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Female Bias in Systemic Lupus Erythematosus is Associated with the Differential Expression of X-Linked Toll-Like Receptor 8.

McDonald G, Cabal N, Vannier A, Umiker B, Yin RH, Orjalo AV, Johansson HE, Han JH, Imanishi-Kari T - Front Immunol (2015)

Bottom Line: Here, we show the results of our investigation into the role of Tlr8 expression in SLE pathogenesis in 564Igi females.Bone marrow-derived macrophages from 564Igi females have a significant increase in Tlr8 expression compared to male-derived cells, and RNA fluorescence in situ hybridization data suggest that Tlr8 may escape X-inactivation in female-derived macrophages.These results propose a model by which females may be more susceptible to SLE pathogenesis due to inefficient inactivation of Tlr8.

View Article: PubMed Central - PubMed

Affiliation: Department of Integrative Physiology and Pathobiology, Tufts University , Boston, MA , USA.

ABSTRACT
Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of anti-nuclear antibodies. SLE is one of many autoimmune disorders that have a strong gender bias, with 70-90% of SLE patients being female. Several explanations have been postulated to account for the severity of autoimmune diseases in females, including hormonal, microbiota, and gene dosage differences. X-linked toll-like receptors (TLRs) have recently been implicated in disease progression in females. Our previous studies using the 564Igi mouse model of SLE on a Tlr7 and Tlr9 double knockout background showed that the presence of Tlr8 on both X chromosomes was required for the production of IgG autoantibodies, Ifn-I expression and granulopoiesis in females. Here, we show the results of our investigation into the role of Tlr8 expression in SLE pathogenesis in 564Igi females. Female mice have an increase in serum pathogenic anti-RNA IgG2a and IgG2b autoantibodies. 564Igi mice have also been shown to have an increase in neutrophils in vivo, which are major contributors to Ifn-α expression. Here, we show that neutrophils from C57BL/6 mice express Ifn-α in response to 564 immune complexes and TLR8 activation. Bone marrow-derived macrophages from 564Igi females have a significant increase in Tlr8 expression compared to male-derived cells, and RNA fluorescence in situ hybridization data suggest that Tlr8 may escape X-inactivation in female-derived macrophages. These results propose a model by which females may be more susceptible to SLE pathogenesis due to inefficient inactivation of Tlr8.

No MeSH data available.


Related in: MedlinePlus

TLR8 agonist induces increased Ifn-α6 expression in neutrophils. Neutrophils were purified from whole bone marrow cell suspensions from the indicated mice by cell sorting as in Figure 2B. Neutrophils were cultured for 16 h in the presence of the TLR8 agonist CLO75 (1 mg/mL) or the TLR7 agonist CLO97 (1 mg/mL). RNA was extracted from the cell culture, converted to cDNA, and Ifn-α6 transcript level was measured by RT-qPCR. Expression was normalized to β-actin and compared to untreated samples from each genotype. Shown is the average ± SEM fold-increase in Ifn-α6 expression in two mice per group tested in independent experiments, each done in triplicate.
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Figure 3: TLR8 agonist induces increased Ifn-α6 expression in neutrophils. Neutrophils were purified from whole bone marrow cell suspensions from the indicated mice by cell sorting as in Figure 2B. Neutrophils were cultured for 16 h in the presence of the TLR8 agonist CLO75 (1 mg/mL) or the TLR7 agonist CLO97 (1 mg/mL). RNA was extracted from the cell culture, converted to cDNA, and Ifn-α6 transcript level was measured by RT-qPCR. Expression was normalized to β-actin and compared to untreated samples from each genotype. Shown is the average ± SEM fold-increase in Ifn-α6 expression in two mice per group tested in independent experiments, each done in triplicate.

Mentions: To examine the role of Tlr8 expression in IFNα production in neutrophils, we cultured purified neutrophils from C57BL/6 mice in the presence of the TLR8 agonist CLO75 or the TLR7 agonist CLO97 and measured Ifn-α6 expression. Neutrophils from C57BL/6 mice treated with both CLO75 and CLO97 had increased Ifn-α6 expression. However, CLO75 increased Ifn-α6 significantly more than CLO97 (Figure 3, green). Neutrophils from Tlr8-deficient mice responded poorly to both CLO75 and CLO97 (Figure 3, blue). Tlr7 expression is significantly decreased in Tlr8-deficient neutrophils (15), which may explain the poor response of Tlr8-deficient cells to a TLR7 agonist. Still, these data show that activation of TLR8 induces Ifn-α6 expression in neutrophils.


