The Role of Type III Interferons in Human Disease.

PURPOSE: This literature review summarizes the main immunological characteristics of type III interferons (IFN) and highlights the clinically relevant aspects and future therapeutic perspectives for these inflammatory molecules. SOURCE: Relevant articles in PubMed MEDLINE from the first publication (2003) until 2020. N=101 articles were included in this review. PRINCIPAL FINDINGS: Type III IFNs represent a relatively newly described inflammatory cytokine family. Although they induce substantially similar signalling to the well-known type I IFNs, significant functional differences make these molecules remarkable. Type III IFNs have extensive biological effects, contributing to the pathogenesis of several diseases and also offering new diagnostic and therapeutic approaches: 1) their potent anti-viral properties make them promising therapeutics against viral hepatitis and even against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is causing the current coronavirus disease 2019 (COVID-19) pandemic; 2) imbalances in the IFN-λs contribute to several forms of chronic inflammation (e.g., systemic and organ-specific autoimmune diseases) and potentially predict disease progression and therapeutic response to biologic therapies; and 3) the antitumor properties of the type III IFNs open up new therapeutic perspectives against malignant diseases. CONCLUSION: Over the last 18 years, researchers have gathered extensive information about the presence and role of these versatile inflammatory cytokines in human diseases, but further research is needed to clarify the mechanistic background of those observations. Better understanding of their biological activities will permit us to use type III IFNs more efficiently in new diagnostic approaches and individualized therapies, consequently improving patient care.

Toll-like receptor 2 activation induces C-C chemokine receptor 2-dependent natural killer cell recruitment to the peritoneum.

Natural killer (NK) cells are innate effector cells with critical roles not only in tumor immunosurveillance and viral immunity, but also in bacterial and fungal infections. Toll-like receptor 2 (TLR2) can be important in the early and sustained immune responses to pathogens and tumors through the induction of cytokines and chemokines that recruit and activate immune effector cells. We investigated the role of TLR2 activation in NK cell recruitment with a view to informing approaches to induce or regulate peritoneal NK cell responses therapeutically. Peritoneal injection of TLR2 activators, including peptidoglycan and the lipopeptides FSL-1 and Pam3 CSK4 , resulted in NK cell recruitment after 16 h with increased NK cell numbers maintained for 48 h. TLR2 activators induced large amounts of CCR2 ligands, but much smaller amounts of CCR5 and CXCR3 ligands. Consistent with this observation, NK cell migration was abrogated in CCR2-deficient mice after peritoneal FSL-1 injection. Adoptive transfer of CCR2-deficient NK cells prior to peritoneal FSL-1 activation confirmed a cell-intrinsic component of CCR2-mediated NK cell migration. TLR2 activation did not induce an activated NK cell phenotype, but significant changes included an increase in the KLRG1+ subset and decreased NKG2D expression. Although not activated in vivo, peritoneal NK cells could be activated by interleukin (IL)-12 and IL-18 ex vivo to express CD69 and interferonγ. These data demonstrate that TLR2-mediated immune activation is a potent inducer of NK cell recruitment via a CCR2-dependent mechanism and that NK cells recruited by this mechanism can respond to additional signals to exert effector cell functions.

CCR4 and CXCR3 play different roles in the migration of T cells to inflammation in skin, arthritic joints, and lymph nodes.

CCR4 and CXCR3 are expressed on several T-cell subsets in inflamed tissues, yet their role in tissue-specific recruitment is unclear. We examined the contributions of CCR4 and CXCR3 to T-cell recruitment into inflamed joints in collagen-induced arthritis, antigen-draining lymph nodes (LNs) and dermal inflammatory sites (poly I:C, LPS, concanavalin A, and delayed type hypersensitivity), using labeled activated T cells from CXCR3(-/-), CCR4(-/-), and WT mice. Both CXCR3 and CCR4 deficiency reduced the development of arthritis, but did not affect Th1-cell recruitment to the inflamed joints. Accumulation in inflamed LNs was highly CXCR3 dependent. In contrast, CCR4-deficient Th1 cells had an increased accumulation in these LNs. Migration to all four dermal inflammatory sites by activated Th1 and T cytotoxic cells and memory CD4(+) T cells was partially CXCR3-dependent, but Treg-cell migration was independent of CXCR3. The subset of cells expressing CCR4 has skin-migrating properties, but CCR4 itself is not required for the migration. Thus, migration into these inflamed tissues is CCR4-independent, and partially dependent on CXCR3, except for Treg cells, which require neither receptor. CCR4 may therefore affect retention of T cells in different tissues rather than trafficking out of the blood.

