Apoptosis resistance in peripheral blood lymphocytes of alopecia areata patients

Functional interrogation of lymphocyte subsets in alopecia areata using single-cell RNA sequencing

Alopecia areata (AA) is among the most prevalent autoimmune diseases, but the development of innovative therapeutic strategies has lagged due to an incomplete understanding of the immunological underpinnings of disease. Here, we performed single-cell RNA sequencing (scRNAseq) of skin-infiltrating immune cells from the graft-induced C3H/HeJ mouse model of AA, coupled with antibody-based depletion to interrogate the functional role of specific cell types in AA in vivo. Since AA is predominantly T cell-mediated, we focused on dissecting lymphocyte function in AA. Both our scRNAseq and functional studies established CD8+ T cells as the primary disease-driving cell type in AA. Only the depletion of CD8+ T cells, but not CD4+ T cells, NK, B, or γδ T cells, was sufficient to prevent and reverse AA. Selective depletion of regulatory T cells (Treg) showed that Treg are protective against AA in C3H/HeJ mice, suggesting that failure of Treg-mediated immunosuppression is not a major disease mechanism in AA. Focused analyses of CD8+ T cells revealed five subsets, whose heterogeneity is defined by an "effectorness gradient" of interrelated transcriptional states that culminate in increased effector function and tissue residency. scRNAseq of human AA skin showed that CD8+ T cells in human AA follow a similar trajectory, underscoring that shared mechanisms drive disease in both murine and human AA. Our study represents a comprehensive, systematic interrogation of lymphocyte heterogeneity in AA and uncovers a novel framework for AA-associated CD8+ T cells with implications for the design of future therapeutics.

CD4, CD8 and natural killer cells are depressed in patients with alopecia areata: their association with disease activity

BACKGROUND

Alopecia areata (AA) is a common inflammatory disorder targeting the hair follicles leading to non-scaring hair loss. The pathogenesis of AA is still unclear, despite the accumulating evidence of the immune-mediated nature of this disease. So, in this study, we aimed to assess the level of CD4 T cells, CD8 T cells and natural killer (NK) cells in the peripheral blood of patients with active AA and control subjects, and to evaluate the association between the level of those cells and the duration of disease in different subtypes of AA.

RESULTS

Fifty female patients and 50 age- and sex-matched healthy controls were enrolled in this case control study. CBC analysis and the level of CD4, CD8 T cells and NK cells were evaluated during the active stage of the disease. We found that CD4, CD8 T cells and NK cells proportion was significantly lower (P < 0.05) in patients with active stage AA compared with healthy subjects, however, the ratio of CD4:CD8 T cells was significantly higher in patients than control subjects. The level of CD4, CD8 T cells CD56 bright CD16^- % NK cells were positively correlated with the disease duration.

CONCLUSION

Active stage of AA disease is associated with a reduction of the circulating CD4, CD8 T cells and NK cells and an increase in CD4/CD8 T cells ratio, however, the level of those cells were higher with prolonged disease duration. Our findings confirm that immune mechanisms are involved in the pathogenesis of AA.

Estimation of CD3, CD4, and CD8 in Iraqi patients with alopecia areata and alopecia universalis

BACKGROUND

Alopecia areata is considered to be an autoimmune disease characterized by T-cell response and production of cytokines around the anagen stage.

AIM OF THE STUDY

The aim of this study was to assess T cells in blood using immune biomarkers (CD3, CD4, and CD8) in patients with AA and AU compared with healthy individuals.

MATERIALS AND METHODS

This study was carried out at private clinic and in the Department of Dermatology in Al Karama Teaching Hospital. The study groups included 58 patients from different geographic areas in Iraq, with ages ranging from 5 to 48 years from the end of August 2019 to the January 2020; AA patient group included 19, AU patient group included, 11 and control group included 30 with no scalp or body lesions in their disease history. All patients were clinically diagnosed to detect clinical types of disease in the scalp, in the body, and any hair-bearing area. Venous blood samples were collected from all participants where CD3 T cell, CD4 T cell, and CD8 T cell in whole blood were estimated by flow cytometry technique.

RESULTS

The present study has found the males are more susceptible to infection than the females in both types of disease. There was no significant difference (p > 0.05) detected for immune biomarkers (CD3, CD4, and CD8) in blood between patient groups in comparison with healthy individuals, but there was a significant decrease (p ≤ 0.05) in immune biomarkers (CD8, CD3) according to stress status in AU and in CD8 T cell between patient groups. CD4/CD8 ratio increased in alopecia patients.

