Abstract P1-01-19: The role of S100A7 in microbiota mediated inflammation and breast cancer progression

Introduction

While it is accepted that inflammation is a key component of cancer development, the intricate mechanism linking the two are not fully defined. Unparalleled progress has been underway to provide better understanding of this mechanism. We investigate the role of bacterial microbiota in promoting an inflammatory environment through the induction of the pro-inflammatory molecule, S100A7, and its activation of STAT-3 signaling pathways to promote tumor growth and metastasis in breast cancer (BC).

Methods

Immune-competent mouse models of orthotopic breast cancer was used to identify and characterize populations of bacterial microbiota in the cancerous breast tissue at tumor onset. Isolated tissues were homogenized and cultured, then processed for DNA extraction. Bacterial species were identified by aligning the sequences on NCBI BLAST.

Mouse mammary tissue and tumors were analyzed for S100a7 after intraperitoneal exposure to LPS after cancer cell injections. Isolated tissues were analyzed by IHC, Western Blot analysis and real time RT-PCR.

mRNA and Protein expression using real time PCR, western blot and flow cytometry, and binding assays analyzed expression and affinity of LPS/S100A7/TLR4 in BC cell lines in vitro under varying conditions.

Protein expression and In vitro functional assays including matrigel invasion and wound closure assays determined the effect of LPS/S100A7 on TLR4 and STAT-3 expression and signaling pathways in promoting tumor invasiveness.

Results

We observed microbiota in cancerous breast tissue, which is predominantly composed of Gram-negative bacteria at tumor onset. The population of mainly gram negative bacteria at tumor initiation is unique from those populations from feces and skin. This suggests that breast tissue microbiota may be a potential source of LPS in breast tumors.

Stimulation with LPS induces secretion/expression of S100A7 in mouse mammary tissue and tumors, as well as BC cell lines. Furthermore, inhibition of LPS by polymixin B decreases S100A7 to basal levels in BC cell lines.

LPS/S100A7 combinational treatment has an additive effect on the invasive potential induced by LPS in BC cell lines as shown by invasion assays and wound closure assays. S100A7 over expression increases TLR4 expression as observed by TLR4 mRNA by real time PCR and protein by flow cytometry. Furthermore, secreted S100A7 protein promotes interaction between S100A7 protein and TLR4 receptor in cell lines with endogenous TLR4 expression.

In addition, both S100A7 and LPS stimulation of TLR4 can activate STAT3 signaling pathway, and inhibition of either S100A7 and or TLR4 impairs the invasiveness of BC cell lines.

Conclusion

A unique population of gram negative bacteria characterizes breast cancer tissues. LPS of bacterial cells walls, representative of gram negative bacteria induces S100A7, which interacts with TLR4 to activate the STAT-3 pathway in tumors. This LPS-S100A7-TLR4-STAT3 axis in turn increases the invasiveness of tumor cells to promote tumor metastasis. This suggests that microbiota plays an important role in the initiation and progression of breast cancer through regulation of the pro-inflammatory molecule S100A7.

Citation Format: Wilkie T, Zhao H, Nasser M, Ahirwar D, Mishra S, Satoskar A, Pancholi V, Ganju R. The role of S100A7 in microbiota mediated inflammation and breast cancer progression [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-01-19.

Leishmaniasis: clinical syndromes and treatment

Leishmaniasis is a global term for cutaneous and visceral anthroponotic and zoonotic diseases caused by the vector-borne parasites of the genus Leishmania. These diseases afflict at least 2 million people each year with more than 350 million at risk in 98 countries worldwide. These are diseases mostly of the impoverished making prevention, diagnosis and treatment difficult. Therapy of leishmaniasis ranges from local treatment of cutaneous lesions to systemic, often toxic, therapy for disseminated cutaneous, mucocutaneous and deadly visceral disease. This review is a summary of the clinical syndromes caused by Leishmania and treatment regimens currently used for various forms of leishmaniasis.

The pathogenesis of acute allograft dysfunction in desensitized renal transplant recipients

BACKGROUND

Acute allograft rejection after HLA desensitization is common early post-transplant but the sequence of histopathologic changes leading to graft dysfunction has not been well defined.