Effector T cell interactions with meningeal vascular structures in nascent autoimmune CNS lesions.

The tissues of the central nervous system are effectively shielded from the blood circulation by specialized vessels that are impermeable not only to cells, but also to most macromolecules circulating in the blood. Despite this seemingly absolute seclusion, central nervous system tissues are subject to immune surveillance and are vulnerable to autoimmune attacks. Using intravital two-photon imaging in a Lewis rat model of experimental autoimmune encephalomyelitis, here we present in real-time the interactive processes between effector T cells and cerebral structures from their first arrival to manifest autoimmune disease. We observed that incoming effector T cells successively scanned three planes. The T cells got arrested to leptomeningeal vessels and immediately monitored the luminal surface, crawling preferentially against the blood flow. After diapedesis, the cells continued their scan on the abluminal vascular surface and the underlying leptomeningeal (pial) membrane. There, the T cells encountered phagocytes that effectively present antigens, foreign as well as myelin proteins. These contacts stimulated the effector T cells to produce pro-inflammatory mediators, and provided a trigger to tissue invasion and the formation of inflammatory infiltrations.

Fatal pneumococcal meningitis in a 7-year-old girl with interleukin-1 receptor activated kinase deficiency (IRAK-4) despite prophylactic antibiotic and IgG responses to Streptococcus pneumoniae vaccines.

UNLABELLED: IRAK-4 deficiency causes IL-1R and TLR signaling failure, resulting in minimal clinical features despite invasive bacterial infection. We report the course of a 7-year-old IRAK-4-deficient girl presenting in the first year with multiple occult Staphylococcus aureus lymphadenitis. She was managed with antibiotic prophylaxis (sulfa/trimethoprim/PenV, then - due to neutropenia - Cefprozil), pneumococcal vaccination (PCV-7, Pneumovax23, PCV-13) and vigilance. Pneumococcal-specific IgG levels were monitored. No bacterial infections occurred on prophylaxis for 6 years after initial presentation. IgG response to pneumococcal polysaccharide was satisfactory but short-lived, requiring frequent boosting. At age 7, patient developed a morning headache and vomited once. Cefprozil was administered and re-dosed. Over 12 h, she was fatigued without other symptoms. Low fever accompanied another emesis. A few hours later she was confused, and purpuric rash appeared. Emergency physicians diagnosed sepsis/meningitis and started vancomycin-ceftriaxone. Respiratory failure and cerebellar herniation occurred <24 h after first symptoms. Blood and CSF grew Streptococcus pneumoniae type 6C resistant to second-generation cephalosporins. The patient's latest PCV-13 vaccination was 6 weeks before death, which included serotype 6A. Immunoglobulins were normal except IgG4 was increased (3.4 g/L). IgG response to vaccine antigens was satisfactory. IgG to 6A is reported to cross-react with 6C, but this was not the case here. CONCLUSION: Despite antibiotic prophylaxis and repeated vaccination, even older IRAK-4-deficient patients are at high risk of rapidly fatal infection due to emergence of antibiotic resistance. These patients need early assessment at any age, bacterial culturing, alternative empiric antibiotic therapy and close observation when even vaguely unwell. Based on increasingly recognized immunological and/or clinical impairments in B cell function, and possibly other defects, long-term IgG prophylaxis in addition to antibiotics is recommended.

Differing requirements for CCR4, E-selectin, and α4ß1 for the migration of memory CD4 and activated T cells to dermal inflammation.

