Spatial organisation of microbiota in quiescent adenoiditis and tonsillitis.

BACKGROUND: The reasons for recurrent adenotonsillitis are poorly understood. METHODS: The in situ composition of microbiota of nasal (5 children, 25 adults) and of hypertrophied adenoid and tonsillar tissue (50 children, 20 adults) was investigated using a broad range of fluorescent oligonucleotide probes targeted to bacterial rRNA. None of the patients had clinical signs of infection at the time of surgery. RESULTS: Multiple foci of ongoing purulent infections were found within hypertrophied adenoid and tonsillar tissue in 83% of patients, including islands and lawns of bacteria adherent to the epithelium, with concomitant marked inflammatory response, fissures filled with bacteria and pus, and diffuse infiltration of the tonsils by bacteria, microabscesses, and macrophages containing phagocytosed microorganisms. Haemophilusinfluenzae mainly diffusely infiltrated the tissue, Streptococcus and Bacteroides were typically found in fissures, and Fusobacteria,Pseudomonas and Burkholderia were exclusively located within adherent bacterial layers and infiltrates. The microbiota were always polymicrobial. CONCLUSIONS: Purulent processes persist during asymptomatic periods of adenotonsillitis. Most bacteria involved in this process are covered by a thick inflammatory infiltrate, are deeply invading, or are located within macrophages. The distribution of the bacteria within tonsils may be responsible for the failure of antibiotic treatment.

Bacterial biofilm within diseased pancreatic and biliary tracts.

BACKGROUND: Bacterial community structures in human pancreatic and biliary tracts were evaluated. METHODS: Gall bladder stones from 153 patients, 20 gall bladder walls, six common duct stones, 52 biliary stents, 21 duodenal biopsies, nine pancreatic duct biopsies, and five bile ducts were investigated using fluorescence in situ hybridisation (FISH) with ribosomal RNA targeted Cy3/Cy5 (carbocyanine) labelled oligonucleotide probes. RESULT: Duodenal, gall bladder, and bile duct walls were free of bacteria. A dense multispecies bacterial biofilm was present within the pancreatic duct of patients with calcific pancreatitis and within biliary stents, irrespective of diagnosis. The concentration, density, and amenability of the biofilm to FISH and DNA staining declined progressively with the grade of stent occlusion. The lowest detectable bacterial concentrations were found by FISH in completely occluded stents and brown/mixed gall stones. Bacteria were not detectable with FISH in cholesterol gall stones. CONCLUSIONS: A wide range of different branches and groups of bacteria participate in the development of biofilms on the surfaces of foreign bodies, such as biliary stents, mixed gall stones, or calcific pancreatic ducts, but not on the surface of pure cholesterol gall stones. Occlusion of stents leads to progressive extinction of the biofilm and mummification of its components. Deposition of cholesterol or other substances within the biofilm matrix may be a novel mechanism of host defence against bacteria present in these biofilms.

B cells in epithelial and perivascular compartments of human adult thymus.

The thymus is the site of T-cell differentiation. However, the relatively recent observation that B cells are also present in the human thymus has prompted studies to determine the origin and function of these B cells. Our studies show that phenotypically distinguishable B cell populations are located within both the thymic medulla and the thymic perivascular space and that cellular trafficking occurs between these compartments, including B cells trafficking from the periphery. The numbers of thymic B cells increase with age, correlating with increases in lymphocyte-rich regions of thymic perivascular space that are prominent between ages 10 and 50 years. B cells within both thymic epithelial and perivascular compartments contain mutated immunoglobulin VH sequences characteristic of post-germinal center B cells, suggesting that the B cells that most often give rise to thymic B-cell lymphomas may originate from either the thymic medulla or perivascular space.

Age-related thymic atrophy in the guinea pig.

