Biology subjects

Dent, A.

Publications and source records attributed to Dent, A..

3 recordsLinked to original sources

bioRxiv2024

IgM plays a prominent role in naturally acquired immunity against Plasmodium falciparum gametocytes

The development of transmission-blocking vaccines against Plasmodium falciparum malaria could facilitate malaria elimination. However, limitations in the knowledge of the human immune responses against P. falciparum transmission stages, known as gametocytes, represent a critical roadblock to vaccine development. We evaluated human antibodies acquired through natural malaria exposure to whole gametocytes and recombinant antigens expressed by transmission stages, including the major transmission-blocking vaccine candidates Pfs230 and Pfs48/45 and other transmission stages, Pf38, Pf12 and Pf41. Among individuals residing in Kenya and Papua New Guinea, we found substantial antibody responses to whole gametocytes and to all recombinant transmission stage antigens with high levels of IgG, IgG subclasses and IgM. Complement fixation by antibodies to gametocytes is key for effective transmission-blocking activity. We found that purified IgM was substantially more potent than IgG at mediating complement fixation and activation. Higher antibody levels were generally observed in individuals positive for P. falciparum infection, including gametocyte positive individuals, and these antibodies generally increased with age. Our findings reveal that IgM is a prominent feature of antibody responses to gametocytes and that antibodies target multiple antigens. The further demonstration that IgM has high functional activity against gametocytes suggests IgM plays an important role in immunity to transmission stages. Our data provide new insights to inform the development of potent transmission-blocking vaccines.

immunology↗

bioRxiv2020

Tissue-resident CD4+ T helper cells assist protective respiratory mucosal B and CD8+ T cell memory responses

The roles of CD4+ T helper cells (TH) in shaping localized memory B and CD8+ T cell immunity in the mucosal tissues are largely unexplored. Here, we report that lung TH cells provide local assistance for the optimal development of tissue-resident memory B (BRM) and CD8+ T (TRM) cells following the resolution of primary influenza virus infection. We identify a population of tissue-resident CD4+ TH (aka TRH) cells that co-exhibit follicular T helper (TFH) and TRM cell features and mediate local help of CD4+ T cells to B and CD8+ T cells. Optimal TRH cell formation requires lung B cells and transcription factors involved in TFH or TRM development. Further, we show that TRH cells deliver local help to B and CD8 T cells through CD40L and IL-21-dependent mechanisms. Our data have uncovered a new tissue-resident TH cell population that is specialized in assisting the development of mucosal protective B and CD8+ T cell responses in situ.

immunology↗

bioRxiv2019

Inhibition of Stearoyl-CoA desaturase suppresses follicular help T and germinal center B cell responses

Stearoyl-CoA desaturases (SCD) are endoplasmic reticulum (ER) associated enzymes that catalyze the synthesis of the monounsaturated fatty acids (MUFAs). As such, SCD play important roles in maintaining the intracellular balance between saturated fatty acid (SFAs) and MUFAs. The roles of SCD in CD4+ T helper cell responses are currently unexplored. Here, we have found that murine and human follicular helper T (TFH) cells express higher levels of SCD1 compared to non-TFH cells. Further, the expression of SCD1 in TFH cells is dependent on the TFH lineage-specification transcription factor BCL6. We found that the inhibition of SCD1 impaired TFH cell maintenance and shifted the balance between TFH and follicular regulatory T (TFR) cells in the spleen. Consequently, SCD1 inhibition dampened germinal center B cell responses following influenza immunization. Mechanistically, we found that SCD inhibition led to increased ER stress and enhanced TFH cell apoptosis in vitro and in vivo. These results reveal a possible link between fatty acid metabolism and cellular and humoral responses induced by immunization or potentially, autoimmunity.

immunology↗