Role of IL-32 Gamma on Bone Metabolism in Autoimmune Arthritis

Association between inflammatory markers and bone mineral density: a cross-sectional study from NHANES 2007-2010

PURPOSE

Monocyte-to-lymphocyte ratio (MLR), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) are acknowledged as novel inflammatory markers. However, studies investigating the correlation between inflammatory markers and osteoporosis (OP) remain scarce. We aimed to investigate the relationship between NLR, MLR, PLR and bone mineral density (BMD).

METHODS

A total of 9054 participants from the National Health and Nutrition Examination Survey were included in the study. MLR, NLR and PLR were calculated for each patient based on routine blood tests. Given the complex study design and sample weights, the relationship between inflammatory markers and BMD was evaluated through weighted multivariable-adjusted logistic regression and smooth curve fittings. In addition, several subgroup analyses were conducted to assess the robustness of the outcomes.

RESULTS

This study observed no significant relationship between MLR and lumbar spine BMD (P = 0.604). However, NLR was positively correlated with lumbar spine BMD (β = 0.004, 95% CI: 0.001 to 0.006, P = 0.001) and PLR was negatively linked to lumbar spine BMD (β = - 0.001, 95% CI: - 0.001 to - 0.000, P = 0.002) after accounting for covariates. When bone density measurements were changed to the total femur and femoral neck, PLR was still significantly positively correlated with total femur (β = - 0.001, 95% CI: - 0.001, - 0.000, P = 0.001) and femoral neck BMD (β = - 0.001, 95% CI: - 0.002, - 0.001, P < 0.001). After converting PLR to a categorical variable (quartiles), participants in the highest PLR quartile had a 0.011/cm² lower BMD than those in the lowest PLR quartile (β = - 0.011, 95% CI: - 0.019, - 0.004, P = 0.005). According to subgroup analyses stratified by gender and age, the negative correlation with PLR and lumbar spine BMD remained in males and age < 18 groups, but not in female and other age groups.

CONCLUSIONS

NLR and PLR were positively and negatively correlated with lumbar BMD, respectively. And PLR might serve as a potential inflammatory predictor of osteoporosis outperforming MLR and NLR. The complex correlation between the inflammation markers and bone metabolism requires further evaluation in large prospective studies.

Interleukin-32 as a biomarker in rheumatic diseases: A narrative review

Interleukin-32 (IL-32) is an important cytokine involved in the innate and adaptive immune responses. The role of IL-32 has been studied in the context of various diseases. A growing body of research has investigated the role of IL-32 in rheumatic diseases including inflammatory arthritides (rheumatoid arthritis, ankylosing spondylitis, and psoriatic arthritis) and connective tissue diseases (systemic lupus erythematosus, systemic sclerosis, granulomatosis and polyangiitis, and giant cell arteritis). IL-32 has been shown to play different roles according to the type of rheumatic diseases. Hence, the putative role of IL-32 as a biomarker is also different in each rheumatic disease: IL-32 could serve as a biomarker for disease activity in some diseases, whereas in other diseases it could be a biomarker for certain disease manifestations. In this narrative review, we summarize the associations between IL-32 and various rheumatic diseases and discuss the putative role of IL-32 as a biomarker in each disease.

Microarchitecture of historic bone samples with tuberculosis

Tuberculosis is among the leading causes of death from infectious diseases and affects many organ systems, including the skeleton. Skeletal tuberculosis is an extrapulmonary stage of tuberculosis, which occurs after the early and post-primary pulmonary stages of the disease. The aim of our study was to assess the microarchitecture of historic dry bone samples of subjects who have died of tuberculosis documented by post-mortem examinations. These preparations date to the pre-antibiotic era, and were provided by the Pathological-Anatomical Collection in the “Fools Tower” of the Natural History Museum Vienna (PASiN-NHM).

We investigated macerated samples of 20 vertebral bodies, 19 femoral heads, and 20 tibiae of a total of 59 individuals diagnosed with tuberculosis from the nineteenth and early twentieth century. 10 femora and 10 tibiae from body donors that did not exhibit signs of infection and 10 (unaffected) vertebrae kept at the PASiN-NHM were studied as controls. The affected regions of the bone samples (and the corresponding regions of the control bones) were analyzed by microcomputed tomography using a Viscom X 8060 II system. Obtained images were analyzed semi-quantitatively. In samples with tuberculosis, independent of the investigated skeletal region, trabecular defects and decreased trabecular thickness were observed. Cortical porosity was seen in affected vertebrae and tibia; in tuberculous tibiae (but not in the femora) cortical thickness was decreased. In half of the individuals, cortical sclerosis was present; signs of ankylosis were observed mainly at the femoral heads affected with tuberculosis. We conclude that a combination of several alterations at the trabecular compartment could be suggestive of the presence of tuberculosis in historic skeletal remains.

Interleukin-32 in Pathogenesis of Atopic Diseases: Proinflammatory or Anti-Inflammatory Role?

