Granuloma Formation In Mice Research Articles

Mouse innate-like B-1 lymphocytes promote inhaled particle-induced in vitro granuloma formation and inflammation in conjunction with macrophages

The current paradigm for explaining lung granulomatous diseases induced by inhaled particles is mainly based on macrophages. This mechanism is now challenging because B lymphocytes also infiltrate injured tissue, and the deficiency in B lymphocytes is associated with limited lung granulomas in silica-treated mice. Here, we investigated how B lymphocytes respond to micro- and nanoparticles by combining in vivo and in vitro mouse models. We first demonstrated that innate-like B-1 lymphocytes (not conventional B-2 lymphocytes or plasma cells) specifically accumulated during granuloma formation in mice instilled with crystalline silica (DQ12, 2.5 mg/mouse) and carbon nanotubes (CNT Mitsui, 0.2 mg/mouse). In comparison to macrophages, peritoneal B-1 lymphocytes purified from naïve mice were resistant to the pyroptotic activity of reactive particles (up to 1 mg/mL) but clustered to establish in vitro cell/particle aggregates. Mouse B-1 lymphocytes (not B-2 lymphocytes) in coculture with macrophages and CNT (0.1 µg/mL) organized three-dimensional spheroid structures in Matrigel and stimulated the release of TIMP-1. Furthermore, purified B-1 lymphocytes are sensitive to nanosilica toxicity through radical generation in culture. Nanosilica-exposed B-1 lymphocytes released proinflammatory cytokines and alarmins. In conclusion, our data indicate that in addition to macrophages, B-1 lymphocytes participate in micrometric particle-induced granuloma formation and display inflammatory functions in response to nanoparticles.

Mice infected with the hypervirulent Mycobacterium tuberculosis HN878 strain develop lung lesions resembling human tubercle granulomas

Abstract The aerosol infection of mice with lab-adapted Mycobacterium tuberculosis (Mtb) strains in not an ideal model to study the immune parameters crucial for structural organization of protective human tuberculosis (TB) granulomas. Since experimentation in larger animals that mimic human lung granulomatous responses is expensive, a cost-effective animal model recapitulating morphological aspects of human granulomas is needed. Here, we addressed whether the use of hypervirulent Mtb strains could be a better strategy to improve the mouse model of TB. Hence, we infected C57BL/6 mice with a low dose of aerosolized Mtb HN878 and histologically analyzed infected lung tissues at different time points after infection. We found that granulomas that developed early after Mtb HN878 infection resemble human and NHPs granulomas, except for the lack of multinucleated giant cells. These structures displayed a central core of macrophages surrounded by a lymphocyte cuff. Immunofluorescence analysis showed that the presence of Mtb within mouse human-like granulomas was restricted to the central core area where some macrophages also expressed iNOS. Furthermore, increased formation of B cell lymphoid follicles expressing CXCL13 and germinal center markers was observed at the peripheral lymphocyte cuffs of human-like granulomas. As B cell follicles are indicators of protective immunity in humans, we addressed whether their formation was crucial for Mtb control. In Ighm−/− B cell deficient mice, we found an increased susceptibility to Mtb HN878 infection and enhanced lung inflammation at 50 days post-infection as compared to wild-type mice. Thus, our data supports the use of Mtb HN878 infection to model human TB granuloma formation in mice.

Anti-inflammatory, antinociceptive and antidiarrhoeal activities of methanol and ethyl acetate extract of Hemigraphis alternata leaves in mice