CCR4 on T cells is suggested to mediate skin homing in mice. Our objective was to determine the interaction of CCR4, E-selectin ligand (ESL), and α(4)ß(1) on memory and activated T cells in recruitment to dermal inflammation. mAbs to rat CCR4 were developed. CCR4 was on 5-21% of memory CD4 cells, and 20% were also ESL(+). Anti-TCR-activated CD4 and CD8 cells were 40-55% CCR4(+), and ∼75% of both CCR4(+) and CCR4(-) cells were ESL(+). CCR4(+) memory CD4 cells migrated 4- to 7-fold more to dermal inflammation induced by IFN-γ, TNF, TLR agonists, and delayed-type hypersensitivity than CCR4(-) cells. CCR4(+) activated CD4 cells migrated only 5-50% more than CCR4(-) cells to these sites. E-selectin blockade inhibited ∼60% of CCR4(+) activated CD4 cell migration but was less effective on memory cells where α(4)ß(1) was more important. Anti-α(4)ß(1) also inhibited CCR4(-) activated CD4 cells more than CCR4(+) cells. Anti-E-selectin reduced activated CD8 more than CD4 cell migration. These findings modify our understanding of CCR4, ESL, α(4)ß(1), and dermal tropism. There is no strict relationship between CCR4 and ESL for skin homing of CD4 cells, because the activation state and inflammatory stimulus are critical determinants. Dermal homing memory CD4 cells express CCR4 and depend more on α(4)ß(1) than ESL. Activated CD4 cells do not require CCR4, but CCR4(+) cells are more dependent on ESL than on α(4)ß(1), and CCR4(-) cells preferentially use α(4)ß(1). The differentiation from activated to memory CD4 cells increases the dependence on CCR4 for skin homing and decreases the requirement for ESL.

Differences in IDO1+ dendritic cells and soluble CTLA-4 are associated with differential clinical responses to methotrexate treatment in rheumatoid arthritis.

Objective: Antigen-presenting dendritic cells (DCs) and monocytes play an essential role in rheumatoid arthritis (RA) pathogenesis, however, their tolerogenic potential remains unclear. Herein, the tolerogenic profiles of DCs are characterized in treatment-naïve RA patients to determine their role to inflammatory arthritis management. Methods: Thirty-six treatment-naïve RA patients were enrolled, of which 62% were non-responders to methotrexate (MTX) monotherapy based on disease activity score (DAS) after 6-months of therapy. DC and monocyte subset frequencies, activation (CD40, CD86, CD209 expression), and tolerogenic profile (intracellular indoleamine-2,3-dioxygenase [IDO1] and cytotoxic T lymphocyte antigen 4 [CTLA-4] expression) were examined in the baseline peripheral blood by multicolor flow-cytometry. Soluble CTLA-4 (sCTLA-4) levels in plasma were measured. Results: DC subsets were decreased in RA compared to healthy controls (HC), and the frequency of conventional DCs (cDC) inversely correlated with inflammatory markers and improvement in disease activity. CD141+ cDC1s were the major IDO1-expressing cells. IDO1+cDC1s were reduced in RA patients compared to HC. The baseline frequency of IDO1+cDC1s inversely correlated with improvement in disease activity. CTLA-4 expression in CD1c+ cDC2s and monocytes was lower in RA patients compared to HC. Moreover, MTX-responders had a significantly lower frequency of IDO1+cDC1 cells and higher level of sCTLA-4 in the plasma compared to MTX non-responders. There was a strong predictive association of low IDO1+cDC1 cells, low sCTLA-4 and non-response to MTX. Conclusions: Our findings reveal altered DC and monocytes immunophenotypes that are associated with RA pathology and treatment response. The frequencies of tolerogenic IDO1+cDC1s and the low level of sCTLA-4 are strongly associated with MTX non-responsiveness and therapeutic outcome. These results suggest that investigation of the association IDO1+cDC1 and sCTLA-4 with response to treatment may be more generalizable to other autoimmune diseases.

Virus stimulation of human mast cells results in the recruitment of CD56⁺ T cells by a mechanism dependent on CCR5 ligands.

