Impact of dietary deviation on disease progression and gut microbiome composition in lupus-prone SNF1 mice

Environmental factors, including microbes and diet, play a key role in initiating autoimmunity in genetically predisposed individuals. However, the influence of gut microflora in the initiation and progression of systemic lupus erythematosus (SLE) is not well understood. In this study, we have examined the impact of drinking water pH on immune response, disease incidence and gut microbiome in a spontaneous mouse model of SLE. Our results show that (SWR × NZB) F1 (SNF1 ) mice that were given acidic pH water (AW) developed nephritis at a slower pace compared to those on neutral pH water (NW). Immunological analyses revealed that the NW-recipient mice carry relatively higher levels of circulating autoantibodies against nuclear antigen (nAg) as well as plasma cells. Importantly, 16S rRNA gene-targeted sequencing revealed that the composition of gut microbiome is significantly different between NW and AW groups of mice. In addition, analysis of cytokine and transcription factor expression revealed that immune response in the gut mucosa of NW recipient mice is dominated by T helper type 17 (Th17) and Th9-associated factors. Segmented filamentous bacteria (SFB) promote a Th17 response and autoimmunity in mouse models of arthritis and multiple sclerosis. Interestingly, however, not only was SFB colonization unaffected by the pH of drinking water, but also SFB failed to cause a profound increase in Th17 response and had no significant effect on lupus incidence. Overall, these observations show that simple dietary deviations such as the pH of drinking water can influence lupus incidence and affect the composition of gut microbiome.

Gender bias in lupus: does immune response initiated in the gut mucosa have a role?

The risk of developing systemic lupus erythematosus (SLE) is approximately nine times higher among women compared to men. However, very little is understood concerning the underlying mechanisms that contribute to this gender bias. Further, whether there is a link between immune response initiated in the gut mucosa, the progression of SLE and the associated gender bias has never been investigated. In this report, we show a potential link between the immune response of the gut mucosa and SLE and the gender bias of lupus for the first time, to our knowledge. Both plasma cell- and gut-imprinted- α4β7 T cell frequencies were significantly higher in the spleen and gut mucosa of female (SWR × NZB)F1 (SNF1 ) mice compared to that of their male counterparts. Importantly, female SNF1 mice not only showed profoundly higher CD45(+) immune cell densities, but also carried large numbers of interleukin (IL)-17-, IL-22- and IL-9-producing cells in the lamina propria (LP) compared to their male counterparts. Intestinal mucosa of female SNF1 mice expressed higher levels of a large array of proinflammatory molecules, including type 1 interferons and Toll-like receptors 7 and 8 (TLR-7 and TLR-8), even before puberty. Our work, therefore, indicates that the gut immune system may play a role in the initiation and progression of disease in SLE and the associated gender bias.

A social cognitive model of health for HIV-positive adults receiving care in India

In-depth interviews were conducted with 50 HIV-positive adults (23 women, 27 men) with access to care at a non-governmental organization in Chennai, India to gain a broad understanding of how they managed their HIV infection. Using a Social Cognitive Model of Health, we identified factors within the model's three domains--Personal, Environmental, and Behavioral--that are applicable to this socio-cultural context. The Personal domain's factors were a positive self-concept, family-focused goals, and treatment optimism; the Environmental domain comprised family-based support, treatment availability, access and quality, and HIV stigma and discrimination; and the Behavior domain's factors were medication adherence and health habits, sexual behavior, and social relationships and emotional well-being. Significant differences for many of the factors within the three domains were observed across married men and women, widowed women, unmarried men, and female sex workers. Implications for an enhanced intervention for HIV-infected individuals in similar treatment settings are discussed.

The humoral immune response in melioidosis patients during therapy

BACKGROUND

This study was undertaken to identify and quantify the class and subclass antibody responses to the culture filtrate antigen (CFA) of Burkholderia pseudomallei in melioidosis patients under long-term maintenance or eradication therapy.