CONCLUSION

In current study, There was no significant difference detected for biomarkers (CD3, CD4, and CD8) in blood between patient groups and healthy control, but significantly decrease in CD8 T cell and CD3T cell according to stress in AU, and in CD8T cell between patient groups according to stress This research may have proven one of the theories. Study of CD markers receptors and B cell receptors these will help for future studies.

Novel therapies for alopecia areata: The era of rational drug development

Treatments for alopecia areata (AA) have evolved over the decades from broad and nonspecific therapies to those that are now more targeted and rationally selected. This was achieved by means of close cooperation and communication between clinicians and basic scientists, which resulted in the elucidation and understanding of the unique pathophysiology of AA. In this review we discuss this evolution and how novel therapies for AA have changed over the decades, what we have in our current arsenal of drugs for this potentially devastating disease, and what the future holds.

Altered expression of intracellular Toll-like receptors in peripheral blood mononuclear cells from patients with alopecia areata

BACKGROUND

Toll-like receptors (TLRs) are pattern-recognition-receptors that sense a variety of pathogens and initiation of innate and adaptive immune responses. This study was undertaken to investigate the expression of TLRs in peripheral blood-mononuclear cells (PBMCs) of AA patients and to determine whether TLR-mediated inflammatory signals are important for the perspective of AA management.

METHODS

Gene expression of TLRs and T-helper (Th) type-1, Th-2, Th-17 and regulatory T-cell cytokines in PBMCs was quantified by TaqMan Assays. Production of these cytokines in serum samples was determined by sandwich ELISAs.

RESULTS

All TLRs (TLRs 1-10) were expressed in PBMCs of AA patients. Importantly intracellular TLRs (TLRs 3, 7, 8 and 9) were significantly up-regulated in AA patients as compared with controls (p < 0.05). Interleukin (IL)-2, TNF-α, and IL-17A gene expression in patients' PBMCs and their secretion in patients' sera were significantly higher as compared with their respective controls (p < 0.05). Whereas, TGF-β gene expression in patients' PBMCs and TGF-β protein level in patients' sera were significantly lower as compared with their controls (p < 0.05).

CONCLUSION

This is the first report that shows the comprehensive expression profile of TLRs in AA patients. We conclude that up-regulated expression of intracellular TLRs in PBMCs of AA patients may play an active role in abnormal regulation of Th-1, Th-17 and regulatory T-cell cytokines in alopecia areata.

GENERAL SIGNIFICANCE

Targeting of TLRs and their associated inflammatory signaling will open new areas of research; this may lead to the development of novel therapeutic targets for the treatment of AA or other skin disorders.

The role of lymphocytes in the development and treatment of alopecia areata

Alopecia areata (AA) development is associated with both innate and adaptive immune cell activation, migration to peri- and intra-follicular regions, and hair follicle disruption. Both CD4(+) and CD8(+) lymphocytes are abundant in AA lesions; however, CD8(+) cytotoxic T lymphocytes are more likely to enter inside hair follicles, circumstantially suggesting that they have a significant role to play in AA development. Several rodent models recapitulate important features of the human autoimmune disease and demonstrate that CD8(+) cytotoxic T lymphocytes are fundamentally required for AA induction and perpetuation. However, the initiating events, the self-antigens involved, and the molecular signaling pathways, all need further exploration. Studying CD8(+) cytotoxic T lymphocytes and their fate decisions in AA development may reveal new and improved treatment approaches.

What causes alopecia areata?

The pathobiology of alopecia areata (AA), one of the most frequent autoimmune diseases and a major unsolved clinical problem, has intrigued dermatologists, hair biologists and immunologists for decades. Simultaneously, both affected patients and the physicians who take care of them are increasingly frustrated that there is still no fully satisfactory treatment. Much of this frustration results from the fact that the pathobiology of AA remains unclear, and no single AA pathogenesis concept can claim to be universally accepted. In fact, some investigators still harbour doubts whether this even is an autoimmune disease, and the relative importance of CD8(+) T cells, CD4(+) T cells and NKGD2(+) NK or NKT cells and the exact role of genetic factors in AA pathogenesis remain bones of contention. Also, is AA one disease, a spectrum of distinct disease entities or only a response pattern of normal hair follicles to immunologically mediated damage? During the past decade, substantial progress has been made in basic AA-related research, in the development of new models for translationally relevant AA research and in the identification of new therapeutic agents and targets for future AA management. This calls for a re-evaluation and public debate of currently prevalent AA pathobiology concepts. The present Controversies feature takes on this challenge, hoping to attract more skin biologists, immunologists and professional autoimmunity experts to this biologically fascinating and clinically important model disease.