Atopic diseases, such as atopic dermatitis (AD), allergic asthma (AA), and allergic rhinitis (AR), are increasingly becoming a worldwide issue. This atopic triad originates at an early age and on a multifactorial basis, causing significant discomfort to susceptible individuals. The global case number is now reaching new highs, so exploring immune system regulation and its components is becoming critical. One cytokine, interleukin-32 (IL-32), is involved in inflammation and regulation of the immune system. It has nine isoforms that show varying degrees of expression, both intracellularly and extracellularly. IL-32 is secreted by immune cells, such as monocytes, macrophages, natural killer cells, and T cells, and by nonimmune cells, including fibroblasts, keratinocytes, and endothelial cells. Its production is regulated and augmented by microorganisms, mitogens, and other cytokines. Early studies demonstrated that IL-32 was an immune regulator that functioned to protect against inflammatory diseases, including AD, AA, and AR, and proposed a proinflammatory role for IL-32 in immune regulation and symptom exacerbation. However, several later reports suggested that IL-32 is downregulated in inflammatory diseases and exerts an anti-inflammatory effect. This review article focuses on recent findings regarding the detrimental and protective roles of IL-32 in development and management of inflammatory diseases. The exact role of IL-32 in AD, AA, and AR still remains to be elucidated. Future research should explore new avenues of IL-32 functionality in human inflammatory diseases.

Targeting TIGIT Inhibits Bladder Cancer Metastasis Through Suppressing IL-32

Bladder cancer is a highly metastatic tumor and one of the most common malignancies originating in the urinary tract. Despite the efficacy of immune checkpoints, including programmed cell death-1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), the effect of immunotherapy for bladder cancer remains unsatisfactory. Therefore, it is urgent to develop new targets to expand immunotherapeutic options. In this study, we utilized single-cell sequencing to explore the cell composition of tumors and detected a subset of Treg cells with high expression of T-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT) and interleukin (IL)-32. The antitumor immune response was suppressed by this subset of Treg cells, while IL-32 promoted bladder cancer metastasis. Nevertheless, targeting TIGIT not only reversed immunosuppression by restoring the antitumor immune response mediated by T cells but also suppressed the secretion of IL-32 and inhibited the metastasis of bladder cancer cells. Thus, our study provided novel insights into immunosuppression in bladder cancer and highlighted TIGIT as a novel target for immunotherapy of bladder cancer. We also illustrated the mechanism of the dual effect of targeting TIGIT and revealed the metastasis-promoting effect of IL-32 in bladder cancer. Collectively, these findings raise the possibility of utilizing TIGIT as a target against bladder cancer from the bench to the bedside.

Increased levels of interleukin-32 isoforms alpha, beta, gamma, and delta in the gingival crevicular fluid and plasma of the patients with periodontitis

BACKGROUND AND OBJECTIVE

Interleukin (IL)-32, which has been recently reported to be associated with periodontitis, has been suggested to have pleiotropic effect due to its 9 different isoforms. The aim of this study was to investigate the levels of IL-32α, IL-32β, IL-32γ, IL-32δ isoforms in gingival crevicular fluid (GCF) and plasma before and after non-surgical periodontal treatment in patients with periodontitis (P).

MATERIALS AND METHODS

Twenty-seven P and 27 periodontally healthy controls (C) were recruited in this study. Non-surgical periodontal treatment was performed to periodontitis patients. GCF and plasma sampling and clinical periodontal parameters were evaluated before and 1 month after treatment. Enzyme-linked immunosorbent assay was used to analyze the levels of IL-32α, IL-32β, IL-32γ, IL-32δ isoforms in GCF and plasma samples.

RESULTS

The levels of IL-32α, IL-32β, IL-32γ, and IL-32δ in plasma and GCF were significantly higher in patients with periodontitis than healthy controls (P < .001). In P group, plasma and GCF IL-32α, IL-32β, IL-32γ, and IL-32δ levels after non-surgical periodontal treatment were lower when compared to baseline (P < .001). Moreover, there was a positive correlation between GCF and plasma IL-32α, IL-32β, IL-32γ, and IL-32δ levels in all groups at baseline and after treatment (P < .05).

CONCLUSION

The study supported that there was a relationship between elevated levels of IL-32 isoforms and periodontitis. Also, our novel findings suggest that the pro-inflammatory role of IL-32 in the periodontitis may be originated from IL-32α, IL-32β, IL-32γ, and IL-32δ isoforms.