BackgroundThe study was designed to investigate the qualitative phytochemical constituents and evaluate the anti-inflammatory, anti-nociceptive and anti-diarrhoeal activities of methanol (MHAL) and ethyl acetate (EAHAL) extract of Hemigraphis alternata leaves in Swiss albino mice.MethodsQualitative phytochemical constituents of MHAL and EAHAL were determined by different tests such as Molisch’s test, Fehling test, Mayer’s test, Frothing test, FeCl3 test, Alkali test, Salkowski’s test, Keller-killiani test and CuSO4 test. In addition, Xylene induced-ear edema test and Cotton pellet-induced granuloma formation test had been performed to evaluate the anti-inflammatory activity. Moreover, Formalin-induced paw licking test, Acetic acid-induced writhing tests and Castor oil induced antidiarrheal test had been performed to evaluate the anti-nociceptive and anti-diarrhoeal activities respectively.ResultsThese crude extracts were figured the presence of carbohydrates, flavonoids, tannins, glycosides, triterpenoids, fat and fixed oils. No mortality, behavioral changes or sign of any toxicity were observed up to the dose as high as 4000 mg/kg in mice. During anti-inflammatory test, MHAL 400 mg/kg and EAHAL 200 mg/kg & 400 mg/kg were significantly reduced ear weight differences and granuloma formation in mice. Highest percentage inhibition was offered by EAHAL 400 mg/kg dose (35.15 ± 11.78% and 34.76 ± 11.30%) in both anti-inflammatory tests respectively. In anti-nociceptive experiments, all extracts were significantly reduced paw licking and abdominal writhing of mice. Highest percentage inhibition was offered by EAHAL 400 mg/kg dose (88.21 ± 2.23% and 54.00 ± 2.38%) in both anti-nociceptive tests respectively. In addition, both extracts were showed significant inhibition of percentage of diarrhea in anti-diarrhoeal models except EAHAL 200 mg/kg dose and the apex percentage inhibition is offered by MHAL 400 mg/kg dose (67.73 ± 5.77%).ConclusionThese results confirm that the leaves extract of Hemigraphis alternata are nontoxic and may provide a source of plant compounds with anti-inflammatory, anti-nociceptive and anti-diarrhoeal activities.

In Vitro and In Vivo Anti-Inflammatory Effects of Polyphyllin VII through Downregulating MAPK and NF-κB Pathways.

Background: Polyphyllin VII (PP7), a steroidal saponin from Paris polyphylla, has been found to exert strong anticancer activity. Little is known about the anti-inflammatory property of PP7. In this study, the anti-inflammatory activity and its underlying mechanisms of PP7 were evaluated in lipopolysaccharide (LPS)-stimulated RAW264.7 cells and in multiple animal models. Methods: The content of nitric oxide (NO) was determined by spectrophotometry. The levels of prostaglandin E2 (PGE2) and cytokines were measured by enzyme-linked immunosorbent assay (ELISA) assay. The mRNA expression of pro-inflammatory genes was determined by qPCR. The total and phosphorylated protein levels were examined by Western blotting. The in vivo anti-inflammatory activities were evaluated by using mouse and zebrafish models. Results: PP7 reduced the production of NO and PGE2 and the protein and mRNA expressions of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) and enzymes (inducible NO synthase [iNOS], cyclooxygenase-2 [COX-2], and Matrix metalloproteinase-9 [MMP-9]) in LPS-induced RAW264.7 cells by suppressing the NF-κB and MAPKs pathways. Notably, PP7 markedly inhibited xylene-induced ear edema and cotton pellet-induced granuloma formation in mice and suppressed LPS and CuSO4-induced inflammation and toxicity in zebrafish embryos. Conclusion: This study demonstrates that PP7 exerts strong anti-inflammatory activities in multiple in vitro and in vivo models and suggests that PP7 is a potential novel therapeutic agent for inflammatory diseases.

Vitamin A mediates conversion of monocyte-derived macrophages into tissue-resident macrophages during alternative activation.

Whether activated inflammatory macrophages can adopt features of tissue resident macrophages and what mechanisms mediate this phenotypic conversion remain unclear. Here we show that vitamin A was required for phenotypic conversion of interleukin 4 (IL-4)-activated monocyte-derived F4/80intCD206+PD-L2+MHCII+ macrophages into macrophages with a tissue-resident F4/80hiCD206−PD-L2−MHCII−UCP1+ phenotype in the peritoneal cavity of mice and during liver granuloma formation in mice infected with Schistosoma mansoni. Phenotypic conversion of F4/80intCD206+ macrophages into F4/80hiCD206− macrophages was associated with almost complete remodeling of the chromatin landscape, as well as alteration of the transcriptional profiles. Vitamin A deficient mice infected with S. mansoni had disrupted liver granuloma architecture and increased mortality, indicating that failure to convert from F4/80intCD206+ macrophages to F4/80hiCD206− macrophages may lead to dysregulated inflammation during helminth infection.

TORmented macrophages spontaneously form granulomas.

Elevated signaling via the metabolic checkpoint kinase mTORC1 in macrophages stimulates spontaneous granuloma formation in mice and is associated with the progression of sarcoidosis in humans.