The trafficking of effector cells to sites of infection is crucial for antiviral responses. However, the mechanisms of recruitment of the interferon-γ-producing and cytotoxic CD56(+) T cells are poorly understood. Human mast cells are sentinel cells found in the skin and airway and produce selected proinflammatory mediators in response to multiple pathogen-associated signals. The role of human mast cell-derived chemokines in T-cell recruitment to virus infection was examined. Supernatants from primary human cord blood-derived mast cells (CBMCs) infected with mammalian reovirus were examined for chemokine production and utilized in chemotaxis assays. Virus-infected CBMCs produced several chemokines, including CCL3, CCL4, and CCL5. Supernatants from reovirus-infected CBMCs selectively induced the chemotaxis of CD8(+) T cells (10±1%) and CD3(+)CD56(+) T cells (19±5%). CD56(+) T-cell migration was inhibited by pertussis toxin (65±9%) and met-RANTES (56±7%), a CCR1/CCR5 antagonist. CD56(+) T cells expressed CCR5, but little CCR1. The depletion of CCL3, CCL4, and CCL5 from reovirus-infected CBMC supernatants significantly (41±10%) inhibited CD56(+) T-cell chemotaxis. This study demonstrates a novel role for mast cells and CCR5 in CD56(+) T-cell trafficking and suggests that human mast cells enhance immunity to viruses through the selective recruitment of cytotoxic effector cells to virus infection sites. These findings could be exploited to enhance local T-cell responses in chronic viral infection and malignancies at mast cell-rich sites.

Differentially Expressed Inflammation-Regulating MicroRNAs in Oligoarticular Juvenile Idiopathic Arthritis.

OBJECTIVE: To evaluate microRNA expression in synovial fluid (SF), plasma, and leukocytes from patients with juvenile idiopathic arthritis (JIA). METHODS: MicroRNA expression in pooled JIA plasma and SF was assessed by absolute quantitative droplet digital PCR array. The results were validated in individual patient samples. MicroRNA content in leukocytes and extracellular vesicles was evaluated by real-time PCR in JIA blood and SF. Blood microRNA expression was compared with healthy controls (HCs). Principal component analysis was used to profile JIA plasma and SF microRNAs, and the potential biological consequences of microRNA dysregulation were investigated by pathway analysis. RESULTS: MiR-15a-5p and miR-409-3p levels were higher in JIA plasma than in HC plasma. JIA SF contained elevated levels of miR-21-5p, miR-27a-3p, miR-146b-5p, miR-155-5p, and miR-423-5p, and decreased miR-192-5p and miR-451a, compared to JIA plasma. Extracellular vesicle analysis demonstrated variable encapsulation among selected microRNAs, with only miR-155-5p being represented substantially in extracellular vesicles. SF leukocytes also had higher expression of miR-21-5p, miR-27a-3p, miR-146b-5p, and miR-155-5p, and lower expression of miR-409-3p and miR-451a, relative to blood. No differences were observed between JIA and HC blood leukocytes. Clusters of microRNAs were commonly altered in JIA joint fluid and leukocytes compared to JIA blood samples. In silico analysis predicted that differentially expressed microRNAs in JIA target the transforming growth factor (TGF)-ß pathway. CONCLUSION: The expression of multiple microRNAs is dysregulated in JIA both locally and systemically, which may inhibit the TGF-ß pathway. These findings advance our knowledge of JIA immunopathogenesis and may lead to the development of targeted therapies.

Coexpression of chemokine receptors CCR5, CXCR3, and CCR4 and ligands for P- and E-selectin on T lymphocytes of patients with juvenile idiopathic arthritis.

