnormal conceptus development, which justifies the maintenance of CL in the absence of a conceptus structure detected by ultrasonography. In the third study, was detected changes in the steroidogenesis of pregnancies derived of IFV and cloning by SCNT during the last month of pregnancy, which are compatible with the hyperactivation of the aromatase enzyme during the last month of IFV derived pregnancies, and hyperactivation of the enzymes P450C11 and P450C21 thirty days before parturition in pregnancies derived of cloning by SCNT. The present study concludes that conceptus derived of IFV and cloning by SCNT present a prolonged stimulus of ISGs, cloned conceptus with anomalous development presents a stimulus of ISGs, which justifies the CL function maintenance, and, ultimately, the steroidogenic cascade that culminates with the term is altered in pregnancies derived from IFV and cloning by SCNT.

No description available.

No description available.

The purposes of this study was to demonstrate the induction of alpha interferon mRNA in Sendai virus-induced Namalava cells, to follow the level of alpha interferon mRNA synthesis at the transcriptional level, and to determine whether the Namalava cell line expresses the c-myc oncogene and to what degree. The amount of c-myc message deteted in Namalva cell RNA was about one-tenth that of Daudi cell RNA, whereas no difference in the amount of the c-Ha-ras message was observed between the two cell lines.

Cutaneous lupus erythematosus (CLE) is an autoimmune disease that resolves with or without permanent scars depending on the subtype. Interferons (IFNs), including the skin specific IFNλ mainly activate STAT1, which results in inflammation in CLE and may play a significant role in scar formation in chronic discoid CLE. IL-22 activates STAT3 and it is emerging as a mediator with significant impact on normal wound repair, epidermal hyperproliferation and prevention of fibrosis. This work focussed on understanding the regulation and functional impact of IL-22 and IFNλ on skin cells. The counter-regulatory effect of IL-22 on the activities of IFNλ was assessed through downstream interferon stimulated genes (ISGs) expression in healthy and CLE keratinocytes. Cell proliferation and gap closure were investigated in skin resident cells using cell trace dye and scratch assay. Dermal fibroblasts were assessed for the presence of IFNλR1 and IL-22R1, downstream activities of the receptors. Results showed that IL-22 accelerated “scratch” closure in keratinocytes while IFNλ caused a delay in closure. IL-22 significantly downregulated IFNλ-induced chemokines expression in healthy, but not CLE keratinocytes. Reduced IL-22R1 expression and “STAT3 signature genes” was observed in CLE keratinocytes. A key finding of this project is that dermal fibroblasts respond to both IFNλ and IL-22. This work shows that IL-22 can reduce the damaging effect of IFNs in inflamed skin and also identifies dermal fibroblasts as important cells in skin immune responses. In conclusion, IL-10 family members can have both beneficial and destructive effects on the skin organ depending on the micro milieu and cell-type involved. Manipulating the balance of IL-10 family members in the skin may offer new therapeutic approach for both psoriasis and CLE. / University of Bradford and Centre for Skin Sciences

Thesis (Ph.D.)--University of Alabama at Birmingham, 2008. / Title from PDF title page (viewed on Sept. 17, 2009). Includes bibliographical references.

