Gastrointestinal Lymphoid Tissue Research Articles

VEDOLIZUMAB DOES NOT ALTER IMMUNOGLOBULIN LEVELS IN BREASTMILK OF MOTHERS WITH IBD

Abstract Diarrheal diseases are a major cause of infant mortality worldwide. Breastfeeding helps prevent such diseases by passive transfer of maternal antibodies against gastrointestinal pathogens previously encountered by the mother. The antibody secreting cells (ASC) that populate the lactating mammary gland (LMG) are educated in gastrointestinal lymphoid tissues, thus they express integrin a4b7. To recruit these ASC, the LMG expresses MAdCAM-1 and CCL28. Vedolizumab (vedo) blocks a combinatorial epitope on integrin a4b7, interfering with lymphocyte recruitment to the gut. Given the shared homing determinants between the gut and LMG, we investigated whether vedo might interfere with ASC trafficking to the LMG, therefore decreasing immunoglobulin (Ig) levels in breast milk. We measured Ig levels by ELISA in cryopreserved breast milk from mothers enrolled in Mommy’s Milk biorepository at the University of California, San Diego without and with Ulcerative Colitis(UC) or Crohn’s Disease(CD) and lactating mothers with UC and CD treated with vedo for more than 18 months. Milk samples were collected between 1 month and 15.45 months after childbirth. The levels of secretory IgA (SIgA) in breast milk of mothers without IBD (n=45) was not different from those of mothers with CD not on vedo (n=15) (301 ± 147 ug/mL vs. 322 ± 207 ug/mL). However, milk SIgA from mothers with UC not on vedo (n=7) were lower than non-IBD controls (213 ± 149 ug/mL vs. 301 ± 147ug/mL, p<0.01). We then compared milk SIgA from patients with CD and UC treated with vedo (CD: n= 9; 256 ± 80ug/mL, UC: n=10; 283 ± 87 ug/mL) with those from non-IBD controls (n=45; 301 ± 147ug/mL) and found no differences. Similarly, SIgA levels were not different between CD with or without vedo (256 ± 80 ug/mL vs. 322 ± 207 ug/mL) and as compared with non-IBD controls SIgA in patients with UC with vedo were unexpectedly higher than UC without vedo (283 ±87 ug/mL vs 213 ± 149 ug/mL, p<0.05). The levels of secretory IgM (SIgM) in milk were not different between mothers with UC or CD treated with vedo compared with non-IBD controls (65 ± 34 ug/mL, 69 ± 32 ug/mL, and 56 ± 37 ug/mL, respectively). Similarly, no significant difference was seen between patients with UC or CD not treated with vedo compared with the non-IBD controls (58±26 ug/mL, and 46 ± 24 ug/mL respectively). We conclude that vedo does not reduce SIgA nor SIgM levels in lactating mothers with IBD. We speculate that the higher SIgA in patients with UC treated with vedo is due to the small sample size. Vedo does not interfere with passive immunity during the lactation period, thus ASC must be able to use another integrin to arrest on microvessels of the LMG during the final stages of pregnancy.