A correlative studies between osteoporosis and blood cell composition: Implications for auxiliary diagnosis of osteoporosis

Osteoporosis is defined as a metabolic skeletal disease characterized by a decrease of the bone mass per unit volume, caused by a variety of reasons. Increasing evidence indicate that the host inflammatory response was correlated with the occurrence and development of osteoporosis, and it has been recognized that T lymphocytes and B lymphocytes play a critical role in pathogenesis of inflammatory bone disease. Between January 2018 and December 2018, retrospective analysis of 487 patients (exclusion of patients with recent infections and hematologic disorders whose leukocyte counts or classifications are markedly abnormal) who underwent bone mineral density (BMD) examinations in Huzhou Central Hospital. The patients were divided into normal bone density group, osteopenia group, and osteoporosis group according to the T score of BMD in the left femoral neck, respectively. Statistics of the lymphocyte ratio and the monocyte ratio in the blood routine examination results during the same period were performed so as to make a comparison of the differences among the groups. The correlation of the lymphocyte ratio and monocyte ratio with the T score of BMD in the left femoral neck was also analyzed. The difference between neutrocyte ratio lymphocyte ratio and the monocyte ratio was statistically significant in both males and females among the normal bone density group, osteopenia group and osteoporosis group (P < .01 or P < .05). Inflammation plays an important role in the progression of osteoporosis. By monitoring these three indicators in blood routine examination, early intervention for osteoporosis may become possible.

Inhibition of IL-32 Expression Ameliorates Cerebral Ischemia-Reperfusion Injury via the NOD/MAPK/NF-κB Signaling Pathway

Cerebral ischemia represents a major cause of disability, yet its precise mechanism remains unknown. In addition, ischemia-reperfusion injury which occurs during the blood recovery process increases the risk of mortality, and is not adequately addressed with current treatment. To improve therapeutic options, it is important to explore the vital substances that play a pivotal role in ischemia-reperfusion injury. This study is the first to investigate the role of IL-32, a vital pro-inflammatory factor, in models of cerebral ischemia-reperfusion injury. The results showed that IL-32 was highly expressed in both in vivo and in vitro models. The proteins of the NOD/MAPK/NF-κB pathway were also up-regulated, indicating a potential signaling pathway mechanism. Inhibition of IL-32 and blocking of the NOD/MAPK/NF-κB pathway increased cell survival, decreased the level of inflammatory factors and inflammasomes, and attenuated nitrosative stress. Taken together, the results show that inhibition of IL-32 expression ameliorates cerebral ischemia-reperfusion injury via the NOD/MAPK/NF-κB signaling pathway. The findings in this study reveal that IL-32 is a vital target of ischemia-reperfusion injury, providing a new avenue for treatment development.

Expression of interleukin-32 in bone marrow of patients with myeloma and its prognostic significance

BACKGROUND

The guiding effect of prognostic stratification in multiple myeloma (MM) for treatment has been increasingly emphasized in recent years. The stratification of risk factors based on the International Staging System (ISS), Durie-Salmon (DS) staging and related indicators is affected by the renal function of patients, resulting in poor performance. This study assesses the relationship between interleukin-32 (IL-32) and related risk factors in 67 patients with MM and their clinical outcomes.

AIM

To investigate the feasibility of IL-32 in evaluating prognosis in patients with MM and the factors influencing prognosis.

METHODS

This was a pragmatic, prospective observational study of patients with MM at a single center. According to IL-32 level, patients were divided into two groups. The variables under consideration included age, blood β₂-microglobulin, albumin, C-reactive protein, serum calcium, serum creatinine, lactate dehydrogenase, M protein type, ISS stage, DS stage, and IL-32 levels and minimal residual disease (MRD) after induction treatment. The main outcomes were progression-free survival (PFS) and overall survival (OS).

RESULTS

IL-32 was an important factor affecting PFS and OS in patients with MM. Compared with patients with IL-32 levels ≥ 856.4 pg/mL, patients with IL-32 levels < 856.4 pg/mL had longer PFS (P = 0.0387) and OS (P = 0.0379); Univariate analysis showed that IL-32 level and MRD were significantly associated with OS and PFS (P < 0.05). Multivariate analysis showed that IL-32 levels ≥ 856.4 pg/mL and MRD positive were still independent risk factors for OS and PFS (P < 0.05).

CONCLUSION

IL-32 is valuable for assessing the prognosis of MM patients. IL-32 level combined with MRD may be a useful routine evaluation index for MM patients after treatment.

Structural Characteristics of Seven IL-32 Variants

IL-32 exists as seven mRNA transcripts that can translate into distinct individual IL-32 variants with specific protein domains. These translated protein domains of IL-32 variants code for specific functions that allow for interaction with different molecules intracellularly or extracellularly. The longest variant is IL-32γ possessing 234 amino acid residues with all 11 protein domains, while the shortest variant is IL-32α possessing 131 amino acid residues with three of the protein domains. The first domain exists in 6 variants except IL-32δ variant, which has a distinct translation initiation codon due to mRNA splicing. The last eleventh domain is common domain for all seven IL-32 variants. Numerous studies in different fields, such as inflammation, autoimmunity, pathogen infection, and cancer biology, have claimed the specific biological activity of individual IL-32 variant despite the absence of sufficient data. There are 4 additional IL-32 variants without proper transcripts. In this review, the structural characteristics of seven IL-32 transcripts are described based on the specific protein domains.