Analysis of Novel Immunological Biomarkers Related to Rheumatoid Arthritis Disease Severity

Rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPAs) are the most frequently used rheumatoid arthritis (RA) diagnostic markers, but they are unable to anticipate the patient's evolution or response to treatment. The aim of this study was to identify possible severity biomarkers to predict an upcoming flare-up or remission period. To address this objective, sera and anticoagulated blood samples were collected from healthy controls (HCs; n = 39) and from early RA (n = 10), flare-up (n = 5), and remission (n = 16) patients. We analyzed leukocyte phenotype markers, regulatory T cells, cell proliferation, and cytokine profiles. Flare-up patients showed increased percentages of cluster of differentiation (CD)3+CD4- lymphocytes (p < 0.01) and granulocytes (p < 0.05) but a decreased natural killer (NK)/T lymphocyte ratio (p < 0.05). Analysis of leukocyte markers by principal component analysis (PCA) and receiver operating characteristic (ROC) curves showed that CD45RO+ (p < 0.0001) and CD45RA+ (p < 0.0001) B lymphocyte expression can discriminate between HCs and early RA patients, while CD3+CD4- lymphocyte percentage (p < 0.0424) and CD45RA+ (p < 0.0424), CD62L+ (p < 0.0284), and CD11a+ (p < 0.0185) B lymphocyte expression can differentiate between flare-up and RA remission subjects. Thus, the combined study of these leukocyte surface markers could have potential as disease severity biomarkers for RA, whose fluctuations could be related to the development of the characteristic pro-inflammatory environment.

Frequency of Effector Memory Cells Expressing Integrin α4β7 Is Associated With TGF-β1 Levels in Therapy Naïve HIV Infected Women With Low CD4+ T Cell Count

Integrin α₄β₇ expressing CD4⁺ T cells are preferred targets for HIV infection and are thought to be predictors of disease progression. Concurrent analysis of integrin α₄β₇ expressing innate and adaptive immune cells was carried out in antiretroviral (ART) therapy naïve HIV infected women in order to determine its contribution to HIV induced immune dysfunction. Our results demonstrate a HIV infection associated decrease in the frequency of integrin α₄β₇ expressing endocervical T cells along with an increase in the frequency of integrin α₄β₇ expressing peripheral monocytes and central memory CD4⁺ T cells, which are considered to be viral reservoirs. We report for the first time an increase in levels of soluble MAdCAM-1 (sMAdCAM-1) in HIV infected individuals as well as an increased frequency and count of integrin β7Hi CD8⁺ memory T cells. Correlation analysis indicates that the frequency of effector memory CD8⁺ T cells expressing integrin α₄β₇ is associated with levels of both sMAdCAM-1 and TGF-β1. The results of this study also suggest HIV induced alterations in T cell homeostasis to be on account of disparate actions of sMAdCAM-1 and TGF-β1 on integrin α₄β₇ expressing T cells. The immune correlates identified in this study warrant further investigation to determine their utility in monitoring disease progression.

NIX-Mediated Mitophagy Promotes Effector Memory Formation in Antigen-Specific CD8+ T Cells

Autophagy plays a critical role in the maintenance of immunological memory. However, the molecular mechanisms involved in autophagy-regulated effector memory formation in CD8⁺ T cells remain unclear. Here we show that deficiency in NIX-dependent mitophagy leads to metabolic defects in effector memory T cells. Deletion of NIX caused HIF1α accumulation and altered cellular metabolism from long-chain fatty acid to short/branched-chain fatty acid oxidation, thereby compromising ATP synthesis during effector memory formation. Preventing HIF1α accumulation restored long-chain fatty acid metabolism and effector memory formation in antigen-specific CD8⁺ T cells. Our study suggests that NIX-mediated mitophagy is critical for effector memory formation in T cells.