Delayed type hypersensitivity-induced myeloid-derived suppressor cells regulate autoreactive T cells

Mild but efficient treatments of autoimmune diseases are urgently required. One such therapy, long-term maintenance of chronic delayed type hypersensitivity, has been described for alopecia areata (AA), a hair follicle-affecting autoimmune disease. The molecular mechanisms underlying the therapeutic efficacy are unknown, but may involve myeloid-derived suppressor cells (MDSCs). AA-affected mice were treated with squaric acid dibutyl ester (SADBE). The immunoreactivity of SADBE-treated AA lymphocytes and of AA lymphocytes co-cultured with SADBE-induced MDSCs was analyzed. The curative effect of SADBE was abolished by all-transretinoic acid, which drives MDSCs into differentiation, confirming a central role for MDSCs in therapeutic SADBE treatment. SADBE and SADBE-induced MDSCs strongly interfered with sustained autoreactive T-cell proliferation in response to AA skin lysate (autoantigen), which was accompanied by weak ζ-chain down-regulation and strongly impaired Lck activation. In contrast, activation of the mitochondrial apoptosis pathway and blockade of the anti-apoptotic PI3K/Akt pathway by SADBE-induced MDSCs did not require T-cell receptor engagement. Apoptosis induction correlated with high TNF-α expression in SADBE-induced MDSCs and elevated TNFRI levels in AA lymphocytes. SADBE-induced MDSCs interfere with persisting autoreactive T-cell proliferation and promote apoptosis of these T cells, which qualifies MDSCs induced and maintained by chronic delayed type hypersensitivity reactions as promising therapeutics in organ-related autoimmune diseases.

Cytokines and other mediators in alopecia areata

Alopecia areata, a disease of the hair follicles with multifactorial etiology and a strong component of autoimmune origin, has been extensively studied as far as the role of several cytokines is concerned. So far, IFN-gamma, interleukins, TNF-alpha, are cytokines that are well known to play a major role in the pathogenesis of the disease, while several studies have shown that many more pathways exist. Among them, MIG, IP-10, BAFF, HLA antigens, MIG, as well as stress hormones are implicated in disease onset and activity. Within the scope of this paper, the authors attempt to shed light upon the complexity of alopecia areata underlying mechanisms and indicate pathways that may suggest future treatments.

Recent advances and opportunities in research on lupus: environmental influences and mechanisms of disease

We summarize research on mechanisms through which environmental agents may affect the pathogenesis of lupus, discuss three exposures that have been the focus of research in this area, and propose recommendations for new research initiatives. We examined studies pertaining to key mechanistic events and specific exposures. Apoptosis leading to increased production or decreased clearance of immunogenic intracellular self-antigens and defective apoptosis of autoreactive immune cells both have been implicated in the loss of self-tolerance. The adjuvant or bystander effect is also needed to produce a sustained autoimmune response. Activation of toll-like receptors is one mechanism through which these effects may occur. Abnormal DNA methylation may contribute to the pathogenesis of lupus. Each of the specific exposures has been shown, in humans or in mice, to act upon one or more of these pathogenic steps. Specific recommendations for the continued advancement of our understanding of environmental influences on lupus and other autoimmune diseases include the development and use of mouse models with varying degrees of penetrance and manifestations of disease, identification of molecular or physiologic targets of specific exposures, development and use of improved exposure assessment methodologies, and multisite collaborations designed to examine understudied environmental exposures in humans.

Recent advances and opportunities in research on lupus: environmental influences and mechanisms of disease

OBJECTIVES

In this review we summarize research on mechanisms through which environmental agents may affect the pathogenesis of lupus, discuss three exposures that have been the focus of research in this area, and propose recommendations for new research initiatives.

DATA SOURCES AND SYNTHESIS

We examined studies pertaining to key mechanistic events and specific exposures. Apoptosis leading to increased production or decreased clearance of immunogenic intracellular self-antigens and defective apoptosis of autoreactive immune cells both have been implicated in the loss of self-tolerance. The adjuvant or bystander effect is also needed to produce a sustained autoimmune response. Activation of toll-like receptors is one mechanism through which these effects may occur. Abnormal DNA methylation may also contribute to the pathogenesis of lupus. Each of the specific exposures we examined--Epstein-Barr virus, silica, and trichloroethylene--has been shown, in humans or in mice, to act upon one or more of these pathogenic steps. Specific recommendations for the continued advancement of our understanding of environmental influences on lupus and other autoimmune diseases include the development and use of mouse models with varying degrees of penetrance and manifestations of disease, identification of molecular or physiologic targets of specific exposures, development and use of improved exposure assessment methodologies, and multisite collaborations designed to examine understudied environmental exposures in humans.