OBJECTIVE: To investigate P- and E-selectin ligand coexpression with chemokine receptors (CKRs) on T cells in the synovial fluid (SF) and blood of children with juvenile idiopathic arthritis (JIA). METHODS: Sixteen patients with polyarticular or persistent oligoarticular JIA (ages 5.3-15.1 years) were studied. SF and venous blood were collected, and immunostaining for the expression of CCR4, CCR5, CXCR3, and P- or E-selectin ligands was performed. RESULTS: Compared to blood, SF was greatly enriched for CD4+ T cells bearing CCR5, CCR4, CXCR3, and both P- and E-selectin ligand. Twenty-five percent of the CD4+ T cells in SF expressed both CCR5 and CCR4, some also coexpressing CXCR3. Such cells were rare in blood. Half of the few CCR5+ T cells in blood coexpressed P- or E-selectin ligand, a phenotype that was enriched up to 50-fold in SF. A minority of CCR4+ and CXCR3+ cells in blood (∼25%) coexpressed selectin ligand; these were enriched 4-8-fold in SF. Most CCR4-expressing CD4+ T cells expressed both E-selectin ligand and cutaneous lymphocyte antigen. CONCLUSION: CCR4-, CCR5-, CXCR3-, and selectin ligand-expressing CD4+ T cells preferentially accumulate in the joints of children with JIA. The marked enrichment of CCR5+ T cells coexpressing P-selectin and/or E-selectin ligand in CD4+ SF T cells suggests that the few such cells in blood selectively migrate to inflamed joints via endothelial P- and E-selectin- and CCR5-activating chemokines. The predominance of CCR4-expressing CD4+ T cells coexpressing E-selectin ligand suggests that such cells migrate not only to areas of cutaneous inflammation, as previously reported, but also to the joints in JIA. Combined targeting of CCR5- and E-selectin-dependent mechanisms may be a relevant treatment strategy.

Prolidase deficiency, a rare inborn error of immunity, clinical phenotypes, immunological features, and proposed treatments in twins.

BACKGROUND: Prolidase deficiency (PD) is an autosomal recessive inborn multisystemic disease caused by mutations in the PEPD gene encoding the enzyme prolidase D, leading to defects in turnover of proline-containing proteins, such as collagen. PD is categorized as a metabolic disease, but also as an inborn error of immunity. PD presents with a range of findings including dysmorphic features, intellectual disabilities, recurrent infections, intractable skin ulceration, autoimmunity, and splenomegaly. Despite symptoms of immune dysregulation, only very limited immunologic assessments have been reported and standard therapies for PD have not been described. We report twin females with PD, including comprehensive immunologic profiles and treatment modalities used. CASE PRESENTATION: Patient 1 had recurrent infections in childhood. At age 13, she presented with telangiectasia, followed by painful, refractory skin ulcerations on her lower limbs, where skin biopsy excluded vasculitis. She had typical dysmorphic features of PD. Next-generation sequencing revealed pathogenic compound heterozygous mutations (premature stop codons) in the PEPD gene. Patient 2 had the same mutations, typical PD facial features, atopy, and telangiectasias, but no skin ulceration. Both patients had imidodipeptiduria. Lymphocyte subset analysis revealed low-normal frequency of Treg cells and decreased frequency of expression of the checkpoint molecule CTLA-4 in CD4+ TEM cells. Analysis of Th1, Th2, and Th17 profiles revealed increased inflammatory IL-17+ CD8+ TEM cells in both patients and overexpression of the activation marker HLA-DR on CD4+ TEM cells, reflecting a highly activated proinflammatory state. Neither PD patient had specific antibody deficiencies despite low CD4+CXCR5+ Tfh cells and low class-switched memory B cells. Plasma IL-18 levels were exceptionally high. CONCLUSIONS: Immunologic abnormalities including skewed frequencies of activated inflammatory CD4+ and CD8+ TEM cells, decreased CTLA-4 expression, and defects in memory B cells may be a feature of immune dysregulation associated with PD; however, a larger sample size is required to validate these findings. The high IL-18 plasma levels suggest underlying autoinflammatory processes.

CXCR3 blockade inhibits T-cell migration into the CNS during EAE and prevents development of adoptively transferred, but not actively induced, disease.

