Macrophage Migration Inhibitory Factor (MIF) and D-Dopachrome Tautomerase (DDT): Pathways to Tumorigenesis and Therapeutic Opportunities.

Discovered as inflammatory cytokines, MIF and DDT exhibit widespread expression and have emerged as critical mediators in the response to infection, inflammation, and more recently, in cancer. In this comprehensive review, we provide details on their structures, binding partners, regulatory mechanisms, and roles in cancer. We also elaborate on their significant impact in driving tumorigenesis across various cancer types, supported by extensive in vitro, in vivo, bioinformatic, and clinical studies. To date, only a limited number of clinical trials have explored MIF as a therapeutic target in cancer patients, and DDT has not been evaluated. The ongoing pursuit of optimal strategies for targeting MIF and DDT highlights their potential as promising antitumor candidates. Dual inhibition of MIF and DDT may allow for the most effective suppression of canonical and non-canonical signaling pathways, warranting further investigations and clinical exploration.

IL-1 receptor 1 signaling shapes the development of viral antigen-specific CD4+ T cell responses following COVID-19 mRNA vaccination.

BACKGROUND: The innate immune cytokine interleukin (IL)-1 can affect T cell immunity, a critical factor in host defense. In a previous study, we identified a subset of human CD4+ T cells which express IL-1 receptor 1 (IL-1R1). However, the expression of such receptor by viral antigen-specific CD4+ T cells and its biological implication remain largely unexplored. This led us to investigate the implication of IL-1R1 in the development of viral antigen-specific CD4+ T cell responses in humans, including healthy individuals and patients with primary antibody deficiency (PAD), and animals. METHODS: We characterized CD4+ T cells specific for SARS-CoV-2 spike (S) protein, influenza virus, and cytomegalovirus utilizing multiplexed single cell RNA-seq, mass cytometry and flow cytometry followed by an animal study. FINDINGS: In healthy individuals, CD4+ T cells specific for viral antigens, including S protein, highly expressed IL-1R1. IL-1ß promoted interferon (IFN)-γ expression by S protein-stimulated CD4+ T cells, supporting the functional implication of IL-1R1. Following the 2nd dose of COVID-19 mRNA vaccines, S protein-specific CD4+ T cells with high levels of IL-1R1 increased, likely reflecting repetitive antigenic stimulation. The expression levels of IL-1R1 by such cells correlated with the development of serum anti-S protein IgG antibody. A similar finding of increased expression of IL-1R1 by S protein-specific CD4+ T cells was also observed in patients with PAD following COVID-19 mRNA vaccination although the expression levels of IL-1R1 by such cells did not correlate with the levels of serum anti-S protein IgG antibody. In mice immunized with COVID-19 mRNA vaccine, neutralizing IL-1R1 decreased IFN-γ expression by S protein-specific CD4+ T cells and the development of anti-S protein IgG antibody. INTERPRETATION: Our results demonstrate the significance of IL-1R1 expression in CD4+ T cells for the development of viral antigen-specific CD4+ T cell responses, contributing to humoral immunity. This provides an insight into the regulation of adaptive immune responses to viruses via the IL-1 and IL-1R1 interface. FUNDING: Moderna to HJP, National Institutes of Health (NIH) 1R01AG056728 and R01AG055362 to IK and KL2 TR001862 to JJS, Quest Diagnostics to IK and RB, and the Mathers Foundation to RB.

MIF-Modulated Spinal Proteins Associated with Persistent Bladder Pain: A Proteomics Study.

