Stable infiltration of myeloid cells, especially tumor-associated M2 macrophages, acts as one of the essential features of the tumor immune microenvironment by promoting the malignant progression of hepatocellular carcinoma (HCC). However, the factors affecting the infiltration of M2 macrophages are not fully understood. In this study, we found the molecular subtypes of HCC with the worst prognosis are characterized by immune disorders dominated by myeloid cell infiltration. Myeloid cell nuclear differentiation antigen (MNDA) was significantly elevated in the most aggressive subtype and exhibited a positively correlation with M2 infiltration and HCC metastasis. Moreover, MNDA functioned as an independent prognostic predictor and has a good synergistic effect with some existing prognostic clinical indicators. We further confirmed that MNDA was primarily expressed in tumor M2 macrophages and contributed to the enhancement of its polarization by upregulating the expression of the M2 polarization enhancers. Furthermore, MNDA could drive the secretion of M2 macrophage-derived pro-metastasis proteins to accelerate HCC cells metastasis both in vivo and in vitro. In summary, MNDA exerts a protumor role by promoting M2 macrophages polarization and HCC metastasis, and can serve as a potential biomarker and therapeutic target for HCC.

Inflammation control is critical during the innate immune response. Such response is triggered by the detection of molecules originating from pathogens or damaged host cells by pattern-recognition receptors (PRRs). PRRs subsequently initiate intra-cellular signalling through different pathways, resulting in i) the production of inflammatory cytokines, including type I interferon (IFN), and ii) the initiation of a cascade of events that promote both immediate host responses as well as adaptive immune responses. All human PYRIN and HIN-200 domains (PYHIN) protein family members were initially proposed to be PRRs, although this view has been challenged by reports that revealed their impact on other cellular mechanisms. Of relevance here, the human PYHIN factor myeloid nuclear differentiation antigen (MNDA) has recently been shown to directly control the transcription of genes encoding factors that regulate programmed cell death and inflammation. While MNDA is mainly found in the nucleus of leukocytes of both myeloid (neutrophils and monocytes) and lymphoid (B-cell) origin, its subcellular localization has been shown to be modulated in response to genotoxic agents that induce apoptosis and by bacterial constituents, mediators of inflammation. Prior studies have noted the importance of MNDA as a marker for certain forms of lymphoma, and as a clinical prognostic factor for hematopoietic diseases characterized by defective regulation of apoptosis. Abnormal expression of MNDA has also been associated with altered levels of cytokines and other inflammatory mediators. Refining our comprehension of the regulatory mechanisms governing the expression of MNDA and other PYHIN proteins, as well as enhancing our definition of their molecular functions, could significantly influence the management and treatment strategies of numerous human diseases. Here, we review the current state of knowledge regarding PYHIN proteins and their role in innate and adaptive immune responses. Emphasis will be placed on the regulation, function, and relevance of MNDA expression in the control of gene transcription and RNA stability during cell death and inflammation.

OBJECTIVE: MNDA (myeloid nuclear differentiation antigen) has been considered as a potential diagnostic marker for marginal zone lymphoma (MZL), but its utility in distinguishing MZL from other B-cell non-Hodgkin lymphomas (B-NHLs) and its clinicopathologic relevance in diffuse large B-cell lymphoma (DLBCL) are ambiguous. We comprehensively investigated MNDA expression in a large series of B-NHLs and evaluated its diagnostic value.
METHODS: MNDA expression in a cohort of 1293 cases of B-NHLs and 338  cases of reactive lymphoid hyperplasia (RLH) was determined using immunohistochemistry and compared among different types of B-NHL. The clinicopathologic relevance of MNDA in DLBCL was investigated.
RESULTS: MNDA was highly expressed in MZLs (437/663, 65.9%), compared with the confined staining in marginal zone B-cells in RLH; whereas neoplastic cells with plasmacytic differentiation lost MNDA expression. MNDA expression was significantly higher in mantle cell lymphoma (MCL, 79.6%, p = 0.006), whereas lower in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL, 44.8%, p = 0.001) and lymphoplasmacytic lymphoma (LPL, 25%, p = 0.016), and dramatically lower in follicular lymphoma (FL, 5.2%, p < 0.001), compared with MZL. 29.6% (63/213) of DLBCLs were positive for MNDA. The cases in non-GCB group exhibited a higher rate of MNDA positivity (39.8%) compared to those in GCB group (16.3%) (p < 0.001), and MNDA staining was more frequently observed in DLBCLs with BCL2/MYC double-expression (50%) than those without BCL2/MYC double-expression (24.8%) (p = 0.001). Furthermore, there was a significant correlation between MNDA and CD5 expression in DLBCL (p = 0.036).
CONCLUSIONS: MNDA was highly expressed in MZL with a potential utility in differential diagnosis between MZL and RLH as well as FL, whereas its value in distinguishing MZL from MCL, CLL/SLL is limited. In addition, MNDA expression in DLBCL was more frequently seen in the non-GCB group and the BCL2/MYC double-expression group, and demonstrated a correlation with CD5, which deserves further investigation. The clinical relevance of MNDA and its correlation with the prognosis of these lymphomas also warrant to be fully elucidated.

