Topics of Research

Inflammasomes and Other Innate Immune Receptors

The main focus of the lab is the family of innate immune receptors called the NLR (Nucleotide binding, leucine rich repeat proteins, or NOD-like receptors). Our lab first described this family in humans and it has remained a major focus of the lab. NLR family members are crucial in the regulation of inflammation. Among the NLR proteins, we study the inflammasome effectors NLRP1, NLRP3 and AIM2. We also study several NLRs that attenuate inflammation including NLRP12, NLRX1, and NLRC3. These proteins are studied in the context of:

Infectious diseases, with a focus on viral infection including influenza, HIV, DNA viruses such as Herpes virus and more recently, SARS-CoV-2;
Inflammatory diseases, with a focus on inflammatory bowel diseases;
Autoimmune diseases, with a focus on models of multiple sclerosis and T cell-mediated colitis;
Cancer, with a focus on how these proteins affect cancer outcome including impact on cancer immunotherapy;
Metabolic diseases, with a focus on the role of these proteins in obesity and insulin resistance;
Cross-talk with adaptive immunity, with a focus on NLRs that are expressed in lymphocytes and have clear functions in T cells;

In addition to a focus on NLR biology and disease relevance, we also conduct basic molecular biology and biochemistry in the field. For example, we discovered that a novel innate inhibitory sensor, NLRC3 is a strong cytosolic DNA binding protein. In addition, we demonstrated that viral DNA binding to NLRC3 caused an allosteric change in the protein, leading to enhanced ATPase activity of the nucleotide-binding domain and caused NLRC3 to release its target, the STING and TBK1 protein. This novel mechanism was published in Immunity and a figure from this paper can be seen to the right.

Neuroinflammation Research

Computationally derived binding model of NLRC3 binding with with HSV-60 (left) and HSV-15 (right) dsDNA.

Li and Deng et al. Viral DNA Binding to NLRC3, an Inhibitory Nucleic Acid Sensor, Unleashes STING, a Cyclic Dinucleotide Receptor that Activates Type I Interferon. Immunity. 2019 Mar 19; 50(3): 591–599.e6.

The Ting lab also aims to better understand the inflammation that occurs in a number of neurologic diseases such as multiple sclerosis (MS), general demyelination and more recently Alzheimer’s. Using mice with mutations in inflammatory genes, the Ting lab found that many of these genes, such as NLRs and TNF, are not only crucial in disease progression (demyelination), but also in disease resolution (remyelination). Below we showed that mice that lack NLRC4 or NLRP3 showed reduced demylination when mice are treated with cuprizone, a copper chelating agent that when given to mice mimics the autoimmune disease, Multiple Sclerosis (MS). Thus, this data indicates that targeting these two proteins may slow MS progression.

0 weeks 3 weeks

Representative images of brain sections of untreated (0 wk) and 3-wk cuprizone–treated WT, Nlrc4−/−, and Nlrp3−/− stained for the presence of myelin at the corpus callosum (purple dashed lines) with myelin (stained with LFB in blue)

Freeman et al. NLR members NLRC4 and NLRP3 mediate sterile inflammasome activation in microglia and astrocytes. J Exp Med. 2017 May 1;214(5):1351-1370. doi: 10.1084/jem.20150237

Using a second model of MS, called experimental autoimmune encephalomyelitis (EAE), we also showed that another NLR protein, NLRC3, when expressed in T cells helps reduce disease severity. Below we show that knocking out NLRC3 specifically in T cells results in a significant increase in EAE symptoms. In addition, we showed that when CD4 T cells are isolated, the cells that lack NLRC3 have an increased activation state (illustrated by an increase in cell metabolism or ECAR).