Anti-inflammatory activity of the essential oil obtained from Ocimum basilicum complexed with β-cyclodextrin (β-CD) in mice

Cyclodextrins (CDs) are cyclic oligosaccharides can enhance the bioavailability of drugs. Ocimum basilicum is an aromatic plant found in Brazil used in culinary. The essential oil of this plant presents anti-edematogenic and anti-inflammatory activities in acute and chronic inflammation. The aim of this study was to investigate the anti-inflammatory effects of the essential oil obtained from O. basilicum complexed with β – cyclodextrin (OBEO/β-CD) in mice. The complexation with β-cyclodextrin (β-CD) was performed by different methods and analyzed by differential scanning calorimetry (DSC), thermogravimetry (TG) and scanning electron microscopy (SEM). The anti-inflammatory activity was evaluated using mice models of paw edema induced by carrageenan, dextran, histamine and arachidonic acid (AA); vascular permeability and peritonitis induced by carrageenan and granuloma induced by cotton block introduction. The DSC, TG and SEM analysis indicated that the OBEO was successfully complexed with β-CD. The oral administration of OEOB/β-CD prevented paw edema formation by decreasing vascular permeability in vivo, inhibited leukocyte recruitment to the peritoneal cavity, and inhibited granuloma formation in mice. Our results indicate that conjugation with β-CD improves the anti-inflammatory effects of OBEO in mice models of acute and chronic inflammation, indicating that this complex can be used in anti-inflammatory drug development.

Pulmonary fibrosis in a mouse model of sarcoid granulomatosis induced by booster challenge withPropionibacterium acnes

Pulmonary fibrosis (PF) associated with chronic sarcoidosis remains poorly understood, and no experimental model is currently available for this condition. Previous studies have shown that Propionibacterium acnes (PA) was associated with sarcoidosis and induced granuloma formation in mice. Here, we investigated whether repeated challenge with PA induces persistent inflammation leading to sarcoidosis followed by PF in mice. Specifically, C57BL/6 mice were inoculated intraperitoneally and subjected to intratracheal challenge with PA, and then were booster-challenged with either PA or phosphate-buffered saline on day 28. Inflammation, granulomata, and features of fibrosis were evaluated every 7 days until day 70. Complete remission of lung granulomata was apparent on day 42 in the sarcoid-remission group. However, granulomata was present from days 21 to 70 in mice that received PA boosting. Inflammatory cell counts and Th1 cytokine levels in lung lavage fluids were elevated up to day 70. Furthermore, fibrotic changes in the lungs were observed around granulomatous and peribronchovascular regions after PA boosting. Taken together, these findings suggest that development of PF following sarcoidosis may result from continuous PA infection and inflammation. Repeated boosting with PA to induce PF might be a useful model for future studies of sarcoidosis-associated PF.

Qualitative phytochemical screening and evaluation of anti-inflammatory, analgesic and antipyretic activities of Microcos paniculata barks and fruits

ObjectiveThe main objectives of this study were to qualitatively evaluate the profile of phytochemical constituents present in methanolic extract of Microcos paniculata bark (BME) and fruit (FME), as well as to evaluate their anti-inflammatory, analgesic and antipyretic activities. MethodsPhytochemical constituents of BME and FME were determined by different qualitative tests such as Molisch's test, Fehling's test, alkaloid test, frothing test, FeCl3 test, alkali test, Salkowski's test and Baljet test. The anti-inflammatory, analgesic and antipyretic activities of the extracts were evaluated through proteinase-inhibitory assay, xylene-induced ear edema test, cotton pellet-induced granuloma formation in mice, formalin test, acetic acid-induced writhing test, tail immersion test and Brewer's yeast-induced pyrexia in mice. ResultsM. paniculata extracts revealed the presence of carbohydrates, alkaloids, saponins, tannins, flavonoids and triterpenoids. All of the extracts showed significant (P<0.05, vs aspirin group) proteinase-inhibitory activity, whereas the highest effect elicited by plant extracts was exhibited by the BME (75.94% proteinase inhibition activity) with a half-maximal inhibitory concentration (IC50) of 61.31 μg/mL. Each extract at the doses of 200 and 400 mg/kg body weight showed significant (P<0.05, vs control) percentage inhibition of ear edema and granuloma formation. These extracts significantly (P<0.05, vs control) reduced the paw licking and abdominal writhing of mice. In addition, BME 400 mg/kg, and FME at 200 and 400 mg/kg showed significant (P<0.05, vs control) analgesic activities at 60 min in the tail immersion test. Again, the significant (P<0.05, vs control) post-treatment antipyretic activities were found by BME 200 and 400 mg/kg and FME 400 mg/kg respectively. ConclusionStudy results indicate that M. paniculata may provide a source of plant compounds with anti-inflammatory, analgesic and antipyretic activities.

