Lymphocyte Homing: Chemokines and Adhesion Molecules in T cell and IgA Plasma Cell Localization in the Mucosal Immune System

Role of Epstein-Barr Virus in Pathogenesis and Racial Distribution of IgA Nephropathy

IgA nephropathy (IgAN) is the dominant type of primary glomerulonephritis worldwide. However, IgAN rarely affects African Blacks and is uncommon in African Americans. Polymeric IgA1 with galactose-deficient hinge-region glycans is recognized as auto-antigen by glycan-specific antibodies, leading to formation of circulating immune complexes with nephritogenic consequences. Because human B cells infected in vitro with Epstein-Barr virus (EBV) secrete galactose-deficient IgA1, we examined peripheral blood B cells from adult IgAN patients, and relevant controls, for the presence of EBV and their phenotypic markers. We found that IgAN patients had more lymphoblasts/plasmablasts that were surface-positive for IgA, infected with EBV, and displayed increased expression of homing receptors for targeting the upper respiratory tract. Upon polyclonal stimulation, these cells produced more galactose-deficient IgA1 than did cells from healthy controls. Unexpectedly, in healthy African Americans, EBV was detected preferentially in surface IgM- and IgD-positive cells. Importantly, most African Blacks and African Americans acquire EBV within 2 years of birth. At that time, the IgA system is naturally deficient, manifested as low serum IgA levels and few IgA-producing cells. Consequently, EBV infects cells secreting immunoglobulins other than IgA. Our novel data implicate Epstein-Barr virus infected IgA⁺ cells as the source of galactose-deficient IgA1 and basis for expression of relevant homing receptors. Moreover, the temporal sequence of racial-specific differences in Epstein-Barr virus infection as related to the naturally delayed maturation of the IgA system explains the racial disparity in the prevalence of IgAN.

Cytokine profiles in tears accompanying the secondary conjunctival responses induced by nasal allergy

PURPOSE/AIM

Allergic conjunctivitis (AC) occurs either in a primary form, due to the allergic reaction localized in the conjunctivae or in a secondary form, induced by an allergic reaction initiated primarily in the nasal mucosa. The purpose of this study was to investigate the cytokine profiles in tears associated with the secondary conjunctival response (SCR) types.

MATERIALS AND METHODS

In 47 AC patients developing 16 immediate (SICR; p < 0.01), 20 late (SLCR; p < 0.001) and 11 delayed (SDYCR; p < 0.05) responses to nasal provocation tests (NPTs) with allergens, the NPTs were repeated and combined with recording of cytokine concentrations in the tears.

RESULTS

The SCRs were associated with significant concentration changes of particular cytokines in tears (p < 0.05) as follows: (1): SICRs: interleukin (IL)-3, IL-4, IL-10 and granulocyte macrophage colony-stimulating factor (GM-CSF); (2) SLCRs: IL-3, IL-4, IL-5, IL-8, IL-10, IL-12p40, GM-CSF and granulocyte colony-stimulating factor (G-CSF); and (3) SDYCRs: IL-2, IL-8, IL-10, interferon gamma, G-CSF and tumor necrosis factor alpha. No significant cytokine changes were recorded in tears during the phosphate-buffered saline controls or negative SCRs.

CONCLUSIONS

Different cytokine profiles in the tears accompanying the immediate, late and delayed types of SCR, induced by nasal allergy, would indicate involvement of different hypersensitivity mechanisms in the particular SCR types. The low cytokine concentrations in tears recorded during the SCRs may suggest their origin from the nasal mucosa. These results emphasize the diagnostic value of NPTs with allergens combined with monitoring of various ocular features in patients suffering from the secondary form of AC. These results may also have an impact on the therapeutical approach to this clinical entity.

Delayed but effective induction of mucosal memory immune responses against genital HSV-2 in the absence of secondary lymphoid organs

To examine whether local immunization in the absence of secondary lymphoid organs (SLOs) could establish effective antiviral memory responses in the female genital tract, we examined immunity in the vaginal tracts of LTα-/- mice, LTα-/- SPL (splenectomized), and control C57BL/6 (WT) mice. All three groups of mice were immunized intravaginally (IVAG) with attenuated thymidine kinase-negative (TK(-)) Herpes simplex virus type 2 (HSV-2) and challenged 4-6 weeks later with wild-type (WT) HSV-2. Both groups of LTα-/- mice exhibited delayed viral clearance and prolonged genital pathology after immunization. Following IVAG WT HSV-2 challenge, LTα-/- and LTα-/- SPL mice had significantly lower levels of HSV-2-specific IgG and IgA in the vaginal secretions. Although the frequency of B and T cells in the vaginal mucosa was comparable or higher in both groups of LTα-/- mice, lower frequency of HSV-2-specific interferon-γ (IFNγ)-producing CD3+ T cells was seen after immunization and after challenge, compared with WT group. Despite this, immunized mice in all three groups showed complete sterile protection against IVAG WT HSV-2 challenge. These results show that even in the absence of SLOs, IVAG immunization generates effector memory immune responses at genital mucosa that can provide antiviral protection against subsequent viral exposures. This will inform new strategies to design mucosal vaccines against sexually transmitted infections.

