trypanosoma cruzi , the causative agent of chagas disease , presents high genetic and biologic variability , and the different strains described can differ in their morphology , tissue tropism , virulence and pathogenicity , susceptibility to chemotherapeutic agents , and antigenic composition , among other features . after an extensive literature review and assessment of biological , biochemical , and molecular phylogenetic markers from different strains , researchers currently classify t. cruzi into six discrete genetic subdivisions , or  discrete typing units  ( dtus ) , designated as t. cruzi i ( tci ) , tcii , tciii , tciv , tcv , and tcvi [ 2 , 3 ] . tci and tcii dtus are the first ancestral groups , and the other groups were generated from these two dtus . the strains from tci and tcii are considered the major causative agents of chagas disease all over the world and especially in south america , where the disease and the two groups are more prevalent [ 2 , 3 ] . the tci strains are mainly relevant to acute infections and severe cases of acute myocarditis [ 4 , 5 ] , and the strains from tcii and tciv are more relevant to the cardiac and digestive forms of chagas disease . the dtu tcv is most commonly found in the congenital transmission of chagas disease , and tciii is considered rare in human infections . it is widely accepted and demonstrated that , beyond the strain that causes the disease , the differences in the clinical and epidemiological features of chagas disease are also related to the host immune response . thus , the establishment of t. cruzi infection depends on a series of events involving interactions between the parasite and the host . first , the parasite infects the host cell , either by active penetration   or by t. cruzi - host cell phagocytosis . subsequently , the parasite develops and spreads to these cells and may also modulate the cells ' biology . if the infected cells are immune cells , one of the main features of t. cruzi is its ability to modulate these immune defense effectors ' mechanisms . one of the main cell types of the host immune response that is targeted by t. cruzi is the dendritic cells ( dcs ) . dcs are antigen - presenting cells that are derived from bone marrow precursors and that participate in the activation of the innate and adaptive immune responses . once differentiated , dcs migrate to peripheral tissues , recognize , capture , and process antigens at these sites ( e.g. , via toll - like receptors ( tlrs ) ) , and become activated . once activated , the cells migrate via ccr7 to secondary lymphoid organs , where they present the antigens to t cells and produce cytokines such as il-12 , il-10 , tnf- , and il-6 , which contribute to the activation and differentiation of antigen - specific t lymphocytes . in the dc - t cell interaction in lymphoid organs , the major histocompatibility complex ( mhc i or mhc ii ) interacts with the t cell receptor ( tcr ) , and costimulatory molecules such as cd40 , cd80 , cd83 , and cd86 interact with their respective costimulatory ligands on the t cells , providing necessary molecular signals that result in the proliferation and differentiation of naive t cells [ 10 , 11 ] . protozoa such as t. cruzi modulate the function of dcs by interfering with these cells ' recognition , migration , maturation , and antigen presentation . it is known that t. cruzi inhibits the expression of mhc ii , cd40 , cd80 , and cd86 , hampers the production and secretion of il-12 , tnf- , and il-6 and increases the production of the cytokine il-10 , and inhibits the presentation of antigens in murine and human dcs in vitro [ 9 , 1215 ] . because the cited studies showed that the dcs had an anti - inflammatory profile , certain authors classify these cells as regulatory dcs . corroborating the in vitro findings , in vivo experiments have also demonstrated that t. cruzi is able to impair many aspects of dc biology . during acute infection , splenic dcs ' migration and expression of the costimulatory molecule cd86 in addition to the inhibition of costimulatory molecules , it is known that t. cruzi can induce the expression of coinhibitory molecules , such as pd - l1 and its ligand , pd-1 . these molecules can trigger inhibitory signals to t cells , which culminate in less activation and more apoptosis of t lymphocytes . chagas disease presents diverse clinical manifestations , and such diversity is suggested to be dependent on the heterogeneity among t. cruzi strains , their evasion mechanisms , and even variation in the host immune