We have characterized age-related thymic atrophy in the guinea pig, including identification of antibodies that allow immunohistochemical assessment of thymopoiesis. Age-related thymic atrophy in guinea pigs more closely resembles what occurs in humans histologically and in thymus weight, cellularity, and percent functional area than do other rodent models. The guinea pig model is thus particularly well-suited to study the role of the thymic perivascular space in age-related thymic atrophy. We next tested the hypothesis that dietary supplementation with Vitamin C could prevent or delay age-related thymic atrophy. Thymus histology, weight, cellularity, and percent functional area did not differ at 12 months between groups that received 3, 30, or 150 mg Vitamin C daily from 4 months of age. Thus long-term supplementation with up to 130 mg/kg/day Vitamin C is insufficient to influence the time course and extent of age-related thymic atrophy in guinea pigs.

Zinc alpha-2-glycoprotein is expressed by malignant prostatic epithelium and may serve as a potential serum marker for prostate cancer.

Zinc alpha-2-glycoprotein (ZAG) is a M(r) 41,000 glycoprotein secreted by a variety of normal epithelia. ZAG was recently shown to stimulate lipolysis in adipocytes, leading to the development of cachexia in animals with ZAG-producing tumors. To understand the possible contribution of ZAG to the development of cachexia in men with prostate cancer, ZAG production by normal and malignant prostate tissue was investigated using immunohistochemical assays. Anti-ZAG monoclonal antibodies reacted strongly with normal prostate epithelium but not with other components of prostate or seminal vesicles. The majority of prostate cancers tested (35 of 48; 73%) also reacted with anti-ZAG antibodies. High-grade tumors expressed significantly less ZAG than moderate-grade tumors (mean ZAG score 1.1 versus 1.9; P < 0.01). Men with ZAG-producing prostate carcinomas had elevated levels of serum ZAG relative to their normal age- and race-matched controls (P < 0.02). Furthermore, s.c. growth of human ZAG-producing murine tumors in syngeneic mice and orthotopic growth of ZAG-producing human prostate carcinomas in nude rats resulted in readily detectable levels of human ZAG in the serum. Taken together, these studies show that ZAG production by prostate cancer can lead to systemically elevated serum ZAG levels that may be useful diagnostically. The effects of elevated systemic ZAG on cachexia-associated complications in patients with advanced prostate cancer deserves additional investigation.

Thymopoiesis in HIV-infected adults after highly active antiretroviral therapy.

The thymus of HIV-seropositive patients can enlarge as CD4+ T cell counts increase on highly active anti-retroviral therapy (HAART). This may indicate development of new T cells or represent mature peripheral T cells recirculating to the thymus. To define the etiology of the enlargement, the thymuses of two HIV-infected individuals on HAART were biopsied. For more than 3 years before initiation of HAART, both patients (38 and 41 years of age) had documented CD4+ T lymphopenia. Peripheral blood samples were obtained to assess circulating CD4+ CD45RA+ CD62L+ T cells, which were thought to have recently developed in the thymus. Peripheral blood T cells from both patients and thymocytes from the second patient were also tested for levels of DNA episomes formed during T cell receptor gene rearrangement (T cell receptor rearrangement excision circles, TRECs). With HAART, peripheral blood CD4+ T cell counts increased from approximately 60/mm(3) to 552/mm(3) and 750/mm(3) for patients 1 and 2, respectively. Thymic biopsies from both patients showed normal thymus histology with active thymopoiesis. Percentages of peripheral blood CD4+ CD45RA+ CD62L+ T cells and quantitation of T cell TRECs also reflected active thymopoiesis in both patients. Thus, in these two HIV-seropositive adults examined after initiation of HAART, thymic enlargement represented active thymopoiesis. Thymopoiesis in adult AIDS patients may contribute to immune reconstitution even after prolonged CD4+ T lymphopenia.

Unarmed, tumor-specific monoclonal antibody effectively treats brain tumors.