It is difficult to histologically differentiate extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) from chronic gastritis (CG)/ reactive lymphoid hyperplasia (RLH). To determine whether immunohistochemistry for IRTA1 and MNDA can differentiate gastric MALT lymphoma from CG/RLH, we investigated 81 stomach biopsy specimens [Wotherspoon grade (WG) 1, 11 cases; WG 2, 9 cases; WG 3, 20 cases; WG 4, 31 cases; and WG 5, 10 cases]. According to a previously reported algorithm involving PCR for immunoglobulin heavy (IgH) chain locus rearrangement, all 81 cases were divided into three groups: CG/RLH (55 cases), MALT lymphoma (19 cases) groups, and IgH undetectable group (7 cases). We analyzed the CG/RLH and MALT lymphoma groups. The median percentage of IRTA1-positive cells was 0% (range 0%-90.6%) in the CG/RLH group and 43.5% (range 0%-97.6%) in the MALT lymphoma group (p < 0.0001). The median percentage of MNDA-positive cells was 32.4% (range 0%-97.6%) in the CG/RLH group and 55.1% (range 0%-97.6%) in the MALT lymphoma group (p = 0.0044). These results indicate that immunohistochemistry for IRTA1 and MNDA can help differentiate gastric MALT lymphoma from CG/RLH.

The differential diagnosis between lymphoplasmacytic lymphoma (LPL) and marginal zone B-cell lymphoma, particularly splenic type (SMZL), can be challenging on onset of bone marrow biopsy (BMB) since morphology and phenotype are not specific and clinical features can overlap or be mildly developed at diagnosis. The LPL-specific L265P mutation in the MYD88 gene is not available in all laboratories, and genetic aberrancies identified in SMZL (del7q, mutations of NOTCH2 and KLF2) are seldom searched in routine practice. The study aim is to investigate the potential role of myeloid nuclear differentiation antigen (MNDA) expression in this specific differential diagnosis. We report MNDA reactivity in 559 patients with small B-cell lymphoma including bone marrow biopsies from 90 LPL and 91 SMZL cases. MYD88 p.Leu265Pro mutation status was assessed and confirmed as positive in 24 of 90 LPL cases, which served as the test set. MNDA staining was negative in 23 of 24 LPL cases in the test set (96%). In the 157 remaining cases (66 LPL, 91 SMZL), which served as the validation set, the MYD88 p.Leu265Pro mutation was unavailable and MNDA was more frequently expressed in SMZL (p < 0.00001). In addition, immunohistochemical features more consistent with SMZL (i.e., presence of CD23+ follicular dendritic cell meshworks, polytypic plasma cells, DBA44 reactivity) were more often present in MNDA-positive cases (statistically significant for 2 such parameters). On the widest case series so far published focusing on LPL and SMZL immunohistochemical diagnosis at onset of BMB, we demonstrated that MNDA expression significantly support the diagnosis of SMZL. This observation may be of particular help in cases where the MYD88 p.Leu265Pro mutational status and/or SMZL-related genetic aberrations are unavailable.

UNASSIGNED: Clinical and pathological differential diagnosis of small B-cell lymphomas (SBCLs) is still controversial and may create difficulty with their overlapping morphology, phenotype, differentiation to plasma cells. We aimed to examine the expression of the markers ımmune receptor translocation -associated protein 1 (IRTA1), myeloid cell nuclear differentiation antigen (MNDA), lymphoid enhancer-binding factor-1 (LEF1) and stathmin1 in SBCL cases involving different sites which may have plasma cell differentiation.
UNASSIGNED: We studied 154 involved tissue samples, from 116 patients and evaluated the staining distribution of the markers. The expressions were evaluated on 21 chronic lymphocytic leukemia/ lymphoma (CLL/SLL), 7 follicular lymphoma (FL), 14 nodal marginal zone lymphoma (NMZL), 17 extranodal marginal zone lymphoma (ENMZL), 55 splenic marginal zone lymphoma (SMZL), 22 marginal zone lymphoma -not otherwise specified (MZL-NOS) and 18 lymphoplasmacytic lymphoma/Waldenström\'s macroglobulinemia (LPL/WS) cases by immunohistochemistry.
UNASSIGNED: The results confirmed that LEF1 was the most sensitive and specific markers for CLL/SLL and Stathmin for FL (p <0.001). MNDA and IRTA1 were useful markers to distinguish marginal zone lymphomas.
UNASSIGNED: Our results suggest LEF 1 for CLL/SLL and Stathmin for FL are reliable markers. LEF1, MNDA, Stathmin1 and IRTA1 are helpful with other routinely used immunohistochemical markers in a diagnostic algorithm considering their limitations.