response itself [ 19 , 20 ] . despite all of this information and the vast literature on the anti - t . cruzi immune response , the majority of studies published so far have only evaluated a single strain of this parasite . given the diversity of the strains , the differential ability of each to generate disease , and the importance of dcs to mounting a successful immune response against t. cruzi , we sought to evaluate whether different strains of tci and tcii differentially modulate the biology of dcs . the blood trypomastigote forms of the t. cruzi strains used in this study were obtained from the collection of strains of the discipline of parasitology , federal university of tringulo mineiro , and they were cryopreserved in liquid nitrogen at 186c . the four selected strains were as follows : aq1.7 , isolated from triatoma sordida captured in the city of agua quente , ba ; mutum , isolated from panstrongylus megistus captured in the city of uberaba , mg ; 1849 , isolated from an hiv+ patient presenting the cardiodigestive form of chagas disease ; and 2369 , isolated from an hiv+ patient presenting the neurological form of chagas disease . the aq1.7 and mutum strains are classified as belonging to the dtu tci , and strains 1849 and 2369 are classified as belonging to the dtu tcii ( e. lages - silva , personal communication ) . the epimastigotes were thawed and placed in a culture of llc - mk2 cell monolayers in lit medium . the cells were incubated at 37c in a humidified atmosphere containing 5% co2 , and the medium ( dmem , sigma , st . louis , mo , usa ) was periodically replaced until blood trypomastigotes were observed in the culture supernatant . female c57bl/6 mice ( 68 weeks of age ) , used for obtaining dcs , were bred and maintained under standard conditions in the animal facilities of the institute of biological and natural sciences , federal university of tringulo mineiro , uberaba , mg , brazil . all animal experiments were performed in accordance with a protocol ( protocol number 299 ) approved by the university federal of tringulo mineiro institutional animal care and use committee . ultrapure escherichia coli 0111:b4 lipopolysaccharide ( lps ) was purchased from invivogen ( san diego , ca , usa ) . granulocyte macrophage - colony stimulating factor ( gm - csf ) , a selective inductor of dcs , was purchased from peprotech ( rocky hill , nj , usa ) . the doses of lps and gm - csf used in this work were determined based on the manufacturers ' recommendations and/or our own dose - response studies ( data not shown ) . antibodies for flow cytometry and cytokine kits ( opteia elisa sets ) were purchased from ebioscience ( san diego , ca ) or bd biosciences ( san jose , ca ) . briefly , bone marrow cells from femurs and tibias were cultured in 10  ml of complete rpmi medium ( rpmi 1640 medium with 10% heat - inactivated fbs , 2  mm l - glutamine , 100  iu penicillin , 100  g / ml streptomycin , and 0.05  mm 2-mercaptoethanol ) and 25  ng / ml gm - csf . at day 0 , the cells were seeded at 2  10 per 100 mm petri dish . at days 3 and 6 , another 10  ml of complete medium containing 50  ng / ml gm - csf was added to the 10  ml already present in the dishes . the differentiated cells harvested on days 6 - 7 of culture were analyzed for the expression of cd11c and cd11b by flow cytometry . only cultures of dcs that had percentages of differentiation above 75% ( cd11c+cd11b+ ) were used in this work . to assess the infectivity of the four strains , bone marrow - derived dcs were resuspended in 24-well plates at a concentration of 2  10  cells / well . the trypomastigote forms of t. cruzi , obtained from the culture of llc - mk2 cells , were incubated with phosphate - buffered saline ( pbs ) plus 1  nm cfse for 5  min in the dark for staining . afterward , the parasites were added to the dc cultures for 18  h at a parasite - cell ratio of 3  :  1 . the cells were then collected , washed to remove parasites that had not invaded the cells , and analyzed using a facscalibur cytometer ( becton dickinson , mountain view , ca , usa ) . cd11c+cfse+ cells ( 50,000 events / tube ) were analyzed using cellquest 5.1 and flowjo 10 ( treestar , ashland , or , usa ) software . bone marrow - derived dcs were distributed in 24-well plates at a concentration of 2  10  cells / well , and t. cruzi trypomastigotes from the different strains were added to the cultures for 18  h at a parasite - cell ratio of 3  :  1 . afterward , the dcs were washed with pbs , and annexin v - fluorescein isothiocyanate ( annexin v - fitc ; 2.5  g / ml ) and propidium iodide ( pi ; 2.5  g / ml ) staining was performed according to the manufacturer 's specifications ( bd biosciences ) . a minimum of 30  10 dcs per t. cruzi strain infection were analyzed by fluorescence - activated cell sorting ( facs ) , and annexin v  pi cells were considered as viable cells . the data acquired using a facscalibur cytometer were analyzed using cellquest 5.1 and flowjo 10 software . bone marrow - derived dcs w0065re incubated with the aq1.7 , mutum , 1849 , or 2369 strain of t. cruzi or with lps for 18  h. lps was only used as a positive control in the experiment . next , the supernatant of each culture was collected and used for the measurement of cytokine and chemokine levels . measurements of the levels of the cytokines il-12p40 , tnf- , il-10 , and il-6 and of the chemokine ccl2 were performed using a specific solid - phase sandwich enzyme - linked immunosorbent assay ( elisa ) . for the measurement of il-6 and il-12p40 levels , samples were diluted 10 and 20 times , respectively . bd opteia elisa sets were used according to the manufacturer 's instructions ( bd biosciences ) . the concentrations of the cytokines were calculated by linear regression on the absorbance values obtained for the recombinant cytokines and expressed as pg / ml . the sensitivity of the tests ranged from 2 to 20  pg / ml . none of the culture supernatants was thawed more than once . to evaluate the effect of the different strains of t. cruzi on the activation of dcs , we exposed dcs to the four strains of t. cruzi or lps ( positive control ) . after incubation , the dcs were collected for flow cytometric analysis . briefly , after incubation with fc block for 30  min on ice , the collected dcs were washed with 1x pbs and cultured with the following antibodies for 30  min : pe - cy7-conjugated anti - cd11c ; pe - conjugated anti - mhc ii , anti - ccr5 , anti - pd - l1 , or anti - tlr2 ; or fitc - conjugated anti - cd11b , anti - cd40 , anti - cd80 , anti - cd83 , anti - cd86 , anti - ccr7 , or anti - tlr4 . after washing the cells twice in pbs , data acquisition was performed using a facscalibur with cellquest 5.1 software and analyzed with flowjo software . the acquired results are expressed as the mean fluorescence intensity ( mfi , arbitrary unit standardized for all experiments based on negative controls ) of positive cells and/or the relative frequency ( % ) obtained with each antibody within the studied gates . appropriate isotype - matched irrelevant mabs were used as negative controls for each dc molecule analyzed . a statistical analysis was performed using the program graphpad prism 5.0 ( graphpad software , san diego , ca , usa ) . in general terms , the experiments demonstrated that the strains aq1.7 , mutum , 1849 , and 2369 have different capacities to infect dcs ( figure 1 ) . in figure 1(a ) , we present a scheme demonstrating t. cruzi cfse staining that had a positivity of nearly 99% , which is representative of all strains studied . furthermore , we demonstrated that dcs and t. cruzi present different fsc  ssc patterns , allowing the determination of dc infection without nonintracellular t. cruzi interference ( figure 1(b ) ) . representative dot plots ( figure 1(c ) ) and the percentages and the mfis of cfse+ dcs ( figure 1(d ) ) demonstrated that the mutum strain showed a lower rate of invasion ( 10.33% ) , whereas strain 2369 had the highest rate of infectivity ( 60.81% ) . the strains aq1.7 and 1849 had intermediate rates of infection compared with the mutum and 2369 strains ; in particular , these strains showed infectivity rates of 22.88 and 34.18 , respectively ( figures 1(c ) and 1(d ) ) . as can be observed in figure 1(d ) , both the percentage and the mfi of the infectivity of the different strains of t. cruzi presented great similarity . it is also possible to observe that , even within the same dtu ( tci : aq1.7 compared with mutum ; tcii : 1849 compared with 2369 ) , the percent infectivity may vary significantly ( figure 1(d ) ) . knowing that all t. cruzi strains used in this study were able to infect dcs , although at very different rates , we performed an assay to determine whether differentially infected dcs would have altered viability after parasite invasion . the apoptosis assay demonstrated that the different strains used were not capable of altering the viability of the dcs after infection ( figure 2 ) . as we can see in figures 2(a ) and 2(b ) , both the representative dot plots and the percentages of viable