METHODS

We evaluated the early pathogenesis and sequence of antibody-mediated graft damage of 35 desensitized living donor kidney recipients by studying the course of biopsies taken in the very early post-transplant period (<1 month).

RESULTS

A total of 14 of the 35 patients met criteria for acute antibody-mediated rejection (AMR). In these patients, the chronologic sequence of pathologic changes was C4d peritubular capillary deposition, acute tubular injury, and peritubular capillaritis, followed by glomerulitis and interstitial inflammation. Classic AMR lesions occurred early, followed by mononuclear cellular infiltration, which comprised CD4 and CD8 T cells and monocytes. Development of graft dysfunction in most patients occurred concurrently with the emergence of graft cellular infiltration, rather than at the earlier time of antibody deposition as detected via C4d deposition.

CONCLUSION

These data provide novel insight into the sequence of pathologic changes in patients with AMR post-transplant after HLA desensitization.

Macrophage migration inhibitory factor promotes central nervous system pathology through local microglial activation and macrophage trafficking (60.3)

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). It is reported that cerebrospinal fluid from MS patients during relapse contains higher levels of MIF than samples collected during remission. While the potent pro-inflammatory properties of MIF are well established, the precise contribution to neuroinflammation is not well defined. We have previously shown that despite their ability to generate pathogenic T cells, MIF-/- mice fail to develop experimental autoimmune encephalomyelitis (EAE), and have reduced CNS pathology. These findings suggest that MIF acts within the CNS to potentiate disease progression. We observed that MIF-treated microglia upregulate inflammatory mediators associated with MS and EAE including IL-1, IL-6, TNF-α, iNOS, and CCL2, and exhibit morphological changes consistent with activation. We extended these findings in vivo, performing stereotactic spinal microinjection of rMIF into naïve mice, which resulted in targeted microglial reactivity and cellular infiltration. To determine the role of MIF in the CNS during EAE, we examined the ability of rMIF spinal microinjection to restore CNS pathology in MIF-/- mice. Notably, rMIF microinjection was sufficient to restore CNS pathology in EAE-resistant MIF-/- mice following induction of EAE. Taken together, these studies implicate MIF as a CNS inflammatory mediator that may contribute to the development and maintenance of MS lesions.

Macrophage migration inhibitory factor promotes central nervous system pathology in a model of neuroinflammation (35.8)

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS). Cerebrospinal fluid collected from MS patients during relapse was found to contain greater levels of macrophage migration inhibitory factor (MIF) than samples collected during remission. We have shown that induction of experimental autoimmune encephalomyelitis (EAE) in MIF-deficient mice results in reduced clinical signs and CNS inflammatory infiltrates relative to wild type controls. However, there was no difference in T cell function in the periphery between the two groups. These findings suggest that MIF acts within the CNS to potentiate disease progression. The potent pro-inflammatory properties of MIF are well established; however, the precise contribution of MIF to neuroinflammation is not well defined. MIF is expressed by many cell types in the CNS including infiltrating macrophages and resident microglia, suggesting that MIF may enhance the inflammatory environment of MS lesions. To assess the contribution of MIF to CNS inflammation, primary microglial cultures were treated with increasing doses of rMIF, which upregulated inflammatory mediators associated with MS and EAE: IL-1β, iNOS, and CCL2. We are currently exploring the role of MIF in vivo using an intraspinal model of neuroinflammation. Taken together, these data suggest that inhibition of MIF may serve as a therapeutic strategy for resolving CNS inflammation.

A critical mediator of leukocyte extravasation during inflammatory disease (50.8)