S3636 MALT Lymphoma: An Unlikely Diagnosis of Gastric Subepithelial Lesion

Introduction: MALT lymphoma is one of the most common types of extra-nodal non-Hodgkin lymphomas which originate from marginal zone B-cells in the gastrointestinal mucosal-associated lymphoid tissues. Although the most frequent location which MALT can be found is stomach, it is a rare disorder. Most cases are associated with h. pylori infection of the stomach. It is typically a low-grade neoplasia, characterized by a dense lymphoid infiltration that invades and destroys gastric glands and results in the so-called “lymphoepithelial lesion”. We present a case that was an atypical presentation of Malt lymphoma. Case Description/Methods: A 56-year-old male presented with anemia. Initial endoscopic evaluation revealed several large gastric subepithelial lesions in the antrum and body of the stomach that were ulcerated. After biopsies showed only chronic inflammation, the patient was referred to our center for further evaluation with EUS. There were multiple bulky confluent submucosal hypoechoic lesions seen with ulcerated mucosa overlying involving the gastric body, angularis and proximal antrum. Given the large size it was difficult to determine from which wall layer they originated. Also, there were multiple malignant appearing lymph nodes seen adjacent to the stomach. Biopsies through both fine needle biopsy and forceps biopsies, the pathology report revealed low grade B-cell lymphoma with clonal plasmacytic differentiation, suggestive of marginal zone of mucosa-associated lymphoid tissue lymphoma (MALT). (Figure) Discussion: MALT lymphoma is typically an indolent low-grade tumor that usually presents with a more subtle endoscopic appearance. In this case of MALT lymphoma, the tumor was bulky, ulcerated and had metastasized to lymph nodes around the stomach. Also, there was no evidence of h. pylori infection. MALT lymphoma should considered on the differential diagnosis of any gastric lesion given the presentation can be so varied.Figure 1.: EGD and EUS showing the lesion.

Effect of Abdominal Lymphatic Pump Treatment on Disease Activity in a Rat Model of Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD), such as ulcerative colitis and Crohn disease, are chronic relapsing inflammatory diseases that affect 1.5 million people in the United States. Lymphatic pump treatment (LPT) techniques were designed to enhance the movement of lymph and can be used to relieve symptoms in patients with IBD and other gastrointestinal disorders. To determine whether LPT would decrease gastrointestinal inflammation and reduce disease severity in rats with acute IBD. On day 0, rats were randomized into control or experimental groups. Control rats received normal drinking water for days 0 to 9. On days 0 to 9, rats in the experimental groups received drinking water containing 3.5% dextran sodium sulfate (DSS). On day 3, experimental rats were randomized into 3 groups. On days 3 to 8, experimental rats received either (1) no treatment or anesthesia (DSS alone); (2) 4 minutes of LPT with anesthesia administration (DSS+LPT); or (3) 4 minutes of sham treatment (ie, light touch) and anesthesia (DSS+sham). On day 9, colons and gastrointestinal lymphoid tissue were collected. Colon weight, histologic changes, disease activity index (DAI) score, and the concentration of leukocytes were measured. At day 9, the mean (SD) DAI score in the DSS+LPT group (1.0 [0.1]) was significantly decreased (P<.01) compared with the DAI score of DSS-alone rats (1.5 [0.1]). While the DAI in DSS+LPT rats was reduced on days 8 to 9, this difference was not statistically different (P>.05) compared with DSS+sham (1.3 [0.1]). No significant differences were found in colon weight, histopathologic findings, or the concentration of gastrointestinal leukocytes between DSS alone, DSS+sham, or DSS+LPT (P>.05). While DSS+LPT reduced IBD compared with DSS+sham, the decrease was not statistically significant. Considering the growing use of adjunctive treatment for the management of IBD, it is important to identify the effect of osteopathic manipulative medicine on IBD progression.

Oral vaccination with influenza hemagglutinin combined with human pulmonary surfactant-mimicking synthetic adjuvant SF-10 induces efficient local and systemic immunity compared with nasal and subcutaneous vaccination and provides protective immunity in mice