Antinociceptive and anti-inflammatory effects of rosmarinic acid isolated from Thunbergia laurifolia Lindl.

Rosmarinic acid (RA) was isolated from an ethanolic extract of Thunbergia laurifolia leaves. The antinociceptive activity of RA was assessed in mice using hot-plate, acetic acid-induced writhing, and formalin tests. The anti-inflammatory effects of RA were determined in two mouse models of carrageenan-induced paw edema and cotton pellet-induced granuloma formation. Orally administered RA (50, 100, and 150mg/kg) showed significant (p<0.001) antinociceptive activity in the hot-plate test and this effect was reversed by naloxone. RA at doses of 50 and 100mg/kg significantly reduced acetic acid-induced writhing by 52% (p<0.01) and 85% (p<0.001), respectively, and RA at 100mg/kg also caused significant inhibition of formalin-induced pain in the early and late phases (p<0.01 and p<0.001, respectively). RA at 100mg/kg significantly suppressed carrageenan-induced paw edema at 3, 4, 5 and 6h after carrageenan injection (p<0.01, p<0.05 p<0.01, and p<0.05, respectively) and showed significant activity against PGE2-induced paw edema. RA at 100mg/kg also inhibited cotton pellet-induced granuloma formation in mice. Taken together, these results demonstrate that RA possesses both central and peripheral antinociceptive activities and has anti-inflammatory effects against acute and chronic inflammation. While further evaluation regarding the safety profile of RA is needed, these data may provide a basis for the rational use of RA and T. laurifolia for treatment of pain and inflammatory disorders.

Anti-rheumatoid arthritic activity of flavonoids from Daphne genkwa

The aim of the study was to investigate the anti-rheumatoid arthritic activity of four flavonoids from Daphne genkwa (FFD) in vivo and in vitro. Flavonoids of D. genkwa were extracted by refluxing with ethanol and purified by polyamide resin. An in vivo carrageenan-induced paw edema model, tampon-granuloma model and Freund's complete adjuvant (FCA)-induced arthritis mouse model were used to evaluate the anti-rheumatoid arthritic activities of FFD. Moreover, nitric oxide (NO) release and neutral red uptake (NRU) in lipopolysaccharide (LPS)-induced murine macrophage RAW264.7 cells were used to evaluate the anti-inflammatory effect in vitro. In addition, antioxidant effect of FFD was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. A high dose of FFD significantly reduced the degree of acute inflammatory paw edema in mice as a response to carrageenan administration (p<0.01). FFD displayed a dose-dependent inhibition of granuloma formation in mice (p<0.05). FFD also inhibited chronic inflammation in adjuvant-induced arthritis rats when administered orally at the dose of 50mg/kg/day (p<0.001). In addition, FFD suppressed the production of NO and exhibited immunoregulatory function in LPS-activated RAW264.7 cells in a dose-related manner. Simultaneously, FFD revealed conspicuous antioxidant activity with IC50 values of 18.20μg/ml. FFD possesses significant anti-inflammatory and antioxidant activity, which could be a potential therapeutic agent for chronic inflammatory disorders such as rheumatoid arthritis.

In vitro and in vivo anti-inflammatory effects of IMMLG5521, a coumarin derivative

Several coumarin derivatives have been reported to present multiple biological activities. In this study, in vitro the compound IMMLG5521 (0.1, 1, 10μM) can inhibit the release of β-glucuronidase from PAF-stimulated polymorphonuclear leukocytes, the compound IMMLG5521 (0.1, 1, 10μM) can inhibit NO production and decrease TNF-α and IL-β release from LPS-stimulated RAW264.7 cells. In vivo, we evaluated the effect of IMMLG5521 on acute and chronic inflammation models. Our data showed that IMMLG5521 (6mg/kg, 12mg/kg) could inhibit xylene-induced ear swelling and cotton pellet-induced granuloma formation in mice. Taken together, the compound IMMLG5521 inhibited the release of inflammatory factors and mediators in vitro, decreased inflammation response in mice. The compound IMMLG5521 can inhibit inflammation in vitro and in vivo.