CONCLUSIONS

The advances made in the past decade concerning our understanding of mechanisms involved in the development of lupus and the influence of environmental agents on this process provide a strong foundation for further developments in this field.

Pulse corticosteroid therapy for alopecia areata: study of 139 patients

BACKGROUND/AIM

Recent reports of pulse corticosteroid therapy for alopecia areata (AA) show its efficacy for patients with a history of < or = 1 year but not for recalcitrant cases or alopecia totalis/universalis. The purpose of this study was to evaluate the efficacy and safety of pulse corticosteroid therapy for recent-onset AA patients.

METHOD

A total of 139 severe AA patients aged >15 years were included in this study. The duration from the onset of active hair loss was within 12 months for 125 (89.9%) of those patients.

RESULTS

Of the patients, 72.7% had hair loss on > 50% of their scalp area. Among the recent-onset group (duration of AA < or = 6 months), 59.4% were good responders (> 75% regrowth of alopecia lesions), while 15.8% with > 6 months duration showed a good response. Recent-onset AA patients with less severe disease (< or = 50% hair loss) responded at a rate of 88.0%, but only 21.4% of recent-onset patients with 100% hair loss responded. No serious adverse effects were observed.

CD44v7 ligation downregulates the inflammatory immune response in Crohn's disease patients by apoptosis induction in mononuclear cells from the lamina propria

Deletion of exon CD44v7 abrogates experimental colitis by apoptosis induction in intestinal mononuclear cells. Here we show that CD44v7 expression was upregulated upon CD40 ligation in human mononuclear cells, and examined whether ligation of CD44v7 also affects activation and apoptosis in lamina propria mononuclear cells (LPMC) from Crohn's disease (CD) patients. Thirty five patients with chronic inflammatory bowel disease (IBD), fourteen controls and four patients with diverticulitis were evaluated. CD44v7 was upregulated predominantly in the inflamed mucosa of CD patients. Furthermore, incubation with an anti-CD44v7 antibody induced apoptosis in LPMC isolated from inflamed mucosa of CD patients, but not from non-inflamed mucosa, from patients with ulcerative colitis (UC) or from normal controls. CD40 ligation and simultaneous incubation with anti-CD44v7 significantly downregulated CD80 in dendritic cells, thus inhibiting a critical second signal for naive T-cell activation. The apoptotic signal was mediated via the intrinsic mitochondrial pathway with decreased Bcl-2 and increased 7A6 (a mitochondrial membrane protein) expression. It was Fas independent and required caspases-3 and -9 activation. The process is highly specific for macrophage activation via CD40. These findings point to a novel mechanism of apoptosis induction in CD patients mediated by CD44v7 ligation.

Association between thyroid autoimmune dysfunction and non-thyroid autoimmune diseases

PURPOSE

To assess the prevalence of the association between thyroid autoimmune dysfunction in patients with and without Graves orbitopathy and non-thyroid autoimmune diseases.

METHODS

Retrospective review of the medical records of 254 consecutive patients with thyroid autoimmune disease with (n = 150) and without (n = 104) orbitopathy who had been followed at the same institution by ophthalmologists and general clinicians. All medical records contained information on any systemic diseases of the patients and a detailed description of their eye examinations. The mean follow-up period was 5.25 +/- 4.67 years.

RESULTS

Non-thyroid autoimmune diseases were detected in 24 (9.4%) patients. Type 1 diabetes was the most prevalent non-thyroid autoimmune disease diagnosed in the patients without orbitopathy (7 patients, 6.7%). For the patients with orbitopathy, vitiligo was the most prevalent condition, affecting 6 patients (4%). Other diseases including systemic sclerosis, systemic lupus erythematosus, myasthenia gravis, Sjögren syndrome, and rheumatoid arthritis were seen in a few patients in both groups. The time intervals between the diagnoses of the orbitopathy and the non-thyroid autoimmune disease were highly variable, ranging from none (concomitance of the 2 conditions) to decades.