We reported previously that a synthetic mucosal adjuvant SF-10, which mimics human pulmonary surfactant, delivers antigen to mucosal dendritic cells in the nasal cavity and promotes induction of humoral and cellular immunity. The aim of the present study was to determine the effects of oral administration of antigen combined with SF-10 (antigen-SF-10) on systemic and local immunity. Oral administration of ovalbumin, a model antigen, combined with SF-10 enhanced ovalbumin uptake into intestinal antigen presenting MHC II+CD11c+ cells and their CD11b+CD103+ and CD11b+CD103- subtype dendritic cells, which are the major antigen presenting subsets of the intestinal tract, more efficiently compared to without SF-10. Oral vaccination with influenza hemagglutinin vaccine (HAv)-SF-10 induced HAv-specific IgA and IgG in the serum, and HAv-specific secretory IgA and IgG in bronchoalveolar lavage fluid, nasal washes, gastric extracts and fecal material; their levels were significantly higher than those induced by subcutaneous HAv or intranasal HAv and HAv-SF-10 vaccinations. Enzyme-linked immunospot assay showed high numbers of HAv-specific IgA and IgG antibody secreting cells in the gastrointestinal and respiratory mucosal lymphoid tissues after oral vaccination with HAv-SF-10, but no or very low induction following oral vaccination with HAv alone. Oral vaccination with HAv-SF-10 provided protective immunity against severe influenza A virus infection, which was significantly higher than that induced by HAv combined with cholera toxin. Oral vaccination with HAv-SF-10 was associated with unique cytokine production patterns in the spleen after HAv stimulation; including marked induction of HAv-responsive Th17 cytokines (e.g., IL-17A and IL-22), high induction of Th1 cytokines (e.g., IL-2 and IFN-γ) and moderate induction of Th2 cytokines (e.g., IL-4 and IL-5). These results indicate that oral vaccination with HAv-SF-10 induces more efficient systemic and local immunity than nasal or subcutaneous vaccination with characteristically high levels of secretory HAv-specific IgA in various mucosal organs and protective immunity.

Evidence of disseminated infection by Mycobacterium avium subspecies hominissuis in a pet ferret (Mustela putorius furo)

The infection caused by the zoonotic opportunistic pathogen Mycobacterium avium subsp. hominissuis (Mah) was reported for the first time in a pet ferret. Both owners were HIV-positive. Euthanasia of the pet was recommended due to medical reasons and as a preventive action. Disseminated and open tuberculosis lesions were observed in the gastrointestinal and respiratory systems of the ferret. Ecographic and radiographic surveys showed a severe generalized lymphadenopathy, strong thickening of the gastric wall and peritoneum layer. The histopathological findings revealed a disseminated, granulomatous, chronic inflammation affecting the gastrointestinal tract, lungs, lymphoid tissues (spleen, tonsils and lymph nodes) and liver. Ziehl-Neelsen staining displayed the presence of positive acid-fast bacilli within these granulomas. Bacteriology and sequencing of the isolates yielded Mah sequevar code 3. Ferrets can act as reservoirs of mycobacteria exposing their owners to the infection, which is of major concern in immunodeficient individuals, as those HIV-infected.

Research advances in evaluation and measurement techniques of latent human immunodeficiency virus reservoirs

Latent reservoir (LR) of HIV is the cells (such as CD4(+)T cell) where HIV is able to hide. These cellular reservoirs are located throughout the body, including the spleen, lymph nodes, gastrointestinal lymphoid tissues, and become the major obstacle to cure HIV infection. To truly cure patients, a new strategy "shock and kill" was put forward by scientists, which is to shock HIV-infected cells out of hidden reservoirs in the body and then kill them. Quantitatively evaluating the size of long-lived LR is essential to this strategy. This paper reviews assays that measure the magnitude of the latent HIV reservoir, including Alu-gag PCR, quantitative viral outgrowth assay (Q-VOA) and tat/rev induced limiting dilution assay(TILDA). Alu-gag PCR can differentiate the integrated and un-integrated HIV DNA, however, it cannot distinguish defective virus from competent virus, leading to overestimate the real size of LR. Q-VOA is based on cell culture, and is the golden standard for measuring the LR since it provides a definitive minimal estimate of reservoir size. Its disadvantages are being more costly, large amount of blood sample required, and underestimating the true size, which was resulted from particles being not released after one round of stimulation. TILDA measures cells with inducible msRNA as these transcripts are absent in latently infected cells but induced upon viral reactivation. It requires small blood sample size, does not need extraction of viral nucleic acids, can be completed in 2 d and covers a wide dynamic range of reservoir sizes, but has the disadvantage of overestimating the true size of LR.