Multiple sclerosis (MS) is a demyelinating neurological disease affecting more than 400,000 Americans. MS pathology involves activation of autoreactive lymphocytes and their migration across the blood-brain barrier (BBB) into the central nervous system (CNS). MS patients have a higher level of the ubiquitously expressed, proinflammatory cytokine MIF. Mice lacking MIF have fewer leukocytes in the CNS following induction of experimental autoimmune encephalomyelitis (EAE), an animal model for MS. We found using bone marrow chimeras that mice expressing MIF from myeloid cells had significantly more severe disease than MIF KO mice or mice expressing MIF only in non-myeloid cells (CDI±SD; 28.0±17.9 vs. 10.3±17.9 or 4.7±10.4). Using immunohistochemistry, we found more infiltrates in the CNS of mice expressing MIF from myeloid cells. We utilized a small molecule inhibitor of MIF to evaluate whether disruption of MIF activity could inhibit migration of leukocytes. Mice had reduced severity of EAE following inhibitor administration and reduced migration of leukocytes into the CNS. Other groups have shown that blocking MIF reduces expression of adhesion molecules on the BBB. Our data suggests that during inflammatory disease, MIF from myeloid cells is critical for leukocyte migration and an inhibitor of MIF reduces migration and subsequent clinical disease. (Supported by NIH grant AI 064320 and NMSS grant RG3272)

A distinct role for PI3Kgamma in suppressing the development and progression of experimental autoimmune encephalomyelitis (EAE) (129.30)

Phosphoinositide 3-kinases (PI3K) are intracellular signaling proteins involved in cellular responses such as chemotaxis, proliferation and apoptosis. Selective inhibitors of the PI3Kγ-isoform have recently become available. This study explores the role of PI3Kγ in the development and progression of EAE. PI3Kγ +/+ (wt) and PI3Kγ −/− (ko) mice were immunized for EAE using myelin oligodendrocyte glycoprotein p35-55 (MOG) and assessed for clinical signs, CNS histopathology and T cell activation. WT mice showed a progressive disease course with elevations in inflammatory cytokines increased CNS mononuclear infiltrates. In contrast, ko mice exhibited a delayed onset and dramatically less severe EAE course characterized by decreased T cell activation and inflammatory cytokines (TNF-α, IFN-γ, IL-2, IL-12p40, IL-6, IL-17 and MCP-1). Male ko mice were significantly more protected than ko females. Adoptive transfer of MOG-activated T cells into ko recipients show that ko mice are resistant to passive disease induction. Interestingly, wt recipients of ko donors immunized for EAE were also protected. Furthermore, adoptive transfer of activated GFP+ T cells show marked decreased infiltration of GFP+ T cells into the CNS. Taken together, these findingssuggest that depletion of PI3Kγ results in a down-regulation of the inflammatoryresponse caused by impaired trafficking of cells critical to generation of the immune response.

(Supported by NIH grant AI 064320 and National MS Society Grant RG 3272).

Migration inhibitory factor modulates experimental autoimmune encephalomyelitis through a novel combination of suppressive mediators (131.34)

Multiple sclerosis (MS), an autoimmune disease of the central nervous system (CNS), is more prevalent in women than men. Recent studies suggest that the cytokine migration inhibitory factor (MIF) plays a role in the progression of MS and experimental autoimmune encephalomyelitis (EAE). We have shown that MIF−/− mice have decreased EAE severity relative to wt controls. Here, we evaluate the role of MIF in the context of known suppressive hormones. Serum levels of corticosterone (CORT) and testosterone (TEST) were measured prior to and following EAE induction in the presence and absence of MIF. Basal levels of TEST in MIF−/− mice were notably higher than controls; basal levels of CORT were low and similar between groups. Following EAE, there was little change in CORT and TEST in wt mice; however, TEST decreased and CORT increased in MIF−/− mice following immunization. To evaluate the role of TEST, we removed the testes of male MIF−/− mice and induced EAE. We found no difference in disease severity whether MIF−/− mice were gonadectomized or not; control mice had significantly more severe EAE in the absence of TEST. These findings suggest that CORT plays a larger role than TEST in disease progression, although both hormones appear to be influenced by MIF. Further study of the mechanism of MIF could lead to improved therapies for a variety of autoimmune diseases.