Bladder pain is a prominent symptom in Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS). We studied spinal mechanisms of bladder pain in mice using a model where repeated activation of intravesical Protease Activated Receptor-4 (PAR4) results in persistent bladder hyperalgesia (BHA) with little or no bladder inflammation. Persistent BHA is mediated by spinal macrophage migration inhibitory factor (MIF), and is associated with changes in lumbosacral proteomics. We investigated the contribution of individual spinal MIF receptors to persistent bladder pain as well as the spinal proteomics changes associated with relief of persistent BHA by spinal MIF antagonism. Female mice with persistent BHA received either intrathecal (i.t.) MIF monoclonal antibodies (mAb) or mouse IgG1 (isotype control antibody). MIF antagonism temporarily reversed persistent BHA (peak effect: 2 h), while control IgG1 had no effect. Moreover, i.t. antagonism of the MIF receptors CD74 and C-X-C chemokine receptor type 4 (CXCR4) partially reversed persistent BHA. For proteomics experiments, four separate groups of mice received either repeated intravesical scrambled peptide and sham i.t. injection (control, no pain group) or repeated intravesical PAR4 and: sham i.t.; isotype IgG1 i.t. (15 µg); or MIF mAb (15 µg). L6-S1 spinal segments were excised 2 h post-injection and examined for proteomics changes using LC-MS/MS. Unbiased proteomics analysis identified and relatively quantified 6739 proteins. We selected proteins that showed significant changes compared to control (no pain group) after intravesical PAR4 (sham or IgG i.t. treatment) and showed no significant change after i.t. MIF antagonism. Six proteins decreased during persistent BHA (V-set transmembrane domain-containing protein 2-like confirmed by immunohistochemistry), while two proteins increased. Spinal MIF antagonism reversed protein changes. Therefore, spinal MIF and MIF receptors mediate persistent BHA and changes in specific spinal proteins. These novel MIF-modulated spinal proteins represent possible new targets to disrupt spinal mechanisms that mediate persistent bladder pain.

MIF contribution to progressive brain diseases.

Progressive brain diseases create a huge social and economic burden on modern societies as a major cause of disability and death. Incidence of brain diseases has a significantly increasing trend and merits new therapeutic strategies. At the base of many progressive brain malfunctions is a process of unresolved, chronic inflammation. Macrophage migration inhibitory factor, MIF, is an inflammatory mediator that recently gained interest of neuro-researchers due to its varied effects on the CNS such as participation of nervous system development, neuroendocrine functions, and modulation of neuroinflammation. MIF appears to be a candidate as a new biomarker and target of novel therapeutics against numerous neurologic diseases ranging from cancer, autoimmune diseases, vascular diseases, neurodegenerative pathology to psychiatric disorders. In this review, we will focus on MIF's crucial role in neurological diseases such as multiple sclerosis (MS), Alzheimer's disease (AD) and glioblastoma (GBM).

Potential role of RhoA GTPase regulation in type interferon signaling in systemic lupus erythematosus.

OBJECTIVE: Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by abnormal activation of the type I interferon (IFN) pathway, which results in tissue inflammation and organ damage. We explored the role of the RhoA GTPase in the type I IFN activation pathway to provide a potential basis for targeting GTPase signaling for the treatment of SLE. METHODS: Total RNA was extracted from peripheral blood mononuclear cells (PBMCs) of SLE patients and healthy controls, and the mRNA expression levels of RhoA and IFN-stimulated genes were measured by SYBR Green quantitative reverse transcriptase-polymerase chain reaction. IFN-a-stimulated response element (ISRE)-luciferase reporter gene assays and Western blotting were conducted to assess the biologic function of RhoA. An enzyme-linked immunoassay (ELISA) measured C-X-C motif chemokine ligand 10 (CXCL10) protein expression. RESULTS: Our studies demonstrate that the expression of RhoA in the PBMCs of SLE subjects was significantly higher than in healthy controls and positively correlated with type I IFN scores and type I IFN-stimulated gene (ISGs) expression levels. SiRNA-mediated knockdown of RhoA and the RhoA/ROCK inhibitor Y27632 reduced the activity of the type I IFN-induced ISRE, the signal transducer and activator of transcription 1 (STAT-1) phosphorylation, and the expression of CXCL10 and 2'-5'-oligoadenylate synthetase 1 (OAS1). Finally, we verified that Y27632 could significantly down-regulate the OAS1 and CXCL10 expression levels in the PBMCs of SLE patients. CONCLUSION: Our study shows that RhoA positively regulates the activation of the type I IFN response pathway. Reducing the expression level of RhoA inhibits the abnormal activation of the type I IFN system, and the RhoA/ROCK inhibitor Y27632 decreases aberrant type I IFN signaling in SLE PBMCs, suggesting the possibility of targeting the RhoA GTPase for the treatment of SLE.

A small molecule macrophage migration inhibitory factor agonist ameliorates age-related myocardial intolerance to ischemia-reperfusion insults via metabolic regulation.