dcs infected with the different strains of t. cruzi presented great similarity . when compared with the other groups , dcs were cultured in the presence or absence of the aq1.7 , mutum , 1849 , and 2369 strains of t. cruzi , and their production of il-6 , il-10 , il-12p40 , tnf- , and the chemokine ccl2 was evaluated . in general terms , the results show that dcs infected with different strains of t. cruzi were able to produce different patterns of cytokine and chemokine production ( figure 3 ) . lps was used as a positive control and , as expected , induced high production of the molecules evaluated ( figure 3 ) . when compared with cells that were cultured with medium only , the production of the cytokine tnf- was increased for dcs infected with the strain aq1.7 , mutum , or 1849 ( figure 3(a ) ) . the production of tnf- by dcs infected with the 1849 strain was lower than that induced by the aq1.7 and mutum strains . the 2369 strain did not induce significant production of this cytokine ( figure 3(a ) ) . when compared with cells cultured with medium only , the production of il-6 was reduced in dcs infected with the strain aq1.7 , 1849 , or 2369 ( figure 3(b ) ) . the production of il-12p40 increased in dcs stimulated with any strain , but strain 1849 induced the highest production compared with the other strains ( figure 3(c ) ) . the production of the regulatory cytokine il-10 by dcs increased when the cells were stimulated with any of the strains studied ( figure 3(d ) ) . however , the mutum and 2369 strains induced higher production compared with the aq1.7 and 1849 strains ( figure 3(d ) ) . importantly , the production of il-10 was significantly increased , even when compared with production in cells stimulated with lps alone ( figure 3(d ) ) . the production of the chemokine ccl2 was reduced in dcs infected with the strain aq1.7 , mutum , or 2369 ( figure 4(e ) ) , whereas strain 1849 did not alter this production . it is important to mention that except for tnf- , when dcs were stimulated with different strains of t. cruzi , the production of proinflammatory cytokines and ccl2 was much lower compared with production in cells cultured with only lps or even medium , such as in the cases of il-6 and ccl2 . an increase in the expression of surface molecules is also observed in dcs that undergo complete maturation and antigen presentation . knowing that , we evaluated whether dcs infected with different t. cruzi strains also have different profiles of expression of the costimulatory and stimulatory markers mhc ii , cd83 , cd80 , cd86 , and cd40 . additionally , we evaluated whether the coinhibitory molecule pd - l1 was also modulated by these different strains . in general , the flow cytometric assays demonstrated that dcs infected with the aq1.7 , mutum , 1849 , or 2369 strain showed different patterns of expression of stimulatory and costimulatory markers on their surface ( figure 4 ) . after 18  h of infection , dcs infected with the aq1.7 , mutum , or 1849 strain presented an increased percentage of mhc ii expression on their surface , but the aq1.7 strain induced higher expression compared with the 2369 and 1849 strains ( figure 4(a ) ) . the percentage of expression of cd83 was increased in dcs infected with any strain , and the aq1.7 strain induced the highest expression compared with the 2369 strain ( figure 4(b ) ) . an increase in the percentage of cd80 was not observed only in dcs that were infected with the strain1839 ( figure 4(c ) ) . the percentage of cd86 was increased in dcs infected with any of the evaluated strains , although the cells infected with the 2369 strain exhibited a more pronounced increase ( figure 4(d ) ) . only the 1849 strain was able to increase the percentage of expression of cd40 ( figure 4(e ) ) . the results also showed that all strains were able to induce the expression of the pd - l1 coinhibitory molecule after 18  h of dc infection ( figure 4(f ) ) . to assess whether t. cruzi strains modulate these receptors , dcs were incubated with the aq1.7 , mutum , 1849 , or 2369 strain , and the percentages of expression and the mfis of these molecules were measured . the results of this experiment demonstrated that dcs infected with the aq1.7 strain had increased expression of ccr5 ( figure 5(a ) ) . the mfi of ccr5 was practically unchanged in both groups but significantly decreased following infection with the aq1.7 strain ( figure 5(b ) ) . regarding ccr7 , none of the studied strains modulated the percentage of expression of this receptor ( figure 5(c ) ) . however , the mfi increased for all strains studied , and this effect was more pronounced for the 1849 strain ( figure 5(d ) ) . the modulation of the expression and/or activation of innate immune receptors such as tlrs by endo- and ectoparasites have been suggested as a mechanism of immune evasion [ 2428 ] . as the receptors tlr2 and tlr4 have been implicated in the recognition of t. cruzi antigens [ 28 , 29 ] , we evaluated whether the different strains of t. cruzi are capable of modulating the expression of these receptors . our results demonstrated that dcs infected with different strains of t. cruzi had an increased percentage of expression of tlr2 ( figure 6(a ) ) and that this increase was most prominent in cells infected with the mutum strain . the mfi of tlr2 was not altered by any of the strains tested ( figure 6(b ) ) . dcs infected with strain 1849 or 2369 showed a decrease in the expression of tlr4 compared with noninfected cells ( figure 6(c ) ) . moreover , the aq1.7 , 1849 , and 2369 strains were able to reduce the expression of this receptor ( figure 6(d ) ) . in this report , it is revealed that four distinct tci ( aq1.7 and mutum ) and tcii ( 1849 and 2369 ) strains exhibit different rates of infectivity in dcs and that the rate for each strain is weakly related to dc biological and immune parameters . we demonstrate that the tci strains presented the lowest rates of dc invasion , whereas the tcii strains presented the highest rates . we also show that both the tci and the tcii strains did not induce significant dc death ; however , the production of cytokines , the expression of stimulatory and costimulatory molecules , and the expression of tlrs and chemokine receptors in the dcs varied more between strains than between dtus themselves . it is truly remarkable that the 2369 strain , from the tcii group , yielded the most interesting results ; this strain was the only one that did not induce production of the proinflammatory cytokine tnf-. additionally , this strain induced high production of the anti - inflammatory cytokine il-10 , among the dc surface molecules , did not induce expression of mhc ii and cd40 , induced low expression of cd83 , and , similar to the other strains , also induced high expression of the coinhibitory molecule pd - l1 . as demonstrated in figure 1 , we show that dc infection rates depend on the infective t. cruzi strain because both the percentage and the media intensity of fluorescence of each dc - infecting parasite significantly differed between strains . we believe that this difference is related to the diversity of molecules involved in the entry of t. cruzi into the host cells because these molecules vary between t. cruzi strains [ 3032 ] . it is widely known that t. cruzi infects all nucleated cells in both experimental animals and humans , although the degree of apoptosis induction in certain host cells requires more detailed studies . regarding the effect of t. cruzi on lymphocyte apoptosis , it is already well known that murine splenic cd4 + and cd8 + t lymphocytes increase the expression of cd95 after infection in mice ; this effect is correlated with activation - induced cell death [ 33 , 34 ] . the treatment of these mice with anti - fasl antibodies protects these mice from death due to t. cruzi infection [ 33 , 34 ] . furthermore , previous reports have demonstrated that chagas cardiomyopathy is related to increased apoptosis of cardiomyocytes and augmented fas - fas - l expression in situ [ 35 , 36 ] . additionally , as the strains studied here induced an increase in pd - l1 expression on dcs , this phenomenon could be a relevant pathway involved in t cell apoptosis . however , concerning other host cells , a recent study showed that t. cruzi can also infect and induce apoptosis in macrophages and cardiomyocytes , but this effect is not present in fibroblasts . this ability to infect and induce apoptosis in macrophages and cardiomyocytes is greater in the strains belonging to tci compared with the tcii strains . thus , our findings partially differ from this published work because although each strain infects dcs differently , this difference is not related to dc apoptosis . but we believe that the parasite , instead of inducing apoptosis , controls the immune response by manipulating these cells , since the cells remained viable and the pattern of cytokine production and the expression of co- and stimulatory surface molecules were altered . cells with such characteristics could either induce apoptosis or alter the activation