Submitted by Priscila Nascimento (pnascimento@icict.fiocruz.br) on 2012-11-19T17:50:49Z No. of bitstreams: 1 alvaro-jorge-veloso.pdf: 4310180 bytes, checksum: 6e2b4b0375ed58ab1bdd5831f853ac9b (MD5) / Made available in DSpace on 2012-11-19T17:50:49Z (GMT). No. of bitstreams: 1 alvaro-jorge-veloso.pdf: 4310180 bytes, checksum: 6e2b4b0375ed58ab1bdd5831f853ac9b (MD5) Previous issue date: 2009 / Fundação Oswaldo Cruz. Instituto de Tecnologia em Imunobiológicos. Rio de Janeiro, RJ, Brasil / Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil. / Para testar a atividade biológica do interferon beta (INF-β) no tratamento da esclerose múltipla (EM), é importante que se tenha um modelo animal. Como a infecção pelo vírus da encefalomielite murina de Theiler (do inglês TMEV – Theiler’s Murine Encephalomyelitis Vírus) é capaz de evoluir para uma lesão desmielinizantesimilar a da EM em humanos, este estudo se propõe a estabelecer os parâmetros para avaliar a infecção do TMEV em culturas de células de rim de hamster neonato (do inglês BHK-21– Baby hamster kidney cells). Para tanto foi necessário adaptar a amostra viral TMEV BeAn à cultura BHK-21, estabelecer um ensaio de RT-PCR e padronizar um PCR em tempo real.Também foi construido um vetor plasmidial contendo o gen L* do TMEV para expressãotransitoria em células HEK-293-T e esta construção plasmidial foi utilizada para obtenção de um soro policlonal anti-L* utilizando a metodologia de imunização genética. Como resultados foram obtidos estoques virais de células BHK-21 infectadas pelo TMEV e parte destes estoques foram avaliados quanto à presença de moléculas genômica TMEV, indicativa de replicação viral, por ensaios de RT-PCR e quantificação por PCR em tempo real. Asregiões do genoma do TMEV 3A3B e L* foram aquelas que forneceram melhores resultadosnesta avaliação genômica quantitativa, que deverá ser aplicada para todos os estoques TMEVBHK-21 que foram obtidos. O vetor plasmidial de expressão células HEK-293-T pcDNA4His/Max contendo o gene L* expressou com sucesso transitoriamente esta proteína heteróloga, porém não foi capaz de induzir a formação de anticorpos policlonais anti-L* em coelhos, através da técnica de imunização genética. / In order to evaluate the biologic activity of the therapeutic drug beta interferon to multiple sclerosis, an adequate animal model is necessary.inthis aspect the infection of murine encephalomyelitis virus can evolve to desmielinization that is very similar to human’s multiple sclerosis, the proposal of this study was the establishment of parameters to evaluate the TMEV infection in baby hamster kidney cells-BHK-21. Toward that objective was adapted the TMEV BeAn prototype sample to BHK-21 and also was established a RT-PCR and a real time PCR. Additionally, it was constructed a plasmid vector containing the L* gene of TMEV, for the expression in HEK-293-T cells. This plasmid vector was evaluated in the capacity to produce anti-L* antibodies by genetic immunization. It was possible to obtain stocks of BHK-21 TMEV infected and some of these contents were evaluated as of the quantity of genomic molecules of TMEV as an indicative of viral replication, by RT-PCR and real time PCR. The TMEV genomic regions 3A3B and L*provided best results in the quantitative evaluation. In thefuture, the real time PCR could be used to evaluate all the stocks that were produced. The plasmidial vector pcDNA4His/Max containing the L* gene was able to transiently express the L* protein, but unfortunately, it was not able to induce anti-L* in rabbits.

