Correction: Cholesterol promotes autoimmune pathology through T follicular helper cells

Common and distinct roles for TH2 and TFH cells in shaping the spectrum of allergic diseases

Persistent Antigen and Germinal Center B Cells Sustain T Follicular Helper Cell Responses and Phenotype

Background and AimsCD4+ T follicular helper (Tfh) cells, a new subset of immune cells, have been demonstrated to be involved in the development and prognosis of tumors. However, their functional role in human hepatocellular carcinoma (HCC) is relatively unknown, and the detailed mechanisms in HCC development remain to be described.MethodsA total of 85 HCC patients with hepatitis B virus (HBV) infection, 25 HBV-relative liver cirrhosis (LC) patients, and 20 healthy controls (HC) were randomly enrolled. Flow cytometric analysis, immunohistochemical staining, and relative function (i.e., cytokine secretion, B cell maturation) assays were used to analyze the properties of CXCR5+CD4+ T cells. In addition, the relationship between the frequency of CXCR5+CD4+ T cells and overall survival rates or disease-free survival rates was also analyzed by the Kaplan-Meier method.ResultsThe frequency of circulating CXCR5+CD4+ T cells was significantly decreased in HCC patients compared with HBV-relative liver cirrhosis (LC) patients and healthy controls, and the decrease in circulating CXCR5+CD4+ T cells correlated with disease progression. The proportion of infiltrated CXCR5+CD4+ T cells was significantly decreased in tumor regions compared with nontumor regions. Furthermore, compared with healthy controls, the function of circulating CXCR5+CD4+ T cells in HCC was impaired, with reduced IL-21 secretion and dysfunction in promoting B cell maturation. Importantly, follow-up data indicated that a decreased frequency of circulating CXCR5+CD4+ T cells was also associated with reduced disease-free survival time in HCC patients.ConclusionsImpairment of CD4+ T follicular helper cells may influence the development of HBV-associated HCC. Decreased CD4+ T follicular helper cells may represent a potential prognostic marker and serve as a novel therapeutic target for HCC patients.

T follicular helper cells mediate local production of allergen-specific IgE and IgG4

CD4+ T follicular helper (TFH) cells are key targets for human immunodeficiency virus (HIV)/simian immunodeficiency virus (SIV) replication and contribute to the virus reservoir under antiretroviral therapy (ART). Here, we describe a novel CD3+ CD20+ double-positive (DP) lymphocyte subset, resident in secondary lymphoid organs of humans and rhesus macaques (RMs), that appear predominantly after membrane exchange between TFH and B cells. DP lymphocytes are enriched in cells displaying a TFH phenotype (CD4+ PD1hi CXCR5hi), function (interleukin 21 positive [IL-21+]), and gene expression profile. Importantly, expression of CD40L upon brief in vitro mitogen stimulation identifies, by specific gene-expression signatures, DP cells of TFH-cell origin versus those of B-cell origin. Analysis of 56 RMs showed that DP cells (i) significantly increase following SIV infection, (ii) are reduced after 12 months of ART in comparison to pre-ART levels, and (iii) expand to a significantly higher frequency following ART interruption. Quantification of total SIV-gag DNA on sorted DP cells from chronically infected RMs showed that these cells are susceptible to SIV infection. These data reinforce earlier observations that CD20+ T cells are infected and expanded by HIV infection, while suggesting that these cells phenotypically overlap activated CD4+ TFH cells that acquire CD20 expression via trogocytosis and can be targeted as part of therapeutic strategies aimed at HIV remission. IMPORTANCE The HIV reservoir is largely composed of latently infected memory CD4+ T cells that persist during antiretroviral therapy and constitute a major barrier toward HIV eradication. In particular, CD4+ T follicular helper cells have been demonstrated as key targets for viral replication and persistence under ART. In lymph nodes from HIV-infected humans and SIV-infected rhesus macaques, we show that CD3+ CD20+ lymphocytes emerge after membrane exchange between T cells and B cells and are enriched in phenotypic, functional, and gene expression profiles found in T follicular helper cells. Furthermore, in SIV-infected rhesus macaques, these cells expand following experimental infection and after interruption of ART and harbor SIV DNA at levels similar to those found in CD4+ T cells; thus, CD3+ CD20+ lymphocytes are susceptible to SIV infection and can contribute to SIV persistence.

Emerging cellular networks for regulation of T follicular helper cells

Longitudinal profile of circulating T follicular helper lymphocytes parallels anti-HLA sensitization in renal transplant recipients.