The epidermal growth factor receptor (EGFR) is often amplified and rearranged structurally in tumors of the brain, breast, lung, and ovary. The most common mutation, EGFRvIII, is characterized by an in-frame deletion of 801 base pairs, resulting in the generation of a novel tumor-specific epitope at the fusion junction. A murine homologue of the human EGFRvIII mutation was created, and an IgG2a murine mAb, Y10, was generated that recognizes the human and murine equivalents of this tumor-specific antigen. In vitro, Y10 was found to inhibit DNA synthesis and cellular proliferation and to induce autonomous, complement-mediated, and antibody-dependent cell-mediated cytotoxicity. Systemic treatment with i.p. Y10 of s.c. B16 melanomas transfected to express stably the murine EGFRvIII led to long-term survival in all mice treated (n = 20; P < 0.001). Similar therapy with i.p. Y10 failed to increase median survival of mice with EGFRvIII-expressing B16 melanomas in the brain; however, treatment with a single intratumoral injection of Y10 increased median survival by an average 286%, with 26% long-term survivors (n = 117; P < 0.001). The mechanism of action of Y10 in vivo was shown to be independent of complement, granulocytes, natural killer cells, and T lymphocytes through in vivo complement and cell subset depletions. Treatment with Y10 in Fc receptor knockout mice demonstrated the mechanism of Y10 to be Fc receptor-dependent. These data indicate that an unarmed, tumor-specific mAb may be an effective immunotherapy against human tumors and potentially other pathologic processes in the "immunologically privileged" central nervous system.

The role of the thymus in immune reconstitution in aging, bone marrow transplantation, and HIV-1 infection.

The human thymus is a complex chimeric organ comprised of central (thymic epithelial space) and peripheral (perivascular space) components that functions well into adult life to produce naive T lymphocytes. Recent advances in identifying thymic emigrants and development of safe methods to study thymic function in vivo in adults have provided new opportunities to understand the role that the human thymus plays in immune reconstitution in aging, in bone marrow transplantation, and in HIV-1 infection. The emerging concept is that there are age-dependent contributions of thymic emigrants and proliferation of postthymic T cells to maintain the peripheral T cell pool and to contribute to T cell regeneration, with the thymus contributing more at younger ages and peripheral T cell expansion contributing more in older subjects. New studies have revealed a dynamic interplay between postnatal thymus output and peripheral T cell pool proliferation, which play important roles in determining the nature of immune reconstitution in congenital immunodeficiency diseases, in bone marrow transplantation, and in HIV-1 infection. In this paper, we review recent data on human postnatal thymus function that, taken together, support the notion that the human thymus is functional well into the sixth decade and plays a role throughout life to optimize human immune system function.

Effect of highly active antiretroviral therapy and thymic transplantation on immunoreconstitution in HIV infection.

The purpose of this study was to determine whether thymic transplantation in addition to highly active antiretroviral therapy (HAART) will restore T cell function in HIV infection. Eight treatment-naive HIV-infected patients with CD4+ T cell counts of 200-500/mm3 were randomized into thymic transplantation and control arms. All patients received HAART (zidovudine, lamivudine, and ritonavir) for 6 weeks prior to transplantation. Thymic transplantation was done without immunosuppression, using postnatal HLA-unmatched cultured allogeneic thymus tissue. Patients were immunized every 6 months with the neoantigen keyhole limpet hemocyanin (KLH) and the recall antigen tetanus toxoid (TT). T cell phenotype and function and T cell receptor rearrangement excision circles (TRECs) were assessed. Thymic allografts were biopsied at 2 months. Six HIV-infected patients completed the study. Four patients received cultured allogeneic postnatal thymic grafts, two others were controls. CD4+ T cell counts increased and T cell-proliferative responses to Candida antigen and TT normalized in all patients. Proliferative responses to KLH developed in three of four transplant recipients and one of two controls. Patients responding to KLH after secondary immunization had greater TREC increases compared with the patients who did not respond. All thymic allografts were rejected within 2 months. In summary, four of six patients developed T cell-proliferative responses to the neoantigen KLH over the first 2 years of HAART. The transplanted thymus tissue, however, was rejected. There was no clear difference in restoration of T cell function in the transplant recipients compared with the controls. Increases in TRECs after initiation of HAART may correlate with improved immune function.