of effector cells . knowing that strains of t. cruzi invade dcs to different extents , we investigated whether these strains also stimulate the production of cytokines and chemokines and the expression of inhibitory or stimulatory molecules in such cells . regarding the modulation of the immune response by strains from the same dtu what we know so far is that , regardless of the strain used , infected patients have an immune response with a proinflammatory profile and that tci and tcii strains can produce specifically higher levels of certain cytokines compared with other strains . in this sense , it was found that humans infected with tci strains produce higher levels of the cytokine il-6 , whereas infection with tcii strains induces more il-1 and il-17 production . mixed tci / tcii infection in patients produces more il-22 compared with infection with only one strain . in our study , dc chemokine and cytokine production was not dtu dependent because most of the results were similar and , in certain analyses , there were significant differences only between strains from the same dtu . in particular , the production of il-12 was induced by all strains , and tnf- production was induced by all strains , except for strain 2369 , belonging to tcii . the production of il-6 and ccl2 was similar to or less than production in the cells stimulated with medium only , and the production of il-10 was increased by all of the strains . however , one of the strains in both the tci and the tcii groups induced even higher concentrations compared with the other strain in the same dtu . in summary , we suggest that the modulation of cytokine production by these strains is not dtu dependent . in the case of inhibitory and stimulatory molecules , our results showed that dc expression of these molecules was not polarized by different dtus . the percentages of expression of cd83 , cd86 , and pd - l1 were increased by all strains . additionally , the percentages of expression of mhc ii and cd80 were not induced by one tcii strain , and the expression of cd40 was enhanced by only one of the tcii strains . therefore , these in vitro findings show that t. cruzi modulates both the production of cytokines and the expression of surface molecules in dcs , but this effect is not dtu dependent but strain dependent . thus , we believe that the increases in il-10 and pd - l1 levels , together with the low il-12 levels and the absence of il-6 and ccl2 production , may compromise the antigen - presenting and immunostimulatory functions of dcs . these processes may induce immune tolerance , facilitating t. cruzi escape from both innate and adaptive immunity . prior to activation , dcs present augmented expression of ccr5 , but when activated , these cells downregulate ccr5 and overexpress ccr7 . this differential expression of these chemokine receptors explains the migration of dcs to peripheral sites or toward inflamed tissues or secondary lymphoid organs , such as the lymph nodes and spleen [ 40 , 41 ] . our results showed that only the aq1.7 strain from tci was able to increase the percentage of cells expressing ccr5 , although these cells present a reduction in expression of this receptor ( mfi ) . in contrast , all of the strains induced the expression of ccr7 , and this effect was more pronounced for the 1849 strain from the tcii group . these findings suggest that during t. cruzi infection , the traffic of dcs to peripheral tissues is undisturbed or even augmented , such as in the case of the aq1.7 strain . in the case of ccr7 , we presume that the host is able to mature its infected dcs , which migrate to inflamed tissues or the lymph nodes or spleen to present antigens to t. cruzi - specific t cells . in this case , our results corroborate the findings that have already been published because it has been demonstrated that chronically t. cruzi - infected patients have increased expression of many chemokines and chemokine receptors ( including ccr5 and ccr7 ) in the myocardium and that this phenomenon explains the inflammatory process in the patients after the infection . it is worth mentioning here that chagas cardiomyopathy manifestations in humans are more correlated with tci . as ccr5 is a proinflammatory chemokine receptor and the aq1.7 strain induces more ccr5 + dcs , this receptor could contribute to the inflammatory processes of the patients infected with this strain . tlrs are involved in both protection against and the pathology of chagas disease , and among these receptors , it is estimated that tlr2 , tlr4 , and