Allergen-specific immunotherapy modulates the balance of circulating Tfh and Tfr cells

Primary germinal center-resident T follicular helper cells are a physiologically distinct subset of CXCR5hiPD-1hi T follicular helper cells

T follicular helper (Tfh) cells are defined by a Bcl6+CXCR5hiPD-1hi phenotype, but only a minor fraction of these reside in germinal centers (GCs). Here, we examined whether GC-resident and -nonresident Tfh cells share a common physiology and function. Fluorescently labeled, GC-resident Tfh cells in different mouse models were distinguished by low expression of CD90. CD90neg/lo GCTfh cells required antigen-specific, MHCII+ B cells to develop and stopped proliferating soon after differentiation. In contrast, nonresident, CD90hi Tfh (GCTfh-like) cells developed normally in the absence of MHCII+ B cells and proliferated continu- ously during primary responses. The TCR repertoires of both Tfh subsets overlapped initially but later diverged in association with dendritic cell-dependent proliferation of CD90hi GCTfh-like cells, suggestive of TCR-dependency seen also in TCR-transgenic adoptive transfer experiments. Furthermore, the transcriptomes of CD90neg/lo and CD90hi GCTfh-like cells were enriched in different functional pathways. Thus, GC- resident and nonresident Tfh cells have distinct developmental requirements and activities, implying distinct functions.

In this study, we examined the peripheral blood (PB) central memory (TCM) CD4(+) T cell subsets designated peripheral T follicular helper cells (pTfh cells) and non-pTfh cells to assess HIV permissiveness and persistence. Purified pTfh and non-pTfh cells from healthy HIV-negative donors were tested for HIV permissiveness using green fluorescent protein (GFP)-expressing HIV-1NL4-3/Ba-L, followed by viral reactivation using beads coated with anti-CD3/anti-CD28 monoclonal antibodies. The role of pTfh cells in HIV persistence was analyzed in 12 chronically HIV-1 infected patients before and 48 weeks after initiation of raltegravir-containing combination antiretroviral therapy (cART). Total cellular HIV-1 DNA and episomes containing two copies of the viral long terminal repeat (2LTR circles) were analyzed in using droplet digital PCR in the purified pTfh and non-pTfh cells. Activation-inducible HIV p24 expression was determined by flow cytometry. Results indicate that pTfh cells, in particular PD1(+) pTfh cells, showed greater permissiveness for HIV infection than non-pTfh cells. At week 48 on cART, HIV DNA levels were unchanged from pre-cART levels, although a significant decrease in 2LTR circles was observed in both cell subsets. Inducible HIV p24 expression was higher in pTfh cells than in non-pTfh cells, with the highest frequencies in the PD1(+) CXCR3(-) pTfh cell subset. Frequencies of HLADR(+) CD38(+) activated CD4 T cells correlated with 2LTR circles in pTfh and non-pTfh cells at both time points and with p24(+) cells at entry. In conclusion, among CD4 TCM cells in PB of aviremic patients on cART, pTfh cells, in particular the PD1(+) CXCR3(-) subset, constitute a major HIV reservoir that is sustained by ongoing residual immune activation. The inducible HIV p24 assay is useful for monitoring HIV reservoirs in defined CD4 T cell subsets. Identification of the type and nature of the cellular compartments of circulating HIV reservoirs is important for targeting of HIV cure strategies. In lymph nodes (LN), a subset of CD4 T cells called T follicular helper (Tfh) cells are preferentially infected by HIV. Central memory (TCM) CD4 T cells are the major cellular reservoir for HIV in peripheral blood and contain a subset of CD4 TCM cells expressing chemokine receptor CXCR5 similar in function to LN Tfh cells termed peripheral Tfh (pTfh) cells. We found that the circulating pTfh cells are highly susceptible to HIV infection and that in HIV-infected patients, HIV persists in these cells following plasma virus suppression with potent cART. These pTfh cells, which constitute a subset of TCM CD4 T cells, can be readily monitored in peripheral blood to assess HIV persistence.

Recent findings show that immune cells constitute a large fraction of the tumor microenvironment and modulate tumor progression. Clinical data indicate that chronic inflammation is present at tumor sites and that IL-4 in particular is up-regulated. Current results demonstrate that T follicular helper (Tfh) cells arise in tumor draining lymph nodes where they produce an abundance of IL-4. Deletion of IL-4 expressing Tfh cells improves anti-tumor immunity, delays tumor growth and reduces the immunosuppressive activity of myeloid-derived suppressor cells (MDSC) and M2 macrophages. These findings suggest that IL-4 from Tfh cells impact anti-tumor immunity and constitute an attractive therapeutic target to reduce immune suppression in the tumor microenvironment and thus enhance the efficacy of cancer immunotherapy. Citation Format: Hidekazu Shirota, Dennis M. Klinman, Shuku-ei A. Ito, Chikashi Ishioka. IL-4 derived from T follicular helper cells in tumor draining lymph nodes regulate myeloid cell properties and anti-tumor immunity. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1455.

