Beyond Autoantibodies: Identifying Clinically Relevant Biomarkers in Morphea

Morphea is a localized autoimmune sclerosing skin disorder marked by collagen overproduction and inflammation. Concurrent autoimmune conditions in patients with an autoimmune disease are frequently reported, reinforcing morphea's systemic immunologic context and the need for selective serologic evaluation [1]. In this case–control study, we consecutively included adult morphea patients between April and December 2024 and compared them with hospital employees without known autoimmune diseases. Individuals with zinc supplementation usage or chronic conditions affecting zinc levels were excluded. G*Power indicated detecting an effect size of 0.8 requires 35 participants per group. A total of 74 participants were included (39 cases and 35 controls). The mean age was 35.88 ± 9.13 years, with a female predominance, and no significant age or gender differences. In the case group, the mean age at disease onset was 29.28 ± 11.42 years. Plaque-type disease predominated (87.2%), followed by linear type (12.8%), with lesions most often on trunk (34%) and lower extremities (32%). Methotrexate was the most commonly used treatment (52.6%), followed by tofacitinib (31.6%) (Table 1). Biochemical analysis revealed significantly lower serum zinc levels in morphea patients compared with controls (78.46 ± 20.77 μg/dL vs. 90.71 ± 16.04 μg/dL; p < 0.001) and significantly higher anti-gliadin antibody titers (p = 0.002). Conversely, anti-TTG IgG levels were slightly higher among controls (p = 0.023). No significant between-group differences were observed in fasting blood sugar (FBS), HbA1C, C-reactive protein (CRP), ferritin, TSH, TPO-Ab, anti-TTG IgA, vitamin D, calcium, phosphorus, or hematologic indices (p > 0.05) (Table 2). No statistical associations were observed between laboratory markers and clinical scores (p > 0.05). Our finding of reduced serum zinc and elevated anti-gliadin antibodies in morphea suggests a possible metabolic and gut–skin component in pathogenesis and supports targeted investigation rather than broad, routine serologic evaluation. The slightly higher anti-tTG IgG levels observed in controls are not clinically meaningful, as isolated IgG elevations in adults usually reflect nonspecific reactivity rather than true gluten-related autoimmunity. Therefore, it does not contradict the higher anti-gliadin antibodies seen in morphea. Preclinical data show zinc-based interventions can modify fibrosis: biogenic zinc oxide nanoparticles reduced oxidative stress, improved tissue architecture, and attenuated established liver fibrosis in a murine model, indicating zinc pathways affect fibrogenesis and antioxidant defenses [2]. Separately, work on transglutaminase 2 (TGM2) in dermal fibrosis demonstrates that TGM2 is elevated in fibrotic skin; blocking TGM2 with a neutralizing antibody reduces collagen, CCN2, fibronectin, and α-SMA in patient fibroblasts, lowers active TGF-β/Smad signaling, and TGM2 knockout mice are protected from bleomycin-induced dermal fibrosis [3]. These findings suggest that metabolic factors may influence fibroblast activity and ECM remodeling, possibly involving the TGM2–TGF-β pathway; however, any gut–skin link remains speculative, and current data are plausibility-based rather than causal. Because disease-duration effects were not assessed, it remains uncertain whether reduced zinc levels precede morphea onset or arise with chronicity. The absence of association between morphea and antithyroid antibodies aligns with data showing limited benefit from thyroid and broad autoantibody screening [4, 5]. This study is limited by its single-center design, small sample size, and occupationally biased control group. Also, inflammatory and fibrotic cytokines were not assessed, limiting evaluation of whether zinc and gluten-related abnormalities reflect established profibrotic pathways. In conclusion, these findings support selective, indication-driven testing rather than broad serologic screening, while emphasizing that the observed zinc and anti-gliadin abnormalities are preliminary and not diagnostic of gluten-related disease. Future work should focus on tissue-level studies such as lesional zinc handling, TGM2 expression, and TGF-β activity to clarify whether these biochemical patterns reflect meaningful disease biology. Interventional approaches, including zinc repletion, should be considered only if consistent mechanistic links emerge. At present, gut–skin and metabolic interpretations remain exploratory and hypothesis-generating. Declaration of AI: We used Grammarly to edit the text grammatically and correct writing errors and Gemini to shorten some parts. We did not use any AI to write the text or data analysis. The authors have nothing to report. This study has been approved by the ethics institutional review board of Tehran University of Medical Sciences, Tehran, Iran. (IR.TUMS.MEDICINE.REC.1403.250). The written informed consent was obtained from the patients. The authors declare no conflicts of interest. The data that support the findings of this study are available from the corresponding author upon reasonable request.