Cry protein crystals: a novel platform for protein delivery.

Protein delivery platforms are important tools in the development of novel protein therapeutics and biotechnologies. We have developed a new class of protein delivery agent based on sub-micrometer-sized Cry3Aa protein crystals that naturally form within the bacterium Bacillus thuringiensis. We demonstrate that fusion of the cry3Aa gene to that of various reporter proteins allows for the facile production of Cry3Aa fusion protein crystals for use in subsequent applications. These Cry3Aa fusion protein crystals are efficiently taken up and retained by macrophages and other cell lines in vitro, and can be delivered to mice in vivo via multiple modes of administration. Oral delivery of Cry3Aa fusion protein crystals to C57BL/6 mice leads to their uptake by MHC class II cells, including macrophages in the Peyer’s patches, supporting the notion that the Cry3Aa framework can be used to stabilize cargo protein against degradation for delivery to gastrointestinal lymphoid tissues.

Retraction note to: gut microbiota and related diseases: clinical features. Intern Emerg Med (2010) 5 (Suppl 1):S57-63.

Intestinal microbiota is essential for gut homeostasis. Specifically, the microorganisms inhabiting the gut lumen interact with the intestinal immune system, supply key nutrients for the major components of the gut wall, and modulate energy metabolism. Host-microbiome interactions can be either beneficial or deleterious, driving gastrointestinal lymphoid tissue activities and shaping gut wall structures. This overview briefly focuses on the potential role played by abnormalities in gut microbiota and relative responses of the gastrointestinal tract in the determination of important pathological conditions such as the irritable bowel syndrome, inflammatory bowel diseases and colorectal cancer.

Relation between Caspase recruitment domain-containing membrane-associated guanylate kinase protein 1, clinicopathological features of gastrointestinal lymphoma also and Helicobacter pylori infection

Objective To investigate the relation between the expression of Caspase recruitment domain-containing membrane-associated guanylate kinase protein 1 (CARMA1),clinicopathological features of gastrointestinal mucosa-associated lymphoid tissue (MALT) lymphoma,diffuse large B cell lymphoma (DLBCL),and Helicobacter pylori (H.pylori) infection.Methods From January 1999 to March 2011,34 patients with DLBCL and 20 patients with MALT lymphoma were selected,and at same period 21 cases with reactive hyperplasia of gastrointestinal lymphoid tissue were enrolled in as control.The expression of CARMA1,Ki-67 and cytotoxin-associated gene A (CagA) at protein level were examined by immunohistochemistry.The relative expression quantity of CARMA1 mRNA was detected by real-time polymerase chain reaction (PCR).The condition of H.pylori infection in 25 gastric lymphoma and 10 controls was detected by methylene boric acid and blue staining or semi-nested PCR.Chi-square test was used for counting data analysis,t test for measurement data.Multivariate COX regression analysis was implemented for survival analysis.Survival curve was drawn by Kaplan-Meier method and analyzed by Log-rank test.Results The relative expression quantity of CARMA1 mRNA of 28 patients with DLBLC (3.073±1.846) was higher than that of 14 patients with MALT lymphoma,and the difference was statistically significant (F 0.975,P＜ 0.05).The positive rate of CARMA1 expression at protein level of gastrointestinal lymphoma group (75.9 ％,41/54) was higher than that of control group (47.6％,10/21),and the difference was statistically significant (x2 =5.568,P＜0.05),and the positive rate of CARMA1 expression of MALT lymphoma group (11/20) was lower than that of DLBCL group (88.2％,30/34),and the difference was statistically significant (x2 =5.900,P＜0.05).Among 42 patients with gastrointestinal lymphoma who received surgery,the relative expression quantity of CARMA1 mRNA in cases with high proliferation (2.885±1.837) was higher than that in cases with low proliferation.The expression of CARMA1 mRNA in the cases at advanced stage of the disease (4.416± 1.010) was higher than that in cases at early stage,and the difference was statistically significant (F=3.317 and 2.972,both P＜0.05).Among 54 patients with gastrointestinal lymphoma,the positive rate of CARMA1 expression at protein level of patients with high proliferation (88.6％,31/35) was higher that that of patients with low proliferation (10/19),and the difference was statistically significant (x22 ＝ 6.847,P＜0.05).There were no significant differences in relative expression quantity of CARMA1 mRNA and the positive rate of CARMA1 expression at protein level between 11 gastric lymphoma patients without H.pylori infection and 14 gastric lymphoma patients with H.pylori infection (both P＞0.05).The positive rate of CARMA1 expression at protein level of CagA positive and CagA negative H.pylori infected gastric lymphoma patients was 11/11 and 2/3.The expression of CARMA1 at protein level was correlated with the prognosis of gastrointestinal lymphoma (RR＝4.160,P＜0.05).In the 29 cases of patients with gastrointestinal MALT lymphoma and 18 cases of patients with DLBCL who were followed up,the survival situation of gastrointestinal lymphoma patients with CARMA1 positive expression rate over 50％ was worse than that of patients with the rate less than 50％,and the difference was statistically significant (x2=5.383 and 4.028,both P＜0.05).Conclusions CARMA1 might be involved in the pathogenesis and progression of MALT and DLBCL; and it might be a related factor of poor prognosis.There was no correlation between the expression of CARMA1 and H.pylori infection in these two lymphomas. Key words: Lymphoma; CARMA1; Helicobacter pylori