(Supported by NIH grant AI 064320 and National MS Society grant RG3272)

Sex steroids, pregnancy-associated hormones and immunity to parasitic infection

A wealth of evidence has accumulated that illustrates the ability of sex-associated hormones to influence directly a variety of diverse immunological functions. Thus, it is not surprising that differences have also been noted between the sexes in their relative susceptibility to parasitic infections. Furthermore, during pregnancy, much of the observed maternal immunomodulation, essential for fetal survival, has been attributed to changes in the levels of steroid hormones. These pregnancy-induced alterations in immune function can also have profound effects on the course of parasitic infection. In this article, Craig Roberts, Abhay Satoskar and James Alexander review the immunological basis for differences in the relative susceptibilities of males, non-pregnant females and pregnant females to parasitic infection, particularly leislumaniasis and toxoplasmosis. They also discuss the role of the major sex- and pregnancy-associated hormones in mediating these effects.

Endogenous IL-4 is necessary for effective drug therapy against visceral leishmaniasis

It is well established that a fully competent immune response is required for the successful drug treatment of visceral leishmaniasis. However, recent studies have cast some doubt as to which elements of the immune response synergize with chemotherapeutic treatment. The role of the Th2 response and IL-4 in particular during visceral leishmaniasis awaits clarification. We, therefore, examined the effectiveness of sodium stibogluconate treatment on Leishmania donovani infection in BALB/c wild-type and IL-4-/- mice. Parasite burdens in L. donovani-infected IL-4+/- and IL-4-/-, as we have previously shown for B6/129 mice, were similar, despite an apparent type 1 antibody response in infected IL-4-/- mice, demonstrated by increased levels of parasite-specific IgG2a and decreased IgG1. Unexpectedly IL-4-/- mice responded poorly to sodium stibogluconate treatment with increased parasite burdens in all tissues examined. Furthermore, drug therapy of IL-4-/- but not IL-4+/+ mice resulted in significant reductions in splenocyte IFN-gamma mRNA transcripts and in serum IFN-gamma levels. These results demonstrate that IL-4 has an important role in effective anti-leishmanial chemotherapy which seems to be related to modulation of IFN-gamma production.

Sex-determined resistance against Leishmania mexicana is associated with the preferential induction of a Th1-like response and IFN-gamma production by female but not male DBA/2 mice

Female DBA/2 mice are relatively resistant to infection with Leishmania mexicana compared with male mice. Following subcutaneous infection with 5 x 10(6) L. mexicana, amastigotes lesion growth in male and female DBA/2 mice was measured and the developing immune responses were monitored both in vitro and in vivo. Over the 10 week duration of the experiment all male DBA/2 mice developed rapidly growing non-healing lesions while female mice either developed no lesions whatsoever or developed smaller slower growing lesions than males. Both male and female mice produced parasite specific IgG2a during the course of the disease. However, significant titres of parasite specific IgG1 antibodies could be detected only in male mice indicating a Th2-influenced response in this sex. Furthermore, female mice, unlike male mice, developed significant parasite induced cutaneous delayed-type hypersensitivity footpad responses, indicating a Th1-influenced response in female mice. Although both male and female DBA/2 mice infected with L. mexicana displayed a significant increase in the number of cells in their draining lymph nodes at week 10 post-infection, no significant differences could be observed in the numbers of CD4+, CD8 + T cells as well as B cells between male and female DBA/2 mice. However. following in vitro stimulation, the lymph node cells from female mice displayed significantly higher antigen specific proliferative responses than the males and produced significant amounts of IFN-gamma which could not be detected in the equivalent culture supernatants from male mice. There were no significant differences in the levels of Th2-associated cytokines IL-4 and IL-5, produced by the lymph node cells of both sexes. Treatment of female DBA/2 mice with IFN-gamma neutralizing antibody following L. mexicana infection resulted in lesion growth equivalent to male mice. Conversely, intralesional injections of murine recombinant IFN-gamma significantly inhibited lesion growth in male mice.