CONCLUSIONS

The present data show that several non-thyroid autoimmune diseases may be associated with thyroid autoimmune dysfunction. Patients with Graves disease without orbitopathy are likely to develop polyglandular syndrome due to the occurrence of type 1 diabetes. Patients with Graves orbitopathy should be screened for other autoimmune conditions, especially vitiligo.

In vivo levels of IL-4, IL-10, TGF-β1 and IFN-γ mRNA of the peripheral blood mononuclear cells in patients with alopecia areata in comparison to those in patients with atopic dermatitis

Alopecia areata (AA) has been considered to be supported by an aberrant expression of IFN-gamma as a result of antigen dependent immune response. On the other hand, AA sometimes concurs with atopic diseases, although the mechanism of the concurrence is not clear. This study was designed to elucidate the immune status of AA and the similarity between AA and atopic dermatitis (AD) by analysis of in vivo levels of mRNA of Th1, Th2, and suppressive cytokines of peripheral blood mononuclear cells (PBMC). Using semiquantitative RT-PCR, the levels of cytokine mRNA were measured in freshly isolated PBMC of 47 patients with AA, 15 patients with AD, and 12 healthy controls (HC). The levels of IL-4, IFN-gamma, and TGF-beta1 mRNA were lower in patients with AA than those in HC. The levels of IL-10 mRNA in AA were comparable with those in HC. Decreased levels of IFN-gamma and TGF-beta1 were also shown in patients with AD. These results indicated a similarity (decreased levels of IFN-gamma and TGF-beta1) between AD and AA based on the cytokine profile. In addition, decreased levels of IL-4 mRNA in AA might also explain the experience that the severity of atopic disease coincident with AA is mild in the most of cases. Next, we compared the levels of these cytokine mRNA among the three subgroups of AA that were categorized based on the severity of the symptoms: mild, severe and totalis. Although there was no significant difference between any combinations of the subgroups, there was a tendency to increase the levels of IFN-gamma mRNA and to decrease the levels of IL-4 mRNA according to the severity of alopecia. However, the levels of IFN-gamma mRNA in any subgroups were less than those of HC. These results suggest that IFN-gamma is therefore involved in the pathogenesis of AA, although the information from PBMC is limited. In conclusion, AA might be induced by an aberrant expression of IFN-gamma in individuals whose PBMC produce low amounts of IFN-gamma and TGF-beta1. Further analysis is therefore required to investigate the phenotypes of the population in PBMC with or without reference to regulatory T cells.

Papel das células T reguladoras no desenvolvimento de dermatoses

Células T, em particular as células T CD4+, têm sido associadas a muitos aspectos das doenças de pele. A evidência atual sugere, porém, que o papel dos linfócitos T CD4+ no desenvolvimento de inflamação cutânea excede o de ativador pró-inflamatório das células T de ação que dirigem a resposta imune. Subtipos de células T com capacidade reguladora, tais como Tregs CD4+CD25+high, têm sido identificadas. Observações recentes sugerem que em algumas doenças da pele a função dessas células está modificada. Portanto, o desenvolvimento e a função de Tregs na dermatologia são atualmente um tópico atraente devido a sua importância no controle da resposta do sistema imune contra tumores e doenças infecciosas, bem como inibindo o desenvolvimento de auto-imunidade e alergia. Assim, mecanismos reguladores defeituosos podem permitir a quebra da tolerância imune periférica seguida por inflamação crônica e doença. Detalham-se as anormalidades funcionais e a contribuição de diferentes subtipos de células T reguladoras no desenvolvimento de doenças dermatológicas nesta revisão. Acentuam-se os possíveis alvos terapêuticos e as modificações dos T reguladores causados por imunomoduladores usados no campo da dermatologia.

What Can We Learn from Animal Models of Alopecia areata?

Alopecia areata (AA) is a hair loss disease marked by a focal inflammatory infiltrate of dystrophic anagen stage hair follicles by CD4+ and CD8+ lymphocytes. Although AA is thought to be an autoimmune disorder, definitive proof is lacking. Moreover, characterization of the primary pathogenic mechanisms by which hair loss is induced in AA is limited. In this context, animal models may provide a vital contribution to understanding AA. Recent research using animal models of AA has focused on providing evidence in support of a lymphocyte-mediated pathogenic mechanism consistent with AA as an autoimmune disease. In the future, research with both humans and animal models shall likely concentrate on identifying the primary antigenic epitopes involved in AA and the genetics of AA susceptibility. With a comprehensive understanding of the key elements in AA pathogenesis, new avenues for therapeutic research and intervention will be defined.