Macrophage migration inhibitory factor (MIF) is an innate cytokine that regulates both inflammatory and homeostatic responses. MIF is expressed by cardiomyocytes, where it exerts a protective action against ischemia-reperfusion (I/R) injury by activating AMP-activated protein kinase (AMPK). This effect is attenuated in the senescent heart due to an intrinsic, age-related reduction in MIF expression. We hypothesized that treating the aged heart with the small molecule MIF agonist (MIF20) can reinforce protective MIF signaling in cardiomyocytes, leading to a beneficial effect against I/R stress. The administration of MIF20 at the onset of reperfusion was found to not only decrease myocardial infarct size but also preserves systolic function in the aged heart. Protection from I/R injury was reduced in mice with cardiomyocyte-specific Mif deletion, consistent with the mechanism of action of MIF20 to allosterically increase MIF affinity for its cognate receptor CD74. We further found MIF20 to contribute to the maintenance of mitochondrial fitness and to preserve the contractile properties of aged cardiomyocytes under hypoxia/reoxygenation. MIF20 augments protective metabolic responses by reducing the NADH/NAD ratio, leading to a decrease in the accumulation of reactive oxygen species (ROS) in the aged myocardium under I/R stress. We also identify alterations in the expression levels of the downstream effectors PDK4 and LCAD, which participate in the remodeling of the cardiac metabolic profile. Data from this study demonstrates that pharmacologic augmentation of MIF signaling provides beneficial homeostatic actions on senescent myocardium under I/R stress.

Extracellular macrophage migration inhibitory factor (MIF) downregulates adipose hormone-sensitive lipase (HSL) and contributes to obesity.

Attenuation of adipose hormone sensitive lipase (HSL) may impair lipolysis and exacerbate obesity. We investigate the role of cytokine, macrophage migration inhibitory factor (MIF) in regulating adipose HSL and adipocyte hypertrophy. Extracellular MIF downregulates HSL in an autocrine fashion, by activating the AMPK/JNK signaling pathway upon binding to its membrane receptor, CD74. WT mice fed high fat diet (HFD), as well as mice overexpressing MIF, both had high circulating MIF levels and showed suppression of HSL during the development of obesity. Blocking the extracellular action of MIF by a neutralizing MIF antibody significantly reduced obesity in HFD mice. Interestingly, intracellular MIF binds with COP9 signalosome subunit 5 (Csn5) and JNK, which leads to an opposing effect to inhibit JNK phosphorylation. With global MIF deletion, adipocyte JNK phosphorylation increased, resulting in decreased HSL expression, suggesting that the loss of MIF's intracellular inhibitory action on JNK was dominant in Mif-/- mice. Adipose tissue from Mif-/- mice also exhibited higher Akt and lower PKA phosphorylation following HFD feeding compared with WT, which may contribute to the downregulation of HSL activation during more severe obesity. Both intracellular and extracellular MIF have opposing effects to regulate HSL, but extracellular actions predominate to downregulate HSL and exacerbate the development of obesity during HFD.

Aging gene signature of memory CD8+ T cells is associated with neurocognitive functioning in Alzheimer's disease.

BACKGROUND: Memory CD8+ T cells expand with age. We previously demonstrated an age-associated expansion of effector memory (EM) CD8+ T cells expressing low levels of IL-7 receptor alpha (IL-7Rαlow) and the presence of its gene signature (i.e., IL-7Rαlow aging genes) in peripheral blood of older adults without Alzheimer's disease (AD). Considering age as the strongest risk factor for AD and the recent finding of EM CD8+ T cell expansion, mostly IL-7Rαlow cells, in AD, we investigated whether subjects with AD have alterations in IL-7Rαlow aging gene signature, especially in relation to genes possibly associated with AD and disease severity. RESULTS: We identified a set of 29 candidate genes (i.e., putative AD genes) which could be differentially expressed in peripheral blood of patients with AD through the systematic search of publicly available datasets. Of the 29 putative AD genes, 9 genes (31%) were IL-7Rαlow aging genes (P < 0.001), suggesting the possible implication of IL-7Rαlow aging genes in AD. These findings were validated by RT-qPCR analysis of 40 genes, including 29 putative AD genes, additional 9 top IL-7R⍺low aging but not the putative AD genes, and 2 inflammatory control genes in peripheral blood of cognitively normal persons (CN, 38 subjects) and patients with AD (40 mild cognitive impairment and 43 dementia subjects). The RT-qPCR results showed 8 differentially expressed genes between AD and CN groups; five (62.5%) of which were top IL-7Rαlow aging genes (FGFBP2, GZMH, NUAK1, PRSS23, TGFBR3) not previously reported to be altered in AD. Unbiased clustering analysis revealed 3 clusters of dementia patients with distinct expression levels of the 40 analyzed genes, including IL-7Rαlow aging genes, which were associated with neurocognitive function as determined by MoCA, CDRsob and neuropsychological testing. CONCLUSIONS: We report differential expression of "normal" aging genes associated with IL-7Rαlow EM CD8+ T cells in peripheral blood of patients with AD, and the significance of such gene expression in clustering subjects with dementia due to AD into groups with different levels of cognitive functioning. These results provide a platform for studies investigating the possible implications of age-related immune changes, including those associated with CD8+ T cells, in AD.