Autoreactive T-cell infiltration into the CNS is critical in MS and EAE. The chemokine receptor CXCR3 and its ligands are implicated in MS and mouse EAE, but the contribution of CXCR3 to T-cell migration into the inflamed CNS remains controversial. During active disease in a rat EAE model, blood T-cell, spleen T-cell and T lymphoblast migration into the CNS was inhibited by a CXCR3 blocking mAb by, 30-70%, ∼75% and 50-80%, respectively. However, CXCR3 blockade after active immunization did not inhibit EAE, did not alter total T-cell accumulation in the CNS and did not affect Treg accumulation or the presence of cells producing IFN-γ or IL-17. Conversely, CXCR3 blockade during EAE induced by adoptive transfer of myelin basic protein-activated T cells delayed disease onset, shortened its duration and reduced disease severity. Moreover, CXCR3 blockade inhibited leukocyte infiltration of the CNS>95%, virtually abolishing infiltration of transferred T cells. Thus, CXCR3 plays a major role in T-cell migration to the CNS and can be critical for encephalitogenic T-cell migration into the CNS to induce disease, but CXCR3-independent recruitment can also produce EAE.

High Dose Intravenous IgG Therapy Modulates Multiple NK Cell and T Cell Functions in Patients With Immune Dysregulation.

Intravenous immunoglobulin (IVIG) is an effective immunomodulatory treatment for immune dysregulation diseases. However, the mechanisms by which it reduces systemic inflammation are not well understood. NK cell cytotoxicity is decreased by IVIG in women with reduced fertility, but IVIG effects on NK cells in immune dysregulation are less clear. We hypothesized that IVIG modulation of lymphocyte function, especially in NK cells, is important for resolution of inflammation. Our aim was to identify IVIG-induced changes in a cohort of patients with Kawasaki disease (KD) and those that occur broadly in pediatric patients with various immune dysregulatory diseases. Peripheral blood mononuclear cells (PBMCs) of patients with KD or autoimmune/inflammatory diseases were phenotyped pre and post high dose IVIG treatment by flow cytometry. In KD patients, after IVIG infusion Treg cell frequency and the proportion of activated CD25+ immunoregulatory CD56bright NK cells was increased, and multiple lymphocyte subsets showed increased expression of the lymphoid tissue homing receptor CD62L. Importantly, IVIG treatment decreased the frequency of cells expressing the degranulation marker CD107a among cytotoxic CD56dim NK cells, which was reflected in a significant reduction in target cell killing and in decreased production of multiple pro-inflammatory mediators. Interestingly, the activating receptor CD336 was expressed on a higher proportion of CD56bright NK cells after IVIG in both KD and autoimmune/inflammatory patients while other NK receptors were increased differentially in each cohort. In autoimmune/inflammatory patients IVIG induced the proliferation marker CD71 on a higher percentage of CD56dim NK cells, and in contrast to KD patients, CD107a+ cells were increased in this subset. Furthermore, when PBMCs were stimulated ex vivo with IL-2 or Candida antigen in autologous plasma, more of the CD4+ T cells of KD patients expressed CD25 after IVIG therapy but fewer cytotoxic T cells were degranulated based on CD107a expression. In summary, IVIG treatment in patients with immune dysregulation has multiple effects, especially on NK cell subsets and CD4+ T cells, which are compatible with promoting resolution of inflammation. These novel findings provide insight into the immunomodulatory actions of IVIG in autoimmune and inflammatory conditions.

Human mast cell activation with virus-associated stimuli leads to the selective chemotaxis of natural killer cells by a CXCL8-dependent mechanism.

Human mast cells are found in skin and mucosal surfaces and next to blood vessels. They play a sentinel cell role in immunity, recognizing invading pathogens and producing proinflammatory mediators. Mast cells can recruit granulocytes, and monocytes in allergic disease and bacterial infection, but their ability to recruit antiviral effector cells such as natural killer (NK) cells and T cells has not been fully elucidated. To investigate the role of human mast cells in response to virus-associated stimuli, human cord blood-derived mast cells (CBMCs) were stimulated with polyinosinic.polycytidylic acid, a double-stranded RNA analog, or infected with the double-stranded RNA virus, reovirus serotype 3 Dearing for 24 hours. CBMCs responded to stimulation with polyinosinic.polycytidylic acid by producing a distinct chemokine profile, including CCL4, CXCL8, and CXCL10. CBMCs produced significant amounts of CXCL8 in response to low levels of reovirus infection, while both skin- and lung-derived fibroblasts were unresponsive unless higher doses of reovirus were used. Supernatants from CBMCs infected with reovirus induced substantial NK cell chemotaxis that was highly dependent on CXCL8 and CXCR1. These results suggest a novel role for mast cells in the recruitment of human NK cells to sites of early viral infection via CXCL8.