Protective effect on Leishmania major infection of migration inhibitory factor, TNF-alpha, and IFN-gamma administered orally via attenuated Salmonella typhimurium

The genes encoding murine macrophage migration inhibitory factor (MIF), IL-2, IFN-gamma or TNF-alpha were cloned individually into an expression plasmid under the control of the inducible promoter nirB and transfected into the aroA- aroD- deletion mutant strain of Salmonella typhimurium (BRD509). These S. typhimurium derivatives (henceforward called constructs and termed GIDMIF, GIDIL2, GIDIFN and GIDTNF) expressed their respective cytokines in vitro under anaerobic conditions and stably colonized BALB/c mice up to 14 days after oral administration. The highly susceptible BALB/c mice that had received the constructs orally and that had been subsequently infected via the footpad with Leishmania major, developed significantly reduced disease compared with control mice administered the untransfected Salmonella strain (BRD509). Importantly, a combination of GIDMIF, GIDIFN, and GIDTNF administered orally after L. major infection was able to significantly limit lesion development and reduced parasite loads by up to three orders of magnitude. Spleen and lymph node cells of mice administered this combination expressed markedly higher levels of inducible nitric oxide synthase (iNOS) compared with those from mice receiving an equivalent dose of the control strain of Salmonella (BRD509). These data therefore demonstrate the feasibility of therapeutic treatment in an infectious disease model using cytokines delivered by attenuated Salmonella. The protective effect observed correlates with the induction of inducible nitric oxide synthase in vivo.

Gammadelta T cells are not essential for control of cutaneous Leishmania major infection in genetically resistant C57BL/6 mice

As gammadelta T cells are believed to be involved in host defense against Leishmania major, the role of gammadelta T cells in immunity against this parasite was investigated. The growth of L. major was measured in alphabeta (T cell receptor [TCR] alpha -/-) and gammadelta (TCR delta -/-) TCR-deficient C57BL/6 mice and compared with growth in control (C57BL/6) mice. While TCR alpha -/- mice developed nonhealing lesions containing large numbers of parasites following L. major infection, TCR delta -/- and C57BL/6 mice effectively controlled the infection. Following in vitro stimulation, lymph node cells from C57BL/6 mice produced significantly more interferon (IFN)-gamma than those from TCR delta -/- mice during early and late phases of infection; however, both produced similar levels of IFN-gamma at postinfection week 6. Culture supernatants from both TCR delta -/- and C57BL/6 mice contained interleukin-4, at postinfection week 2 only. These results indicate that gammadelta CD3 T cells are not essential for mediating protection against cutaneous L. major infection in C57BL/6 mice.

SCID mice reconstituted with IL-4-deficient lymphocytes, but not immunocompetent lymphocytes, are resistant to cutaneous leishmaniasis

To characterize the roles of lymphoid- and non-lymphoid-derived IL-4 during cutaneous infection with Leishmania mexicana, the disease was monitored in SCID mice reconstituted with splenocytes from either immunocompetent BALB/c mice or IL-4-deficient BALB/c mice. Whereas following s.c. infection with L. mexicana no lesion growth was observed in BALB/c IL-4(-/-) mice and lesion growth was significantly inhibited in SCID mice, rapid initial lesion growth occurred in both SCID IL-4(+/+) and SCID IL-4(-/-) reconstituted mice. However, after 3 to 4 wk of infection, lesions in SCID IL-4(-/-) but not SCID IL-4(+/+) reconstituted mice began to heal. This paralleled a developing Th1-like phenotype and parasite clearance in the former group and a developing Th2-like phenotype in the latter group. Lesion sites from the healing SCID IL-4(-/-) mice expressed the inducible nitric oxide synthase, whereas the SCID IL-4(+/+) mice with progressive disease did not. These findings indicate that non-lymphocyte-derived IL-4 may play a role in initiating lesion growth following cutaneous infection with L. mexicana, but the presence of lymphocyte-derived IL-4 is essential for disease progression, and in its absence, lesions heal due to a developing Th1 phenotype.

Heart transplants in interferon-gamma, interleukin 4, and interleukin 10 knockout mice. Recipient environment alters graft rejection