Bioactivity guided isolation of antiinflammatory, analgesic, and antipyretic constituents from the leaves of Pedilanthus tithymaloides (L.)

Pedilanthus tithymaloides (PT) leaves are widely used in Indian medicine to treat inflammation and pain, but until recently no systematic study of these activities were reported. This study aimed to evaluate the antiinflammatory, antinociceptive, and antipyretic activity of the chloroform (CE) and methanol extract (ME) of PT leaves and its isolated constituents in animal models. The results revealed significant antiinflammatory activity of CE and ME in carrageenan-induced paw edema (acute), vascular permeability and cotton pellet granuloma (chronic) models. Both extracts also produced significant increase in hot-plate reaction time but decrease in writhing response in a dose-dependent manner, indicating their antinociceptive activity. Moreover, significant antipyretic activity was recorded in yeast-induced pyrexia model. Chemical study of CE and ME yielded five known compounds, namely epifriedelanyl acetate (1), friedelanol (2), β-sitosterol (3), ursolic acid (4), and luteolin (5), along with the new compound 1,2-tetradecanediol 1-(hydrogen sulfate) sodium salt (6). This is the first report showing isolation of compound 5 from PT leaves, and of compound 6, from any plant source. Among these, compounds 4 and 5 (10 mg/kg, p.o.) produced significant inhibition of pain response elicited by acetic acid, increased latency in hot-plate, and caused inhibition of carrageenan-induced edema and cotton pellet-induced granuloma formation in mice. Thus, our results clearly demonstrated the justification of the traditional use of P. tithymaloides leaves as an antiinflammatory drug in primary health care.

Anti-nociceptive and Anti-inflammatory Effects of Cyanocobalamin (Vitamin B12) Against Acute and Chronic Pain and Inflammation in Mice

In this study, the anti-nociceptive and anti-inflammatory effects of cyanocobalamin (Vit B12) against acute and chronic pain and inflammation were evaluated in mice. Vit B12 (0.87, 1 and 1.77 mg/kg) were injected intraperitoneally. The anti-nociceptive effects against acute pain were examined using hot-plate and writhing tests. The chronic pain was examined 14 days after sciatic nerve ligation using the hot-plate test. Morphine (10 mg/kg) was used as a positive control. Anti-inflammatory effects of Vit B12 against acute and chronic inflammation were assessed using xylene-induced edema in ears and granuloma caused by compressed cotton implantation, respectively. In these tests, sodium diclofenac (15 mg/kg) was used as a positive control. Vit B12 showed a dose related effect in acute anti-nociceptive test and increased the anti-nociceptive effect of morphine in chronic treatment. Vit B12 demonstrated an anti-nociceptive effect in chronic studies as single or continues daily treatment and increased significantly the anti-nociceptive effect of morphine. All doses of Vit B12 significantly decreased xylene-induced ear edema. Maximum anti-inflammatory effect (37.5%) was obtained at dose of 1 mg/kg. In chronic inflammation, Vit B12 significantly decreased granuloma formation in mice. In conclusion our work presents some experimental evidence supporting the administration of cyanocobalamin in controlling acute and chronic neuropathic pain. Cyanocobalamin may have anti-inflammatory effect. It may reduce tolerance to anti-nociceptive effect of morphine as well.

The effects of interleukin (IL)-12 and IL-4 deficiency on worm development and granuloma formation in Schistosoma japonicum-infected mice