Association of a Type 2-Polarized T Cell Phenotype With Methotrexate Nonresponse in Patients With Rheumatoid Arthritis.

OBJECTIVE: Rheumatoid arthritis (RA) is a chronic inflammatory disease mediated through complex immunologic pathways. Among RA patients receiving low-dose methotrexate (MTX) monotherapy, approximately one-half exhibit a meaningful clinical response within the first 6 months of starting treatment. Whether baseline immune phenotypes differ between subsequent MTX responders and nonresponders is unknown. This study utilized comprehensive T cell immunophenotyping to identify specific immunologic pathways associated with MTX-nonresponsive joint inflammation in patients with RA. METHODS: In total, 32 patients with recent-onset RA were treated with MTX therapy. After 6 months, 15 patients were categorized as responders and 17 as nonresponders. Comprehensive blood T cell immunophenotyping, using multiparameter immunofluorescence flow cytometry analyses, was performed at baseline and following 6 months of treatment. RESULTS: Baseline measures of disease activity (Disease Activity Score in 28 joints [DAS28], C-reactive protein level, and erythrocyte sedimentation rate) did not differ between MTX responders and nonresponders following MTX treatment. Frequencies of CD4+ and CD8+ T cells were skewed to favor higher CD4:CD8 T cell ratios in MTX responders compared to nonresponders (P < 0.05). The proportion of inducible costimulator-expressing Treg cells was significantly greater among MTX nonresponders. Interleukin-13 (IL-13)-producing, but not interferon-γ- or IL-17-producing, CD4+ effector memory T (Tem) cells were significantly more frequent in MTX nonresponders (P < 0.05). The ratio of IL-13+:IL-17+ Tem cells among CD4+ Tem cells was 1.9-fold higher in MTX nonresponders compared to responders (P < 0.05). Both the CD4:CD8 T cell ratio and the frequency of IL-13+CD4+ Tem cells correlated with changes in the DAS28 score following MTX treatment, whereas T cell expression of immune checkpoint inhibitor markers (CTLA-4, programmed death 1, and T cell immunoglobulin and mucin domain-containing protein 3) did not differ between MTX responders and nonresponders. CONCLUSION: We observed a bias toward type 2-polarized T cell inflammatory responses in the peripheral blood of MTX-nonresponsive RA patients. Targeting the IL-13+CD4+ T cell pathway could be a new therapeutic strategy in RA patients whose disease remains resistant to MTX.

The relative activity of CXCR3 and CCR5 ligands in T lymphocyte migration: concordant and disparate activities in vitro and in vivo.

In chronic inflammatory reactions such as rheumatoid arthritis and multiple sclerosis, T cells in the inflamed tissue express the chemokine receptors CXCR3 and CCR5, and the chemokine ligands (CCL) of these receptors are present in the inflammatory lesions. However, the contribution of these chemokines to T cell recruitment to sites of inflammation is unclear. In addition, the relative roles of the chemokines that bind CXCR3 (CXCL9, CXCL10, CXCL11) and CCR5 (CCL3, CCL4, CCL5) in this process are unknown. The in vitro chemotaxis and in vivo migration of antigen-activated T lymphoblasts and unactivated spleen T cells to chemokines were examined. T lymphoblasts migrated in vitro to CXCR3 ligands with a relative potency of CXCL10 > CXCL11 > CXCL9, but these cells demonstrated much less chemotaxis to the CCR5 ligands. In vivo, T lymphocytes were recruited in large numbers with rapid kinetics to skin sites injected with CXCL10 and CCL5 and less to CCL3, CCL4, CXCL9, and CXCL11. The combination of CCL5 with CXCL10 but not the other chemokines markedly increased recruitment. Coinjection of interferon-gamma, tumor necrosis factor alpha, and interleukin-1alpha to up-regulate endothelial cell adhesion molecule expression with CXCL10 or CCL5 induced an additive increase in lymphoblast migration. Thus, CXCR3 ligands are more chemotactic than CCR5 ligands in vitro; however, in vivo, CXCL10 and CCL5 have comparable T cell-recruiting activities to cutaneous sites and are more potent than the other CXCR3 and CCR5 chemokines. Therefore, in vitro chemotaxis induced by these chemokines is not necessarily predictive of their in vivo lymphocyte-recruiting activity.