Submitted by Priscila Nascimento (pnascimento@icict.fiocruz.br) on 2012-11-21T11:40:46Z No. of bitstreams: 1 carina-cantelli-pacheco-de-oliveira.pdf: 4119562 bytes, checksum: e15daef4939ba93f9357a8bbf218d494 (MD5) / Made available in DSpace on 2012-11-21T11:40:46Z (GMT). No. of bitstreams: 1 carina-cantelli-pacheco-de-oliveira.pdf: 4119562 bytes, checksum: e15daef4939ba93f9357a8bbf218d494 (MD5) Previous issue date: 2009 / Fundação Oswaldo Cruz. Instituto de Tecnologia em Imunobiológicos. Rio de Janeiro, RJ, Brasil / Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil. / O interferon beta (IFN-β) é uma proteína globular consistindo de cinco cadeias α-helicais e como biofármaco é principalmente utilizado para o tratamento da esclerose múltipla (EM). A EM é uma doença até o momento sem cura e das terapias imunomodulatórias disponíveis para melhoria do quadro da EM, o IFN-βé o biofármaco disponível mais bem caracterizado. Duas formas do IFN-βhumano recombinante são clinicamente utilizadas: IFN-β-1a, produzida em células de ovários de hamster chinês (CHO), similar ao IFN-βnativo; e a forma IFN-β-1b, produzida em sistema de Escherichia coli, não possuindo moléculas de açúcar na cadeia polipeptídica expressa. Testes para detecção e quantificação dos IFNs são principalmente do tipo ELISA sendo cruciais nos processos de desenvolvimento, monitoramento e no controle de qualidade, devido principalmente a relação sensibilidade/especificidade necessária. Os anticorpos monoclonais (Mabs) de alta afinidade, produzidos para estes testes são extremamente sensíveis e específicos e representam uma forma adequada de padronização de um ELISA para detecção e quantificação do IFN-β. Neste estudo, quatorze MAbs anti-IFN-βforam obtidos através da imunização genética e parcialmente caracterizados. Todos reconheceram no ELISA o IFN-βhumano recombinante. Os MAbs anti-IFN-βidentificados como AE9, AG8, AE6, AH7, AA11, AB1 e AA4 foram os mais reativos. Todos os quatorze MAbs foram isotipados e apresentaram um perfil com simultânea expressão tanto de IgM quantode IgG2a. Este perfil não-usual foi confirmado pela reação em cadeia da polimerase precedida da transcrição reversa específica para IgG e IgM. Somente um MAb denominado AG8 reagiu em Western-blotcom a isoforma monomérica de 18 KDa do IFN-β. Este estudo representou o primeiro passo em direção ao propósito de obtenção do ELISA descrito acima. / Beta interferon (IFN-β) is a globular protein consisting of five α-helical chains. As biopharmaceutical product it is mainly used for treatment of multiple sclerosis (MS). MS is a health disorder with no cure available so far. Its symptoms can be alleviated with immunomodulatory drugs. IFN-βis the most well characterized biopharmaceutical product in terms of structure and side affects. Two forms of human recombinant IFN-βare used in the treatment of MS: IFN-β-1a, expressed in Chinese hamster ovary cells, is similar to native IFN-β; and IFN-β-1b expressed in the Escherichia coli expression system. IFN-β-1b does not present glycosilation and therefore differs from native IFN-β. Tests to detect and to quantify IFNs are mainly enzyme-linked immunosorbent assays (ELISA). These tests are reliable and can be used in biopharmaceutical product development processes. Monitoring and quality control of IFN-βare quite important, mainly because of the physical and chemical nature of IFN-βas well the necessary sensitivity and specificity that allow for a precise characterization of the final product. Monoclonal antibodies (MAbs) used in ELISA to detect and quantify IFN-βusually present high affinity and specificity. In this study, fourteen MAbs against human recombinant IFN-βwere obtained by genetic immunization and partially characterized. All antibodies recognized human IFN-β. The anti-IFN-βMAbs AE9, AG8, AE6, AH7, AA11, AB1 and AA4 were the most reactives. All fourteen MAbs were subjected to antibody isotype characterization and presented a simultaneous expression of both IgM and IgG2a. Thisunusual profile was confirmed by specific reverse transcription polymerase chain reaction for IgG and IgM messenger RNA. Only MAb AG8 recognized the 18 KDa isoform of IFN-β. This study represents the first step towards the development of the ELISA described above.