Leukemia inhibitory factor, oncostatin M, IL-6, and stem cell factor mRNA expression in human thymus increases with age and is associated with thymic atrophy.

The roles that thymus cytokines might play in regulating thymic atrophy are not known. Reversing thymic atrophy is important for immune reconstitution in adults. We have studied cytokine mRNA steady-state levels in 45 normal human (aged 3 days to 78 years) and 34 myasthenia gravis thymuses (aged 4 to 75 years) during aging, and correlated cytokine mRNA levels with thymic signal joint (sj) TCR delta excision circle (TREC) levels, a molecular marker for active thymopoiesis. LIF, oncostatin M (OSM), IL-6, M-CSF, and stem cell factor (SCF) mRNA were elevated in normal and myasthenia gravis-aged thymuses, and correlated with decreased levels of thymopoiesis, as determined by either decreased keratin-positive thymic epithelial space or decreased thymic sjTRECs. IL-7 is a key cytokine required during the early stages of thymocyte development. Interestingly, IL-7 mRNA expression did not fall with aging in either normal or myasthenia gravis thymuses. In vivo administration of LIF, OSM, IL-6, or SCF, but not M-CSF, i.p. to mice over 3 days induced thymic atrophy with loss of CD4+, CD8+ cortical thymocytes. Taken together, these data suggest a role for thymic cytokines in the process of thymic atrophy.

The human thymus during aging.

The human thymus is required for establishment of a normal T cell repertoire in fetal development, as children born without a thymus (DiGeorge Syndrome) lack thymus-derived (T) and T cell immunity. While the function of the thymus in children for production of new T cells is clear, it has not been obvious that the adult thymus can produce significant numbers of new T cells. Until recently, no assays were available to directly evaluate postnatal thymic function. This paper reviews work on human thymic aging at Duke University School of Medicine and discusses the relevance of this work to devising new strategies for T cell immune reconstitution in man.

Transplantation of thymus tissue in complete DiGeorge syndrome.

BACKGROUND: The DiGeorge syndrome is a congenital disorder that affects the heart, parathyroid glands, and thymus. In complete DiGeorge syndrome, patients have severely reduced T-cell function. METHODS: We treated five infants (age, one to four months) with complete DiGeorge syndrome by transplantation of cultured postnatal thymus tissue. Follow-up evaluations included immune phenotyping and proliferative studies of peripheral-blood mononuclear cells plus biopsy of the thymus allograft. Thymic production of new T cells was assessed in peripheral blood by tests for T-cell-receptor recombination excision circles, which are formed from excised DNA during the rearrangement of T-cell-receptor genes. RESULTS: After the transplantation of thymus tissue, T-cell proliferative responses to mitogens developed in four of the five patients. Two of the patients survived with restoration of immune function; three patients died from infection or abnormalities unrelated to transplantation. Biopsies of grafted thymus in the surviving patients showed normal morphologic features and active T-cell production. In three patients, donor T cells could be detected about four weeks after transplantation, although there was no evidence of graft-versus-host disease on biopsy or at autopsy. In one patient, the T-cell development within the graft was demonstrated to accompany the appearance of recently developed T cells in the periphery and coincided with the onset of normal T-cell function. In one patient, there was evidence of thymus function and CD45RA+CD62L+ T cells more than five years after transplantation. CONCLUSIONS: In some infants with profound immunodeficiency and complete DiGeorge syndrome, the transplantation of thymus tissue can restore normal immune function. Early thymus transplantation - before the development of infectious complications - may promote successful immune reconstitution.

Analysis of the human thymic perivascular space during aging.