Uchimura et al. The Innate Immune Sensor NLRC3 Acts as a Rheostat that Fine-Tunes T Cell Responses in Infection and Autoimmunity. Immunity. 2018 Dec 18; 49(6): 1049–1061.e6. doi: 10.1016/j.immuni.2018.10.008

Microbiome Research

A major direction in the lab is to understand the interaction between the gut microbiota and the immune system. We have investigated the role of the microbiome in immune-dependent disease models. We found that the microbiome is altered in mice lacking specific NLR proteins and these changes results in an altered disease progression. We demonstrated that NLRP12 restrains the inflammatory responses, producing a microbiota that attenuates colitis and obesity. We have used germ free mice among other strategies to address the importance of this finding. Remarkably we find that Lachnospiraceae bacteria is missing in gut microbiota of NLRP12 deficient mice. This presence of this bacteria can attenuate colitis and reduce weight gain. Furthermore we have identified metabolites from the bacteria that are important in these disease process. We are interested in testing microbiome that can reduce inflammation in other organs or tissues, such as during viral infection and neuroinflammation. We are also examining the role of microbiota in protection against different cancer therapies (see mitigation of radiation).

Cohousing (CoHo) vs. single-housing (SiHo) strategy with (b) DSS treatment of WT and Nlrp12−/− mice or (c) percent weight increase of animals shown

(b) Chen and Wilson et al. NLRP12 attenuates colon inflammation by maintaining colonic microbial diversity and promoting protective commensal bacterial growth. Nat Immunol. 2017 May;18(5):541-551. doi: 10.1038/ni.3690

(c) Truax and Chen et al. The Inhibitory Innate Immune Sensor NLRP12 Maintains a Threshold against Obesity by Regulating Gut Microbiota Homeostasis. Cell Host Microbe. 2018 Sep 12;24(3):364-378.e6. doi: 10.1016/j.chom.2018.08.009.

Immune Agonizing Microparticles

The Ting lab has collaborated with Dr. Kristy Ainslie's Laboratory in the UNC School of Pharmacy to characterize a STING-agonizing polymeric microparticle (MP) delivery system. The Ainslie Lab has developed and characterized the biodegradable, acid-sensitive polymer Acetalted Dextran (Ace-DEX) and used an electrospray technique to encapsulate the STING agonizing compound cycle di-GMP AMP (cGAMP). Researchers in the Ting Lab have utilized this potent MP delivery system both as an influenza vaccine adjuvant and in cancer immunotherapy. We are testing this platform as an adjuvant for universal flu vaccine, and have promising data. Existing data indicate that this adjuvant is superior to most adjuvants on the market that we have compared in side-to-side studies in mice and ferrets. For cancer vaccines, we have shown that the adjuvant activates both T and NK dependent anti-cancer effects. Thus the Ace-DEX MPs demonstrate efficacy at 100-1000x lower doses compared to treatment with soluble cGAMP and show biologic efficacy by greatly enhancing the efficacy of influenza vaccine and cancer vaccines.

As mentioned above, we also have active programs examining the roles of innate immunity and their receptors during cancer progression and therapy.

cGAMP Ace-DEX MPs

Influenza Vaccine Adjuvant

Cancer Immunotherapy

Influenza: Junkins, Gallovic, and Johnson et al. A robust microparticle platform for a STING-targeted adjuvant that enhances both humoral and cellular immunity during vaccination. J Control Release. 2018 Jan 28; 270: 1–13.

Cancer Immunotherapy: Watkins-Schulz et al. A microparticle platform for STING-targeted immunotherapy enhances natural killer cell- and CD8+ T cell-mediated anti-tumor immunity. Biomaterials. 2019 Jun;205:94-105. doi: 10.1016/j.biomaterials.2019.03.011

Mitigation of Acute Radiation Toxicity

The Ting lab has also investigated the use of immune activating molecules, termed PAMPs, in the mitigation of radiation toxicity. We showed that the use of FSL-1, a synthetic lipoprotein that activates the innate immune receptor toll-like receptor 2/6, post radiation can reduce the clinical score, weight loss, and death after radiation exposure. This has huge promise in national defense, as well as in cancer patients undergoing radiation therapy.

In addition to PAMPs we have also identified gut commensal bacteria that can attenuate radiation induced damage. We have shown that pre-feeding mice with specific bacteria and their metabolites can profoundly reduce radiation side effects.

Kurkjian et al. The Toll-Like Receptor 2/6 Agonist, FSL-1 Lipopeptide, Therapeutically Mitigates Acute Radiation Syndrome. Sci Rep. 2017 Dec 11;7(1):17355. doi: 10.1038/s41598-017-17729-9.