MATERIALS AND METHODS

Sequential sera samples from seven melioidosis patients collected between January 1992 and April 1998 were analyzed for immunoglobulin (Ig) types and IgG isotypes by ELISA using B. pseudomallei CFA.

RESULTS

Melioidosis patients generated a strong IgG, IgA and IgM response to the CFA of B. pseudomallei throughout the infection and IgG1 and IgG2 were the predominant IgG istotypes produced. Although high levels of these antibodies were detected in all the seven patients, the IgG, IgG1 and IgG2 antibodies showed a consistent response and good correlation with the clinical history in all cases.

CONCLUSION

This study suggests that monitoring IgG antibody or IgG1 or IgG2 isotype antibody levels to CFA in patients under maintenance or eradication antibiotic therapy may be useful as a tool to detect the status of infection and as a guideline to determine the duration of maintenance antimicrobial therapy.

Targeted delivery of anti-CTLA-4 antibody downregulates T cell function in vitro and in vivo

CTLA-4 is a T cell surface molecule that binds to the costimulatory molecules CD80 and CD86 on antigen-presenting cells and downregulates T cell function. Therefore, we wanted to test whether antigen-specific activated T cells could be inhibited through directed CTLA-4 signaling using a bispecific antibody (BiAb) capable of simultaneously binding to CTLA-4 and a tissue-specific antigen. The BiAb was prepared by linking two separate monoclonal antibodies against CTLA-4 and the thyroid-stimulating hormone receptor (TSHR). The mouse B cell lymphoma line M12 (H2(d)) was used to induce alloreactive T cells in CBA/J mice (H2(k)); M12 cells stably transfected with the cDNA encoding murine TSHR (mM12) were used to restimulate the alloresponse in vitro. Results of assays for in vitro T cell proliferation, IL-2 production, and cytotoxicity in the presence of BiAb demonstrated that the BiAb could inhibit the T cell alloresponse when stimulated with mM12 cells but not with M12 cells. This effect was dependent on binding of TSHR-bound BiAb to CTLA-4, since the addition of soluble CTLA-4-Ig blocked the inhibitory effect. Injection of mM12 cells, along with the BiAb, not with antibodies against TSHR or CTLA-4 either separately or together, into CBA/J mice (H2(k)) downregulated alloreactive T cell responses. Our study demonstrated that the presence of CTLA-4 signaling molecules on the surface of target cells can protect those cells from immune attack by antigen-specific T cells and suggested that a similar approach could have potential therapeutic value in transplant rejection and tissue-specific autoimmune diseases.

A 43-kDa circulating filarial antigen fraction of Wuchereria bancrofti in immunoprophylaxis against Brugia malayi in jirds

A 43 kiloDaltan (kDa) antigen fraction (CFA2-6) isolated from microfilaraemic plasma of bancroftian filarial patients showed selective reactivity with sera samples collected from endemic normals. Antibodies raised against this antigen showed a strong reactivity with the surface of Brugia malayi infective larvae as well as microfilariae. Similar antigenic determinants were detected in the parasite extracts, but not in the excretory-secretory products. Further analysis was done on the immunoprophylactic potential of CFA2-6 in inducing immunity against Brugia malayi in Meriones unguiculatus (jird) in vivo. A strong protective response of approximately 84% was observed against the development of the filarial parasite in the jirds immunized with CFA2-6. The immunized jirds also showed a significant clearance (87%) of microfilariae inoculated intravenously. Approximately 65% of infective larvae failed to survive in jirds transferred with anti-CFA2-6 serum compared to the jirds transferred with sera from the control jirds. Passive transfer of anti-CFA2-6 antibody to the jirds followed by intravenous inoculation of microfilariae resulted in the reduction of 77% of circulating microfilariae. This study suggests that the 43-kDa CFA2-6 could stimulate a strong protective immune response against infective larvae and microfilariae in experimental animals.