Plasmacytoid dendritic cells of the gut: relevance to immunity and pathology.

Plasmacytoid dendritic cells (pDCs) are bone marrow-derived immune cells with the ability to express copious amounts of type I and III interferon (IFN) and can differentiate into antigen-presenting dendritic cells as a result of stimulation by pathogen-derived nucleic acid. These powerful combined functionalities allow pDCs to bridge the innate and adaptive immune systems resulting in a concerted pathogen response. The contribution of pDCs to gastrointestinal immunity is only now being elucidated and is proving to be a critical component in systemic immunity. This review will explore the immunology of pDCs and will discuss their involvement in human disease and tolerance with an emphasis on those in the gastrointestinal lymphoid tissue.

Distribution of lymphoid depletion and viral antigen in alpacas experimentally infected with Bovine viral diarrhea virus 1

It was hypothesized that acute postnatal Bovine viral diarrhea virus 1 (BVDV-1) infection leads to leukopenia and lymphoid depletion of gut-associated lymphoid tissues similar to acute disease in calves. The objectives of the current study were to characterize the pathologic effects, viremia, viral shedding, and viral antigen deposition in 6-24-month-old, acutely infected alpacas following experimental infection with noncytopathic BVDV-1 subgenotype 1b (BVDV C0-6). The BVDV-1 isolate was obtained from a cria with naturally occurring persistent infection. Lymphocytopenia occurred 3-7 days postinfection, with a 50% reduction in peripheral lymphocytes in infected alpacas. Depletion of B-cell populations in gut-associated lymphoid tissues was evident microscopically. Populations of T cells in parafollicular zones and in nodular aggregates along the superficial submucosa remained intact. The BVDV antigen was deposited most consistently in submucosal gastrointestinal aggregated lymphoid tissues of ileum, proximal colon, and stomach compartment three. Viral antigen was more variably evident in other lymphoid tissues. Antigen distribution correlated well with histologic lesions in gastrointestinal aggregated lymphoid tissues, confirming the role of virus in lymphoid depletion. Nasal shedding was detected in all challenged alpacas on day 6 and in 4 out of 12 challenged alpacas on day 9. Viremia was present as early as day 3, and present in all challenged alpacas on days 5, 6, 7, and 9 postchallenge. Lymphocytopenia and depletion of gastrointestinal aggregated lymphoid tissues associated with acute BVDV-1 infection likely results in immune compromise and is expected to exacerbate concurrent infections even though uncomplicated BVDV-1 infection was clinically unapparent.