To study the role of cytokines in long-term cardiac allografts we have used recipient mice with targeted gene deletions (-/-) in IFN-gamma, IL-4, or IL-10. In wild-type and IL-4 -/- recipients immunosuppressed with a 30-d course of anti-CD4 and anti-CD8, graft survival was > 87 d. This time was significantly reduced in IFN-gamma -/- (62 +/- 19 d, P < 0.05) and IL-10 -/- recipients (55 +/- 4 d, P < 0.0001). Histology showed mononuclear cell infiltration, patchy necrosis, fibrosis, and vascular thickening in all groups. Intragraft transcript levels measured by 32P-reverse transcriptase PCR showed different inflammatory patterns. IFN-gamma -/- recipients had higher IL-2 transcripts and selective alteration in macrophage activation that may have contributed to decreased graft survival. Decreased graft survival in IL-10 -/- recipients was associated with increases in iNOS and IFN-gamma-driven responses. Finally, in grafts from IL-4 -/- recipients, there were increases in CD3 transcripts concurrent with TNF-alpha levels. This increase suggests that IL-4 may regulate T cell infiltration through TNF-alpha-mediated inflammatory cell recruitment. Concurrent evaluation of these three isolated cytokine deletions has shown that the recipient environment caused distinct graft modifications.

SCID mice reconstituted with IL-4-deficient lymphocytes, but not immunocompetent lymphocytes, are resistant to cutaneous leishmaniasis

To characterize the roles of lymphoid- and non-lymphoid-derived IL-4 during cutaneous infection with Leishmania mexicana, the disease was monitored in SCID mice reconstituted with splenocytes from either immunocompetent BALB/c mice or IL-4-deficient BALB/c mice. Whereas following s.c. infection with L. mexicana no lesion growth was observed in BALB/c IL-4(-/-) mice and lesion growth was significantly inhibited in SCID mice, rapid initial lesion growth occurred in both SCID IL-4(+/+) and SCID IL-4(-/-) reconstituted mice. However, after 3 to 4 wk of infection, lesions in SCID IL-4(-/-) but not SCID IL-4(+/+) reconstituted mice began to heal. This paralleled a developing Th1-like phenotype and parasite clearance in the former group and a developing Th2-like phenotype in the latter group. Lesion sites from the healing SCID IL-4(-/-) mice expressed the inducible nitric oxide synthase, whereas the SCID IL-4(+/+) mice with progressive disease did not. These findings indicate that non-lymphocyte-derived IL-4 may play a role in initiating lesion growth following cutaneous infection with L. mexicana, but the presence of lymphocyte-derived IL-4 is essential for disease progression, and in its absence, lesions heal due to a developing Th1 phenotype.

In interleukin-4-deficient mice, alum not only generates T helper 1 responses equivalent to freund's complete adjuvant, but continues to induce T helper 2 cytokine production

The role of interleukin (IL)-4 in the activity of two frequently used vaccine adjuvants, Freund's complete adjuvant (FCA) and the aluminum hydroxide gels (alum), was studied using the standard antigen ovalbumin (OVA) in IL-4 genedisrupted mice (IL-4 -/-). In the absence of adjuvant, there was an overall reduction in antibody production to OVA in IL-4 -/- mice and significantly greater amounts of interferon (IFN)-gamma were produced following restimulation of splenocytes with antigen in vitro compared with immunocompetent controls (IL-4 +/+). FCA and alum boosted the immune response to OVA in both IL-4 -/- and IL-4 +/+ mice. In IL-4 +/+ mice, while FCA stimulated a wide-spectrum immunoglobulin response, including both Th1-associated IgG2a and Th2-associated IgG1, alum enhanced only Th2 antibody production and no OVA-specific IgG2a could be detected. In IL-4-deficient mice, however, not only was IgG2a production increased in all adjuvant-treated groups, but alum was as potent at stimulating this antibody subclass as FCA. Similarly, increased production in vitro by splenocytes of the Th1 cytokine IFN-gamma, equivalent to that produced after inoculation with FCA/OVA, was only detected in IL-4 -/- mice inoculated with alum/OVA. There was no IgE production in IL-4 -/- mice and OVA-specific IgG1 production, although still at significant levels, was reduced compared with wild-type mice irrespective of the adjuvant used. However, although production of the Th2 cytokine IL-5 was totally inhibited in IL-4-deficient mice inoculated with FCA/OVA, there was no significant difference in IL-5 production between the two strains when alum was used as adjuvant.