Mucosa-associated epithelial chemokine/CCL28 expression in the uterus attracts CCR10+ IgA plasma cells following mucosal vaccination via estrogen control

Previous studies demonstrated cross talk between mucosal and reproductive organs during secretory IgA Ab induction. In this study, we aimed to clarify the underlying mechanisms of this cross talk. We found significantly higher titers of Ag-specific secretory IgA Ab in the vaginal wash after mucosal vaccination by both the intranasal (i.n.) and the intravaginal routes but not by the s.c. route. Interestingly, Ag-specific IgA Ab-secreting cells (ASCs) were found mainly in the uterus but not in the cervix and vaginal canal after i.n. vaccination. The fact that most Ag-specific IgA ASCs isolated from the uteri of vaccinated mice migrated toward mucosa-associated epithelial chemokine (MEC)/CCL28 suggests dominant expression of CCR10 on the IgA ASCs. Further, IgA ASCs in the uteri of vaccinated mice were reduced drastically in mice treated with neutralizing anti-MEC/CCL28 Ab. Most intriguingly, the female sex hormone estrogen directly regulated MEC/CCL28 expression and was augmented by i.n. vaccination with cholera toxin or stimulators for innate immunity. Further, blockage of estrogen function in the uterus by oral administration of the estrogen antagonist raloxifene significantly inhibited migration of Ag-specific IgA ASCs after i.n. vaccination with OVA plus cholera toxin. Taken together, these data strongly suggest that CCR10(+) IgA ASCs induced by mucosal vaccination via the i.n. route migrate into the uterus in a MEC/CCL28-dependent manner and that estrogen might have a crucial role in the protection against genital infection by regulating MEC/CCL28 expression in the uterus.

Allergic conjunctivitis and nasal allergy

Allergic conjunctivitis (AC) can be divided into the primary form (caused by an allergic reaction occurring primarily in the conjunctivae) and the secondary form (induced by allergic reaction originating primarily in the nasal mucosa, where the released mediators can reach conjunctiva through the lacrimal system, the blood, the lymphatic network, or the neurogenic network). Patients with primary AC develop an immediate, late, or delayed conjunctival response (CR) during conjunctival provocation tests. Patients with secondary AC develop an immediate, late, or delayed type of secondary CR, induced by the nasal allergic reaction, due to the nasal allergen challenge. Various hypersensitivity mechanisms may be involved in the particular CR types. The secondarily induced AC and CRs can only be confirmed by nasal provocations tests, performed by rhinomanometry combined with recording of conjunctival signs. The existence of the primary and secondarily induced AC has an impact on treatment of this disorder.

Seasonal and perennial allergic conjunctivitis: the possible role of nasal allergy

BACKGROUND

There is a link between conjunctiva and nose. Nasal allergy is suspected to be involved in some cases of conjunctivitis. This work aims to investigate the possible role of nasal allergy in seasonal (SAC) and perennial (PAC) allergic conjunctivitis and the value of nasal challenges with allergens (nasal provocation tests [NPTs]) for the diagnostic procedures of the conjunctivitis.

METHODS

In 61 adults suffering from SAC or PAC with a positive history and skin tests, but responding insufficiently to the local treatment, 122 NPTs and 61 control nasal challenges with phosphate-buffered saline (PBS) were performed using rhinomanometry combined with recording of ocular response. In 16 control subjects suffering only from allergic rhinitis without a history of conjunctivitis, 16 positive NPTs were repeated and supplemented with registration of ocular features.

RESULTS

Of the 61 patients, 55 developed 103 positive nasal responses of various types (P < 0.01), 82 of which were accompanied by significant conjunctival response (P < 0.01) without any corneal involvement. No significant ocular responses were recorded during 61 control PBS challenges (P > 0.05) as well as during 16 challenges in control subjects (P > 0.1).

CONCLUSIONS

These results illustrate a possible involvement of nasal allergy in some patients with allergic conjunctivitis (SAC and PAC) and the value of the nasal challenges with allergen combined with registration of the ocular features in the diagnostic approach to these disorders.

Salmonella enterica serovar Typhi live vector vaccines finally come of age

Attenuated Salmonella Typhi vaccine strains hold great promise as live vectors for presentation of foreign antigens from unrelated bacterial, viral and parasitic pathogens to the immune system. Although this approach has proved quite successful in experimental animal models for eliciting antigen-specific mucosal, humoral and cellular responses, results have been disappointing for clinical trials carried out thus far. We hypothesize that the paucity of human responses to foreign antigens delivered by live vectors suggests that the strains and genetic approaches used to date have resulted in overattenuated vaccine strains with severely reduced immunogenicity. However, remarkable advances have now been made in the genetics of foreign antigen expression, understanding mechanisms of live vector immunity and refining immunization strategies. The time has now come for development of multivalent live vectors in which stable antigen expression and export is balanced with metabolic fitness to create highly immunogenic vaccines.

Intestinal IgA synthesis: a primitive form of adaptive immunity that regulates microbial communities in the gut

Our intestine is colonized by an impressive community of commensals that has profound effects on the immune functions. The relationship between gut microbiota and the immune system is one of reciprocity: Commensals have important contributions in nutrient processing and education of the immune system, and, conversely, the immune system, particularly gut-associated lymphoid tissues (GALT), plays a key role in shaping the repertoire of gut microbiota. In this chapter we attempt to discuss the mechanisms that underlie this reciprocity and emphasize the key role of mucosal IgA in maintenance of an appropriate segmental distribution of microbiota, which is necessary for immune homeostasis.

The scientific and public-health imperative for a vaccine against dental caries

Dental caries is caused by one of the most ubiquitous bacterial infections of humans. In many countries such as Brazil and China, this disease is reaching epidemic proportions, and it is clear that a more effective public-health measure to combat dental caries is needed, because disadvantaged children are the most severely affected. One of the main groups of oral microorganisms, the mutans streptococci, has been associated with the aetiology of dental caries, and preclinical studies of immunological interventions have shown the feasibility of interfering with this disease. Moreover, clinical trials have indicated that a mucosal immune response to a crucial antigen(s) of mutans streptococci can influence the pathogenesis of dental caries. Evidence that this antigen(s) is appropriate for use in a vaccine against dental caries, as well as evidence for an appropriate target population of individuals and a logical time of administration, has now emerged.