The RhoA GTPase regulates Type I Interferon Signaling in Systemic lupus erythematosus.

Objective: Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by abnormal activation of the type I interferon (IFN) pathway, which results in tissue inflammation and organ damage. We explored the role of the RhoA GTPase in the type I IFN activation pathway to provide a potential basis for targeting GTPase signaling for the treatment of SLE. Methods: Total RNA was extracted from peripheral blood mononuclear cells (PBMCs) of SLE patients and healthy controls, and the mRNA expression levels of RhoA and IFN-stimulated genes were measured by SYBR Green quantitative reverse transcriptase-polymerase chain reaction. IFN-stimulated response element (ISRE)-luciferase reporter gene assays and Western blotting were conducted to asssess the biologic function of RhoA. An Enzyme-Linked Immunoassay (ELISA) measured C-X-C motif chemokine ligand 10(CXCL10)protein expression. Results: Our studies demonstrated that the expression of RhoA in the PBMCs of SLE subjects was significantly higher than healthy controls and positively correlated with type I IFN scores and type I IFN-stimulated gene (ISGs) expression levels. SiRNA-mediated knockdown of RhoA and the RhoA/ROCK inhibitor Y27632 reduced the activity of the type I IFN-induced ISRE, the signal transducer and activator of transcription 1 (STAT-1) phosphorylation, and the expression of CXCL10 and 2'-5'-oligoadenylate synthetase 1(OAS1). Finally,we verified that Y27632 could significantly down-regulate the OAS1 and CXCL10 expression levels in PBMCs of SLE patients. Conclusion: Our study shows that RhoA positively regulates the activation of the type I IFN response pathway. Reducing the expression level of RhoA inhibits the abnormal activation of the type I IFN system, and the RhoA/ROCK inhibitor Y27632 decreases aberrant type I IFN signaling in SLE PBMCs, suggesting the possibility of targeting the RhoA GTPase for the treatment of SLE.

Mural cell-derived chemokines provide a protective niche to safeguard vascular macrophages and limit chronic inflammation.

Maladaptive, non-resolving inflammation contributes to chronic inflammatory diseases such as atherosclerosis. Because macrophages remove necrotic cells, defective macrophage programs can promote chronic inflammation with persistent tissue injury. Here, we investigated the mechanisms sustaining vascular macrophages. Intravital imaging revealed a spatiotemporal macrophage niche across vascular beds alongside mural cells (MCs)-pericytes and smooth muscle cells. Single-cell transcriptomics, co-culture, and genetic deletion experiments revealed MC-derived expression of the chemokines CCL2 and MIF, which actively preserved macrophage survival and their homeostatic functions. In atherosclerosis, this positioned macrophages in viable plaque areas, away from the necrotic core, and maintained a homeostatic macrophage phenotype. Disruption of this MC-macrophage unit via MC-specific deletion of these chemokines triggered detrimental macrophage relocalizing, exacerbated plaque necrosis, inflammation, and atheroprogression. In line, CCL2 inhibition at advanced stages of atherosclerosis showed detrimental effects. This work presents a MC-driven safeguard toward maintaining the homeostatic vascular macrophage niche.

Urothelial Oxidative Stress and ERK Activation Mediate HMGB1-Induced Bladder Pain.