Gupta et al. demonstrate that mitophagy mediated by NIX, a mitochondrial outer membrane protein, plays a critical role in CD8⁺ T cell effector memory formation by regulating mitochondrial superoxide-dependent HIF1α protein accumulation and fatty acid metabolism. These findings elucidate the molecular mechanisms regulating T cell effector memory formation against viruses.

Influenza-derived peptides cross-react with allergens and provide asthma protection

BACKGROUND

The hygiene hypothesis is the leading concept to explain the current asthma epidemic, which is built on the observation that a lack of bacterial contact early in life induces allergic T_H2 immune responses.

OBJECTIVE

Because little is known about the contribution of respiratory tract viruses in this context, we evaluated the effect of prior influenza infection on the development of allergic asthma.

METHODS

Mice were infected with influenza and, once recovered, subjected to an ovalbumin- or house dust mite-induced experimental asthma protocol. Influenza-polarized effector memory T (Tem) cells were transferred adoptively to allergen-sensitized animals before allergen challenge. A comprehensive in silico analysis assessed homologies between virus- and allergen-derived proteins. Influenza-polarized Tem cells were stimulated ex vivo with candidate peptides. Mice were immunized with a pool of virus-derived T-cell epitopes.

RESULTS

In 2 murine models we found a long-lasting preventive effect against experimental asthma features. Protection could be attributed about equally to CD4⁺ and CD8⁺ Tem cells from influenza-infected mice. An in silico bioinformatic analysis identified 4 influenza- and 3 allergen-derived MHC class I and MHC class II candidate T-cell epitopes with potential antigen-specific cross-reactivity between influenza and allergens. Lymphocytes from influenza-infected mice produced IFN-γ and IL-2 but not IL-5 on stimulation with the aforementioned peptides. Immunization with a mixture of the influenza peptides conferred asthma protection, and peptide-immunized mice transferred protection through CD4⁺ and CD8⁺ Tem cells.

CONCLUSION

For the first time, our results illustrate heterologous immunity of virus-infected animals toward allergens. This finding extends the original hygiene hypothesis.

Fine phenotypic and functional characterization of effector cluster of differentiation 8 positive T cells in human patients with primary biliary cirrhosis

In primary biliary cirrhosis (PBC), patients develop a multilineage response to a highly restricted peptide of the E2 component of pyruvate dehydrogenase (PDC-E2) involving autoantibody and autoreactive cluster of differentiation (CD)4(+) and CD8(+) T-cell responses. Recent data from murine models have suggested that liver-infiltrating CD8(+) cells play a critical role in biliary destruction in PBC. We hypothesized that chronic antigen stimulation of CD8(+) T cells alters effector memory T cell (T(EM) ) frequency and function similar to that seen with chronic viral infections, including failure to terminally differentiate and relative resistance to apoptosis. We have rigorously phenotyped CD8(+) T-cell subpopulations from 132 subjects, including 76 patients with PBC and 56 controls, and report a higher frequency of T(EM) cells characterized as CD45RO(high) CD57(+) CD8(high), but expressing the gut homing integrin, α4β7, in peripheral blood mononuclear cells of PBC. These CD8(high) T(EM) cells have reduced expression of Annexin V after TCR stimulation. Consistent with a T(EM) phenotype, CD45RO(high) CD57(+) CD8(high) T cells express higher levels of granzyme A, granzyme B, perforin, CCR5 and α4β7, and lower levels of CCR7 and CD28 than other CD8(high) T cells. Furthermore, interleukin (IL)-5 produced by CD8(+) CD57(+) T lymphocytes upon in vitro T-cell receptor stimulation are increased in PBC. Histologically, CD8(+) CD57(+) T cells accumulate around the portal area in PBC. Moreover, CD8(+) CD57(+) T cells respond specifically to the major histocompatibility class I epitope of PDC-E2.

CONCLUSION

In conclusion, our data demonstrate that CD45RO(high) CD57(+) CD8(high) T cells are a subset of terminally differentiated cytotoxic T(EM) cells, which could play a critical role in the progressive destruction of biliary epithelial cells.