Role of the transcription factor Sp1 in regulating the expression of the murine cathepsin E gene

Cathepsin E (CE) is an intracellular aspartic proteinase that is exclusively expressed in cells of the gastrointestinal tracts, lymphoid tissues, urinary organs and red blood cells. However, the molecular mechanism by which CE is predominantly expressed in these cells remains unknown. Here, we report the identification of several transcription start sites of the CE gene and their regulatory factors in gastric adenosarcoma cells. We first identified several unique transcription start sites in mouse CE genes by an oligo cap method. Their analysis also revealed the existence of a non-coding region ∼24-kb upstream of exon 1 in the CE gene and also the existence of two transcripts for CE. Luciferase analyses in upstream of exon 1 revealed that this site contained putative binding regions for the transcription factors Sp1, AP-1 and cEts-1 essential for the expression of CE gene. Moreover, electrophoretic mobility shift assays revealed that the protein-oligonucleotides complex of the Sp1 site were supershifted by an anti-Sp1 antibody. The chromatin immunoprecipitation assay showed that Sp1 bound to the CE promoter region. In addition, overexpression of the Sp1 protein increased the expression of the CE protein. Altogether, these results suggest that Sp1 binding plays a particularly important role in the regulation of CE gene expression.

Assessment of gastrointestinal pH, fluid and lymphoid tissue in the guinea pig, rabbit and pig, and implications for their use in drug development

Laboratory animals are often used in drug delivery and research. However, basic information about their gastrointestinal pH, fluid volume, and lymphoid tissue is not completely known. We have investigated these post-mortem in healthy guinea pigs, rabbits and pigs, to assess their suitability for pre-clinical studies by comparing the results with reported human literature. The mean gastric pH (fed ad libitum) was 2.9 and 4.4 in guinea pig and pig, respectively. In contrast, a very low pH (1.6) was recorded in the rabbits. The small intestinal pH was found in the range of 6.4–7.4 in the guinea pigs and rabbits, whereas lower pH (6.1–6.7) was recorded in the pig, which may have consequences for ionisable or pH responsive systems when tested in pig. A relatively lower pH than in the small intestine was found in the caecum (6.0–6.4) and colon (6.1–6.6) of the guinea pig, rabbit and the pig. The water content in the gastrointestinal tract of guinea pig, rabbit and pig was 51 g, 153 g and 1546 g, respectively. When normalized to the body weight, the guinea pig, had larger amounts of water compared to the rabbit and the pig (guinea pig > rabbit > pig); in contrast, a reverse order was found when normalized to per unit length of the gut (guinea pig < rabbit < pig). The lymphoid tissue distribution (lymphoid follicles, Peyer's patches and long strips) along the length of the gut in these animals is presented; in particular, an abundance of lymphoid tissue was found in pig's stomach, small intestine and caecum, and rabbit's appendix. Their ample presence indicated the potential utility of these animal species in oral and colonic vaccination. These differences in the gastrointestinal parameters of the guinea pig, rabbit and pig reiterates the crucial importance of correctly selecting animal models for pre-clinical studies.

RETRACTED ARTICLE: Gut microbiota and related diseases: clinical features

Intestinal microbiota is essential for gut homeostasis. Specifically, the microorganisms inhabiting the gut lumen interact with the intestinal immune system, supply key nutrients for the major components of the gut wall, and modulate energy metabolism. Host-microbiome interactions can be either beneficial or deleterious, driving gastrointestinal lymphoid tissue activities and shaping gut wall structures. This overview briefly focuses on the potential role played by abnormalities in gut microbiota and relative responses of the gastrointestinal tract in the determination of important pathological conditions such as the irritable bowel syndrome, inflammatory bowel diseases and colorectal cancer.