CD4(+) T-helper (Th) cell is widely recognized to be capable of influencing worm development and egg granuloma formation after schistosome infection. Interleukin (IL)-12 and IL-4 play key roles in regulation of Th cell differentiation. In the present study, we subcutaneously inoculated mice with hybridoma cells secreting monoclonal antibodies to neutralize IL-12 and IL-4 and explored the effects of IL-12 and IL-4 deficiency on the worm development and granuloma formation in mice infected with cercariae of Schistosoma japonicum. It was found that deficiency of host IL-12 and IL-4 supported normal parasite survival and fecundity. However, worm development (length and female fecundity) was significantly enhanced in anti-IL-12-treated mice. Mean length of worms in anti-IL-12-treated group was significantly greater than that of intact controls on day28 after infection (females, 11.84 ± 1.20mm vs. 9.45 ± 1.34; males, 9.35 ± 1.21mm vs. 8.10 ± 0.85mm, p < 0.05). Liver egg load per pair of worms (1,770.12 ± 470.67 vs. 806.08 ± 232.37, p < 0.05) and uterine egg load of ovigerous females (93.08 ± 27.85 vs. 46.05 ± 34.24, p < 0.05) in anti-IL-12-treated mice were significantly higher than those in intact control 28days postinfection. But these effects diminished 42days postinfection (p > 0.05). Granuloma size in anti-IL-12-treated mice was significantly larger than that in intact mice 42days postinfection (398.3 ± 80.7μm vs. 294.4 ± 72.2μm, p < 0.05). Granuloma fibrosis dramatically intensified in anti-IL-12-treated mice but diminished in anti-IL-4-treated mice. The results suggest that IL-12 may play an impeditive role in the development of S. japonicum and in granuloma formation as well as fibrosis. IL-4 may promote granuloma formation but have no effect on worm development.

Immunostimulatory Properties of Dendritic Cells after Leishmania donovani Infection Using an In Vitro Model of Liver Microenvironment

BackgroundRecent advances demonstrated that liver dendritic cells (DCs) promote immunologic hyporesponsiveness that may contribute to hepatic tolerance. Although there has been significant work on the phenotypic and functional roles of such DCs, the impact of liver microenvironment on the immune properties of infected DC is still poorly explored, probably because of the limitations of modelization.Methodology/Principal FindingsHere, we hypothesized that DC tolerogenic properties have an impact on the antimicrobial response, particularly during the infection by the protozoan parasite Leishmania donovani. Indeed, a lymphocytic Th2 environment was reported to favour the growth and proliferation of L. donovani. We first modelized an adequate monocyte-differentiated DC model, either in rat liver epithelial cell- or in a human hepatic non-parenchymal cell-conditioned medium in order to infect them further. We established that DCs differentiated in a hepatic microenvironment displayed a CD14+/CD16+/CD123+ phenotype, secreted low IL-12p70 and had an impaired capacity to stimulate allogeneic T lymphocyte proliferation and IFNγ secretion. We then infected DCs with L. donovani in the in vitro-defined hepatic microenvironment. The infection of hepatic DCs restored their capacity to stimulate allogeneic T-cell proliferation and to induce lymphocytic secretion of IFNγ. Such characteristics were recently shown to favour granuloma formation in mice liver.Conclusions/SignificanceOur results suggest that the specific immunostimulatory properties of infected hepatic DCs might amplify the granuloma maturation, which warrants the effective control of infection in the liver during visceral leishmaniasis.

Transient role of CD4+CD25+ regulatory T cells in mycobacterial infection in mice

CD4(+)CD25(+) regulatory T (Treg) cells cause immune suppression by inhibiting T cell effector functions and play pivotal roles not only in self-tolerance but also in immune response to parasitic microbial pathogens. Mycobacteria are major parasitic bacterial pathogens, but the role of CD4(+)CD25(+) Treg cells in mycobacterial infection is not yet defined. In this study we found that, at the early stage of infection, depletion of CD25(+) cells reduced both bacterial load and granuloma formation in mice infected with Mycobacterium tuberculosis strains, such as M. tuberculosis Erdman or M. tuberculosis Kurono. However, at a later stage of infection, bacterial burden and histopathology were similar regardless of depletion of CD25(+) cells. Severe combined immunodeficient (SCID) mice reconstituted with CD4(+)CD25(-) T cells alone or a combination of CD4(+)CD25(+) and CD4(+)CD25(-) T cells showed similar bacterial loads and survival kinetics after infection with M. tuberculosis Erdman. Consistent with in vivo data, in vitro studies revealed that mycobacterial antigens, purified protein derivative of tuberculin (PPD), failed to induce the suppressive function of CD4(+)CD25(+) Treg cells to CD4(+)CD25(-) effector T cells, as demonstrated by the lack of response of CD4(+)CD25(+) T cells to PPD, in mice chronically infected with Mycobacterium bovis bacillus Calmette-Guérin and M. tuberculosis. Our data show that CD4(+)CD25(+) Treg cells have a transient effect at the early stage of mycobacterial infection but, contrary to the expectation, have little impact on the overall course of infection.