tlr9 are the most important [ 26 , 44 ] . here , we demonstrate that different strains are capable of enhancing the expression of tlr2 , and this effect was more pronounced for the mutum strain , which belongs to the tci group . decreases in the percentage and the mean intensity of tlr4 + dcs were more evident in the strains belonging to tcii . we speculate that the results for tlr2 expression could contribute , in a second moment , to an increased production of il-10 by infected dcs since t. cruzi has molecules that bind to tlr-2 and this and other receptors such as mannose receptors and dectin-1 activate signaling that leads to the production of anti - inflammatory cytokines such as il-10 . indeed , it is already known that ectoparasites and several species of microorganisms evade the host immune system by inducing the production of il-10 in a tlr2-dependent manner [ 25 , 26 , 4549 ] . this phenomenon seemed to have occurred in our study because this increase was very significant . it is known that tlr4 induces large amounts of proinflammatory cytokines , such as il-12 and tnf-. as the tcii strains induced the lowest production of tnf- , this observation could be explained , even in part , by lower expression of the tlr4 receptor . in fact , it has already been demonstrated in vivo that tlr4 signaling is required for optimal production of ifn- , tnf- , and nitric oxide ( no ) in the spleen of t. cruzi - infected animals . moreover , deglycoinositol phospholipids containing ceramide molecules are recognized by tlr4 and trigger the production of il-12 and tnf- in macrophages [ 24 , 50 ] . thus , decreased expression of this receptor or different amounts of these molecules on the t. cruzi surface could explain the lower binding of t. cruzi molecules and their consequently lower production . in summary , we demonstrate , for the first time in protozoa organism , that depending on the strain the parasite may modulate dc biology with different intensities dcs are essential cells to combat protozoa invaders and trigger antiprotozoa innate and acquired responses so , depending on how they are modulated , the host defense may be completely hampered . based on our results , it is essential to evaluate the effect of different dtus of t. cruzi in the modulation of the antigen - presenting properties of dcs to t cells so that the patterns of mice immune response are completely changed . these results will corroborate the findings presented here and explain why strains belonging to each population lead to many pathological outcomes associated with acute and chronic chagas disease . taken together , our results demonstrate that tci and tcii strains of t. cruzi may modulate dc biology to different extents . in general terms , whereas strains belonging to both dtus induce the production and expression of anti - inflammatory molecules , such as il-10 production and pd - l1 and tlr2 expression , proinflammatory parameters are variably modulated , depending on the strain . these observations suggest that each strain of t. cruzi has possibly evolved specific evasion strategies that subvert dcs and consequently the host proinflammatory / immune responses .
dendritic cells ( dcs ) are major immune components , and depending on how these cells are modulated , the protective host immune response changes drastically . 
 trypanosoma cruzi is a parasite with high genetic variability and modulates dcs by interfering with their capacity for antigen recognition , migration , and maturation . despite recent efforts , the association between dcs and t. cruzi i ( tci ) and tcii populations is unknown . 
 herein , it was demonstrated that aq1.7 and mutum tci strains present low rates of invasion of bone marrow - derived dcs , whereas the 1849 and 2369 tcii strains present higher rates . whereas the four strains similarly induced the expression of pd - l1 , the production and expression of il-10 and tlr-2 , respectively , in dcs 
 were differentially increased . 
 the production of tnf- , il-12 , il-6 , and ccl2 and the expression of cd40 , cd80 , mhc - ii , ccr5 , and ccr7 changed depending on the strain . 
 the 2369 strain yielded the most remarkable results because greater invasion correlated with an increase in the levels of anti - inflammatory molecules il-10 and pd - l1 but not with a change in the levels of tnf- , mhc - ii , or cd40 molecules . 
 these results suggest that t. cruzi strains belonging to different populations have evolved specific evasion strategies that subvert dcs and consequently the host response .