Different roles for interleukin-4 during the course of Toxoplasma gondii infection

The course of Toxoplasma gondii infection from initiation of disease perorally until day 28 postinfection was compared between interleukin-4 (IL-4) gene knockout (IL-4-/-) mice and their wild-type (IL-4+/+) counterparts on a disease-susceptible genetic background. The rate of mortality was significantly greater in mice deficient in Il-4 than in the immunocompetent controls. Although levels of T. gondii-specific spleen cell proliferation measured in vitro were similar between groups at all time points examined throughout infection, the quantities of cytokines released into the culture supernatant differed. Culture supernatants from spleen cells derived from IL-4-deficient mice contained significantly more gamma interferon than those derived from IL-4+/+ mice at day 7 postinfection. Conversely, IL-10 production was significantly greater from the spleen cells derived from wild-type mice at day 28 postinfection. Splenocytes from both groups of mice had a marked inhibition of proliferation in response to soluble tachyzoite antigen as well as reduced proliferation in response to concanavalin A between days 7 and 14 postinfection and marked proliferation on days 21 and 28 postinfection. At day 28 postinfection, histological examination of the brains indicated that IL-4+/+ mice had more severe pathological changes and more cysts than IL-4-/- mice. In addition, although many nonencysted single organisms were present in IL-4+/+ mice within both necrotic lesions and microglial nodules, few nonencysted parasites were found, and no necrotic lesions were present in IL-4-deficient animals. These results suggest that the observed reduction in mortality during the early acute phases of infection may be due to the down-regulatory effects of Il-4 or associated Th2-derived products on proinflammatory cytokines such as gamma interferon. However, the long-term effects of IL-4 are detrimental, possibly because of the ability of this cytokine to inhibit proinflammatory antiparasitic products. This may explain the increased parasite multiplication with cysts observed in the brains of IL-4+/+ mice.

Disruption of the murine interleukin-4 gene inhibits disease progression during Leishmania mexicana infection but does not increase control of Leishmania donovani infection

The growths of both cutaneous leishmaniasis and visceral leishmaniasis caused by Leishmania mexicana and Leishmania donovani, respectively, were measured in interleukin-4 (IL-4) knockout mice (IL-4-/-) and compared with those of similarly infected wild-type (IL-4+/+) control mice. While large, nonhealing, cutaneous lesions containing large numbers of parasites developed in IL-4+/+ mice subcutaneously infected with 5 x 10(6) L. mexicana amastigotes in the shaven rump, in IL-4-/- mice no lesions whatsoever developed and parasites were difficult to detect. Systemic spread and metastasis were also noted in IL-4+/+ but not IL-4-/- mice. In contrast, IL-4-/- mice infected intravenously with 10(7) L. donovani amastigotes were found to have consistently higher parasite burdens in their livers throughout infection than did their wild-type counterparts. However, these differences were only significant at 15 days postinfection. While the results reported here pertaining to L. donovani largely support previous studies, those related to L. mexicana provide new observations. The immunological responses of IL-4-/- and IL-4+/+ mice infected with L. mexicana were, therefore, examined both in vivo and in vitro. Although neither IL-4-/- nor IL-4+/+ mice infected with L. mexicana produced parasite-specific immunoglobulin G2a antibodies, IL-4+/+ mice, unlike IL-4-/- mice, developed significant immunoglobulin G1 antibody titers as infection progressed, indicating a Th2-influenced response in wild-type mice. In addition, IL-4-/- mice, unlike IL-4+/+ mice, developed a significant delayed-type hypersensitivity response, indicating a Th1-influenced response in IL-4-/- mice. Following in vitro stimulation, splenocytes from IL-4+/+ mice infected with L. mexicana displayed significantly higher antigen-specific proliferative responses than did IL-4-/- mice. However, gamma interferon production as measured from the supernatants of the in vitro splenocyte cultures of IL-4-/- mice was significantly higher than that from IL-4+/+ mice. This again would indicate a predominantly Th1-influenced response in the absence of a Th2 response in IL-4-/- mice infected with L. mexicana. On the other hand, at the same time point, draining lymph node cells from IL-4+/+ mice produced significantly higher quantities of IL-5 than did those from IL-4-/- mice following in vitro antigenic stimulation.(ABSTRACT TRUNCATED AT 400 WORDS)

T helper 2 cells are subject to high dose oral tolerance and are not essential for its induction

Oral administration of aqueous protein Ag results in profound immunologic tolerance, and it has been suggested previously that this reflects selective activation of Th subsets. Here we show that the induction of oral tolerance by feeding a single high dose of OVA to mice significantly reduces the production of both Th1- and Th2-dependent cytokines and is accompanied by a marked reduction of specific Abs of both the IgG2a and IgG1 isotypes in vivo. Oral tolerance was also induced normally in IL-4-deficient mice. These results indicate that both subsets of the Th cell are equally susceptible to the induction of tolerance with a single high dose of Ag delivered via the oral route and that this phenomenon does not require Th2 cells.