Interferons are known cytokines that display antiviral, anti-proliferative and immuno-modulatory functions in the host. Interferon-gamma (Ifnγ) is the only type II family interferon that binds to the heterodimeric receptor consisting of two subunits, IfnγR1 and IfnγR2. This specific interaction between Ifnγ and its receptor triggers the activation of Janus Kinase (Jak) – Signal Transducer and Activator of Transcription (Stat) pathway. This triggers a cascade of events leading to modulation of a wide variety of genes resulting in a plethora of responses including antimicrobial activities, induction of Major Histocompatibility Complex encoded molecules etc. The impact of Ifnγ in regulating host defense is observed in patients who lack functional IFNγ or its receptor as they succumb to less virulent strains of intracellular bacteria such as Mycobacterium and Salmonella. Also, mice lacking important downstream signaling components such as Stat1 and Interferon Regulated Factor 1 (Irf1) are known to be highly susceptible to a variety of bacterial and viral infections. Consequently, studies on uncharacterized signaling and regulatory molecules downstream to Ifnγ are of great interest. The modulatory functions of Ifnγ have been attributed to its ability to regulate the expression of a vast number of genes in a Stat1 and Irf1 dependent manner. Also, gene regulation in response to Ifnγ in a target cell such as mouse hepatoma cell line, H6, can be categorized broadly into two subsets: Reactive Oxygen Species (ROS) - Reactive Nitrogen Intermediates (RNI) dependent (e.g. Nos2, Catalase, Id2 etc.) as well as ROS – RNI independent (e.g. Tap1, Lmp2 etc.). However, the effect of Ifnγ induced ROS and RNI in the regulation of the expression of genes at the level of transcriptome and how these could impact cellular and host responses are not well characterized. To investigate these questions, we standardized an in vitro Ifnγ responsive primary cell culture system using mouse adherent peritoneal macrophages (PMs). It needs to be highlighted that this study has, primarily, utilized unstimulated resident PMs. The adherent cells from the peritoneal cavity were positive for macrophage markers such as F4/80 and CD11b, but negative for granulocyte marker Gr1. Also, PMs were resistant to Ifnγ induced cell death, unlike cell lines such as the mouse fibroblast cell line L929, for the time points studied. There are three distinct parts to this study involving the system of PMs: I. To understand the contribution of Nitric Oxide (NO) in regulating the expression of novel Ifnγ responsive genes, PMs from C57BL/6 mice and mice lacking nitric oxide synthase 2 (Nos2-/-), the enzyme isoform responsible for the generation of NO in PMs, were stimulated with Ifnγ for 8 h and microarray analysis was performed. Detailed analysis led to identification of several annotated genes that were uniquely regulated in C57BL/6 and Nos2-/- PMs. Further analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database identified several differentially regulated pathways. Interestingly, a large number of metabolism related pathways, Butirosin and neomycin, Galactose, Phenylalanine and glyoxylate and dicarboxylate, were specifically up-regulated in the C57BL/6 PMs treated with Ifnγ. Similarly, other metabolism related pathways were differentially regulated by Ifnγ in PMs from C57BL/6 and Nos2-/- mice. One of the pathways that was up regulated in a Nos2 dependent manner in the C57BL/6 PMs upon Ifnγ treatment was that of circadian rhythm, which consisted of genes Per1, Bhlhb2 and Bhlhb3. All three are known circadian rhythm regulators, with Bhlhb2 and Bhlhb3 being transcriptional repressors that bind to E-box consensus sequence (CANNTG) as heterodimers, using the basic helix-loop-helix (bHLH) domains, along with other transcriptional regulators. Both Bhlhb2 and Bhlhb3 were up regulated at RNA and protein levels in a kinetic manner upon Ifnγ treatment in L929 cells. Studies with inhibitors to ROS and RNI