Mucosa-Associated Lymphoid Tissue Lymphoma: Multimodality Imaging and Histopathologic Correlation

We will illustrate the imaging features of gastrointestinal and nongastrointestinal mucosa-associated lymphoid tissue (MALT) lymphoma and their correlation with histopathologic findings. The radiologic features to distinguish gastrointestinal MALT lymphoma from other types of lymphomas will also be described. Differences in clinical behavior and management make it exceedingly important to differentiate MALT lymphoma from other types of lymphomas. Radiologic and histopathologic findings need to be taken into account before making a diagnosis and treatment plan.

Measurements of rat and mouse gastrointestinal pH, fluid and lymphoid tissue, and implications for in-vivo experiments

To use rodent models effectively in in-vivo investigations on oral drug and vaccine delivery, the conditions in the gastrointestinal tract must be understood. Some fundamental information is currently unavailable or incomplete. We have investigated the pH, water content and lymphoid tissue distribution along the gastrointestinal tract, as well as the stomach volume, as these were critical to our investigations on pH-responsive drug delivery and colonic vaccination. The observed values were compared with those in man as an indication of the validity of the rodent model. The mouse stomach pH was 3.0 (fed) and 4.0 (fasted), and the corresponding values in the rat were 3.2 (fed) and 3.9 (fasted). The mean intestinal pH was lower than that in man (<pH 5.2 in the mouse; <pH 6.6 in the rat). This brings into question the use of rodents in investigations on enteric-coated drug carriers targeted to the large intestine/distal gut. The water content in the gastrointestinal tract in the fed and fasted mouse was 0.98+/-0.4 and 0.81+/-1.3 mL, respectively, and in the fed and fasted rat was 7.8+/-1.5 and 3.2+/-1.8 mL. When normalized for body weight, there was more water per kg body weight in the gastrointestinal tracts of the mouse and rat, than in man. The stomach capacity was found to be approximately 0.4 and 3.4 mL for mice and rats, respectively. The low fluid volume and stomach capacity have implications for the testing of solid dosage forms in these animal models. Substantial amounts of lymphoid tissue analogous to small intestinal Peyer's patches were measured in the rat and mouse colon, showing the feasibility of colonic vaccination, a route which might prove to have different applications to the more commonly studied oral vaccines. The existence of lymphoid tissue in the mouse and rat caecum has also been reported.

Dynamic T cell migration program provides resident memory within intestinal epithelium.

Migration to intestinal mucosa putatively depends on local activation because gastrointestinal lymphoid tissue induces expression of intestinal homing molecules, whereas skin-draining lymph nodes do not. This paradigm is difficult to reconcile with reports of intestinal T cell responses after alternative routes of immunization. We reconcile this discrepancy by demonstrating that activation within spleen results in intermediate induction of homing potential to the intestinal mucosa. We further demonstrate that memory T cells within small intestine epithelium do not routinely recirculate with memory T cells in other tissues, and we provide evidence that homing is similarly dynamic in humans after subcutaneous live yellow fever vaccine immunization. These data explain why systemic immunization routes induce local cell-mediated immunity within the intestine and indicate that this tissue must be seeded with memory T cell precursors shortly after activation.