Female Bias in Systemic Lupus Erythematosus is Associated with the Differential Expression of X-Linked Toll-Like Receptor 8.

McDonald G, Cabal N, Vannier A, Umiker B, Yin RH, Orjalo AV, Johansson HE, Han JH, Imanishi-Kari T - Front Immunol (2015)

TLR8 agonist induces increased Ifn-α6 expression in neutrophils. Neutrophils were purified from whole bone marrow cell suspensions from the indicated mice by cell sorting as in Figure 2B. Neutrophils were cultured for 16 h in the presence of the TLR8 agonist CLO75 (1 mg/mL) or the TLR7 agonist CLO97 (1 mg/mL). RNA was extracted from the cell culture, converted to cDNA, and Ifn-α6 transcript level was measured by RT-qPCR. Expression was normalized to β-actin and compared to untreated samples from each genotype. Shown is the average ± SEM fold-increase in Ifn-α6 expression in two mice per group tested in independent experiments, each done in triplicate.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4561825&req=5

Figure 3: TLR8 agonist induces increased Ifn-α6 expression in neutrophils. Neutrophils were purified from whole bone marrow cell suspensions from the indicated mice by cell sorting as in Figure 2B. Neutrophils were cultured for 16 h in the presence of the TLR8 agonist CLO75 (1 mg/mL) or the TLR7 agonist CLO97 (1 mg/mL). RNA was extracted from the cell culture, converted to cDNA, and Ifn-α6 transcript level was measured by RT-qPCR. Expression was normalized to β-actin and compared to untreated samples from each genotype. Shown is the average ± SEM fold-increase in Ifn-α6 expression in two mice per group tested in independent experiments, each done in triplicate.
Mentions: To examine the role of Tlr8 expression in IFNα production in neutrophils, we cultured purified neutrophils from C57BL/6 mice in the presence of the TLR8 agonist CLO75 or the TLR7 agonist CLO97 and measured Ifn-α6 expression. Neutrophils from C57BL/6 mice treated with both CLO75 and CLO97 had increased Ifn-α6 expression. However, CLO75 increased Ifn-α6 significantly more than CLO97 (Figure 3, green). Neutrophils from Tlr8-deficient mice responded poorly to both CLO75 and CLO97 (Figure 3, blue). Tlr7 expression is significantly decreased in Tlr8-deficient neutrophils (15), which may explain the poor response of Tlr8-deficient cells to a TLR7 agonist. Still, these data show that activation of TLR8 induces Ifn-α6 expression in neutrophils.

Bottom Line: Here, we show the results of our investigation into the role of Tlr8 expression in SLE pathogenesis in 564Igi females.Bone marrow-derived macrophages from 564Igi females have a significant increase in Tlr8 expression compared to male-derived cells, and RNA fluorescence in situ hybridization data suggest that Tlr8 may escape X-inactivation in female-derived macrophages.These results propose a model by which females may be more susceptible to SLE pathogenesis due to inefficient inactivation of Tlr8.

View Article: PubMed Central - PubMed

Affiliation: Department of Integrative Physiology and Pathobiology, Tufts University , Boston, MA , USA.

ABSTRACT
Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of anti-nuclear antibodies. SLE is one of many autoimmune disorders that have a strong gender bias, with 70-90% of SLE patients being female. Several explanations have been postulated to account for the severity of autoimmune diseases in females, including hormonal, microbiota, and gene dosage differences. X-linked toll-like receptors (TLRs) have recently been implicated in disease progression in females. Our previous studies using the 564Igi mouse model of SLE on a Tlr7 and Tlr9 double knockout background showed that the presence of Tlr8 on both X chromosomes was required for the production of IgG autoantibodies, Ifn-I expression and granulopoiesis in females. Here, we show the results of our investigation into the role of Tlr8 expression in SLE pathogenesis in 564Igi females. Female mice have an increase in serum pathogenic anti-RNA IgG2a and IgG2b autoantibodies. 564Igi mice have also been shown to have an increase in neutrophils in vivo, which are major contributors to Ifn-α expression. Here, we show that neutrophils from C57BL/6 mice express Ifn-α in response to 564 immune complexes and TLR8 activation. Bone marrow-derived macrophages from 564Igi females have a significant increase in Tlr8 expression compared to male-derived cells, and RNA fluorescence in situ hybridization data suggest that Tlr8 may escape X-inactivation in female-derived macrophages. These results propose a model by which females may be more susceptible to SLE pathogenesis due to inefficient inactivation of Tlr8.

No MeSH data available.


Related in: MedlinePlus