Activation of intravesical protease activated receptors-4 (PAR4) results in bladder pain through the release of urothelial macrophage migration inhibitory factor (MIF) and high mobility group box-1 (HMGB1). We aimed to identify HMGB1 downstream signaling events at the bladder that mediate HMGB1-induced bladder pain in MIF-deficient mice to exclude any MIF-related effects. We studied whether oxidative stress and ERK activation are involved by examining bladder tissue in mice treated with intravesical disulfide HMGB1 for 1 h and analyzed with Western blot and immunohistochemistry. HMGB1 intravesical treatment increased urothelium 4HNE and phospho-ERK1/2 staining, suggesting that HMGB1 increased urothelial oxidative stress and ERK activation. Furthermore, we examined the functional roles of these events. We evaluated lower abdominal mechanical thresholds (an index of bladder pain) before and 24 h after intravesical PAR4 or disulfide HMGB1. Intravesical pre-treatments (10 min prior) included: N-acetylcysteine amide (NACA, reactive oxygen species scavenger) and FR180204 (FR, selective ERK1/2 inhibitor). Awake micturition parameters (voided volume; frequency) were assessed at 24 h after treatment. Bladders were collected for histology at the end of the experiment. Pre-treatment with NACA or FR significantly prevented HMGB1-induced bladder pain. No significant effects were noted on micturition volume, frequency, inflammation, or edema. Thus, HMGB1 activates downstream urothelial oxidative stress production and ERK1/2 activation to mediate bladder pain. Further dissection of HMGB1 downstream signaling pathway may lead to novel potential therapeutic strategies to treat bladder pain.

Macrophage migration inhibitory factor (MIF) and its homolog D-dopachrome tautomerase (D-DT) are significant promotors of UVB- but not chemically induced non-melanoma skin cancer.

Non-melanoma skin cancer (NMSC) is the most common cancer in Caucasians worldwide. We investigated the pathophysiological role of MIF and its homolog D-DT in UVB- and chemically induced NMSC using Mif-/-, D-dt-/- and Mif-/-/D-dt-/- mice on a hairless SKH1 background. Knockout of both cytokines showed similar attenuating effects on inflammation after acute UVB irradiation and tumor formation during chronic UVB irradiation, without additive protective effects noted in double knockout mice, indicating that both cytokines activate a similar signaling threshold. In contrast, genetic deletion of Mif and D-dt had no major effects on chemically induced skin tumors. To get insight into the contributing mechanisms, we used an in vitro 3D skin model with incorporated macrophages. Application of recombinant MIF and D-DT led to an accumulation of macrophages within the epidermal part that could be reversed by selective inhibitors of MIF and D-DT pathways. In summary, our data indicate that MIF and D-DT contribute to the development and progression of UVB- but not chemically induced NMSC, a role at least partially accounted by effects of both cytokines on epidermal macrophage accumulation. These data highlight that MIF and D-DT are both potential therapeutic targets for the prevention of photocarcinogenesis but not chemical carcinogenesis.

A pref-1-controlled non-inflammatory mechanism of insulin resistance.

While insulin resistance (IR) is associated with inflammation in white adipose tissue, we report a non-inflammatory adipose mechanism of high fat-induced IR mediated by loss of Pref-1. Pref-1, released from adipose Pref-1+ cells with characteristics of M2 macrophages, endothelial cells or progenitors, inhibits MIF release from both Pref-1+ cells and adipocytes by binding with integrin ß1 and inhibiting the mobilization of p115. High palmitic acid induces PAR2 expression in Pref-1+ cells, downregulating Pref-1 expression and release in an AMPK-dependent manner. The loss of Pref-1 increases adipose MIF secretion contributing to non-inflammatory IR in obesity. Treatment with Pref-1 blunts the increase in circulating plasma MIF levels and subsequent IR induced by a high palmitic acid diet. Thus, high levels of fatty acids suppress Pref-1 expression and secretion, through increased activation of PAR2, resulting in an increase in MIF secretion and a non-inflammatory adipose mechanism of IR.

The MIF promoter SNP rs755622 is associated with immune activation in glioblastoma.

Intratumoral heterogeneity is a defining hallmark of glioblastoma, driving drug resistance and ultimately recurrence. Many somatic drivers of microenvironmental change have been shown to affect this heterogeneity and, ultimately, the treatment response. However, little is known about how germline mutations affect the tumoral microenvironment. Here, we find that the single-nucleotide polymorphism (SNP) rs755622 in the promoter of the cytokine macrophage migration inhibitory factor (MIF) is associated with increased leukocyte infiltration in glioblastoma. Furthermore, we identified an association between rs755622 and lactotransferrin expression, which could also be used as a biomarker for immune-infiltrated tumors. These findings demonstrate that a germline SNP in the promoter region of MIF may affect the immune microenvironment and further reveal a link between lactotransferrin and immune activation.