Effects of CpG- oligodeoxynucleotides on dendritic cell development

Dendritic cell (DC) development begins in the bone marrow and immature progenitors reach their sites of residence in lymphoid organs. The mechanism of DC development in the bone marrow and in peripheral lymphoid organs is poorly understood. Here, we examined the effects of synthetic oligodeoxynucleotides containing a CpG motif (CpG-ODNs) on the development of DC from the bone marrow cells. Approximately 15% of bone marrow cells expressed CD11c surface antigen in the in vitro culture for 8 days in the presence of IL-3. However, the addition of a phosphorothioate-modified CpG-ODN (PTO-CpG-ODN), but not a phosphodiester-modified ODN (PO-CpG-ODN), suppressed the expression of CD11c surface antigen. Also, we examined the effects of CpG-ODNs on the maintenance of DCs resident in the gastrointestinal lymphoid tissues, where immature progenitors may be challenged by a variety of ODN derived from microflora. The population of CD11c(+)B220(int)Gr-1(low) cells decreased by the addition of PTO-CpG-ODN when the lymphocytes from mesenteric lymph nodes as well as spleen are cultured for 2 days in the presence of GM-CSF. In contrast, this population increased in the case of the lymphocytes from Peyer's patches. It thus follows that PTO-CpG-ODN plays a regulatory role in the differentiation of bone marrow cells into DCs and in the functional maintenance of DCs at peripheral lymphoid organs.

HIV Expression in Surgical Specimens

We determined the HIV-1 RNA and Gag p24 protein expression in gastrointestinal tract-associated lymphoid tissue (GALT), deep lymph nodes (LNs), and inflammatory lesions, acquired during surgery on HIV-infected patients. Surgically excised gastrointestinal tract specimens, LNs, and cervices removed from HIV-1-infected patients for various clinical conditions were studied by immunohistochemistry (IHC) for Gag p24 HIV protein and in situ hybridization (ISH) for HIV-specific RNA. Fragments of some specimens were also submitted in glutaraldehyde for TEM analysis. Germinal centers (GC) in the GALT had at least as much HIV RNA and p24 protein deposited on their follicular dendritic cell (FDC) networks as did GC in LNs draining or associated with areas of inflammation or ulceration. The level of viral expression in the deep LNs, e.g., mesenteric and retroperitoneal, was at least equivalent to that seen in superficial LNs, i.e., inguinal, axillary, and cervical, and tonsils and adenoids. HIV expressing T and B lymphocytes and macrophages were seen in GALT and LNs. Virus-expressing mononuclear cells (MNC) were also seen in inflammatory lesions such as gastrointestinal ulcers and acute appendicitis. Abundant virus was seen in the cervix of patients with and without cancer and in LNs of patients with metastatic cancer. Individual and clusters of mature HIV particles were identified by TEM in LN GC and in GALT. Gastrointestinal tract lymphoid tissue, inflammatory lesions, and deep LNs showed levels of HIV RNA and Gag p24 protein expression in the range seen in superficial LNs.

Hyperplastic Lymphoid Tissue in HIV/AIDS: An Electron Microscopic Study

The purpose of this study was to characterize the ultrastructure of lymphoid tissue from HIV/AIDS patients and to evaluate it as a reservoir and source of HIV. HIV has been demonstrated in lymph nodes and tonsils and adenoids, by immunohistochemistry (IHC), in situ hybridization (ISH), and transmission electron microscopy (TEM), to be associated with germinal center (GC) follicular dendritic cells (FDC). The presence of HIV in the larger gastrointestinal tract-associated lymphoid tissue (GALT) has been much less studied. Whether FDC themselves are productively infected by HIV in any of the lymphoid sites is controversial. Lymph nodes, tonsils, and gastrointestinal biopsies were fixed in neutral buffered glutaraldehyde and prepared for TEM. Mature HIV particles were abundant in GC of hyperplastic lymph nodes, tonsils, and the GALT. They were enmeshed within an electron-dense matrix associated with an all-encompassing branching FDC network of processes. HIV particles were seen budding from both FDC and lymphocytes. The greatest numbers of particles were seen in hyperplastic lymphoid tissue from untreated individuals and in lymph nodes co-infected with opportunistic organisms, such as Mycobacterium aviumcomplex. In addition to HIV, unidentifiable “particles” of varying sizes, possibly including other viruses, were regularly seen in association with FDC. Ultrastructural study graphically demonstrated the abundance of HIV particles associated with the complex FDC network of hyperplastic lymph nodes, tonsils, and GALT. HIV was shown to productively infect FDC, as well as lymphocytes.