BACKGROUND: It has been proposed that primary cutaneous marginal zone lymphomas (PCMZLs) include a MALT-lymphoma-like IgM+ subset and a class-switched subset, which is unlike most other MALT lymphomas. Whether expression of the MALT lymphoma-associated biomarkers IRTA1 and MNDA would support this concept and whether they might help explain why some patients have both subtypes is uncertain.
METHODS: Twenty-five PCMZLs from 21 patients were stained for IRTA1 by in situ hybridization and for MNDA by immunohistochemistry. In two patients, polymerase chain reaction (PCR)-based B-cell clonality studies were performed on biopsy specimens of metachronous lesions, which expressed different heavy chains. All results were correlated with the histopathologic and clinical findings.
RESULTS: Five of six IgM+ PCMZLs were IRTA1+ vs three of 18 evaluable class-switched cases (P = 0.0069). Two of the class-switched IRTA1+ cases were in patients with clonally-related IRTA1+ IgM+ PCMZLs. IRTA1 positivity showed a statistically significant correlation with several MALT-lymphoma-associated histopathologic findings. In contrast, all PCMZL cases showed at least some MNDA expression with no differences between IgM+ and class-switched cases.
CONCLUSIONS: IRTA1 identifies MALT-lymphoma-like PCMZLs that are largely but not exclusively IgM+. This supports the concept of two PCMZL subsets but suggests their distinction should not be based solely on their heavy chain expression.

The diagnosis of marginal zone lymphomas (MZL) is challenged by the lack of specific markers that distinguish them from other low-grade non-Hodgkin B-cell lymphomas. Myeloid cell nuclear differentiation antigen (MNDA) is a nuclear protein that labels myelomonocytic cells as well as B lymphocytes that localize to the marginal zone areas of splenic white pulp. We evaluated MNDA expression in a large series of B-cell lymphomas to assess the sensitivity and specificity of this antigen for the characterization of MZL. A total of 440 tissue sections containing extramedullary B-cell lymphomas and 216 bone marrow biopsies containing atypical or neoplastic lymphoid infiltrates were stained for MNDA by immunohistochemistry. Among the extramedullary lymphoma cases, approximately 67% of nodal MZL, 61% of extranodal MZL, and 24% of splenic MZL expressed MNDA. MNDA was also infrequently expressed in other B-cell neoplasms including mantle cell lymphoma (6%), chronic lymphocytic leukemia/small lymphocytic lymphoma (13%), follicular lymphoma (FL) (4%), lymphoplasmacytic lymphoma (25%), and diffuse large B-cell lymphoma (3%). In contrast, MNDA was only expressed in 2.3% of all bone marrow biopsies involved by lymphoid infiltrates, including 2 cases of FL and one case of MZL. Collectively, these data support the inclusion of MNDA in the diagnostic evaluation of extramedullary B-cell lymphomas, particularly those in which the differential diagnosis is between low-grade FL and MZL.

Sepsis and septic shock are characterized by prolonged inflammation and delayed resolution, which are associated with suppression of neutrophil apoptosis. The role of the intrinsic apoptotic pathway and intracellular factors in regulation of neutrophil apoptosis remain incompletely understood. We previously reported that the nuclear factor MNDA (myeloid nuclear differentiation antigen) is fundamental to execution of the constitutive neutrophil death program. During neutrophil apoptosis MNDA is cleaved by caspases and relocated to the cytoplasm. However, when challenged with known mediators of sepsis, human neutrophils of healthy donors or neutrophils from patients with sepsis exhibited impaired MNDA relocation/cleavage parallel with myeloid cell leukemia-1 (MCL-1) accumulation and suppression of apoptosis. MNDA knockdown in a model cell line indicated that upon induction of apoptosis, MNDA promotes proteasomal degradation of MCL-1, thereby aggravating mitochondrial dysfunction. Thus, MNDA is central to a novel nucleus-mitochondrion circuit that promotes progression of apoptosis. Disruption of this circuit contributes to neutrophil longevity, thereby identifying MNDA as a potential therapeutic target in sepsis and other inflammatory pathologies.