revealed that up regulation of Bhlhb2 and Bhlhb3 was RNI, but not ROS, dependent in response to Ifnγ. Interestingly, the RNI inhibitor, NG-Methyl-L-Arginine (LNMA) rescued Ifnγ induced ROS. On the other hand, ROS inhibitors, e.g. Apocyanin and polyethylene glycol Catalase (PEG-Catalase), did not affect the nitrite amounts in the supernatant. These experiments suggested that RNI was upstream to ROS in L929 cells and both contributed to Ifnγ induced cell death. The knockdown of Bhlhb3 using specific siRNAs in the untreated L929 cells increased Bhlhb2 amounts, but not vice versa. This observation is consistent with the fact that Bhlhb3 is a known repressor of Bhlhb2. However, this repression of Bhlhb2 by Bhlhb3 was not detected upon Ifnγ treatment in L929 cells possibly because of heterodimerization of Bhlhb3 with other Ifnγ induced transcriptional modulators. Finally, knockdown of either of the proteins did not affect induced nitrite but decreased ROS amounts resulting in significant rescue of Ifnγ induced cell death of L929 cells. Thus, Bhlhb2 and Bhlhb3 are novel Ifnγ induced proteins that are NO dependent and contribute to Ifnγ induced cell death. Ifnγ and Nos2 are known to elicit antibacterial defense in the host. Interestingly, recent studies have implicated circadian rhythm to regulate bacterial infection in mice. Therefore, regulation of both Bhlhb2 and Bhlhb3 upon Ifnγ treatment and during Salmonella enterica Serovar Typhimurium (S. typhimurium) infection in the bone marrow derived macrophages (BMDMs) was performed. Both Bhlhb2 and Bhlhb3 were induced in a Nos2 dependent manner upon Ifnγ addition in BMDMs. Similar to L929 cells, Bhlhb3 repressed Bhlhb2 in the untreated BMDMs. Also, infection of BMDMs with S. typhimurium increased the protein amounts of Bhlhb2, while repressing Bhlhb3. Importantly, knockdown of Bhlhb2 resulted in higher colony forming units (CFU), whereas knockdown of Bhlhb3 reduced CFU in BMDMs 18 h post infection with S. typhimurium. Thus, Bhlhb2 induced whereas Bhlhb3 repressed antibacterial defense in BMDMs. The exact mechanism downstream to these two proteins and their inter-relationship in regulating S. typhimurium infection is of considerable interest and will be studied in future. II. Macrophages are known to produce a large number of different cytokines and chemokines upon activation. To identify novel cytokines and chemokines that may be differentially regulated in response to Ifnγ, a protein array was performed using the supernatants of C57BL/6 PMs treated with and without Ifnγ. Chemokine Ccl3 was found to be repressed by Ifnγ in the supernatant of PMs. Further analysis using Enzyme Linked Immuno-Sorbent Assay (ELISA) revealed that both Ccl3 and Ccl4, highly homologous proteins that chemo-attract almost all types of leukocytes, were repressed upon Ifnγ treatment. This response was ligand and cell specific as Lip polysaccharide (LPS) stimulation of PMs and Ifnγ stimulation of thioglycollate elicited PMs did not result in repression of Ccl3 and Ccl4. Also, studies with fludarabine, an inhibitor to Stat1, revealed that the repression of Ccl3 and Ccl4 as well as induction of Cxcl10 in response to Ifnγ was Stat1 dependent. Importantly, the use of LNMA as well as PMs from Nos2-/- mice established the role of Nos2 in the repression of Ccl3 and Ccl4, but not Cxcl10 induction, in response to Ifnγ. Furthermore, activation of p38 Mapk, but not Jnk, was downstream to Nos2 activation and contributed functionally to the repression of Ccl3 and Ccl4 in response to Ifnγ. Finally, the transcriptional repressor, Activating Transcription Factor 3 (Atf3), was induced in a Stat1-Nos2-p38 Mapk dependent manner and knockdown of Atf3 using siRNAs established the functional role of the same in the repression of Ccl3 and Ccl4 in response to Ifnγ. Further, to understand the regulation of Ccl3 and Ccl4, their modulation upon S. typhimuirum infection of BMDMs was performed. Apart from regulating the CFU in BMDMs, Ifnγ and Nos2 functionally