Aging gene signature of IL-7 receptor alpha low effector memory CD8+ T cells is associated with neurocognitive functioning in Alzheimer's disease.

CD45RA+ effector memory (EM) CD8+ T cell expansion was reported in Alzheimer's disease (AD). Such cells are IL-7 receptor alpha (IL-7Rα)low EM CD8+ T cells, which expand with age and have a unique aging gene signature (i.e., IL-7Rαlow aging genes). Here we investigated whether IL-7Rαlow aging genes and previously reported AD and memory (ADM) genes overlapped with clinical significance in AD patients. RT-qPCR analysis of 40 genes, including 29 ADM, 9 top IL-7Ralow aging and 2 control genes, showed 8 differentially expressed genes between AD and cognitively normal groups; five (62.5%) of which were top IL-7Rαlow aging genes. Over-representation analysis revealed that these genes were highly present in molecular and biological pathways associated with AD. Distinct expression levels of these genes were associated with neuropsychological testing performance in 3 subgroups of dementia participants. Our findings support the possible implication of the IL-7Rαlow aging gene signature with AD.

Clinical features and high-risk indicators of central nervous system involvement in primary Sjögren's syndrome.

BACKGROUND: Evidence for central nervous system involvement in primary Sjögren's syndrome (pSS) patients is controversial and extremely limited. We aimed to describe the clinical profiles and high-risk indicators of primary Sjögren's syndrome (pSS) patients with central nervous system (CNS) involvement (pSS-CNS). METHODS: A total of 412 participants with pSS from a hospital in China from January 2012 to December 2019 were enrolled in the retrospective study. 42 pSS-CNS patients were compared with 370 pSS patients without CNS involvement. The clinical features, laboratory examinations, imaging characteristics, and treatment of the pSS-CNS cases were systematically analyzed. Potential risk factors related to pSS-CNS patients were identified by multivariate logistic regression analysis. RESULTS: The prevalence of central nervous system involvement in the studied pSS patients was 10.2% (42/412), with 31.3% (14/42) of pSS patients having neurological manifestations as the initial symptom. The manifestations of hemiparesis (35.7%, 15/42), paraparesis (28.6%, 12/42), dysphonia (31.0%, 13/42), blurred vision (21.4%, 9/42), and dysfunctional proprioception (23.8%, 10/42) were more common in the pSS-CNS patients. Cerebral infarction (57.1%, 24/42), demyelination (31.0%, 13/42), myelitis (23.8%, 11/42), and angiostenosis (21.4%, 9/42) were most often found on MRI or CT scan imaging in the pSS-CNS patients. Intrathecal IgG level and total protein of cerebrospinal fluid were increased in 50% (8/16) of the pSS-CNS group. In comparison with patients without CNS involvement, the pSS-CNS patients were found to also have kidney and lung involvement, hematologic abnormalities, positive ANA and anti-SSA antibody tests, and reduced complement 3 (C3) and complement 4 (C4) levels (all p < 0.05). The prevalence of lung involvement, immune thrombocytopenia, and high-titer ANA (1:1000) were significantly higher in pSS-CNS disease activity compared to those in the moderately active group. Multivariate analysis identified lung involvement, anti-SSA positivity, and low C3 levels as prognostic factors for pSS-CNS. After high-dose glucocorticoids and immunosuppressive therapy, 60.5% (26/38) of pSS-CNS patients improved, 36.8% (14/38) were unresponsive to treatment, and 2.6% (1/38) died. CONCLUSION: Clinical features are diverse in pSS-CNS patients, and the morbidity rate is low. CNS involvement was the initial presentation in state percentage here pSS patients. Pulmonary involvement, a positive anti-SSA antibody test, and reduced C3 levels are potential risk factors for CNS involvement in pSS. Treatment with high-dose glucocorticoids and immunosuppressive therapy appeared effective in 60% of pSS-CNS patients. Key Points • The CNS manifestations of pSS are diverse, and CNS imaging and CSF analysis are important for the diagnosis. • Pulmonary involvement, positive anti-SSA, and reduced C3 levels are potential risk factors of pSS-CNS. • About 60% of pSS-CNS patients were responsive to high-dose glucocorticoid administration and immunosuppressive therapy.