The perivascular space (PVS) of human thymus increases in volume during aging as thymopoiesis declines. Understanding the composition of the PVS is therefore vital to understanding mechanisms of thymic atrophy. We have analyzed 87 normal and 31 myasthenia gravis (MG) thymus tissues from patients ranging in age from newborn to 78 years, using immunohistologic and molecular assays. We confirmed that although thymic epithelial space (TES) volume decreases progressively with age, thymopoiesis with active T-cell receptor gene rearrangement continued normally within the TES into late life. Hematopoietic cells present in the adult PVS include T cells, B cells, and monocytes. Eosinophils are prominent in PVS of infants 2 years of age or younger. In the normal adult and the MG thymus, the PVS includes mature single-positive (CD1a(-) and CD4(+) or CD8(+)) T lymphocytes that express CD45RO, and contains clusters of T cells expressing the TIA-1 cytotoxic granule antigen, suggesting a peripheral origin. PBMCs bind in vitro to MECA-79(+) high endothelial venules present in the PVS, suggesting a mechanism for the recruitment of peripheral cells to thymic PVS. Therefore, in both normal subjects and MG patients, thymic PVS may be a compartment of the peripheral immune system that is not directly involved in thymopoiesis.

Possible extrathymic development of nonfunctional T cells in a patient with complete DiGeorge syndrome.

Complete DiGeorge syndrome is characterized by the clinical triad of cardiac malformation, hypocalcemia, and T cell immunodeficiency due to congenital athymia. We describe an infant with complete DiGeorge syndrome who at presentation had no circulating T cells detectable by flow cytometry. The patient spontaneously developed circulating T cells but these cells did not proliferate in response to mitogens. The T cell receptor Vbeta repertoire was severely restricted. All T cells were host, not maternal, as assessed by fluorescent in situ hybridization evaluation of 22q11 hemizygosity. At autopsy, this patient had no grossly detectable thymus tissue and no microscopic evidence for thymopoiesis. These findings suggest that appearance of T cells in infants with complete DiGeorge syndrome may represent oligoclonal expansions of a small number of T cells that may have matured extrathymically and which do not respond in vitro to mitogen stimulation.

Thymic function, aging, and AIDS.

For the first time, physicians are challenged by clinical states in which the T-cell pool is destroyed postnatally in large numbers of patients. One such state is AIDS; another is the immune damage of cancer chemotherapy. Accordingly, study of postnatal thymic function is now a matter of clinical urgency. Ongoing work may point toward new strategies for repairing a damaged T-cell repertoire.

Analysis of the adult thymus in reconstitution of T lymphocytes in HIV-1 infection.

A key question in understanding the status of the immune system in HIV-1 infection is whether the adult thymus contributes to reconstitution of peripheral T lymphocytes. We analyzed the thymus in adult patients who died of HIV-1 infection. In addition, we studied the clinical course of HIV-1 infection in three patients thymectomized for myasthenia gravis and determined the effect of antiretroviral therapy on CD4(+) T cells. We found that five of seven patients had thymus tissue at autopsy and that all thymuses identified had inflammatory infiltrates surrounding lymphodepleted thymic epithelium. Two of seven patients also had areas of thymopoiesis; one of these patients had peripheral blood CD4(+) T-cell levels of <50/mm3 for 51 months prior to death. Of three thymectomized patients, one rapidly progressed to AIDS, one progressed to AIDS over seven years (normal progressor), whereas the third remains asymptomatic at least seven years after seroconversion. Both latter patients had rises in peripheral blood CD4(+) T cells after antiretroviral therapy. Most patients who died of complications of HIV-1 infection did not have functional thymus tissue, and when present, thymopoiesis did not prevent prolonged lymphopenia. Thymectomy before HIV-1 infection did not preclude either peripheral CD4(+) T-cell rises or clinical responses after antiretroviral therapy.

The human thymus. A chimeric organ comprised of central and peripheral lymphoid components.