T helper 2 cells are subject to high dose oral tolerance and are not essential for its induction

Oral administration of aqueous protein Ag results in profound immunologic tolerance, and it has been suggested previously that this reflects selective activation of Th subsets. Here we show that the induction of oral tolerance by feeding a single high dose of OVA to mice significantly reduces the production of both Th1- and Th2-dependent cytokines and is accompanied by a marked reduction of specific Abs of both the IgG2a and IgG1 isotypes in vivo. Oral tolerance was also induced normally in IL-4-deficient mice. These results indicate that both subsets of the Th cell are equally susceptible to the induction of tolerance with a single high dose of Ag delivered via the oral route and that this phenomenon does not require Th2 cells.

Sex-determined susceptibility and differential IFN-gamma and TNF-alpha mRNA expression in DBA/2 mice infected with Leishmania mexicana

Female DBA/2 mice have been shown to be relatively resistant to infection with Leishmania mexicana when compared with male mice. In order to determine the immunological basis behind this difference the draining lymph nodes from male and female DBA/2 mice were excised and the RNA extracted at different time-points following infection. Following reverse transcription, the polymerase chain reaction (PCR) was used to identify mRNA transcripts for interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha), interleukin-4 (IL-4), IL-10 and IL-12. The evolution of cytokine mRNA production was slow in both male and female mice as no newly synthesized transcripts were identified 5 weeks after infection. IL-10 was expressed constitutively in non-infected mice and was present throughout the experiment in all animals. By week 8, a clear dichotomy in cytokine mRNA expression was emerging between the resistant female and susceptible male mice. Whereas all females expressed IFN-gamma and one also expressed TNF-alpha only two out of five males expressed IFN-gamma and four out of five expressed TNF-alpha. The greatest lesion sizes at this time were recorded from those mice expressing TNF-alpha but not IFN-gamma. No differences in IL-4 or IL-12 were noted with transcripts for both cytokines present in both sexes at week 8. By week 12 males had developed large non-healing nodules and in females lesions had either disappeared or were slow growing. At this time only transcripts for TNF-alpha were present in males and only those for IFN-gamma were detected in females. Treatment of female mice following infection with IFN-gamma neutralizing antibody resulted in lesion growth equivalent to male mice. IFN-gamma production would, therefore, appear sufficient to limit the growth of L. mexicana in female DBA/2 mice while TNF-alpha production in the absence of IFN-gamma confers no protection to DBA/2 male mice.

Incidence of Helicobacter pylori associated gastritis in the urban population from India

Endoscopic gastric biopsies from 109 patients showing chronic active gastritis on histology were analysed to detect Helicobacter pylori by Gimenez technique. Incidence of H. pylori positivity was found to be 50.4%. The organisms were detected mainly above the epithelial surface and in the crypts. All the patients were residents from Bombay or its suburbs.

Brain abscess caused by Cladosporium trichoides

Brain abscess caused by the fungus Cladosporium trichoides is rare. Only 20 cases of brain abscess caused by this fungus are reported in the literature. We report a case of brain abscess caused by Cladosporium trichoides in a healthy adult male. The relevant literature on this subject is reviewed.

Prevalence of hepatitis B surface antigen (HBsAg) in blood donors from Bombay

Analysis of serum samples from 3104 blood donors from Bombay screened for hepatitis B surface antigen (HBsAg) by ELISA. HBsAg was detected in 4.7% of the subjects. Relatives showed a significantly higher prevalence of HBsAg than volunteer donors. There was no significant association between HBsAg positivity and a particular blood group.