repressed Ccl3 and Ccl4 upon S. typhimurium infection. Oral infection of mice with S. typhimurium was performed and mice lacking Ifnγ and Nos2 were found to have greater CFU in their organs as well as more leukocytes in the infected liver sections in comparison to the infected C57BL/6 mice. Importanly, absence of Ifnγ as well as Nos2 increased the amounts of Ccl3 and Ccl4 in the sera upon S. typhimurium infection in comparison to the C57BL/6 infected mice. Overall, this part of the study identified Ifnγ and Nos2 to repress chemokines Ccl3 and Ccl4 in macrophages and in mice upon S. typhimurium infection. III. While working on the above mentioned studies, it was noticed that addition of Ifnγ to PMs induced in a dose and time dependent manner aggregation of cells. Experiments with LPS, TG PECs and BMDMs established that Ifnγ induced aggregation of PMs was ligand and cell type specific. A panel of cell surface integrins and selectins were screened for regulation upon Ifnγ addition, namely Icam1, Lfa1, CD11b, P-selectin and E-selectin. Most of the cell surface integrins were repressed by Ifnγ in a kinetic manner. Interestingly, CD11b as well as E-Selectin co-localized to the sites of interactions between the PMs upon Ifnγ treatment. Studies with Reopro, a purified F(ab’)2 to glycoprotein GPIIb that is also known to functionally block CD11b, revealed the functional contribution of CD11b during Ifn induced aggregation of PMs. Further, studies with specific inhibitors identified RNI, but not ROS, to contribute to Ifnγ induced PM aggregation. Also, lack of Nos2 in PMs upon Ifnγ treatment resulted in minimal aggregation together with morphological changes, e.g. flattening of cells. Since differences in the morphology of PMs was observed in the absence of Nos2 upon Ifnγ treatment, the regulation and roles of cytoskeleton proteins, Actin and tubulin, during Ifnγ induced aggregation of PMs was studied. Upon Ifnγ stimuli, actin and tubulin get stabilized. On the other hand, the absence of Nos2 leads to depolymerization of actin, while tubulin failed to stabilize to the membrane, in response to Ifnγ. Further, addition of actin and tubulin depolymerizing agents, Cytochalasin D and Colcemid respectively, decreased Ifnγ induced aggregation of PMs. Live cell imaging studies revealed that PMs needed actin, but not tubulin or CD11b, for mobility. Upon Ifnγ treatment, PMs from C57BL/6 mice exhibited reduced mobility and aggregated with each other. The Nos2-/- PMs exhibited lower mobility compared to C57BL/6 PMs and, upon Ifnγ treatment, underwent morphological changes with time, e.g. flattening. On the other hand, Nos2 is important for endogenous mobility and maintaining the cellular morphology in response to Ifnγ. To understand the physiological relevance of our observations, oral infection of C57BL/6 and Nos2-/- mice with S. typhimurium was performed. Four days post infection, no significant differences in the number of peritoneal cells were found. Importantly, PMs from infected Nos2-/- mice had higher CFU in comparison to C57BL/6 mice. However, the amounts of cytokines such as Ifnγ, Tnfα, Il6 and Il1β in the peritoneal lavage were not significantly different between the two infected strains. Interestingly, PMs isolated from infected Nos2-/- mice displayed distinct morphology, e.g. flattening. In comparison, infected C57BL/6 PMs aggregated when cultured for 24 h in vitro. In the future, it will be interesting to address the functional roles of aggregates of macrophages during physiologically relevant responses such as combating intracellular bacterial infection. This part of the study adds a new dimension to the ability of Ifnγ in the regulation of macrophage-macrophage interactions and their roles during intracellular bacterial infections. Overall, the present study has elucidated hitherto uncharacterized roles of Nos2 and mechanisms involved in regulation of novel functional responses of PMs to Ifnγ and during S. typhimurium infection.

No description available.