The human thymus is a lymphoepithelial organ in which T cells develop during fetal life. After maturation and selection in the fetal thymic microenvironment, T cells emigrate to peripheral lymphoid tissues such as the spleen, gut, and lymph nodes, and establish the peripheral T cell repertoire. Although the thymus has enormous regenerative capacity during fetal development, the regenerative capacity of the human postnatal thymus decreases over time. With the advent of intensive chemotherapy regimens for a variety of cancer syndromes, and the discovery that infection with the Human Immunodeficiency Virus (HIV) leads to severe loss of CD4+ T cells, has come the need to understand the role of the human thymus in reconstitution of the immune system in adults. During a recent study of the thymus in HIV infection, we observed many CD8+ T cells in AIDS thymuses that had markers consistent with those of mature effector cytotoxic T cells usually found in peripheral immune tissues, and noted these CD8+ effector T cells were predominately located in a thymic zone termed the thymic perivascular space. This article reviews our own work on the thymus in HIV-1 infection, and discusses the work of others that, taken together, suggest that the thymus contains peripheral immune cell components not only in the setting of HIV infection, but also in myasthenia gravis, as well as throughout normal life during the process of thymus involution. Thus, the human thymus can be thought of as a chimeric organ comprised of both central and peripheral lymphoid tissues. These observations have led us to postulate that the thymic epithelial atrophy and decrease in thymopoiesis that occurs in myasthenia gravis, HIV-1 infection, and thymic involution may in part derive from cytokines or other factors produced by peripheral immune cells within the thymic perivascular space.

Orgaran during rotational atherectomy in the setting of heparin-induced thrombocytopenia.

Heparin is considered necessary during percutaneous coronary interventions; however, heparin is contraindicated in patients with heparin-induced thrombocytopenia and/or heparin antibodies. We describe the successful use of the heparinoid Orgaran (danaparoid sodium) in addition to abciximab (ReoPro) in a patient with heparin antibodies who required rotational atherectomy.

Combination of fosinopril and pravastatin decreases platelet response to thrombin receptor agonist in monkeys.

Both angiotensin-converting enzyme (ACE) inhibitors and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have been shown to decrease cardiovascular morbidity and mortality. Results from clinical trials have suggested that HMG-CoA reductase inhibition might exert a beneficial effect independent of its lipid-lowering effect, and ACE inhibition may exert a benefit independent of blood-pressure lowering. To test the hypothesis that such an effect might be mediated by alteration in platelet reactivity, we studied 55 monkeys receiving both, 1, or neither of the ACE inhibitor fosinopril and the HMG-CoA reductase inhibitor pravastatin. Platelet responsiveness to collagen and to the thrombin receptor agonist (TRA) SFLRRN-NH2 was determined by aggregometry. For each agonist, the maximum rate and extent of aggregation were measured for each dose, and the concentration required for half-maximal response (C50) was determined. Each drug, when given alone, slightly decreased the dose of agonist required to produce 50% response in the rate and extent of platelet aggregation relative to control. The combination of the 2 drugs, however, produced a significant increase in the dose of TRA required to produce 50% response in the rate and extent of aggregation relative to either drug alone or the control group. This was not true for collagen. The magnitude of the change relative to the control group, 47% for rate and 30% for extent of aggregation, could confer considerable protection by changing the threshold for thrombin-induced platelet aggregation and, thus, decrease thrombosis.

Local production of TGF beta1 inhibits cerebral edema, enhances TNF-alpha induced apoptosis and improves survival in a murine glioma model.

We have previously reported that local secretion of either TNF-alpha or TGF beta1 by intracerebral SMA-560 malignant glioma tumor cells can reduce or eliminate tumor growth in mice. However, the use of TNF-alpha, while improving the overall survival of tumor bearing animals, was associated with early toxic deaths due to cerebral edema. In the present study, we demonstrate that TNF-alpha induces apoptosis of the SMA 560 cell line, as does TGF beta1, and that these two cytokines act in an additive fashion to enhance apoptosis and thus, to inhibit SMA 560 cell growth in vitro. Next, we show that the production of TGF beta1 when added to TNF-alpha production by central nervous system tumors in vivo abrogates any early deaths seen due to TNF-alpha toxicity and leads to a larger percentage of animals surviving CNS tumor challenge. Finally, we demonstrate that the production of TGF beta1 by tumor cells is associated with the abolition of tumor-associated cerebral edema in both TNF-alpha and in non-TNF-alpha producing tumors. These results are important for the development of effective and less toxic therapies for brain tumors, as well as for examining the pathogenesis of tumor-related cerebral edema.