Upon infection or immunization, dendritic cells (DCs) present antigens (Ags) to naïve CD4 +T cells. As a result, a fraction of the responding CD4 +T cells upregulate Bcl6 and differentiate into T follicular helper (Tfh) cells, which migrate into the B cell follicles. Once in the B cell follicles, Tfh cells help promote the development and maintenance of the germinal centers (GC). Importantly, limiting the number of Tfh cells is critical for maintaining the selective pressure in the GC, thereby allowing the Darwinian selection that leads to affinity maturation. However, the mechanisms that regulate Tfh cell numbers and prevent excessive Tfh help remains unknown. Using an influenza virus infection model, we show here that Tfh cell differentiation is limited to the first 72h of the infection. After this time, whereas DCs continue to present viral antigens and efficiently prime naïve T cells, responding CD4 +T cells fail to upregulate Bcl6 and preferentially differentiate into effector Th1 cells. Mechanistically, we demonstrate that the lack of Tfh cell differentiation after day three was due to the presence of the early-primed Tfh cells. Our results indicate that early-primed Tfh cells produce large amounts of IL-2 in the proximity of the B cell follicles, thereby limiting the differentiation of new Tfh cells after day three. Collectively, our data demonstrate that early-primed Tfh cells act as a self-regulating factor that shields the B cell follicles early after infection, thereby preventing the continuous differentiation of Tfh cells regardless of the presence of viral antigens. These data demonstrate a new self-competitive mechanism that critically contributes to limiting Tfh cell expansion after infection. This work was supported by The University of Alabama at Birmingham (UAB) and the National Institutes of Health grant 1R01AI162698-01A1 to A.B.-T

Neuromyelitis optica spectrum disorder (NMOSD) is a severe autoimmune disease of the central nervous system. The existence of autoantibody targeting aquaporin-4 (AQP4-Ab) indicates the involvement of humoral immunity in the pathogenesis of this disease. Rituximab (RTX), a monoclonal antibody against CD20, has been used to treat NMOSD by depleting circulating B cells and overall satisfactory outcome has been achieved. Although T follicular helper cells have been proved to regulate B cell activation and antibody production, the role of these cells in NMOSD and the impact of RTX treatment on these cells remain less understood. In this study, we found that frequencies of circulating T follicular helper (cTfh) cells and B cells together with the related cytokines, IL-21 and IL-6, were closely correlated with disease activity of NMOSD. Furthermore, B cell depletion with RTX treatment inhibited the expansion of cTfh cells, and these effects were achieved through eliminating IL-6-producing B cells and blocking the direct contact between cTfh cells and B cells. These findings imply the complicated cross talk between cTfh cells and B cells and may provide a novel therapeutic target for NMOSD.

BackgroundChronic inflammation is involved in the development of abdominal aortic aneurysm (AAA). A tertiary lymphoid structure (TLS) within vascular lesions has recently been focused on for its role in modulation of inflammation in local tissues. We aimed to elucidate the relationships between TLS and pathophysiology of AAA.MethodsAbdominal aortic samples obtained from 37 patients with AAA (men/women: 34/3, age: 72.8±9.9 years) and 15 autopsied patients who died from non‐aortic events (men/women: 11/4, age: 65.5±9.8 years) were investigated.ResultsTLSs in AAA lesions were confirmed by focal infiltration of CD3‐positive cells surrounding germinal center‐like structures containing CD20‐positive cells between the tunica adventitia and tunica media layers. The formation of a TLS was significantly more prevalent in AAA patients than in autopsied patients. The number of TLSs in AAA lesions was positively correlated with sac diameter (r=0.357, P=0.035) and the amount of intraluminal thrombosis (r=0.466, P=0.005). T cells and B cells were predominant cellular populations among CD45+ cells in AAA lesions. There was a significantly positive correlation between the proportions of interfollicular T follicular helper (CD3+CD4+CD45RA−CXCR5+PD‐1+) cells and double negative B (CD3−CD19+IgD−CD27−) cells, and they were positively correlated with sac diameter, intraluminal thrombosis, and serum lipids. Deposited single‐cell RNA‐sequencing data for AAA showed that T follicular helper cells and double negative B cells were associated with lipid metabolism, T cell activation/proliferation and inflammation.ConclusionsThe formation of a TLS in AAA lesions is associated with sac diameter and intraluminal thrombosis in connection with interfollicular T follicular helper cells and double negative B cells, which may contribute to the pathophysiology of AAA and might be novel therapeutic targets for the development of AAA.