Expression of lymphocyte homing receptors alpha4beta7 and MAdCAM-l in young and old rats.

The elderly constitute the most rapidly growing subpopulation in the United States. This age group represents a significant burden on the healthcare system due, in part, to increases in morbidity and mortality associated with an increase in the incidence of intestinal infectious diseases. Our previous studies suggest that impaired homing of IgA immunoblasts from the Peyer's patches to the intestinal lamina propria contributes to the diminished intestinal immune response in the elderly. The present study employs flow cytometry and quantitative immunohistochemistry to assess age-related changes in the numbers of peripheral blood mononuclear cells expressing the homing integrin alpha4beta7 and vascular endothelial cells in the intestine expressing its specific receptor, the address in MAdCAM-1, in inbred Fischer 344 rats. The proportion of alpha4beta7-positive mononuclear cells in young rats is significantly greater than that measured in the blood of senescent animals. Although the density of intestinal lamina propria blood vessels with MAdCAM-1-positive endothelium was greater in young adult rats in comparison to old animals, this difference achieved only borderline statistical significance. This is the first study to examine the expression of these two critical lymphocyte homing molecules as a function of age.

The use of immunoglobulin therapy for patients with primary immune deficiency: an evidence-based practice guideline.

The standard treatment for patients with primary antibody deficiency is immunoglobulin (IG), but the care of these patients is complex. These guidelines, initiated by the Canadian Blood Services and the National Advisory Committee on Blood and Blood Products, have been developed to facilitate and standardize the care of these patients by the various physician specialties that are responsible for their care. A panel of national expert immunologists and methodologists developed salient clinical questions; and a systematic, expert, and bibliography literature search up to July 2008 was conducted. One thousand eighty-seven citations were retrieved, and 102 reports were used in the preparation of this guideline. The recommendations provide guidance (1) on the complexity of the treatment of these patients; (2) the established benefits of IG on morbidity and mortality; (3) dosage, routes of administration, and management of reactions; (4) the various IG formulations available; (5) vaccination of these patients; and (6) research priorities.

Blockade of chemokine receptor CXCR3 inhibits T cell recruitment to inflamed joints and decreases the severity of adjuvant arthritis.

T lymphocytes expressing the chemokine receptors, CCR2, CCR5, CXCR3, and CXCR6 are increased in inflamed tissues in rheumatoid arthritis. The role of CXCR3 in autoimmune arthritis induced in Lewis rats was investigated. CXCR3+ T cells migrated 2- to 3-fold more than CXCR3- T cells to inflamed joints in arthritic animals. CXCR3-expressing in vivo Ag-activated T lymphoblasts and in vitro-activated lymph node cells from arthritic animals were strongly recruited to the arthritic joints, and treatment with anti-CXCR3 mAb significantly inhibited this T cell recruitment by 40-60%. Immune T cells from the spleen and lymph nodes of actively immunized arthritic donors adoptively transferred arthritis to naive rats. Treatment with anti-CXCR3 mAb delayed the onset of arthritis and significantly reduced the severity of joint inflammation with a >50% decrease in the clinical arthritis score. Blockade of CXCR3 also significantly reduced the weight loss in the arthritic animals and inhibited neutrophil accumulation in the joints by 50-60%. There was a marked reduction in the leukocyte infiltration of the synovium in the presence of CXCR3 blockade and a decrease in the loss of articular cartilage of the joints. In conclusion, CXCR3 on T cells has an essential role in T cell recruitment to inflamed joints and the development of joint inflammation in adjuvant arthritis.