TLR9 regulates the mycobacteria-elicited pulmonary granulomatous immune response in mice through DC-derived Notch ligand delta-like 4

TLR9 activation is important for the maintenance of mycobacteria-elicited pulmonary granulomatous responses, hallmarks of protective immune responses following mycobacterial infection. However, the mechanism or mechanisms underlying this effect of TLR9 are not clear. Here, we show that Tlr9-deficient mice challenged with a Mycobacterium antigen display an altered Th17 cytokine profile, decreased accumulation of granuloma-associated myeloid DCs, and profoundly impaired delta-like 4 (dll4) Notch ligand expression. Mechanistic analysis revealed that WT bone marrow-derived DCs but not macrophages promoted the differentiation of Th17 cells from bacillus Calmette-Guérin-challenged (BCG-challenged) lung CD4+ T cells. Both lung and bone marrow DCs isolated from Tlr9-deficient mice inoculated with Mycobacterium antigen expressed lower levels of dll4 Notch ligand than the same cells isolated from WT mice. Passively immunizing WT mice with neutralizing antibodies specific for dll4 during granuloma formation resulted in larger granulomas and lower levels of Th17-related cytokines. In addition, dll4 specifically regulated Th17 activation in vitro. Together, these results suggest dll4 plays an important role in promoting Th17 effector activity during a mycobacterial challenge. Furthermore, TLR9 seems to be required for optimal dll4 expression and the regulation of Mycobacterium antigen-elicited granuloma formation in mice.

The effects of T cell deficiency on the development of worms and granuloma formation in mice infected with Schistosoma japonicum

It is widely accepted that the immune response of the host attacks the parasite and the parasite appears to develop strategies to evade the assault. However, there is increasing evidence that the development of a parasite may be also positively influenced by the immune response of host. In this paper, we explore the effects of T cell deficiency on the development of the worms and granuloma formation in mice infected with cercariae of Schistosoma japonicum. T cell-deficient (nude) mice supported normal parasite survival and fecundity, but compared to normal mice delayed the worms' development (length and female fecundity) until 28 days after infection. However, these differences equaled out at 35 and 42 days. The nude mice apparently suppressed the size of granuloma in the livers around the eggs of S. japonicum. The granulomas were composed predominantly of neutrophils but with significantly fewer eosinophils in nude compared to normal mice. In addition, hepatocyte necrosis occurred in the vicinity of granulomas in nude but not normal mice. This is consistent with egg-granuloma formation in the host being dependent on T-lymphocyte functions and shows that the effect of T cell deficiency on the development of the worms is transitory in S. japonicum.

CCR8 Is Expressed by Antigen-Elicited, IL-10-Producing CD4+CD25+ T Cells, Which Regulate Th2-Mediated Granuloma Formation in Mice

CCR8 was initially described as a Th2 cell-restricted receptor, but this has not been fully tested in vivo. The present study used ex vivo and in vivo approaches to examine the distribution and functional significance of CCR8 among CD4+ T cells. Populations of cytokine-secreting CD4+ T cells were generated in primed mice with Th1 or Th2 cell-mediated pulmonary granulomas, respectively elicited by i.v. challenge with either Mycobacteria bovis purified protein derivative- or Schistosoma mansoni egg Ag (SEA)-coated beads. Cytokine-producing CD4+ T cells were isolated from Ag-stimulated draining lymph node cultures by positive selection. Quantitative analysis of cytokine mRNA indicated enriched populations of IFN-gamma-, IL-4-, and IL-10-producing cells. Analysis of chemokine receptor mRNA indicated that IL-10+ cells selectively expressed CCR8 in the SEA bead-elicited type 2 response. The IL-10+CCR8+ populations were CD25+ and CD44+ but lacked enhanced Foxp3 expression. Adoptive transfer to naive recipients indicated that IL-10+ T cells alone could not transfer type 2 inflammation. Analysis of SEA bead-challenged CCR8-/- mice indicated significantly impaired IL-10 production as well as reductions in granuloma eosinophils. Adoptive transfer of CD4+CCR8+/+ T cells corrected cytokine and inflammation defects, but the granuloma eosinophil recruitment defect persisted when donor cells were depleted of IL-10+ cells. Accordingly, local IL-10 production correlated with CCR8 ligand (CCL1) expression and the appearance of CCR8+ cells in granulomatous lungs. Thus, IL-10-producing, CCR8+CD4+CD25+CD44+ T cells are generated during SEA challenge, which augment the Th2-mediated eosinophil-rich response to the parasite Ags.